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Emissions Policy Renewables

The capacity factor of wind

Guest Post by John Morgan. John is Chief Scientist at a Sydney startup developing smart grid and grid scale energy storage technologies.  You can follow John on twitter at @JohnDPMorgan.

A lot of ink is spilled on wind intermittency, and not necessarily based in data.  So I have extracted and analyzed a high resolution dataset of a year’s worth of Australian wind power for a number of interesting properties.  I previously wrote about the capacity factor as a limit to the share of electricity that wind and solar can acquire, so I also ask how wind capacity factor changes with time, place and season.  In particular, how does it change during sunlight hours and what does it mean for the capacity factor limit on renewable energy penetration?

Australian wind fleet data

The Australian Energy Market Operator (AEMO) publishes data on all generators connected to the National Electricity Market (NEM) grid, which covers the eastern states including Tasmania, but excludes Western Australia and the Northern Territory.  The data includes power generation every five minutes for every generator for the last year, their capacities as registered with the grid operator, and more.  It is not very accessible, being in the form of thousands of SCADA data files, many of which contain errors.  But with a bit of work the data can be extracted.  Here, for instance, is the output of all grid-connected wind farms at five minute resolution over one year:

Wind capacity factor

Here is the top level summary of the Australian wind farm fleet over the last year:

The nameplate capacity is the total capacity of all wind farms – 3753 MW.  But the whole fleet only manages 3238 MW at peak.The whole is less than the sum of its parts – half a gigawatt less in this case. Why is this?

The fleet is comprised of wind farms distributed over a large area of eastern Australia.  To achieve maximum theoretical power the wind would have to be blowing at the optimum speed for each wind farm, at all wind farms, simultaneously.  This is a statistical improbability and quite possibly a hydrodynamic impossibility, as it would require a high velocity correlated flow field over very large distances.

So while we often hear that the wind is always blowing somewhere, it is equally true that it is always not blowing somewhere else, and the fleet output never achieves full capacity.  Australia in theory has 3753 MW of wind capacity, but this will never be realized in practice.  Similarly, statements like: “The US added x GW of wind capacity last year”, overstate the capacity addition because the new wind build is unlikely to ever produce its maximum power in full correlation with the rest of the fleet.

In other words, national capacity statistics overstate the potential output of wind.  The flip side of this is that the capacity factor limit underestimates the potential for wind penetration.  We can push the penetration of wind a bit higher than the capacity factor – generation would start to exceed demand at 33% share, rather than 29% share.

Wind correlation times and the synoptic scale

Over what distances are wind farm outputs correlated?  Its actually easier to ask, over what period in time is wind power correlated?  This information is contained in the wind power autocorrelation function, which we can calculate from the dataset:

The autocorrelation function tells us how long the influence of a particular state of wind persists.  If its windy now, for how long will it remain windy?  Surely for the next five minutes.  But will it still be windy tomorrow?  The autocorrelation function is a “memory” function that tells us how long wind “remembers” how hard it was blowing.

The autocorrelation function decays in about 40 hours (since we have 5 minute data the x-axis is in units of 5 minute “lag”s).  This means wind, on average, bears no relation to its output 40 or more hours ago.  Wind has a “correlation time” of about 40 hours.

Its interesting to interpret this as the time for a body of moving air to pass over a windfarm.  If we knew how fast it was moving we’d know how big it was.  Wind resource maps suggest a velocity of about 7-8 ms-1, so that interpretation suggests a wind correlation distance of about 1200 km – the “synoptic scale”.  This seems a pretty reasonable estimate of the size of weather systems and can in fact be done for a single wind farm with a similar result.  Its remarkable to be able to pull large scale geographic information out of just the power fluctuations of a single wind farm!

http://www.seabreeze.com.au/Photos/View/2871107/Weather/Australia-wind-energy-map/

If we wanted to cover intermittency we would need to ensure our wind fleet is dispersed over distances of 1200 km and more, so that the output of at least some of its wind farms will be uncorrelated.  This smooths the output of the wind fleet, reducing maximum output below the nameplate capacity, but increasing the amount of energy that can be integrated without having to spill, store or manage excess generation.

Wind power ramp rates

Wind output is constantly changing and requires the rest of the grid to be flexible enough to ramp up power or shed load to balance wind fluctuation.  This rate of change is just the time derivative of wind power.  The plot below shows this “acceleration rate” throughout the year.  It’s a normal distribution, the symmetry showing that wind power picks up as fast as it drops off, and that the grid needs to be responsive at a rate of 20 MW per minute, in both directions, to cover most conditions.

As more wind is added, the flexibility of the rest of the grid will have to increase proportionately – double the wind energy would require about 40 MW/min ramp rate.  But this additional ramping ability must be delivered by the shrinking dispatcheable generator sector.  So the intrinsic flexibility of the rest of the grid must increase, and faster than in simple proportion to wind penetration.  Practically that means increasingly strong pressure to shift from coal generation to gas as wind share grows.

Low wind days

Lets look at the distribution of low wind days.  We can ask, for how many days was wind output below some level?  For instance, we can find 29 days in which output was below 10% of capacity, and 127 days below 20% capacity.  127 days is, incidentally, pretty close to the number of weekends and annual leave of most Australians – Australian wind is obviously governed by Australian workplace awards!

The plot below shows the number of days below a particular output level.  Interestingly, the daily average power output never exceeded 75% of capacity, or 2810 MW, almost 1 gigawatt less than installed.  The fleet was never totally becalmed, but the lowest recorded day in the year saw output of just 2.7%.

Also of interest is the number of consecutive low wind days.  This affects the strategies we might use to cover wind outages – whether we store energy in batteries, or with pumped hydroelectricity, or shed load, cut in gas generators, or coal.  For instance, of the 29 days of wind output below 10% of capacity, 15 are single isolated low wind days, and then there are 7 pairs of 2 day long low wind runs.  If we look for sequences of days with less than 20% output, we find 2 runs of 5 low wind days.  The full distribution is shown below.

The number and distribution of low wind days show that while wind contributes energy, it does not provide capacity.  Alternative generation capacity must be available to meet the near absence of wind about one day in ten, and for two or more days in sequence.  But many of these low wind events are of just a single day duration.  This is a difficult timescale for coal plants, so again, increasing wind penetration drives the residual mix towards gas.

Wind capacity factor by month and day

To get a handle on wind seasonality we can look at monthly output and capacity factors.  Each point in the plot below is the average power output for a day in the year.  The coloured blobs show the distribution of power output in each month.  Also shown is the capacity factor for each month.

The nameplate capacity factor varies from month to month (30%±5% covers it). Every month has low wind days and high wind days and everything in between with little seasonal structure.  The winter months have more high wind days, but they also have more low wind days, and one cannot confidently assert the monthly CF variation is greater than noise, in this year.

We can see this in a box plot of daily capacity factor – the data distribution is very wide and a capacity factor of 25% is consistent with the data for every month.  The highest daily capacity factor for the whole fleet was 75%, and the lowest was 2.7%.  These maximum and minimum output days both occurred in winter, when solar power is at a minimum.

Wind capacity factor by hour

We can push this through to a still finer grain by looking at wind output by hour of the day.  The following plot shows the average capacity factor by hour of the day, for each month.  We can see if wind picks up or drops off in any consistent way through the course of a day.  The summer months show some daily pattern, perhaps, but the rest of the year does not:

Does the wind output drop when the sun is shining?  It would be convenient if it did, as it would allow more solar  power on the grid.  Lets nominate solar hours as 10 am – 4 pm, and compare solar hours with non-solar hours.

There is no difference between wind capacity factor when the sun is high in the sky and when it is not.  Wind does not cooperate with solar by subsiding in the middle of the day.  Possibly wind blows harder when clouds block sunlight.  Unfortunately I don’t have a dataset for solar PV output and can’t test this.  My guess is that the number of days and the number of sites at which such anticorrelation occurs is not large enough to shift the average output of the total fleet enough to change the overall picture.

What does this mean for the capacity factor threshold?

As explained in detail by Jenkins and Trembath, it is increasingly difficult to build more wind or solar capacity as their market share approaches their capacity factor (CF) because they will then, at times, be producing energy in excess of demand.  The economic drag incurred by dealing with surplus generation by storage, curtailment or demand reduction undermines the economics of building additional capacity.  The capacity of wind and solar is thus limited to be roughly numerically equal to 100% of grid demand.

In “Less than the sum of its parts” I argued that adding solar to the mix actually reduces the combined amount of wind and solar energy that can be added to the grid.  This is because solar competes with wind for share of capacity, but contributes less actual energy due to its lower capacity factor.  Building solar thus reduces the maximum amount of renewable energy we can get onto the grid.

You can get around this if wind and solar generate at different times of the day, or year.  But from the data above we can say that wind does not drop during the day or pick up at night, to any significant degree.  The capacity factor of wind during “solar” hours is the same as during “non-solar” hours.

Turning to the seasonal variation, its possible wind has a higher capacity factor in winter when solar output is low, but the evidence of the last year is not compelling.  The lowest wind capacity factor in the year was actually in the winter month of June, and January in high summer was one of the higher producing wind months.  The winter months have more high wind days, but they also have more low wind days.

If there is some seasonal synergy between wind and solar, its not particularly strong, and the contention that the maximum share of renewable energy is achieved by building wind and not solar seems sound.

But the capacity factor threshold does require an adjustment.  Recall the peak wind output was only 3238 MW, less than the nameplate capacity of 3753 MW.  So we could build more capacity without fear of excess generation.  Instead of spillage or storage being required at 29% wind share, we can accommodate a more generous 33% share.  This greater share of wind energy is possible due to the geographic distribution of wind smoothing out some of the peaks.

Conclusions

There’s a lot of information in noise.  Deducing the size of large scale weather systems from the power fluctuations is pretty cool, as is seeing the signature of spatial distribution of wind farms in a one-dimensional time series.  Notably, a national wind fleet will not achieve full output due to geographical smoothing, but this smoothing also increases the capacity factor threshold for wind share a bit, from about 29% to 33%.

As expected, intermittency means wind contributes energy but not capacity to the grid, meaning wind acts as a fuel saver for fossil plants, which must increasingly shift to gas rather than coal as wind penetration grows, to accommodate higher ramp rates.

The capacity factor does not show strong consistent variation across hours, days or months, and share of renewable energy is limited as Jenkins and Trembath describe.  There is little evidence of a synergy between wind and solar in the Australian grid, supporting my earlier conclusion that a combination of wind and solar can displace less fossil energy than wind alone.  If we really wanted to push towards maximum renewable energy, we would build wind and not solar, and variable renewables share could grow to about 33%.

Data

The Australian Energy Market Operator Generation and Load data can be found at this page.

Five minute data for all generators can be extracted by parsing the SCADA data files in this directory.  Data goes back a little over a year.  Older data is not available – AEMO appear to delete the oldest files on this page on a daily basis.

AEMO lists all generators connected to the grid, by technology here, in the spreadsheet “Registration and Exemption List”, in the tab “generators and Scheduled Loads”.  Each generator has a unique identifier, the DUID, allowing it to be located in the SCADA files.

The SCADA files contain a number of errors – in many files the output of many generators is double counted.  A corrected data set was created by filtering out duplicate generator entries.

The data was extracted and analysed with python code using the excellent SciPy scientific python tools, iPython notebook, pandas data analysis library, with MatPlotLib and Seaborn data visualization libraries for plotting.

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

363 replies on “The capacity factor of wind”

To Peter Lang.
The nuclear costs are already double wind +storage so it doesn’t matter whether storage and decommissioning are zero. However the indications from the few plants that are being decommissioned around the world is that the industry supplied estimates of $300-$500m per plant will be woefully inadequate.

To Tony Carden: Roam consulting found in 2012 in a report for AEMO hundreds of sites throughout the NEM suitable for pumped hydro, restricting them to 500MW+ …….. 68 total schemes have been identified, with an assumed capacity of 500 MW each. If all these schemes are built, the installed capacity of new pumped storage would be 34 GW……..

As I have said all along a sensible policy will include thermal storage and load shifting + existing hydro and 1-5GW of batteries, primarily used for grid optimisation but available for backup. In reality, for the next 30 years at least, there will be some residual gas which may only have 5-10% utilisation so supplying perhaps 2-5% of the annual demand but dramatically reducing the investment in new generation .

In addition, according to the BOM there is always wind on very hot peak demand days so there will be some wind. Taking all these factors into account you probably only have to build 15 to 18 GW of storage.

Of coarse most of these measures can be applied to reduce the amount of nuclear required as well but the ratio of cost of nuclear to cost of wind will not change a lot

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Peter Farley,

The nuclear costs are already double wind +storage so it doesn’t matter whether storage and decommissioning are zero.

That is so far from the reality it’s unbelievable. Even with an ideal storage site on El Hierro island wind and storage are not viable. You do need to challenge your beliefs. Do common sense reality checks. If the incentives were removed, there’d be no more wind and solar.

To make significant cuts to global GHG emissions, the world needs a substitute for fossil fuels. Renewables cannot do much. The facts are that renewables cannot meet the requirements (read the links posted in previous comments). They cannot supply more than a small proportion of global electricity, let alone of global energy, let alone future demand as it continues to increase. But nuclear can.

The fact you frequently confuse power and energy and miswrite units demonstrates you do not understanding the subject. I’d suggest you read the links I and others have posted, understand them and then ask questions.

I fully recognise that nuclear is not financially viable in Australia at current prices. But neither is wind or solar (or energy storage at the capacity that would be required to enable these technologies to meet requirements). If we mandated and subsidised nuclear to the same extent that applies to wind and solar, nuclear would be much cheaper (on a properly comparable basis). The LCOE of generation plus grid show clearly that nuclear is a much cheaper option than wind and solar (plus backup and/or storage) at the levels of penetration that would be needed to make a substantial reduction in GHG emissions (see the cost of generation for different proportions of technologies in the CSIRO calculators I linked – I compared five scenarios here: http://forum.onlineopinion.com.au/thread.asp?article=17320#306282 ; add grid costs from the OECD study or Nicholson’s and Brook’s condensed version (linked in an earlier comment). Clearly, nuclear is much cheaper than renewables – and that’s using optimistic learning rates for renewables and no learning rate for nuclear.

Add the risk that renewables cannot do the job by 2050. I estimated that risk to be $54/MWh based on applying the social cost of carbon to the probable undelivered GHG emission reductions.

Even at the high cost of nuclear in the developed countries, nuclear is still by far the least cost way to make major reduction in GHG emissions intensity of electricity. I’ve provided links to authoritative sources in previous comments. You didn’t respond to them.

Furthermore, you have totally misunderstood the ROAM Consulting desk study into potential pumped hydro sites. Probably none of them are viable. If they were we’d have been building them long ago.

Your comments demonstrate you have little understanding of the subject; that together with the fact you won’t listen, won’t read links provided and don’t acknowledge when you have misunderstood, means it’s a waste of time trying to explain anything to you.

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Thank you foe that reference Peter Lang. It is as I expected another example of Peter Farley not understanding what he has read. As this discussion seems to me to be going off topic I will be reverting to OT 23 unless someone posts some in formation specifically about the capacity factor of wind.

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Nuclear better than renewables

Nuclear power is better than renewable energy in all the important criteria. Renewable energy cannot be justified, on a rational basis, to be a major component of the electricity system. Here are some reasons why:

Nuclear power has proven it can supply over 75% of the electricity in a large modern industrial economy, i.e. France, and has been doing so for over 30 years.
Nuclear power is substantially cheaper than renewables
Nuclear power is the safest way to generate electricity; it causes the least fatalities per unit of electricity supplied.
Nuclear power has less environmental impact than renewables.
ERoEI of Gen 3 nuclear is ~75 whereas renewables are around 1 to 9. An ERoEI of around 7 to 14 is needed to support modern society. Only Nuclear, fossil fuels and hydro meet that requirement.
Material requirements per unit of electricity supplied through life for nuclear power are about 1/10th those of renewables
Land area required for nuclear power is very much less than renewables per unit of electricity supplied through life
Nuclear power requires less expensive transmission (shorter distances and smaller transmission capacity in total because the capacity needs to be sufficient for maximum output but intermittent renewables average around 10% to 40% capacity factor whereas nuclear averages around 80% to 90%).
Nuclear fuel is effectively unlimited.
Nuclear fuel requires a minimal amount of space for storage. Many years of nuclear fuel supply can be stored in a warehouse. This has two major benefits:

• Energy security – it means countries can store many years of fuel at little cost, so it gives independence from fuel imports. This gives energy security from economic disruptions or military conflicts.

• Reduced transport – nuclear fuel requires 20,000 to 2 million times less ships, railways, trains, ports, pipelines etc. per unit of energy transported. This reduces shipping costs, the quantities of oil used for the transport, and the environmental impacts of the shipping and the fuel used for transport by 4 to 6 orders of magnitude.

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2.1 Nuclear cheaper and lower emissions than renewables
Renewables v Nuclear: Electricity Bills and Emissions reductions by technology proportions to 2050

The CSIRO ‘MyPower’ calculator shows that, even in Australia where we have cheap, high quality coal close to the main population centres and where nuclear power is strongly opposed, nuclear power would be the cheapest way to reduce emissions: http://www.csiro.au/Outcomes/Energy/MyPower.aspx

MyPower is an online tool created by CSIRO that allows you to see the effect of changing the national ‘electricity mix’ (technologies that generate Australia’s electricity) on future electricity costs and Australia’s carbon emissions.

Below is a comparison of options with different proportions of electricity generation technologies (move the sliders to change the proportions of each technology). The results below show the change in real electricity prices and CO2 emissions in 2050 compared with now.

Change to 2050 in electricity price and emissions by technology mix:

80% coal, 10% gas, 10% renewables, 0% nuclear:
electricity bills increase = 15% and emissions increase = 21%
0% coal, 50% gas, 50% renewables, 0% nuclear:
electricity bills increase = 19% and emissions decrease = 62%.
0% coal, 30% gas, 10% renewables, 60% nuclear:
electricity bills increase = 15% and emissions decrease = 77%.
0% coal, 20% gas, 10% renewables, 70% nuclear:
electricity bills increase = 17% and emissions decrease = 84%.
0% coal, 10% gas, 10% renewables, 80% nuclear:
electricity bills increase = 20% and emissions decrease = 91%.

Source: CSIRO ‘MyPower’ calculator

Points to note:

• For the same real cost increase to 2050 (i.e. 15%), BAU gives a 21% increase in emissions c.f. the nuclear option a 77% decrease in emissions (compare scenarios 1 and 3)

• For a ~20% real cost increase, the renewables option gives 62% decrease c.f. nuclear 91% decrease in emissions (compare scenarios 2 and 5).

• These costs do not include the additional transmission and grid costs. If they did, the cost of renewables would be substantially higher.

3. Conclusion:

Nuclear is the least cost way to significantly reduce the emissions intensity of electricity.

The difference is stark. Nuclear power is far better.

But progress to reduce emissions at least cost is being thwarted by the anti-nuclear activists.

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It looks as though the UK is becoming concerned with the high grid costs imposed by low capacity, intermittent generators like wind.

The UK Secretary of State for Energy and Climate Change, Amber Rudd sets out a new direction for UK energy policy.
https://www.gov.uk/government/speeches/amber-rudds-speech-on-a-new-direction-for-uk-energy-policy

She says; “In the same way generators should pay the cost of pollution, we also want intermittent generators to be responsible for the pressures they add to the system when the wind does not blow or the sun does not shine.”

This direction may explain the interest in developing the pumped storage potential in the UK.

The Quarry Battery Company (QBC) carried out a UK-wide geographical survey that identified suitable sites with low planning risk for some 15 GW of new pumped storage capacity.
http://www.powerengineeringint.com/articles/2015/11/pumped-storage-project-developers-aim-to-boost-capacity.html

Rudd also quotes David McKay; “Climate change is a big problem, it needs big technologies. As the former Chief Scientist at DECC, David Mackay, said: “If everyone does a little, we’ll achieve only a little. We must do a lot. What’s required are big changes.”

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Tom Bond,

Thank you for the link. Unfortunately, it doesn’t give the important figure, i.e. the energy storage capacity (in GWh). It gives the cost at $244 million for 99.9 MW, say $2.5/W. That could supply about 20% capacity factor if powered by reliable baseload power at night but very much less (probably less than 10% on average) idf powered by intermittent renewables (the ideal El Heirro pumped storage facility powered by wind power shows the very low capacity factors achieved in practice).

At 20% capacity factor the cost per average power delivered would be $2.5/20% = $12.50/W.
At 10% capacity factor the cost per average power delivered would be $2.5/10% = $25/W.
Add that to the cost of wind at say $2/W at 20% capacity factor sent to storage (note you’d need enormous overbuild before this could be achieved from excess wind power) = $10/W
Wind + storage = $10/W +$25/W = $35/W

Compare the new plants being built in UAE: 5,400 MW for $20 billion (all up project capital cost) = $3.7/W at 85% capacity factor = $4.36/W

This very simple cost comparison shows wind + storage is around seven times more costly than nuclear to provide reliable power ( $35/W versus $4.36/).

It’s actually much worse than these figures show because:
1. the amount of storage capacity available in quarries is negligible, so next to useless for storage energy from intermittent renewables

Enormous over build of wind would be required before you’d get sufficient excess energy generated by wind to achieve 20% capacity factor from stored energy from wind generation (i.e. at 75% pumped storage round trip efficiency would require about 27% excess capacity factor from wind).
By the time wind is at sufficiently high penetration to produce an excess generation of 27% capacity factor, the CO2 abatement effectiveness of wind would be down to very low because fossil fuels back up is still required or you’d have to turn the whol of England into quarries (look at what’s happening on El Hierro Island – they are having to use the diesel generators to pump water – how ridiculous is that?).
Add the grid costs
Add the expected monetary value of the risks that intermittent renewables cannot meet requirements by 2050.

This is a quick post, so could contain significant errors, but the general message is correct. Storage cannot make intermittent renewables viable.

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Hey Tom,
You are pinching my references. I had already posted this one in OT23. I have just also posted another reference from The Washington Post

Thank you very much though for the reference to the pumped storage report. I notice with interest your comment re low planning risk.

I believe apart from economics, the biggest issue in Australia for pumped storage will be planning approval if the mood of the electorate is the same as it was for the Franklin Gorge and Traveston Dam projects. Mind you Nuclear is going to face a bigger challenge in this area though.

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Tony sorry about that, I found this reference and thought it may be of interest to BNC readers, I had not noticed your post in OT.

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No problems Tom, I posted some references on this thread and got a slap on the wrist for being off topic so I have been very careful where I put my posts since.

Regards Tony Carden

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Tom,

Thank you. I wrote some of those posts. In this one https://bravenewclimate.files.wordpress.com/2009/08/peter-lang-solar-realities.pdf I showed the costs and the area that would have to be inundated to supply the NEM’s 2010 demand profile if all the power was generated by PV at a single location in NSW and energy stored in pumped storage reservoirs with 150 m average elevation difference between upper and lower reservoirs. This is sometimes called a limit analysis or a “book-end” analysis. It is useful to define limits. But it does not claim to be realistic. Recognising this, the results are interesting.

The capacity factor of the solar PV power station, for which we have 2 years of actual ½ hourly data, was as low as 0.8% for the worst days and about 9.4% during 3 months of winter.

The minimum system cost is with 30 days pumped hydro energy storage (about 70 Sydney harbour volumes of water to be pumped up 150 m each day and released each night). This would require 8,000 square kilometres of pumped hydro reservoirs and 3,000 square kilometres of PV panels, total 11,000 square kilometres innundated.

The capital cost of the system was estimated at $2,800 billion. The minimum system cost using Sodium Sulphur batteries would be $4,600 billion.

From the conclusions:

The capital cost of solar power would be 25 times more than nuclear power to provide the NEM’s demand.

The minimum power output, not the peak or average, is the main factor governing solar power’s economic viability.

The least cost solar option would emit 20 times more CO2 (over the full life cycle) and use at least 400 times more land area compared with nuclear.

Government mandates and subsidies hide the true cost of renewable energy

Some of the figures are out of date now, but updating them would not change the conclusions.

A second post, https://bravenewclimate.files.wordpress.com/2009/08/peter-lang-solar-realities.pdf, estimates the cost of constructing a large pumped hydro scheme joining the existing Tantangara and Blowering reservoirs in the Snowy Mountains scheme. The schemes is 9 GW power and 400 GWh energy storage capacity. The revised estimated cost is about $15-20 billion (increased as a result of reviewers’ comments but not updated in the post). The reviewers’ comments are included at the end of the post and should be of interest to anyone interested in what is considered by engineers during the pre-feasibility investigation for hydro projects. There are also many excellent comments on the thread. Some include analyses which explain why intermittent renewables and pumped hydro are not feasible.

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Peter Lang

I am not anti nuclear in high density markets. I have never said the China the US or Europe should not build them or Japan re-open theirs.

However you have not shown any current evidence that anyone is building new nuclear plants with a delivered cost per MW.hr anywhere near the A$90 per MW.hr for wind available in Australia.

You throw around an 11MW grid on El Hiero as proof of the failure of wind plus storage. a single small windfarm with almost zero diversity and low CF turbines. The exact opposite of a modern distributed NEM wide system in Australia. Even so it was never in fact expected to be by the builders until the lower reservoir can be enlarged. http://www.bbc.com/news/magazine-34424606.. You accuse me of selective facts … Pot… kettle..
I point out that the 29 newest windfarms in the US have 39% capacity factors and you say it is a …factoid…. and persist in using 25-30% in your calculations. In the meantime the largest manufacturers have announced new turbines with 8-10% higher annual output again than those installed last year.
I give you the current utilisation of French nuclear power plants and you ignore it. I give you the maximum utilisation of a 100% nuclear grid in Australia is around 60% you ignore it
You completely deny the practical evidence from South Australia that wind has actually displaced coal even more than gas while imports from Victoria have fallen.
EROI is a useful metric but not the only one but again you misuse it. According to Siemens GE etc. your EROI figures for wind are completely out of date. Siemens is claiming between 20 and 30 and GE is saying their next generation units which are actually being tested today will be as high as 50
You don’t seem to be able to grasp the concepts of interest and depreciation or weighted average cost of capital. The annual interest and depreciation on an $10b investment (current cost) at a mythical 5% interest rate on a 20 year payback. (your figure) is $800m. that is $107 per MW.hr. @85% utilization
Using an optimistic 7.5% it is $132 PLUS O&M at $30. Please explain my error
You talk about nuclear providing energy security and completely ignore the costs of building and operating the nuclear fuel fabrication and reprocessing plants in building your independent Australian nuclear network
The cost of integrating renewables into the grid is mainly storage you are double counting when you add grid integration costs to storage.
The CSIRO site you refer to is no longer available however, contracts issued this year for wind in Chile, India, the USA, South Africa and China are all lower cost than nuclear,
You say we cannot generate enough energy from renewables but wind power output alone in the US this year and China next year will exceed Australia’s entire electrical demand

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Peter Farley,
I believe that you are missing the point. John Morgan has provided factual data based on independent data to show that the current capacity factor of wind operating in Australia is 30%. I do not place a lot of weight on what the salespeople from GE, Siemens etc are saying until it is proven in the field.

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PeterF,

This discussion is off topic for this thread. I shouldn’t have replied previously. But anyway I realise there is no point me replying to you. Your comments demonstrate you don’t understand power and energy basics – such as the units – and your comments are a jumble of irrelevant factoids and questions that don’t compare like with like in any meaningful way. You’ve misunderstood or misrepresented much of what I’ve posted in comments above. And you don’t understand even when told repeatedly – for example capacity factor of wind farms is not the capacity factor of wind power delivered to the system, and reduces as penetration increases (read the links I and others have provided and please stop repeating nonsense after you’ve already been told).

Comparisons and options analyses have to be done on a properly comparable basis. I refer you back to my previous comments, e.g.:

begin by defining the essential requirements of the system (e.g. energy security, reliability of supply and low cost of electricity);

state the year your cost projections are for and the constraints and assumptions that are to be used for the options comparison, 

compare options on the basis of the total wholesale cost of electricity and CO2-e emissions avoided (from the system);

We’ve been told not to post off topic comments on this thread.

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The point of the original article was that wind was not economical with penetration above the capacity factor. The CF was claimed to be about 30% and the implication was therefore that nuclear was the only answer to a decarbonised electricity generation system.

I pointed out that it is not so simple that renewables + storage is cheaper than a 100% nuclear grid. You referred to various papers you have prepared over the years which are clearly outdated, for example in your example of solar + storage you used a capital cost of $5m/MW for solar. Current costs for utility solar are about 10% of that. Similarly you estimates for CF for solar, length of transmission lines, area of solar farms and CF of solar were all unduly pessimistic, not to mention the fact that no-one in the world would seriously propose a solar+ pumped storage grid. Have you heard the term “Straw Man”

You say that nuclear uses two orders of magnitude less resources yet a nuclear power plant uses 800,000 tonnes of concrete. 850 wind turbine foundations use 350-400,000 tonnes for the same annual generation.
http://www.nei.org/Master-Document-Folder/Backgrounders/Fact-Sheets/Nuclear-Power-Plants-Contribute-Significantly-to-S.

I have updated my calculations to reflect corrections you have made based on new information eg. Argentina and reduced my cost of nuclear but for Australia it still does not add up.

A. Please point out the error in my latest calculations with the appropriate maths not references to out of date calculations

B. Please demonstrate a grid configuration with 90% or more nuclear generation with better than 65% CF.

C. In your secure local nuclear energy calculation please include all costs of the domestic nuclear fuel cycle

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To Tony Corden

I am afraid if you look back through the posts, all of us have mixed power and energy. At least I stick to units relevant to the grid

You asked how we could store 34GW. I could have been pedantic and asked you what you meant. I agree that storage is measured GW.hrs not GW. However when we are considering peak capacity, Power is the relevant unit, that is why I quoted the 34GW number from ROAM,

I agree that none are viable at the moment, the only way storage or nuclear will be viable in Australia is if a significant reduction in carbon emissions is mandated by regulation or a large carbon price

When we are considering annual capacity, delivered energy is the key, that is why mixing 85% CF and 100% nuclear does not add up.

I am very hopeful that Molten Salt reactors may be viable particularly for “burning” current nuclear waste. I am all for continuing research, however if it fails what do we do.

If we install renewables now, we reduce emissions gradually (see South Australia) and at less cost than current generation nuclear (see Argentina). In 7 or 8 years time when we are approaching 30% wind and 10-15% solar, then we can retest the economics of whatever the best nuclear option the Chinese have come up with.

It may be that we have a 20-50% nuclear grid in 15 years time but on current trends I doubt it

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Peter Farley,
Again you miss the point, with pumped hydro, both GW and GW.hrs are equally important. 35 GW.hrs with 5GW of generating power means the system will run for 7 hrs at 100 % capacity factor. If we were to use all of our existing wind capacity to fill the pumped hydro reservoirs it would take 35 hrs, based on John Morgan’s figures.
Do you know how many litres of water are required to produce this amount of power? Where is this quantity of water available from?

If I was to be pedantic I might point out that my surname is spelt CARDEN.

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To Tony Carden

My humblest apologies for miss spelling your name.

I cannot repeat often enough that I am not anti-nuclear. I am pro low carbon and at the currently available state of the art the way to go is renewables. If MSR’s work at lower cost than renewables great. I do agree with most of the Harvard video except to say that the increase in actual generation (i.e MW.hrs not MWs) is almost an order of magnitude faster in both India and China for renewables rather than nuclear

Back to your points.
At peak demand times it does not matter how many GW.hrs of storage you have if you cannot deliver it. That is why the power of the system is important. I pointed out that there is plenty of evidence that 35GW of peak storage power can be installed.

You obviously did not read the Roam report because all the water is sourced from existing water bodies with new small ponds located either above or below. It does not consider turkey nest dams by the sea which other reports have recommended, it does not consider plants of less than 500GW capacity, It does not consider thermal storage, load shifting, augmenting existing hydro, power to gas etc etc etc

I am not relying on GE or Siemens for capacity of windfarms but US and Australian data. You have many instances above from correspondents other than me to show that the 29% figure is understated and that the capacity factor of new windfarms is higher than old ones. Australia has around 4GW of older technology windfarms. By definition any windfarms built in the future will have newer technology and higher capacity factors and in the final scheme they will be the majority of the farms so the total system capacity factor will be between 37 and 45%

Nuclear proponents on the other hand are relying exclusively on salesmen for nuclear because no-one has built a new nuclear plant in the last 10 years where the LCOE is less than A$140 per MW.hr.

No-one has yet to give any evidence how a 90-100% nuclear grid can be operated economically without large storage and/or exports and thermal backup (see Japan/France)

If you had read my post you would have also noted that I said that the 35GW storage power was a thought experiment and that in a balanced system we probably needed about 15-18GW of peak capacity storage and even that would not all be pumped hydro.

There are three difficult questions that no-one has answered for any future generation scenario.
a) What is the future demand. Electrical demand all around the developed world is trending down. Even in China growth has fallen from 10-13% per year to 1-3% and many of the new coal powered stations in India, China, the US and Germany are losing money now or will face large losses when they open because demand is lower than forecast
b) What is the expected rate of change of the technologies. After all, the IEA predicted in in 2002 that by 2010 there would be 8GW of solar and 50GW of wind. Actual result 42GW of solar and 200GW of wind. In 2009 it forecast coal demand in 2015 of 5.54b tonnes and 2030 about 7b. It will be around 5.3b this year but it is already falling to be on track for around 4b in 2030
c) In any economically viable scenario there will be a need for a lot more storage/demand management both in power and energy. How will this be achieved

Perhaps we should bend our minds to answering these questions rather than each backing our own hobby horse
BNC MODERATOR
Please move this discussion to the Open Thread as it is OT here. Tony has posted his reply there. Thank you.

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No I did not read the Roam report because you did not provide a link to it. I would be happy to read it if you would be kind enough to provide the link.

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Returning to the capacity factor of wind. There are a number of metrics which while useful guides are not set in stone. For example source penetration vs capacity factor.

The current capacity on the NEM is 44GW, peak demand is 32GW or 72% of capacity. The overall Capacity Factor is 50%. Even a 100% available system with just the mandatory minimum reserve cannot be more than 60% CF because of the ratio of peak to average demand.

Spilling wind or solar is economically inefficient but so is not running an expensive thermal plant below capacity. That is why all grids rely on hydro and/or storage of some sort to optimise the use of thermal plants.

The next factor is the demand profile. Many correspondents assume maximum demand has to be available at any time of the day or night and therefore solar is useless for reducing maximum demand. This is not the case, maximum demand is on very hot (therefore windy) afternoons and evenings. If utility scale solar is placed on the western side of the grid, there will always be a significant renewable contribution to the peak. There will be still nights where there is no wind or solar output but demand then is much lower than peak so the backup power does not have to equal the peak demand.

The third factor, which has always been a key consideration in grid planning is diversity. The more widely distributed power sources are, the more evenly distributed is their contribution to the grid. John has hinted at this saying that the optimum wind contribution can be 33% even if the Capacity Factor is 29%. This is based on a wind sector occupying only about 15% of the area of the grid. If wind was more evenly spread throughout the whole grid then the optimum contribution may be 1.2 or 1.3 times the capacity factor.

The combination of diversity and demand correlation can mean that even higher penetration of solar and wind can be economical.

Then there is the question of rising capacity factors. If we build 15,000 class III/IV wind turbines on 155m towers in the best 2% of the NEM area they can reach 65% CF so theoretically all the generation could be wind with existing hydro augmented by some 12GW of solar, with thermal storage, demand management and about half our current gas power stations running 1-200 hours per year.

Peak demand could be met by wind turbines running @ 25% of capacity, solar @20% hydro @85% 4GW of gas, 2GW of biomass, wave, geothermal etc. 1.6GW of demand response and only 5GW from storage. Of course if there were hot north winds then the wind @65%and solar @10% would cover all the demand with the hydro, gas and storage just supplying frequency control

Finally it all depends on costs, In the current grid, when the carbon tax was removed brown coal increased even though it is technically very inefficient. It still drove some high efficiency combined cycle gas and black coal out of the market.

In the future grid, if storage is cheap you build generation capacity equal to 105-110% of annual demand and a lot of storage. If generation is cheap you build generation equal to 200% of average demand (like now) and a lot less storage.

Therefore the optimum mix is not a technical constraint, it is cost driven. There is enough room on the NEM to build 100’s of GW of both wind and solar without impacting more than 1% of farm lands so there is not a space or capacity constraint as there is with hydro, it is just a question of money.

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Peter F,

As usual you are mixing misunderstanidng the meaning of the terms. Most readers here fully understand them. You also frequentely make comparisons tha

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Peter F,

I’d urge you background yourself on the basics: BNC has excellent background papers here: https://bravenewclimate.com/renewable-limits/. Many of your comments suggest you misunderstand and conflate the meaning of terms, such as capacity factor. Most readers here understand them, what they mean and how for example the capacity factor of dispatchable technologies is due mainly to what proportion of the time they are dispatched, not their availability. For example, OCGT might have an average availability of 98% and a capacity factor of 1% to 10%.

You also frequently make comparisons that are not fair comparisons, for example comparing LCOE of dispatchable and non-dispatchable technologies. These are not equivalent or comparable. If you want to compare dispatchable and non dispatchable technologies you need to compare on the basis of system costs to meet the same requirements (e.g. demand profile). To do that you need to add the cost of back-up and/or energy storage and grid costs for the technologies you want to compare are equivalent; i.e. dispatchable.

David Benson posted a link on Open Thread 23 to an excellent report by JP Morgan Deep decarbonisation of electricity grids
https://www.jpmorgan.com/cm/BlobServer/Brave_New_World_-_Annual_energy_piece.pdf?blobkey=id&blobwhere=1320687247153&blobheader=application/pdf&blobheadername1=Cache-Control&blobheadervalue1=private&blobcol=urldata&blobtable=MungoBlobs

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To Peter Lang

As usual you misread what I have said. If you read all my earlier costings they include the cost of storage for renewables and often favour nuclear by not including fast ramping support or spinning reserves.

I have read the JP Morgan report and their analysis is excellent in its breadth and scope. However their argument is not nuclear vs renewables but how much of each. Even with their assumptions which they themselves acknowledge are highly uncertain, they suggest the optimum is probably 40-45% solar and wind, 5-10% hydro 10-15% gas and 35-40% nuclear. This is for California not for the world

My comments:
In favour of nuclear I think costs may fall quicker than they suggest. Also I think that their contention that storage is and will remain more expensive than renewable proponents hope and to that extent I will modify my costs per unit of storage.

However on the other hand, their capacity factor for new wind is clearly too low.

In the Australian case, AEMO has demonstrated that the amount of storage required on the Australian grid appears to be much lower than in other jurisdictions because, system wide, we have much shorter intervals of low wind, low solar than Germany and probably California because of higher average insolation, higher average wind speeds in the required locations and the greater East West spread.

A few minor points that probably don’t make a huge difference to the overall balance.

JP Morgan dismiss CSP on the basis of the poor initial performance of Ivanpah but performance there has almost doubled over the last few months.

They also dismiss offshore wind in Germany but the Germans seem to believe that the higher CF of offshore wind (around 50% in newest farms) reduces the need for high cost backup and is therefore cost effective

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Yes, typical. So bioenergy disappears from the options again even though it is providing 10% or more of baseload electricity in Germany, Austria, Sweden, Denmark, Brazil and a few other more intelligent countries.
This is typical of you engineers, you opt for the most high tech and technically sexy, high cost and complex solutions, and blithely ignore the renewable option that provides jobs, social and environmental benefits, and long term flow-on economic benefits to rural and regional economies.

In the meantime we have just had high winds causing wind farms in SA and Vic and maybe Tas to shut down just as they get to over 90% CF.
Have a look at Snowtown 1 & 2, and Lake Bonney 1, 2 & 3 over the last 24 hours on http://www.anero.id.au.
In Vic the Macarthur wind farm and Morten lane and a few others have done the same thing. The anero site lets you look back in time a day and see just how shakey the management of these sites was in this situation.
Suddenly up to 1000 MW of supply just disappeared out of the AEMO system within Vic and SA over maybe15-30 minutes. Bald Hills in eastern Vic was similar and some of the NSW sites were doing something similar a bit later on.
If you look at the AEMO supply and pricing site you can see for each of SA, Vic and NSW that the pricing due to this wind influence was all over the place from minus $40/MWh up to plus $250. And this is when we only have about 3700 MW as opposed to the projected 8000 MW or more by 2020.

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Andrew,
I do not agree with the zealots who take ideological positions and say we will have 100% renewables or 100% Nuclear. So where Bio-Mass stacks up surely use it. Surely there will be places where wind is the obvious choice etc. Indeed in 200 years time someone may still be running a coal fired power station.

Thank you for your comments about the current Wind Performance, you have actually confirmed some points that I made in this discussion around the 9th and the 10th of November about what was the max speed that wind turbines operate at and what happens when the wind stops. At the risk of repitition:

Kirk ‘Scotty give me everything you’ve got now !!!!!!’

Scotty ‘ Aye captain I already am ! I canne give ye any more!!!!!!’

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<

blockquote>As usual you misread what I have said. If you read all my earlier costings they include the cost of storage for renewables …

<

blockquote>
All your earlier costings are irrelevant because they are not like with like comparisons. It’s been pointed out to you over and over again.

However their argument is not nuclear vs renewables but how much of each. Even with their assumptions which they themselves acknowledge are highly uncertain, they suggest the optimum is probably 40-45% solar and wind, 5-10% hydro 10-15% gas and 35-40% nuclear.

That’s your (mis)interpretation. The JP Morgan report does not compare a range of alternatives from low to high nuclear and low to high renewables. So your point is not valid. What you can draw from the analysis is that nuclear is a much cheaper way than renewables to reduce GHG emissions.

However on the other hand, their capacity factor for new wind is clearly too low.

That’s disingenuous. As the proportion wind energy increases the capacity factor of wind decreases (due to increasing spillage). They report makes that point.

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Eyeballing from the chart on p24, ‘Learning curves for power generation technologies’, the end of the solid lines (i.e. year 2000) I interpret:

Nuclear capital cost = EUR 4,600/kW
Wind capital cost = EUR 1,000/kW

Nuclear capacity = 350,000 MW
Wind capacity = 11,000 MW

Nuclear plants have a life expectancy of 2x to 3x wind farms. And nuclear plants have a capacity factor about 3x wind farms. Therefore, an investment in W of nuclear capacity supplies 6x to 9x the energy that an investment in a W wind farm capacity supplies. That is, EUR 4,600 invested in nuclear would supply the same total energy as EUR 6,000 to EUR 9,000 spent on wind farms.

But it’s much worse than that, because the wind farm also needs backup and energy storage to enable it to be comparable to the reliable, dispatchable energy supplied by a nuclear plant.

It worse still when you compare the CO2 emissions avoided with and without nuclear. Nuclear power displaces baseload generation. A MWh of electricity generated by nuclear avoids all the emissions of the coal fired plants it displaces. The CO2 abatement effectiveness of nuclear is greater than 100%. In contrast, the CO2 abatement effectiveness of wind power is much less than 100%. Various studies suggest CO2 abatement effectiveness declines to about 50% when wind power supplies about 20% of the electricity (Wheatley, 2013 and Wheatley, 2015). It continues to decline as the proportion of wind power increases. At 50% CO2 abatement effectiveness the CO2 abatement cost is double what it would be if 100% effective, http://www.onlineopinion.com.au/view.asp?article=17447&page=0 .

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JP Morgan report, p2:

Transmission costs excluded. We exclude investments in transmission infrastructure often required
to accompany large amounts of renewable energy capacity, which could substantially increase the estimated cost of high-renewable systems. Wind capacity factors may also degrade with a large wind build-out since the most optimal sites are often developed first.

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@dos74,

You are dismissive of the regression analysis based on 5-min generation data (“misleading”, “fatally flawed”, “fundamentally wrong” etc). I think you are mistaken. John Morgan’s post shows the value of the high frequency data.

You are correct that the annual capacity factors quoted in the overview section of my report use installed wind capacity at year end. As you have emphasised more than once, this is not a good approach when installed wind capacity has changed significantly during the year.

Of the 34 wind farms included in the report, 3 were commissioned during 2014. CF for NEM becomes 29.8% when these wind farms are excluded. At regional level, CFs become:

NSW 23% (19%)
SA 32% (31%)
TAS 35% (35%)
VIC 28% (28%)

(Values based on year end capacities are in brackets.)

The substantive part of my report deals with the calculation of emissions avoided. This is unaffected by the definition of capacity factor. The emissions avoided calculation makes use of the full 5-min WPG time-series as an explanatory variable. CFs are simply never used.

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Joe Wheatley, Thank you for that clarification.

To those who have been raising the issue, as I expected it is a trivial change. A lot of hot air about nothing. And it makes absolutely no difference whatsoever to the values of CO2 emissions avoided by wind power in the NEM in 2014 or the CO2 abatement effectiveness of wind power.

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To Peter Lang
You forgot the O&M and security costs O&M of nuclear is 10 times that of renewables. Ontario Power has the largest security force in Canada outside the Canadian military, mainly dedicated to protecting nuclear power plants.

Again you use outdated numbers, the nuclear lifetime generation is now around 2 x wind not 3. Nuclear power capacity in Europe today 120,000MW, Wind 130,000 MW.

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PeterF says that nuclear power capacity in Europe today is 120 GW, and wind capacity 130 GW.

Maybe, but proper comparison requires you to multiply them by their respective capacity factors. If they were 90% and 30% respectively, Europe’s nuclear average production would be 108 GW and wind average production would be only 39 GW. If you multiplied by availability for baseload, the score would be 108 to 0

Is that all that their years of hot air have achieved? I wonder that we will come to witness the collapse of Germany’s heavy industry, while Europe’s zealots crow victory for a cause that the world has meanwhile forgotten.

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Roger Clifton,

Yes!@. Furthermore, reportedly Europe has spent almost 1 trillion euros on renewables. A huge cost for arguable negative benefit, since advocating for and spending money on renewables has delayed genuine progress by decades. If not for that anti-nukes scaremongering over the past 50 or 60 years, global GHG emissions would be around 10%-20% lower than they are and we’d be on a fast trajectory towards much faster emissions reductions by 2030 and 2050. That’s what their obvious obstinacy in the face of the blindingly obvious facts has caused.

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Peter F,

Again you are not comparing like with like and are quoting factoids that are irrelevant,

You forgot the O&M and security costs O&M of nuclear is 10 times that of renewables. Ontario Power has the largest security force in Canada outside the Canadian military, mainly dedicated to protecting nuclear power plants.

No one is forgetting that. It’s included in the FOM costs. Clearly you have negligible understand of the subject, and don’t understand how to do like with like options analyses.

Again you use outdated numbers, the nuclear lifetime generation is now around 2 x wind not 3. Nuclear power capacity in Europe today 120,000MW, Wind 130,000 MW.

Gen III+ uclear plants are expected to last over 60 years. Wind plants are viable for about 20 years on average. But all these silly factoids are just nit-picking Irrelevancies in the context of the huge gap between the mostly nuclear and mostly renewables cost of electricity, CO2 abatement cost and CO2 abatement effectiveness. You continually avoid the key important criteria: cost of electricity from the system, CO2 abatement cost, CO2 abatement effectiveness.

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To Tony Carden:
The world Nuclear Association for nuclear http://www.world-nuclear.org/info/Country-Profiles/Others/European-Union/ and the European Wind Association for wind. The calculation of Nuclear power output for China in 2010 was based on 85% CF of installed capacity at that time.
BNC MODERATOR
Please note that comments may be held in the moderation queue for some time as moderators are volunteers and not available 24/7. Thank you.

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Peter,
Again your references are either wrong, not on point, completely irrelevant or non existent. Repeatedly you have forced me to read material that is wrong. You are making these numbers up.
As when i challenged you on the cost of pumped hydro storage in Australia you admitted that you had no idea. But previously you had claimed to have costed various scenario’s using pumped hydro.
I have taken a decision that all of your comments are disingenuous and i do not wish to engage with you any more.

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To Peter Lang

Your earlier post was about capital cost and capacity factor not total cost. You also quoted the figures about installed capacity. I merely corrected your post.

You project future reliability and life of Gen III reactor plants when none are fully operational and assume that wind turbines won’t last any longer than their initial minimal design life.

I agree that nuclear plants should last 60 years although many Gen II plants have been closed well short of that so let’s say we reach 55 years average life.

Similarly many wind turbines have operated for 30 years not their 20 year design life. In addition a number of those that have been replaced have been replaced due to technical obsolescence rather than old age. This is common with rapidly evolving technology (see computers, phones, earlier generation jet planes, machine tools etc.)

It is true that the EC wide capacity factor of wind is 1/3rd the capacity factor of nuclear (EU wide 82%). however the capacity factor of wind is improving so that new offshore farms are already registering around 50% and new onshore about 35%. In addition all the major manufacturers are announcing high Su turbines, 155m masts, new control systems etc so that many onshore medium wind sites which weren’t even worth building on 5 or 6 years ago will reach capacity factors of 40% by 2018. Meanwhile the UK, Germany and Belgium are increasing the proportion of high CF offshore so by about 2025 the European CF will be around 32-35% whereas it is unlikely that the nuclear CF will change significantly

So making a reasonable assumption that average life of wind is 25 years (25% offshore) and the weighted CF of new plants is 40% x.75 + 50% x.25 =42.5% then the lifetime output of new nuclear is 55/25 x 82/42 = 4.2 x wind not the figure of 9 you used

None of this says we should go 100% wind and I have never advocated that. It simply says that wind and solar will be a significant part of the zero carbon mix with biofuels, hydro and storage. In other countries (eg Portugal and New Zealand) large amounts of hydro, geothermal, wave or tidal may be important.

Then in some countries there will be nuclear maybe as high as 77% in France or Belgium although France has passed a law aiming for 50% nuclear. This is unlikely to be achieved but it is likely that the nuclear generation % will fall.

My argument from the start is that the cost of nuclear in Australia will be higher than other countries due to hot cooling water, lack of, or cost to build nuclear infrastructure, higher construction costs and summer peak demand. Meanwhile Capacity Factor will be lower than in other grids because we can’t export off peak and import at peak like France does.

Conversely our capacity factor of wind and solar will be higher because we only need to use the best quality wind regions in 1-2% of the Grid and average insolation is about 50% higher than Germany For both technologies we will be using much more efficient and cheaper equipment because we don’t have much of the old stuff.

Because of the length of the grid we have a much higher diversity in generation so the grid wide consistency of generation means that the use of storage and backup will be still be essential but used much less and therefore will be a lower proportion of the cost than in a high renewable grid in California or Germany.

Another complicating factor is the payback time either in money or energy. While nuclear has a high ROI/ROE if it lasts 50 or 60 years, but it starts from a long way back. (800,000 tonnes of concrete vs 380,000 tonnes for example) so that if Lockheed’s new fusion reactor suddenly became viable in 2030, we would have a whole fleet of nuclear power stations which had still not recovered the money or energy embedded in them and the fuel cycle, while the wind and solar generators would have recovered their embedded energy and be well on the way to recovering most of their money.

If nuclear costs fall as fast as you think they will and renewables and storage don’t fall as fast as they have been, then nuclear might make up half the Australian grid. On the other hand current “overnight” costs of equipment that can be ordered today suggest that there will not be any nuclear. see The Australian Power Generation Technology Report

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Peter Farley,

Your earlier post was about capital cost and capacity factor not total cost. You also quoted the figures about installed capacity. I merely corrected your post.

I haven’t a clue what you are referring to since you didn’t quote. However,since nearly everything you’ve said on this thread has been disingenuous or just plain wrong, I suspect this assertion is disingenuous, misrepresentation, incorrect, irrelevant or out of context too.

You made a comment earlier referring to the JP Morgan report and mentioning the high uncertainties. Yes of course there are great uncertainties with the predictions. However, we know nuclear can do the job. It’s proved it can in France. But there is no evidence that non-hydro renewables can do the job for most of the world. So there is much greater uncertainty attched to the projections of 80% renewables than there is to 80% nuclear.

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Peter Farley said
@ https://bravenewclimate.com/2015/11/08/the-capacity-factor-of-wind/#comment-434050

However their argument is not nuclear vs renewables but how much of each. Even with their assumptions which they themselves acknowledge are highly uncertain, they suggest the optimum is probably 40-45% solar and wind, 5-10% hydro 10-15% gas and 35-40% nuclear.

Where do they suggest the optimum proportions?

The tables on p9 and p15 of the JP Morgan report show that:

Energiewende with 35% nuclear instead of 0% nuclear, would be 79% the cost of electricity and 28% the CO2 abatement cost.

Caliwende with 35% nuclear instead of 0% nuclear, would be 82% the cost of electricity and 36% the CO2 abatement cost.

This trend suggests that cost of electricity and CO2 abatement cost both decrease as the proportion of nuclear increases and the proportion of wind and solar decreases.

The JP Morgan report does not optimize the technology mix to minimize cost of electricity or CO2 abatement cost. If it did, the cost trends in the tables on p9 and p15 suggest the nuclear proportion for least cost electricity (especially once you include grid costs) would be similar to France plus gas, any additional viable hydro and a relatively small proportion of wind and solar (like France is now).

France has demonstrated what is achievable with a high proportion of nuclear power; i.e. relatively low cost of electricity and very low emissions intensity. France’s nuclear power has been supplying 75% to 80% of electricity for about 30 years, helped by having good hydro resources. Without the hydro resources, gas would be required for most of the load-following in a system that meets requirements and is optimized for minimum cost of electricity and minimum CO2 abatement cost.

The CO2-e emissions intensity of electricity in France will increase if it reduces the proportion of electricity generated by nuclear and increases the proportion generated by intermittent renewables. The CO2-e emissions intensity of electricity in France is 8.6% of Australia’s and 14.5% of Germany’s (IEA, 2014, http://www.oecd-ilibrary.org/energy/co2-emissions-from-fuel-combustion-2014_co2_fuel-2014-en . If France reduces its nuclear proportion and increase its wind and solar proportion it will have to also increase thermal generation proportion for back-up, therefore increasing the emissions intensity of its electricity.

Your assertions that capacity factor of wind will increase as penetration increases are wrong, by a wide margin. The JP Morgan report explains it and I’ve given you references explaining this in a number of previous comments.

Also, you have not provided relevant, valid evidence demonstrating that a large proportion of renewables can supply electricity and cut emissions more cheaply than a large proportion of nuclear.

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Peter Lang

So many misinterpretations of what I have said. You accuse me of not giving references yet you clearly do not read them when I do

I have never said that the US China or Europe even Germany should not use nuclear

If you look at the costs in the JP Morgan report on P20 wind is far cheaper than Nuclear, and so is solar PV, biomass and geothermal and surprisingly even solar CSP so it seems to me that it is logical that you would include as much of those as possible in the grid to lower the overall cost of power. Only when you run out of economical hydro, geothermal and biomass would you consider nuclear as residual load

i did not say wind CF increases because of its increased penetration. Obviously if the technology remained the same, CF would decline as penetration increased (just as it does with nuclear coal or any other source above a certain threshold but that is not the case.
I said wind CF is increasing because of vastly improved technology, for example typical annual output from a new turbine installed in Germany in 2008-10 was about 2-3GW it will be 10-13GW for one installed in 2017 . Further as the number of full load hours increases, cost of grid integration is lowered. Changes to the electronics allow them to supply re-active power even if they are not turning, further reducing grid integration costs

As usual it is you who doesn’t want to understand the technology or the economics

How many times do you have to be told 1. that France’s wholesale electricity generation is more expensive than Germany’s according to France’s electricity directorate 2. France’s current nuclear CF is less than 70% and would be lower if they could not dump off peak power on neighbours with more flexible generation.

You don’t answer the basic question of how does anyone justify building nuclear power plants to provide shoulder and peak demand when their utilisation of the last plant will be about 5% or if the load is shared evenly all plants will have to make money at 60% utilisation.

You assert that if France increases wind and solar its carbon intensity will go up. That is not a fact it is a guess. If wind and solar allow France to make better use of its hydro, carbon intensity can go down. You don’t know I don’t know but as nuclear is covering the base load the liklehood is that more renewables can actually lower the carbon intensity

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Peter Farley is using un-referenced and likely falsified numbers.  Example:

Another complicating factor is the payback time either in money or energy. While nuclear has a high ROI/ROE if it lasts 50 or 60 years, but it starts from a long way back. (800,000 tonnes of concrete vs 380,000 tonnes for example)

His claims are completely opposite to reality.  He asserts e.g. a 2:1 disadvantage for nuclear, while a very quick search on my part found not one but two references (with sources cited) showing roughly a 4:1 disadvantage for wind.

As usual it is you who doesn’t want to understand the technology or the economics

Says the poster who is either deluded or a foul propagandist.

I strongly suggest that BNC put Peter Farley on moderation, and delete any further comments giving un-cited claims.  Just remove his flow of nonsense from the forum; make him either start talking sense or go elsewhere.

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Hi Joseph Wheatley, thanks for taking the time to respond to my comments of your paper.

I’m not sure how many of my previous comments you have read, but let me summarise three issues I have.

Capacity Factor. Thanks for redo-ing your capacity factor calculations taking into account the 3 wind farms which had not commenced generation by the beginning of 2014. I presume you are talking about Bald Hill, Taralga, & Boco Rock. Please note that I used the words “commenced generation” rather than “commissioned”, as I believe this is what you meant, though happy to be corrected if I assumed wrongly. To clarify the difference, a wind farm is commissioned when it has finished construction, which may be a few months or even a year after it first starts generating. For a fair analysis of capacity factor, I believe you also need to exclude wind farms that were still under construction during during 2014. This also includes Portland, Gullen Range, Snowtown Nth & Sth, & Mt Mercer. If you remove these wind farms, then the overall NEM capacity factor for wind increases to 30.4%, and NSW’s CF increases to 29.1%.

Misleading use of carbon emission abatement effectiveness. This is not so much a criticism of your paper, but rather a criticism of how others have interpreted your result. Your paper calculated that wind farms had an abatement effectiveness of 78%. In a comment above, Peter Lang said “Nuclear power displaces baseload generation. A MWh of electricity generated by nuclear avoids all the emissions of the coal fired plants it displaces. The CO2 abatement effectiveness of nuclear is greater than 100%.” I previously pointed out that a new nuclear power plant in Australia was more likely to displace gas generation, which has a higher marginal cost than coal. I suggested that a nuclear plant in SA would be most likely to displace gas generation with a carbon intensity of about 0.6 tCO2/MWh, which would give it an abatement effectiveness of 69%. My point is that people like Peter refer to your calculation of abatement effectiveness, and insinuate that their preferred technology would do much better. It is highly misleading to refer to wind’s abatement effectiveness, without acknowledging that this is highly influenced by the marginal cost of generation of other generators on the network, and that other new generators may not do any better than wind.

Five minute regression analysis does not indicate longer-term trends of carbon abatement effectiveness. When I first read your paper, I was very impressed. It seemed to be a highly comprehensive analysis of wind’s abatement effectiveness. However, after some more thought, I came to believe that it is fundamentally flawed. Please correct me if any of the following is wrong, but my understanding is that your paper uses 5 minute regression analysis to determine, amongst other things, that 1 MWh of wind in SA displaces just 0.06 MWh of brown coal generation in SA, and 0.320 MWh of SA gas generation. From this result, and similar results from the other states, you were able to determine what generation would have occurred in the absence of wind (on a 5 minute basis), and therefore calculate the emissions saved by the wind.

However, five minute regression analysis misses any longer term trends and decision making by other generators. As an example, in the last few years, one of SA’s coal power stations (Playford B) has stopped producing power, and the final remaining coal generator (Northern) is scheduled to close early next year. The owner of the generators blamed in part the rise of renewable generation in the state for the closure. If you look at the long-term trend in generation in SA (I have posted the image twice in earlier comments), it is clear that wind generation in SA has primarily displaced coal generation, and there has been very little trend in gas generation over the same period. This has not been picked up in your 5 minute correlation analysis, which suggests that wind in SA displaces 5 times as much gas as coal in SA. Clearly coal generation does not react over this short period to changes in wind output, but that does not mean wind doesn’t displace coal in the longer term.

So I believe your paper may prove a reliable predictor of wind’s abatement effectiveness over the short term (hours, days and possibly even weeks), but it is a very poor predictor of wind’s abatement effectiveness in the longer term (months & years).

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dos74

This is not so much a criticism of your paper, but rather a criticism of how others have interpreted your result. Your paper calculated that wind farms had an abatement effectiveness of 78%. In a comment above, Peter Lang said “Nuclear power displaces baseload generation. A MWh of electricity generated by nuclear avoids all the emissions of the coal fired plants it displaces. The CO2 abatement effectiveness of nuclear is greater than 100%.” I previously pointed out that a new nuclear power plant in Australia was more likely to displace gas generation, which has a higher marginal cost than coal.

Your comment is not relevant to Wheatley’s analysis and is not a valid criticism of it. Wheatley’s analysis is of historical empirical NEM data for 2014. You are surmising, presuming, assuming about what might be if, if, if. The empirical analysis is not used for that. For what you want, you need to use a modelling approach like SEAI did for Ireland. Your reference to my comments, which were a response to another poster, are irrelevant in the context of critique of Wheatley’s paper. You have conflated two separate discussions, made your own assumptions and misrepresented what I was talking about (which was about the J. P. Morgan paper on Germany and California). I do not appreciate the misrepresentation and disingenuous comments.

I don’t understand why you don’t understand that Wheatley’s analysis is about 1 year, not multiple years. If you want long tern trends you need to repeat the analysis for several years. Then you have to assign causes to the changes, such as effects of government interventionist policies, and changing relative costs of generation technologies over time as in ERCOT where gas prices have come down significantly. I’ve told you all this several times and you still either don’t get it or refuse to accept it.

I’ve also told you the reason wind is replacing coal in SA is because of the RET which effectively mandates renewables and subsidises them through the REC’s. Wheatley’s analysis does not explain the reasons for the displacement of one technology by another, it just estimates how much emissions were avoided by wind generation and what the CO2 abatement effectiveness was for the data analyses.

The fact you haven’t acknowledged your misunderstanding about why the analyses have to be done using short period data (5-minute power output from each generator unit) suggests you still have not understood the analysis.

I again urge you to read Wheatley’s 2013 paper of the Irish study, SEAI report and the Kaffine et al. report of ERCOT 2007-2009. There is no point asking Wheatley to explain the analysis if you won’t take the trouble to try to understand it.

http://joewheatley.net/how-much-co2-does-wind-power-save/

http://joewheatley.net/quantifying-co2-savings-from-wind-power-redux-ireland-2012/

Emissions Savings from Wind Power Generation in Texas
Author(s): Daniel T. Kaffine, Brannin J. McBee, , Jozef Lieskovsky
https://www.iaee.org/en/publications/ejarticle.aspx?id=2509

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Peter, I apologise for quoting you out of context in my above comment, and for giving any impression that you were talking about nuclear abatement effectiveness in Australia.

Your comments on the long-term abatement effectiveness of wind in Australia illustrates that you do not understand my criticism of Wheatley’s paper.

If one was to repeat Wheatley’s analysis in Australia in the years 2009, 2010, 2011, 2012 & 2013, I’m sure that we would again find that wind generation does not (anti) correlate with coal generation, with the implication that wind generation does not displace coal generation. It will show this, despite a clear long-term trend of wind displacing coal.

You seem to be under the impression that I think 5 minute analysis is irrelevant to wind’s carbon abatement effectiveness. That is not the case. I am merely stating that using only 5 minute regression analysis and ignoring analysis based on a slower timescale can provide some highly misleading results.

I repeat my previous analogy. I am confident that brown coal generation is not well correlated to demand in Victoria on a 5-minute time-scale. However, this does not mean that brown coal does not make a significant contribution to meeting Victorian demand.

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dos74,

Peter, I apologise for quoting you out of context in my above comment, and for giving any impression that you were talking about nuclear abatement effectiveness in Australia.

Thank you for the correction/clarification. Appreciated.

Your comments on the long-term abatement effectiveness of wind in Australia illustrates that you do not understand my criticism of Wheatley’s paper.

I think your criticism is invalid and irrelevant to this paper. The paper is an excellent contribution to our knowledge base of the CO2 abatement (in)effectiveness of wind power. Your complaints are not about the paper. They are about a different analysis altogether. Why don’t you do that analysis yourself? Look at the SEAI report for an example of a method.

Analyses over several years would show trends in emissions avoided by wind generation and CO2 abatement effectiveness in the NEM. More accurate and frequent CO2 emissions data from the generators involved in cycling and ramping to back up for wind power would improve the estimates and reduce the uncertainties (95% confidence intervals on the estimates).

If one was to repeat Wheatley’s analysis in Australia in the years 2009, 2010, 2011, 2012 & 2013, I’m sure that we would again find that wind generation does not (anti) correlate with coal generation, with the implication that wind generation does not displace coal generation. It will show this, despite a clear long-term trend of wind displacing coal.

Who cares what wind anti-correlates with (unless you have preconceived ideas about good and bad ways of generating electricity). My interest is in the highlighting the very serious issue of assuming that wind power is 100% effective at savings emissions. It is nowhere near that, as Wheatley’s analysis highlights and quantifies. But that is the assumption that underpins most of the analyses of the emissions avoided by wind generation. I would suggest that belief is what is underpinning you apparent belief that wind replacing coal in SA is necessarily a good thing. Furthermore the CO2 abatement effectiveness of wind power gets worse as wind energy penetration increases. So the CO2 abatement cost with wind is much higher than recognised. The result is that wind is a very high cost way to reduce GHG emissions. Those who are genuinely concerned about achieving deep cuts in GHG emissions should stop advocating for wind power, renewable energy and government interventions in the energy market to implement bad policies, such as the RET.

… I’m sure that we would again find that wind generation does not (anti) correlate with coal generation …

This is something you seem to be concerned about, but why? It seems to me that you think it is a good thing that unreliable, intermittent, high cost, highly subsidised wind power is displacing reliable, dispatchable, low-cost coal generators, presumably because you assume that by doing so you are avoiding the emissions that coal would have caused. Wheatley’s analysis shows that is not the case. Coal power stations in other states do the cycling instead.

What is relevant is the CO2 abatement effectiveness of wind in the NEM, not what is happening in SA, nor which particular generators in which state are being forced to close down by the RET.

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dos74,
As an aside, Referring to the graph that you posted on November 10 on this thread. From the years 08/09 to 13/14 Wind as a percentage grew from 14% to 28%. In the same period Supply from the interconnector grew from 2% to 12%. Do you think that there is a relationship in the similar amounts of growth of electricity supply from the two sources?

Also do you know what is the source of supply for the interconnector i.e. coal, gas, hydro, solar??, wind.

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BNC MODERATOR
Your latest post was again off topic on this page. Please re post on the Open Thread as you have been previously advised several times.

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Hi Tony, between 08/09 and 13/14, both coal and gas generation in SA has reduced. In total, they have reduced at a faster rate than wind has increased. It seems that economics have favoured increased imports rather than maintaining local gas or coal generation. I think it’s as simple as that.

Imports into SA are from Vic, which is predominantly brown coal generation. At first glance this would suggest that the imports are primarily brown coal, though it’s not as simple as that. The brown coal generators are often run at near constant load, and their output does not generally correlate to whether SA is importing or exporting. One would suspect that the increased generation supplying SA from Vic is coming from sources other than brown coal.

So I’m afraid the answer is complicated. Wheatley’s analysis probably provides some clues, but once again I don’t believe it will provide the full story, as it is based on 5 minute regression analysis and does not capture slower relationships.

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David,
i apologize if I have your name wrong.
Surely, to correctly evaluate Wind etc we have to consider its impact on the total system i,e, The NEM, and measure the total changes in system inputs and outputs that occur from Wind or whatever. This is why I am particularly interested in reports from places like Ireland where it is possible to measure the system inputs and outputs as a whole.
Robert Hargraves mentions the results for Ireland. It is towards the very end of the video, about minute 38, referenced here

Hargraves states that Ireland was expecting to reduce GHG emissions by 12% by installing wind farms. After installation and remeasurement the reduction was only 3%.

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The Robert Hargraves statement in the video is probably a misunderstanding. I suspect he was referring to 53% effective at 17% wind energy penetration from the Wheatley empirical study.

Wheatley’s posted a comment on the SEAI report here: http://joewheatley.net/quantifying-co2-savings-from-wind-power-redux-ireland-2012/

In part he says:

The Sustainability Energy Authority of Ireland (SEAI) have a new report which looks at CO_2 emission savings from wind energy in 2012. The electricity grid is simulated using \frac{1}{2}-hourly system demand, known outages, and inter-connector flows as boundary conditions. One simulation is done using actual wind generation in 2012 while another sets wind generation to zero. The difference in total CO_2 corresponds to emissions savings. The SEAI study was carried out using off-the-shelf PLEXOS dispatch modelling software.

[Table summarising the SEAI results]

The savings for RoI is far lower than SEAI’s earlier number 0.49tCO2/MWh. In terms of “effectiveness”, 1 MWh of wind generation displaces the CO_2 equivalent of 0.65MWh of average thermal generation. The earlier SEAI number corresponds to approximately one-for-one displacement. So this is a big change.

SEAI’s simulation findings can be compared to results based on empirical estimates. …

The NI CO_2 savings number is much lower than found by SEAI. In fact, SEAI’s 2012 savings of -0.8tCO_2/MWh is hard to understand, because only \approx \frac{1}{3} of NI generation came from coal.

Simulation and empirical approaches each has advantages and disadvantages. Both are sensitive to imperfections in the wind generation/system demand dataset. However SEAI make a number of claims about the 2011 empirical method results which seem to me to be wrong. …

Points to note:

SEAI’s study is a modelling exercise, not an empirical study of actual data.
SEAI did their study in response to Wheatley’s analysis, but did not analyse the same year or same geographic area so the results are not directly comparable.
SEAI has had to revise downward (very significantly) it’s claims about emissions avoided by wind generation. It also now recognises that CO2 abatement effectiveness decreases as wind energy penetration increases.
Wheatley has pointed out likely errors in the SEAI analysis and also pointed out the SEAI misunderstood or misrepresented his analysis.

All in all, Wheatley’s analysis has stood up to all attempts to discredit it since it was published (nearly 3 years ago). I suggest it is an important contribution to our understanding of the true effectiveness of intermittent renewable energy. Especially significant is that Wheatley’s results are consistent with others and together they provide a persuasive case that CO2 abatement effectiveness decreases with increasing wind energy penetration.

CO2 abatement effectiveness may be around 60% in the NEM when wind energy penetration reaches 15%. That would mean that CO2 abatement cost with wind would be 67% higher than estimates that assume wind energy is 100% effective (i.e. the standard assumption in most analyses). To clarify the significance of this, if the estimated CO2 abatement cost is $60/t CO2 on the assumption effectiveness is 100%, then the estimate should be corrected to $100/t CO2 (i.e. $60/0.6).

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http://www.theenergycollective.com/jessejenkins/2259541/can-market-fixes-overcome-declining-value-wind-and-solar-high-market-shares

I found this explanation of the energy market and particularly the declining value of wind and solar at high penetration rates easy to understand and I quote.

“But once wind and solar have displaced all fossil fuel-consuming resources at a given moment, adding more wind and solar won’t deliver much value. The additional savings of pushing nuclear, hydropower, or even other wind or solar generators off the market at that time is virtually nil. We just don’t save any more fuel (or other operating costs).”

This supports John’s conclusion that variable renewables have an upper limit on market share.

Particularly if the aim is to reduce CO2 emissions.

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John,

A very interested post.

As you say, there is no point in providing many times overcapacity of a renewable resource such as wind or solar if the generation from all the capacity is correlated. But the reverse of this is that it is worth providing additional renewable capacity if generation times are expected to be anti-correlated, or perhaps just uncorrelated to what you already have.

On the matter of wind and solar together there are a few comments.

Firstly the analysis of both wind and solar on the German grid gives different conclusions to yours.

The figures is from https://www.ise.fraunhofer.de/en/downloads-englisch/pdf-files-englisch/news/electricity-production-from-solar-and-wind-in-germany-in-2013.pdf/at_download/file

From the document the nameplate capacity of 35.6 GW of solar and 32.5 GW of wind in October 2013. The points all seem to represent hour slots. At no point does the total exceed 36 GW, and there are very few points higher than the installed capacity of either solar or wind.

The implication is that in Germany at least you can go higher than the maximum capacity factor of wind or solar in configuring total wind + solar renewables capacity without significant renewables overcapacity.

One caveat is that Germany is not an ideal place for solar and solar capacity factors are likely to be much lower (10-12%) than in Australia. Wind capacity factors in Germany may also be lower, which makes it easier for German wind and solar to be anticorrelated (there are just more gaps).

Secondly the analysis of wind capacity factor by month does not take into account one mitigating factor. In Europe and the USA and presumably Australia the typical demand tends to peak during the day. Germany used to have peaks at midday and then an evening peak.

Although solar has a lower CF (capacity factor) than wind – in the range of 10-25% (maybe 30% in places), the solar generation is never at off-peak demand times. So you can afford to configure solar + wind to provide some measure of total overcapacity during peak hours. Then wind capacity could be configured to provide a little more than average demand outside hours with significant daylight.

Provision of 3 or 4 hours of storage, either battery, or maybe provision of some CSP (Concentrated Solar Power) with hot salt storage to cater for the evening peak would clearly also increase the total proportion of solar without wasting significant wind power.

It would be very interesting if John could take into account the daily demand curve and solar generation daily curve in some future analysis.

Thirdly, the cost has to come into it. Assuming that the CCGT backup you need is a fixed capital cost, the cheaper wind and solar is, the more you can afford to overconfigure wind and solar to provide higher levels of CO2 abatement, even if you do throw more more power away (or better, find a productive use for it such as Power to Gas [syngas]). In particular once the LCOE cost of wind and/or solar gets below the fuel (and other true variable costs) of CCGT then you can start overconfiguring. And the IEA are saying that by 2050 solar LCOE costs may get as little as 1.5 US cents / kWh.

Fourthly capacity factors of wind and solar are expected to rise. For wind, the towers will be taller and the rotors bigger, but the generator size may not increase. This captures more wind energy, and throws more away at high wind speeds but also increases generation at lower wind speeds as a fraction of nameplate capacity.

For solar one trick is to overconfigure what are now becoming increasingly cheap panels relative to the harder to reduce costs of the rest of the system. For fixed tilt systems you might also face the panels further to the rest which would not increase the capacity factor, but might make more of a dent in the evening peak.

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The implication is that in Germany at least you can go higher than the maximum capacity factor of wind or solar in configuring total wind + solar renewables capacity without significant renewables overcapacity.

It is recognized you can do it from a purely technical point of view. The point is, it is very costly.

To be financially and economically viable we need the cheapest solution that meets requirements. The main requirements are reliability of supply and cost.

The excellent ERP 2015 report ‘Managing Flexibility Whilst Decarbonising the GB Electricity System’ http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf considered the relevance of weather dependent renewables in Germany to the GB electricity system. The lessons are relevant to other isolated electricity systems, such as the NEM.

At the end of 2014 Germany had 36 GW of wind and 38 GW of solar, with a peak demand of over 70 GW. So at first sight it might be thought that Germany is already tackling issues associated with intermittency that the GB system will have to face if the UK also aims for significant production from renewables. However, closer examination shows us that Germany is not in the same position and the solutions currently employed there are either not possible or unpalatable for the GB system.

…

Therefore Germany does not provide much evidence on how the GB system could deal with high penetration of renewables, as:

• Its production from wind and PV is still quite low compared to scenarios explored here

• Although well short of having surplus renewables generation it chooses to export a lot of production so that high carbon plant runs baseload

• Most of its immediate trading partners (with the exception of the small Danish system) have not yet constructed large amounts of wind and PV

• Germany benefits from being a small part of a very large synchronous system

Virtually all lines of evidence show the least cost way to make large reductions to the emissions intensity of electricity is with a large proportion of nuclear and little or no weather dependent renewables. The ERP analysis is an excellent, recent example. It shows that the least cost way for the Great Britain electricity grid to achieve the same emissions intensity as France (i.e. 42 g/kWh in 2014) would be for GB to install 32 GW of nuclear and no more weather dependent renewables (e.g. wind and solar). http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf

By the way, as has been pointed out to you on several other threads where you have made similar arguments, the low or negative statistical correlation of wind and solar is almost irrelevant for capacity planning because there are periods where there is zero or near zero generation from wind and solar. Such periods can last for days, and weeks, and below average output can last for months. Energy storage is prohibitively expensive.

In short, renewables are not the answer to substantially lowering the emissions intensity of electricity – nuclear is (see Figure 14 in the ERP report).

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@ Peter Davies, 26 December 3015:
See http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf

Figure 5 on Page 14 plus the associated text provide an eloquent demonstration of the of the interaction in UK of new wind and new nuclear when modelling reductions in carbon intensity.

In round figures, in order for the UK to reach its National Renewable Energy Renewable Action Plan goals by combinations of new wind and nuclear generation capacity and to meet the CCC target carbon intensity of generation of 50 g/kwh, the model’s outcomes range between (for UK and subject to modelling assumptions)
• 22GW new nuclear plus 28 GW new wind or
• 30GW new nuclear plus 20 GW new nuclear.

This is an example of where 28 GW nameplate of new wind displaces 8 GW of new nuclear. I have not worked back to an “energy sent out” basis, but even that would be uncomplimentary to wind.

The study, of course, is much more detailed than this simple comparison. The discussion of “No new nuclear” indicates that an infinite addition of new wind will fall very much short of the target.

Further,“…although renewables output in Germany is less than half of demand for nearly all of the time, much of the renewables production (typically half) is exported to its neighbours rather than displacing the highly emitting lignite plant. Figure 3 illustrates this well”.

In similar manner, SA’s grid is only part of the much larger Australia NEM. It is outrageous to draw conclusions about the effectiveness or otherwise of SA’s wind farms without considering the power flows to and from the remainder of the NEM which, as in Germany, support rather than reduce lignite power stations and thus do little to reduce system-wide carbon intensity.

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@singletonengineer (26 Dec 2015)

Fig 5 from http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf is also very interesting. What it shows is that around 70GW of new wind alone can abate 50% of the current UK CO2 emissions. This is an estimate from continuing the top curved line, not from the linear extrapolation given by the second (straight) line down.

However, the chart itself is a very crude calculation, with 3 weaknesses.

It does not include solar as well as wind, and the Fraunhofer chart in my post above shows that wind and solar are anti-correlated in Germany, and therefore presumably UK. Therefore you can achieve a higher abatement of CO2 by including solar in the mix, without significantly increasing the costs.
It is very obvious to anyone that thinks about it a little that just increasing the quantity of a single correlated type of variable generation has limits. However, these limits and the cost effectiveness are significantly higher if more than one type of variable generation is included (e.g. both wind and solar). Mostly the exercises that set out to prove that nuclear is essential or the most cost effective solution fallaciously compare only with increasing quantities of wind from a single location (northern Europe) – and usually existing onshore wind with low capacity factor instead of the likely move to more offshore wind which is likely to have a capacity factor exceeding 50% in the future. Further, the inclusion of North African wind (uncorrelated with the North Sea area) further reduces renewables generation gaps.
It shows only the effects of new nuclear, not those of additional storage or demand response solutions, which are mentioned as alternatives in the text. Some of the industrial demand response solutions, such as new aluminium smelters, provide a significant degree of load flexibility, enabling demand to be increased or decreased at the drop of a hat (or a drop in the wind).

You have to assume we are looking at a 2030 solution, so the strong implication is that two major changes in demand will have happened by then, irrespective of the 2030 solution chosen for UK power generation.

A) Industrial demand response implementation will be well underway by then.
B) Land transport will be mainly electric vehicles EV’s) by then

The wholesale switch to EV’s will depend on battery prices, and charging network implementation, but all the evidence is that batteries will be below the magic $150 / kWh in the late 2020’s, which is considered the magic figure for straight purchase costs to induce consumers to buy EV’s on purchase price comparisons alone. With the simple and obvious change to regulation to ensure EV charging can be controlled by the grid, this will provide a significant measure of demand response flexibility in domestic electricity use.

The effects of the demand flexibility in both these areas, for just wind alone, would probably straighten the line in figure 5, leading to 133 g / kWh with just wind implementation, and considerably lower when anticorrelated solar is added.

By 2050 (or more likely earlier after the Paris ambition to restrict rises to 1.5 degree C) UK generation has to get to zero carbon emissions, not 50g / kWh.

The point about Germany not modulating lignite generation output to complement renewable generation but choosing to export instead is irrelevant. By 2030 there will be no hard coal or lignite generation left in UK or Germany, and the technology filling in the gaps left by wind and solar will be fast start CCGT which is capable of starting in 20 minutes or less, and, once started, capable of the required ramp rates, particularly with some help from national pumped hydro schemes. UK government (whose energy policy seems in some disarray at present) did announce it was shutting coal and would ensure orders for replacement CCGT stations, though it might find it has to subsidise the new CCGT stations somehow before it gets bids to install them.

Everyone understands that this CCGT generation is likely to have a low load factor by 2030. However, the absolute CCGT capital costs are also very low, so this is going to make little difference to the costs of units of power supplied.

In https://www.worldenergy.org/wp-content/uploads/2013/09/WEC_J1143_CostofTECHNOLOGIES_021013_WEB_Final.pdf
the capital cost of UK CCGT is estimated as 0.76M $/MW, whereas, if the same capacity of onshore wind and solar PV together is deployed (which it would be to get high levels of CO2 abatement) the capital cost currently would be 1.5M + 1.6M = 3.1M $/MW. The backup costs are thus some fraction of 20% of current total capital costs – in this scenario where CCGT might be generating some 40-45% of the time, the fraction would be 0.5, so the backup for wind and solar adds some 10% additional cost. If the CCGT is already there and we keep existing nuclear, then the back-up cost is even lower than this.

As wind and solar get much cheaper and fall below CCGT fuel and variable costs) towards 2030 and particularly 2050, the absolute capital cost of CCGT stays the same. But the overall capital costs are lower and since gas fuel is expensive, the LCOE price reduces.

In conclusion the ERP report seems to have focused on a couple of extreme solutions to UK’s problem (mostly wind, mostly nuclear or some combination of just these two), whereas the cheapest and most effective solution will encompass multiple renewal generation types (biomass, solar, wind), industrial process and domestic EV demand response, expansion of pumped hydro storage, interconnection to Norway’s huge pumped hydro potential and interconnections to Iceland’s dirt cheap hydro and geothermal power potential.

Although ERP is a respected body, on this occasion they appear to have missed the mark somewhat, although the report does say “A much deeper examination of the issues raised within this report is needed. ERP’s modelling and analysis has only begun to scratch the surface and ERP does not have the resource or capabilities to take this work much further.”

In short it does not appear to add very much to what is currently known about the UK power grid because of a very constrained analysis which really only states the obvious problems instead of exploring the full continuum of combinations of solutions which will provide an efficient system.

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Fig 5 from http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf is also very interesting. What it shows is that around 70GW of new wind alone can abate 50% of the current UK CO2 emissions. This is an estimate from continuing the top curved line, not from the linear extrapolation given by the second (straight) line down.

True. But 31 GW of nuclear alone can abate 90% and at much lower overall system cost (as shown in Figures 11 and 14). Nuclear can do9 the job, but weather dependent renewables cannot. Furthermore, building weather dependent renewables delays significant progress and means emission will be higher in 2030 and 2050 than if we do not waste money building them but focus on building the least cost solution now.

However, the chart itself is a very crude calculation

Given the nonsense analyses you’ve been doing yourself and trying to justify on other web sites, this comment must be intended as sarcastic, yes?

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In response to my comment :

“The implication is that in Germany at least you can go higher than the maximum capacity factor of wind or solar in configuring total wind + solar renewables capacity without significant renewables overcapacity.”

Peter Lang on 26 Dec 2015 said :

“It is recognized you can do it from a purely technical point of view. The point is, it is very costly.”

By 2030 there will be a significant capability for demand response, such as flexibility of +/- 25% in certain large-impact industrial processes such as aluminium smelting, and in domestic EV charging (EV’s will be pervasive for land transport by 2030). This means that demand can be increased (or reduced) instantaneously using Smart Grid technologies so ensure that virtually all variable renewable generation will be used to satisfy demand, even when a degree of renewables overcapacity is provided. This can be achieved within the capabilities of the existing UK transmission grid which itself is already overconfigured to maintain continuous operation when generation problems require a switch to alternative generation locations.

In this context there is virtually no wasted renewable generation and thus it is no longer costly to provide some overcapacity of the total of wind and solar generation combined.

You have to look outside the current grid implementation to examine the advantages of Smart Grid approaches which will solve a number of issues which high levels of renewables generation would cause on the current UK system – but which would not be present on the expected 2030 or 2050 UK grid implementations.

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Peter Davies,

By 2030 there will be a significant capability for demand response,

Demand response is taken into account in the ERP analysis. The ERP analysis was done by an expert groups who understand the electricity system and know what they are doing. As you have admitted elsewhere your career has been in IT until recently and you are now now studying for a PhD in nano energy storage. There is an enormous amount you could learn by asking question on Brave New Climate. But I’d recommend you take that approach asking.

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The low capacity factor of weather dependent renewables is only one part of what is important and relevant for policy analysis. It is just one of the many issues that in total mean weather dependent renewables cannot supply a large proportion of global electricity and therefore cannot make a large contribution to reducing global GHG emissions. Many lines of evidence show this, for example:

Non-hydro renewables have not managed to do so to date in any large electricity grid, (hydro cannot help; its capacity growth is limited so its share of global electricity generation will decrease over future decades).
Growth rates of wind and solar over 25 years have achieved just 3% (wind) and 1% (solar) of global electricity supply. Over 25 years, wind power has grown at just 1/6th and solar at 1/18th the rate nuclear grew at. The recent growth rates, which are off a near zero base and are driven by enormous incentives, are not an indication of future growth rates. Signs are the recent growth rates may have already peaked.
The cost of electricity and CO2 abatement cost is much higher for wind and solar when all costs are properly included and a proper comparison is done. Adding more intermittent renewable technologies adds cost but does not remove the need for nearly full backup capacity or high cost energy storage.
Industrial countries with a high proportion of non-hydro renewables have high cost electricity and high CO2 emissions intensity. For example, compare France (with a high proportion of nuclear) with Germany (with a high proportion of wind and solar). Germany’s electricity prices are twice France’s and its CO2 emissions intensity is 6x France’s.
Wind and solar are not sustainable – their ERoEI is insufficient to enable them to power modern society and reproduce themselves.
The cost of energy storage that would be needed to make intermittent renewables capable of providing reliable power make intermittent renewables prohibitively expensive – at least five times the cost of nuclear.
CO2 abatement effectiveness decreases as penetration increases – e.g. to around 50% CO2 abatement effectiveness at 20% penetration.

The weight of evidence shows a large proportion of nuclear power is the cheapest way to make large reductions to CO2 emissions intensity of electricity.

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Peter Lang

You make a lot of claims that has no foundation in links or proper analysis.

You can create 100% carbon free energy supply not only to the electric grid but for all purposes. Synfuels has previously been suggested by the author in this brilliant article. https://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/

Or you could power district heating via heat pumps and heat storage, or stop using natural gas and oil for heating and start using solar thermal and or heat pumps.

Or you could use the trick described in the article where the middling of wind power allows slightly higher penetration according to the author.

Besides no one plan to shut down existing hydro power plants or to stop using biomass and both can provide some power production that can regulate the match between demand and supply. More exotic forms of renewables such as OTEC and geothermal are base load power plants with capacity factors on par with Nuclear.

Modern wind turbines have much larger capacity factors than average installed wind turbines so the intermittence is actually decreasing. You might want to read the article and address your critique directly to the author.

As for the growth rates of solar, wind and nuclear it could be very interesting to see links that support your claims if such links indeed exists.

Here is what I found if we try to choose the golden age of nuclear vs the most recent numbers available for wind and solar.

http://www.worldnuclearreport.org/The-World-Nuclear-Industry-Status-52.html

Graph number four gives a good representation of the growth in nuclear power plants.

13 Charts On Solar Panel Cost & Growth Trends


The links shows the development up to 2012 whereafter the market exploded with even high growth rates which increased the capacity by 77% in total 2013 and 2014. http://cleantechnica.com/2015/04/02/global-solar-pv-capacity-ends-2014-177-gw/

Your speculation that “The recent growth rates, which are off a near zero base and are driven by enormous incentives, are not an indication of future growth rates. Signs are the recent growth rates may have already peaked.” are very confusing.

In USA the cost of coal for production in an average performing coal power plant is $0,022/kWh with the current coal prices that has broken down the value of the coal companies to a tiny fraction of previous market valuation. The price of coal does not include delivery of the coal, staff at the coal power plant, depreciation, interest, decommission cost, insurance or anything else needed to run a coal power plant.

The average 20 year wind PPA contract in USA was in 2014 $0.023/kWh or if you include the PTC $0.035/kWh.

Your CO2 abatement philosophy is unintelligible to me. I suggest you read these analyses because they are likely to influence the business decisions going forward http://oilprice.com/Energy/Coal/Goldman-Sachs-Peak-Coal-Is-Here.html or the European counterpart http://www.businessgreen.com/digital_assets/8779/hsbc_Stranded_assets_what_next.pdf http://www.nrel.gov/docs/fy15osti/63604.pdf

2014 was most likely the year where coal peaked and the main reason why is that it is no longer economically viable in most parts of the globe simply because wind and solar now define grid parity.

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@David B Benson

“Aluminum smelting is considerably less flexible than it appears you think it is.”

Sure it is – at the moment. However, have a look at what Trimet is proposing :-

http://www.bloomberg.com/bw/articles/2014-11-26/germanys-trimet-aluminium-turns-smelting-tanks-into-batteries

http://www.resourcereports.com/wind-power-germanys-new-record-trimets-storage-experiment/

http://www.trimet.eu/en/presse/pressemitteilungen/2015/2015-09-17-2014-2015-financial-year-voerde-and-france-successfully-integrated

Currently, at the request of grid managers, electrolytic aluminium smelting cells can be turned off for 2-4 hours, depending on the rate of cooling, and then turned back on before the contents solidify around the anode (which would spell trouble). They only do this for hard cash.

Trimet is proposing to run its cells at a rate such that the power can be changed by up to +/- 25% almost instantaneously to assist in controlling short, medium and long-term fluctuations to the electricity supply. It is conducting preliminary trials.

Now it is true that other companies do not have to follow suit, but the requirement to do this is likely to become pretty pervasive and there is absolutely no technical reason why this technique should not be pervasive. The issues are around grid policy issues and financial rules for demand management. But these problems are soluble.

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“The requirement to do this is likely to become pretty pervasive”. You could equally proclaim the imminent collapse of Western industrialisation. However it is unwise to say it so complacently.

On this website we have witnessed the deaths of more than a thousand unnecessary evacuees from Fukushima proclaimed as a triumph by the renewables movement. In both cases it is triumph for self-righteousness, bigotry and malice.

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@Peter Lang

“Demand response is taken into account in the ERP analysis. The ERP analysis was done by an expert groups who understand the electricity system and know what they are doing. ”

The ERP report mainly just assumes about demand response what you don’t like, which is that demand response effectively eliminates the inefficiencies of large scale wind and solar, meaning they can be cheap sources of CO2 abatement (133 g / kWh with 60 GW of wind capacity) because no power is thrown away. The report also points out that demand response does not help solve the problem of gaps with reduced wind and solar power of more than 24 hours, which is hardly new news.

Demand response is not taken into account specifically in any of the modelling work. In fact, the ERP report specifically says it is excluded.

Unfortunately, the ERP analysis uses DECC prices for commissioning in 2016/7 when doing calculations for a 2030 grid with plenty of wind and solar installed well after this date. Probably by 2030 and certainly by 2050 onshore wind costs will reduce by 40% (based on a 10% reduction per doubling of global wind capacity), and solar PV by 60% or more (18% per doubling). See http://www.irena.org/DocumentDownloads/Publications/IRENA_RE_Power_Costs_2014_report.pdf . That is assuming no technology breakthroughs. The IEA estimate solar PV could be as low as 1.5 cents / kWh by 2050.

Some of the conclusions of the report are thus very suspect because the method section says they are optimising for costs (which are based on current DECC pricing). The pricing data is only available from the references and not from the body of the report – which is not very helpful, and the only pricing reference is for the DECC prices referred to.

As a result, one of their conclusions is that hydrogen as a storage mechanism is too expensive because the efficiency is low (round trip power to gas to power around 42%, or better if heat output is included for community heating). However, this does not take into account the price reductions in solar because that was outside the scope of the prices considered. If solar power in southern Spain is 1.5 US cents per kWh by 2050 then, assuming a 1.5 cents / kWh for HVDC transmission lines to London, the fuel costs of renewable hydrogen in UK for CCGT backup become 7 cents / kWh. CCGT + renewable hydrogen is thus clearly a viable reliable zero emission generation technique for filling the long renewables gaps.

The authors do say they have barely scratched the surface of the modelling which must be done and suggest follow-up activities, some of which are likely to take place at my college (Imperial College London).

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Peter Davies,

Your comments are simply ‘arm waving’, baseless assertions about relative trivia. You have not stated how much difference your trivia would make. It’s a common diversionary tactic to throw up unsupported, baseless assertions as you are doing here and have done on other web sites. Unless you can provide a link to a better, more thorough, more complete, more competent analysis of the GB system, and showing the technology options mixes and true cost of achieving the emissions targets by 2030, you should admit you are barking up the wrong tree trying to argue that weather dependent renewables and your nano storage are a viable option. They are not!

Weather dependent renewables cannot supply a large proportion of global electricity. Many different lines of evidence show this, as summarized in my previous comment: https://bravenewclimate.com/2015/11/08/the-capacity-factor-of-wind/#comment-440447 .

I suggested on another web site you’d make a much greater contribution to the good of humanity if you changes the subject of your PhD from nano storage to nuclear energy.

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The 2015 ERP report Managing Flexibility Whilst Decarbonising the GB Electricity System http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf analyses the costs of reducing CO2 emission from electricity in GB with different mixes of electricity generation technologies.

I’ve interpolated from the charts the CO2 emissions intensity and the electricity cost increase that would be needed to achieve them. The cost increase is from the baseline which is the electricity cost of the existing system with a 70/t CO2 carbon price added. The report states that a £70/t CO2 carbon price would not be sufficient to drive the changes in the electricity system needed to achieve the CO2 emissions reduction targets.

I’ve eyeballed from Figures 5 and 6 some values of CO2 emissions intensity for different mixes of wind and nuclear in the GB electricity system. The fourth column is eyeballed from Figure 11 (left chart); it is the change in total system cost per MWh above the baseline. The rows are ordered by decreasing CO2 emissions intensity. The columns are: ‘Wind, GW’; ‘Nuclear, GW’; ‘CO2, g/kWh’; ‘TSC, % change’.

Wind, GW Nuclear, GW CO2, g/kWh TSC, % change
56 0 180 8.0%
30 10 140 3.2%
56 11 100 11.4%
30 20 60 7.7%
56 18 50 ~15%
42 20 50 11.0%
0 31 50 ~3.0%
0 32 40 ~4.0%
0 35 25 7.7%

For comparison, France’s CO2 emissions intensity was 42 g/kWh in 2014 http://www.rte-france.com/sites/default/files/bilan_electrique_2014_en.pdf; Britain could achieve that with 32 GW of new nuclear and 0 GW new wind.

The table shows the least cost options to achieve the greatest reductions in CO2 emissions intensity of electricity is with mostly nuclear and little or no wind. GB could achieve the same emissions intensity as France with 32 GW of new nuclear, 0 GW of new wind for a ~4% real increase in cost of electricity.

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@ Peter Davies,
The first of those links seems to imply they’ve found a way to make the electrolysis process run backwards, but I can’t understand how they could possibly do so with a graphite electrode. Are they using something else?

If they’re not, even varying the reaction speed is cause for concern because of the amount of CF4 produced.

@ Peter Lang,
“Wind and solar are not sustainable – their ERoEI is insufficient to enable them to power modern society and reproduce themselves.”
No matter how many times you say that, it will never be true. ERoEI is of critical importance in the early stages of research for renewables when even producing positive net energy is a challenge, but solar and wind power are way past that stage now. ERoEI is also of some importance with fossil fuels, as supply is limited. But for wind and solar, with unlimited supply and strongly positive net energy, ERoEI is irrelevant to the needs of modern society. What counts is cost, and most of the cost is unrelated to energy input.

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Peter Davies — Thank you for the information about Trimet. But this won’t help here in Washington state where the last two aluminum smelters are closing at the turn of the year.

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Peter Davis’s comments re demand management and aluminium smelters contains nothing new.

Australian aluminium producers have long offered limited demand reduction, at a price, via their contracted generator. Unfortunately, the details are commercially sensitive and thus are not on public display.

However, 50% reduction for an hour or more is in the correct Australian ballpark.

Many other loads are capable of similar management, given favourable commercial environments. Think: Turning blocks of domestic refrigerators, freezers, air conditioners and pool pumps off for an hour when the market price for electricity is high.

Demand management may be a step in the right direction, but can it ever be the solution to the problem, given Jevon’s paradox?

This thread is/was about capacity factor. Demand management is historically a tool for managing unplanned outages (ie breakdowns), peaks and troughs in demand. To ask demand management to extend its role to accommodate the poor capacity factors which are part and parcel of wind or other weather-dependant terchnologies is hypothetical but not practical in the real world.

I suggest that this discussion be continued either on an OT or on a thread discussing demand management, if one exists.

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@Aidan Stanger

“The first of those links seems to imply [Trimet have] found a way to make the electrolysis process run backwards, but I can’t understand how they could possibly do so with a graphite electrode. Are they using something else?”

Aidan, you are clearly not used to manufacturer marketing speak which the press seems to pick up on because it sounds good! What Trimet are proposing is to run with an average nominal load / electrolysis rate of 100%. When wind power is plentiful and cheap they increase that to 125%. When there is very little wind or solar power then they reduce the rate to 75%. Effectively they are claiming they are acting as a battery, sometimes absorbing excess power, sometimes releasing it, but this is always relative to a nominal load which is ongoing!

“If they’re not [using something other than a grahite anode], even varying the reaction speed is cause for concern because of the amount of CF4 produced.”

From a quick google and scan for the CF4 gas emissions there seems to be no mention that CF4 emissions are rate dependent, but rather more dependent on the process used to electrolyse the aluminium oxide. It also seemed to imply the gases were normally captured (or the operators get free dry cleaning and the atmosphere gets yet more greenhouse gases). I’d be interested to read anything on rate dependence if you have a favourite link.

I was talking to a PhD student at my college who was working on the possibility of provision of similar load rate variation for other industrial processes which are large-scale users of electricity, so aluminium smelting, though likely the first, ought not to be unique.

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@Tony Carden

“I notice that you have a little IF in your statement about solar and a time frame of 2050. I argue that IF the Chinese can solve the technical issues of a Thorium Molten Salt Reactor by 2050 which they seem to have some confidence of doing, then the world of energy production and electricity generation will be revolutionized forever.”

Absolutely there’s an “if”. There’s no doubt solar PV prices will tumble in future, but no-one really knows where they will end up by 2050. Notably the IEA usually underestimates the progress of renewables so it is unusual for them to make an optimistic-looking guess on 2050 solar PV such as 1.5 cents / kWh.

Solving the technical issues of Thorium Molten Salt Reactors, or fusion reactors for that matter, by 2050 would indeed be a great technical achievement, but the problems of nuclear fission have more to do with a poor public perception than anything else, regrettably. If wind and solar can meet the requirements at a reasonable price then the public have a choice if both come to pass.

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I do not see that the issue of Nuclear Power having a poor public perception should deter the scientific community from advocating the facts as they stand, especially when that poor public perception is a result of misinformation, disinformation, and just plain lies.

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Peter Davies –

So the statement that ” It can then resell the power when demand is at its peak” is just inaccurate reporting? Fair enough – that did always seem to be the most likely explanation, and certainly the simplest.

I don’t really know much about CF4 emissions from Al refining, but ISTR reading elsewhere on this site that its formation depends on voltage, which I’d expect to be what controls the reaction speed unless they vary the number of electrodes in use.

I am now aware of any other industrial processes that use both fluoride electrolytes and graphite electrodes.

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@Peter Lang

The average 2014 Nordpool spot price for electricity is approximately $0.03/kWh http://www.nordpoolspot.com/Market-data1/Elspot/Area-Prices/ALL1/Yearly/?view=chart

The reason behind the drop from 2010 to the present is mainly fast dropping wind power costs but there is also an annual variance because the precipitation varies the output from the hydropower and the influence from solar during the summer months.

Polen, Germany, Holland and UK plan more HVDC connections to Nordpool, which will increase demand and thus the average spot prices while also decrease price spikes and limiting the few hours annually where the spot price is negative (producers pay to produce power).

Nordpool electricity is at least a factor 4 cheaper than electricity from Hinckley Point £92.50/MWh ($0.137/kWh) and Nordpool is not inflation regulated 35 year into the future as Hinckley point.

The 1.400MW NSN link has been contracted for €1.5 billion which is €0,933/MW. http://nsninterconnector.com/latest-news/ and the 3.200MW Hinckley Point is budgeted at €24 billion, which is €7,5/MW. https://en.wikipedia.org/wiki/Hinkley_Point_C_nuclear_power_station

UK is paying A FACTOR 8 MORE FOR HINKLEY POINT electricity generation capacity with around 98% availability than for the NSN link access to always ready dispatchable capacity and unlike Hinckley Point or for that matter any nuclear power plant a HVDC transmission connected to Nordpool can ramp up to 100% and down to minus 100% and do it very fast.

The NSN link flexibility will provide UK with the option to increase their own wind capacity and as the article states geographic spread will middle wind power and allow a larger share of the power generation.

Your belief that UK cannot be powered by renewables seems without any sort of rooting in reality and your ideas about cost of energy generation as presented by you appear to be purely fictional because you do not link to a specific market price as available at Nordpool.

Since Nordpool is the largest free electricity market in the world and you not seem to understand what electricity costs and how it is traded I decided to give you this older introduction. http://www.ft.dk/samling/20091/almdel/epu/bilag/354/882165.pdf

Unless you have a PPA or a FIT you are forced to sell at the spot market. In the last few years thermal power plants of any kind have been under a huge pressure because in the Nordpool region selling electricity is unprofitable and their protected access to sell district heating is under siege by electricity driven heat pumps that can produce heat cheaper and move more power consumption to electricity.

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@Tony Carden

The problem you have is that the very word “nuclear” causes a problem. A significant fraction of the population associates nuclear with nuclear bombs (which are not exactly a good sales pitch for the world “nuclear”), and have heard of Three Mile Island, Chernobyl and Fukishima. With PR like that, you don’t really need disinformation, misinformation and lies to turn people off.

Take “nuclear magnetic resonance imaging” as an example. Hospitals used to have departments with such titles. To the best of my knowledge no-one has ever tried to make propaganda against NMRI (nor tried to sell it to the public for that matter), but the very inclusion of the word nuclear has caused enough issues that for the last 15 or 20 years the word “nuclear” has been dropped to give the name MRI (magnetic resonance imaging). Apparently the public felt much safer using it after the rename.

So the best way to make nuclear power more popular would be to rename it. “Fission power” probably would not hack it either.

And it’s the fact “nuclear” is in the name which means that no country has yet got political agreement to the location of a nuclear waste repository.

As for educating the entire world population so they no longer get negative vibes from the word “nuclear”, good luck with that!

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So, no negative vibes associated with undeliverable, high cost, less safe, unworkable, unreliable, weather-dependent, obtrusive so-called renewable wind and solar power either?

Unpalatable as some terms are, in the long run the whole truth beats half-truths.

It is difficult to analyse fine distinctions when slogans and preconceived notions are permitted to dominate discussion, especially discussions about expensive, difficult, multi-decade electricity options.

“Nuclear power” and “fission power” at least are able to be clearly defined and hence understood. Tell me again how the term “renewable” applies to the myriad abandoned solar and wind junk-farms for which photos are available online. Google: “abandoned wind farm image”.

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My statement was said with a deep tone of irony.
I am glad that you have rejected it and I really do agree with you.
What is called for here is LEADERSHIP.
In fact, I am deeply disappointed that in the enlightened 21st Century, a Phd student would advocate the path of ignorance as opposed to the challenge of enlightenment.
Thankfully the genius of Nikola Tesla and others like Barry Marshall was not daunted by the fact that their science was not popular.

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My research has revealed that over the past 20 years, the world has spent $367billion on subsidies for the renewables, especially wind for a return of 2.8% of the world’s electricity and with no measurable reduction in greenhouse gas [CO2] emissions. How’s that for fiscal irresponsibility? I know that it will offend you Peter Lang and anyone else for that matter. The renewables have been a scandalous wasteful folly, inspired by the Greens and other environmental groups and further development of them, especially in South Australia should be terminated. Thanks John Morgan for your study which sits very well with one done by a friend of mine in 2013.I included a summary of his study in the submission I sent to the Scarce Royal Commission. As Barry knows, I’ve been an advocate for nuclear power for Australia and speaking for it since 1998. And if any of the commenters on this blog remain anxious about Australia going nuclear then you need to ask yourself just one question. ” Why are 32 countries, including Japan again, continuing to generate 12 % of the world’s electricity in 436 reactors. Those countries and 17 others are building 70 reactors right now, 174 reactors are firmly planned and 301 proposed for the future? Those are April 2015 World Nuclear Association figures. Incidentally, I asked Ian Lowe why all that nuclear build in July 2013 at the ATSE nuclear conference. Lowe responded with 150 countries aren’t building nuclear reactors. And that from an Emeritus professor??? Aaarrrgghhh!!!

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@Terry Krieg

“My research has revealed that over the past 20 years, the world has spent $367 billion on subsidies for the renewables, especially wind for a return of 2.8% of the world’s electricity and with no measurable reduction in greenhouse gas [CO2] emissions. How’s that for fiscal irresponsibility? ”

Since the world energy expenditure has averaged over $4 trillion pa over the last 20 years, then in that time over $80 trillion has been spent on energy. $367 billion, while notable, represents less than 0.5% of this total.

The purpose of renewables subsidies is to nurture immature technologies to the point where they reach volume installation, allowing mass production efficiencies to kick in. The aim is for the new technology to get to volumes where it needs no subsidies and reduces overall energy costs.

In the case of wind and solar, grid parity is about to be reached. Before 2030 we will be making significant cost savings from these technologies. By 2050 any investment in subsidies for wind and solar up to 2020 will be repaid handsomely by much reduced electricity prices and zero CO2 emissions for electricity generation.

And that’s the way new energy technology is developed.

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@ Peter Davies:
Peter chose to compare expenditure on renewables against the total market and came up with a nonsense figure of 0.5%.

As a percentage of market share of, say, 2%, that subsidy is seen for what it is: a loading of 25%.

Peter’s post then degenerated into arm-waving and motherhood statements, capped off by an unreferenced affirmation about reaching grid parity – whatever that may be in his world.

The term “grid parity” has been used at one extreme to refer to bid prices in the wholesale market, exclusive of system services such as frequency control and transmission services from boondocks to somewhere near a customer. At the other extreme it has been used, in relation to rooftop domestic solar, to retail rates at the meter, but still with an assumption that the domestic supply is a “must take” generator and that all others are subject to curtailing during times of excess generation capacity. Without a reference which is sufficiently detailed to ensure that terms have meaning, statements on such matters as “grid parity” are meaningless.

Meanwhile, the capacity factor of wind remains essentially unchanged, it is backed up almost everywhere by one or more of:
. Open cycle GT, which is almost universally the case;
. Pumped storage or other hydro, which are geographically limited, environmentally challenging and, in the case of pumped storage hydro, come with an 80% (I’m being generous here) round trip energy efficiency. Given that in Europe pumped hydro represents less than 5% of total installed capacity and is further limited by the volume of the upper pondages and transmission system constraints, how effective can pumped hydro ever be at backing up a system with, say, 50% wind power?
. Next door neighbour’s load-following nuclear power, as for example, Germany’s imports from France; or
. Good old (or new) lignite power operated as baseload plant while the surplusses of wind are pushed into the wider European grids, resulting in half of the renewables not being used where they are generated (Germany) but instead diffused throughout adjacent countries, in order to maintain system stability in the face of unreliable weather-dependent diffuse power sources such as wind and solar.

What, I wonder, are Peter’s answers to the stability issues which are demonstrated, time and again, by Germany’s pattern of exports of renewables and imports of stable power from neighbouring countries, all the while maintaining year-on-year increases of CO2-e emissions? As Professor Julius Sumner Miller famously said frequently more than 50 years ago, when science was considered to be a suitable subject for popular TV programs, “Why is it so?”.

Why is it so, that despite receiving 25% subsidy/support, coupled with “must run” market access, plus hugely favorable press, globally and over several decades the wind power industry that meets its own stated goals?

Could it be that there are limits that simply cannot be overcome?

Where are the real groundbreaking, undeniable successes from the hundreds of billions of dollars spent?

The purpose of subsidies is not as Peter stated. It is not to support limited technologies for decades, despite clear evidence of inability to ever meet the twin goals of cost and performance.

Subsidies are for achieving goals. Greater subsidies must be used to achieve greater goals.

Global subsidies must achieve global goals, in this case, a contribution to climate stability through reduction in global carbon emissions. Why is it not so?

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Why is it so that, despite receiving 25% subsidy/support, coupled with “must run” market access, plus hugely favorable press, globally and over several decades, the wind power industry has failed to meet its stated goals?

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…subsidies for the renewables, especially wind for a return of 2.8% of the world’s electricity…
Since the world energy expenditure has averaged over $4 trillion pa over the last 20 years, then in that time over $80 trillion has been spent on energy. $367 billion, while notable, represents less than 0.5% of this total.

Very broadly, 2.8% capacity achieved after 0.5% renewable investment would merciful and madness not to promote.

I cant appreciate were the passion comes from to rile against minutiae of renewable power issues.

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@apasser queried our passion over “capacity”.

As used here, “capacity factor” is the ratio of the average power produced by a wind generator (whether turbine/farm/region) versus its maximum power production. It is about 30%. The passion arises because the un-replaced 70% inevitably comes from fossil carbon emitters. The emitters cannot be eradicated as something bad, while the wind production it backs up is considered a necessary “reduction” of fossil carbon.

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@singletonengineer

Peter chose to compare expenditure on renewables against the total market and came up with a nonsense figure of 0.5%. As a percentage of market share of, say, 2%, that subsidy is seen for what it is: a loading of 25%.

Wind subsidies are an investment for the future. The point of wind (and solar) power is to make future huge and cheap reductions in CO2 emissions. It is nonsensical to quote the cumulative subsidy levels against current global capacity costs at the precise point where wind is just reaching grid parity. This is precisely the point in time where all the subsidy costs of wind have been incurred, but very few of the savings have been realised.

If you project forward to 2030 or 2050 then wind power may generate up to 60% of global electricity, and do so very cheaply. At that point the subsidies of 0.5% of global energy expenditure will be repaid many times over by the benefits.

It seems strange you are prepared to ignore the huge initial government technology research and subsidies for nuclear power development, but are not prepared to do the same for wind power.

The US congress seems to have it about right (and I never thought I would ever say anything nice about the current US congress). The wind energy PTC will remain at 30% this year (2016), gradually tapering off over the period 2017-2019 and expiring in 2020. Thereafter wind is expected to save money for USA utility customers.

However, US onshore wind is at grid parity in some windy places in the USA with no subsidy.

The solar ITC will remain at 30% until the end of 2018, then taper down to a continuing value of 10% in 2022.

Peter’s post then degenerated into arm-waving and motherhood statements, capped off by an unreferenced affirmation about reaching grid parity. The term “grid parity” has been used at one extreme to refer to bid prices in the wholesale market, exclusive of system services such as frequency control and transmission services from boondocks to somewhere near a customer. At the other extreme it has been used, in relation to rooftop domestic solar, to retail rates at the meter, but still with an assumption that the domestic supply is a “must take” generator and that all others are subject to curtailing during times of excess generation capacity.

Unfortunately the term “grid parity” represents different things in different countries. In the USA the grid / utility is generally responsible for new transmission, and in some states must contract for the cheapest generation. In the UK the wholesale generator pays for the grid connection. I’ve no clue what happens in Australia. Hence the definition drives the contractual process – like it or not, and thus the definition of grid parity varies by country.

Being super precise about what grid parity is does not help matters either. The key thing is whether installing wind turbines and solar over 20 or 30 years into a national grid is a cheaper solution overall than nuclear, taking into account the other grid changes which must be made. Wind does require the presence of CCGT for period of calm, but if your grid already has plenty of this then you do not have to pay for more. Existing quantity presence of despatchable hydro and pumped hydro similarly should be factored in. The costing exercise should be a comparison between final systems, not a comparison between components.

As far as rooftop solar is concerned, we are not really talking about “grid parity” but just consumer cost savings against the retail price. A lot of distribution costs will be incurred whether rooftop solar generates power or not, though rooftop solar tends to generate at peak times and save some of the costs of electricity from peaking plant.

Wind and solar is generally “must take” in most places because, once the capital investment has been made, the overall incremental cost to society of wind and solar power is close to zero, whereas for fossil fuel generation the incremental cost includes fuel which is a major component of cost. This ought to be an obvious point.

Meanwhile, the capacity factor of wind remains essentially unchanged

New Wind Turbine Capacity Factor Could Increase From 40% To 60%

The trend towards a higher ratio of turbine blade area swept to generator capacity is bound to push capacity factors higher. Historically this was around 2 m2/kW, but some future turbines are likely to operate at > 6m2/kW. Another factor pushing CF higher is taller towers.

The net of this is that onshore wind in good places already gets up to 40% capacity factor, but the trend towards higher rotor sweep areas to generator capacity is likely to push this up to a maximum of 60%. This does increase the area per turbine, but there is sufficient room in the USA for these. I’ve not researched Australia, but it seems to have plenty of room and a sparse population so my guess is that area per onshore wind turbine is not an issue.

[Wind Power] is backed up almost everywhere by one or more of:
. Open cycle GT, which is almost universally the case;

. Pumped storage or other hydro, which are geographically limited, environmentally challenging and, in the case of pumped storage hydro, come with an 80% (I’m being generous here) round trip energy efficiency. Given that in Europe pumped hydro represents less than 5% of total installed capacity and is further limited by the volume of the upper pondages and transmission system constraints, how effective can pumped hydro ever be at backing up a system with, say, 50% wind power?
. Next door neighbour’s load-following nuclear power, as for example, Germany’s imports from France; or
. Good old (or new) lignite power operated as baseload plant while the surplusses of wind are pushed into the wider European grids, resulting in half of the renewables not being used where they are generated (Germany) but instead diffused throughout adjacent countries, in order to maintain system stability in the face of unreliable weather-dependent diffuse power sources such as wind and solar.

Theargument saying grids can never cope with 50% or more of wind power applies only to current grids – not future ones. Getting to 50% will take time, and by the time we get there the grids will have changed out of all recognition. There won’t be any coal or lignite generation. Germany’s neighbours will have their own wind power and Germany’s thermal plant will all be fast-response CCGT. UK says it will get rid of coal by 2025 and install more fast-response CCGT soon, though there seems to be a bit of an issue with how this will be financed since the current wholesale electricity price is too low to allow any new generation to be profitable without subsidy.

For Europe, Norway has huge hydro storage (84 TWh – equal to more then 10 days of European generation), but no pumped hydro. See http://ahk.de/fileadmin/ahk_norwegen/Dokumente/Presentasjoner/wasserkraft/Design_of_Future_Pumped_Storage_CEDREN_Killingtveit.pdf . But someone has to agree to pay for the conversion. Here’s a document outlining the possible total European pumped hydro potential – https://ec.europa.eu/jrc/sites/default/files/jrc_20130503_assessment_european_phs_potential.pdf which comes up with around 80 TWh in total, with a few caveats.

However, this pumped hydro potential is probably not enough, which is why the Germans are expecting to supplement it with renewable hydrogen for electricity storage (from electrolysis of water, used in fuel cells or hydrogen-compatible CCGT – http://www.power-eng.com/articles/2010/07/hydrogen-fuelled-combined-cycle.htmlthen ), at an end-to-end efficiency of around 45%.

What, I wonder, are Peter’s answers to the stability issues which are demonstrated, time and again, by Germany’s pattern of exports of renewables and imports of stable power from neighbouring countries, all the while maintaining year-on-year increases of CO2-e emissions?

Where is the hard evidence that Germany’s wind power exports destabilise the surrounding country grids? Link please, showing some power flows causing a problem, not just an arm-waving assumption. Germany does not export power without contracts, and these have specific terms in them.

German CO2 emissions from power generation are generally on the way down, although it could make life a bit easier for itself if it slowed down the decommissioning of nuclear a little.

Germany exports more than it imports, and has reduced its recent CO2 emissions in every year but one. Although they commissioned some new coal/lignite plants a few years ago, some of these will no longer be completed, and others are expected to replace older, less efficient coal/lignite plants reducing CO2 emissions for the same electricity output from coal generation.

Why is it so, that despite receiving 25% subsidy/support, coupled with “must run” market access, plus hugely favorable press, globally and over several decades the wind power industry that meets its own stated goals?

Perhaps you would tell us what these goals might be as a quick Google search does not produce anything specific.

My version of the goal is that the subsidies were always intended to bring wind to a volume where the LCOE and other costs of wind were competitive with other forms of generation.

The USA DoE seems to be setting a national goal of 20% penetration of wind power by 2030 and saying it can be done with no more than 0.5 cents / kWh integration costs – http://energy.gov/eere/wind/20-wind-energy-2030-increasing-wind-energys-contribution-us-electricity-supply . Texas will probably be at 50% by then.

Where are the real groundbreaking, undeniable successes from the hundreds of billions of dollars spent? The purpose of subsidies is not as Peter stated. It is not to support limited technologies for decades, despite clear evidence of inability to ever meet the twin goals of cost and performance. Subsidies are for achieving goals. Greater subsidies must be used to achieve greater goals. Global subsidies must achieve global goals, in this case, a contribution to climate stability through reduction in global carbon emissions. Why is it not so?

The purpose of subsidies is to get wind power into volume production, enabling wind power to compete effectively once subsidies are withdrawn. For onshore wind we are pretty much there (UK has withdrawn onshore wind subsidiesl, though maybe a little early). Offshore wind might take another decade. From the Lazard’s chart above, the subsidies have achieved exactly that.

So that is indeed a real groundbreaking success story – wind power reaching LCOE prices competitive with fossil fuel generation, with the US DoE estimating addition grid costs of 0.5 US cents / kWh to cope with every increasing levels of wind.

However, the real success story is yet to come as countries expand wind production to levels in the range of 20-50% of electricity production by 2030.
BNC MODERATOR
Your comment is very long winded, so much so that it is unlikely to be read in full. It would be better to split the post. You also veer off topic – please move to the Open Thread to discuss anything other than the post’s title. Thank you.

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1755 words! Is someone being paid by the word?

I have neither the time nor the patience to read in detail, let alone to respond in detail to a scattergun spread of affirmations, misrepresentations, avoidance and off-topic red herrings. I am probably in breach of one or more site rules because I decline to list and debate each of them one at a time.

Two points, though:

One, Germany does indeed export half of its wind+solar power instead of winding back its brown coal generation. I didn’t say that by so doing, the adjacent nations’ grids have been destabilised, however I do believe that Germany is only able to absorb the output from its huge wind fleets due its being able to offload the peak production (indeed, half) to its neighbours. The Austrians, Czechs and possibly the Poles might have an opinion about potential destabilisation, otherwise, why the proposal to separate the German/Austrian market and why is expensive phase shifting equipment being installed by some of Germany’s neighbours?

Two, discussion about the need to define the term “grid parity price”, has led nowhere. We still don’t know what Peter Davies means when he uses it, and I suspect that he doesn’t want us to know.

John Morgan’s excellent post concerned the applicability of Jenkins and Trembath’s findings to the limits of penetration of wind power in the existing Australian NEM grid, in the light of the most detailed data currently available. It is about engineering and statistical analysis of operational data, not about costs, prices, economics or aspirational goals.

If Peter seeks to discuss the economics of wind power, there are several threads on this site, including the Open Thread, for this.

I thank Peter for providing us an excellent example (or ten) of why long comments deserve tight editing and why limits to the number of comments (or words) per person, per day might be a good thing.

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BNC MODERATOR
Unfortunately, neither Prof Brook or the volunteer moderators have time to to edit, count or limits words on comments. I have advised PD to split comments and make sure they are in th correct thread.
I think that few would read such a long comment anyway and I have advised him so.

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@ apasser:
Your key statement is false in two ways.

“Very broadly, 2.8% capacity achieved after 0.5% renewable investment would merciful and madness not to promote.”

2.8% of electrical energy is less than 1% of total global energy consumption. Like must be compared with like.

The 0.5% figure relates to subsidy. To this must be added all of the developer’s costs to arrive at the investment.

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There is so much evidence to show that weather dependent renewables are ineffective, cannot meet requirements and very expensive, where does one begin?

El Heirro Island’s 100% renewable project. The aim was to supply the island’s electricity with 100% renewable energy. The island has an ideal situation for pumped hydro with a volcano providing a free upper reservoir with 600 m of hydraulic head. It’s built 11.5 MW wind capacity and 11.3 MW pumped hydro capacity. So far it’s a failure.
“

Since full operations began the 11.5MW wind farm has run at an average capacity factor of 13.2% and the hydro plant at an average capacity factor of 1.5%.

”
Renewables generated 30.7% and diesel 69.3% of electricity. http://euanmearns.com/el-hierro-renewable-energy-project-end-2015-performance-review-and-summary/

As an example of the conviction to twaddle by renewable energy advocates look at this amazing article by ScottishScientist: “World’s biggest-ever pumped-storage hydro-scheme, for Scotland?” (and also note his responses to comments): https://scottishscientist.wordpress.com/2015/04/15/worlds-biggest-ever-pumped-storage-hydro-scheme-for-scotland/. This project could never get off the ground (explained in my comment here: https://scottishscientist.wordpress.com/2015/04/15/worlds-biggest-ever-pumped-storage-hydro-scheme-for-scotland/#comment-189 The LCOE is >10 times the LCOE of nuclear. What rational investor would invest in such a scheme and what rational buyer would buy renewable energy at 10 times the cost of nuclear?
The same author advocates solar thermal in the Nabib Desert (Western Africa on the tropic of Capricorn) to power Europe in winter. Again the cost is 10 times the cost of new nuclear in Europe. http://euanmearns.com/blowout-week-104/#comment-14264
One of the common responses is to say these are single technology solutions and not relevant because multi RE technology solutions are cheaper. Nonsense. The excellent ERP 2015 report puts that argument to rest http://erpuk.org/wp-content/uploads/2015/08/ERP-Flex-Man-Full-Report.pdf . UK could achieve the same emissions intensity as France – i.e. 42 g/kWh in 2014 – with 32 GW of new nuclear and no new weather dependent renewables. According to the report, the cheapest way for GB to reduce its emissions to meet its 2030 emissions targets is with all or near all new nuclear and no new weather dependent renewables. Pumped Hydro is very expensive and ineffective. The worst option of all is to close existing nuclear if its life can be extended. It’s an excellent report, broadly applicable, with many valuable lessons for policy advisers.

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I second what Peter Lang said. That report is extraordinary – well written, authoritative (as in well referenced) and fact-filled.

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@Edward Greisch

I read your links with interest. We Danes spend very little on producing electric energy so whether or not we are parasites as your links suggest and dumb as is also suggested is up to you. The link quite correctly mentions that we make money from being the interconnect to Norway and Sweden. The average Nordpool electricity price is less than $0,03/kWh. The subsidies that are available for on shore wind are 25 øre/kWh on top of the market price, but with a cap at 58 øre/kWh for market price + subsidy. The subsidy is available until the turbine has produced an energy amount corresponding to 6.600 hours times the wind turbines rated power + the rotor area in m2 times 5,6 MWh, which is on average 6-8 years so for the remaining 17-19 years of the turbines projected design lifetime the wind turbine sells electricity hour by hour for what can be fetched at Nordpool. Throughout the entire lifetime there is an additional subsidy amounting to 2,3 øre/kWh ($0,0023/kWh).

Further wind turbines are curtailed without compensation when the Nordpool electricity price is negative.

The information is only available in Danish but for those of you who want to check with google translate here is the link to the official administration that handles the energimarket in Denmark. http://www.ens.dk/undergrund-forsyning/el-naturgas-varmeforsyning/elforsyning/elproduktion/stotte-vedvarende-energi-2

To recap this means that the owners of wind turbines sell electricity in the first 6-8 years for a maximum of 60,3 øre/kWh ($0,088/kWh) whereas the average is around 48 øre/kWh ($0,07/kWh). And thereafter are left to the market forces, which provided the current Nordpool average continues will be around 21 øre/kWh ($0,03/kWh) Throughout the lifetime the average selling price will be (7 X $0,07/kWh + 18 X $0,03/kWh)/25 = $0,0402/kWh.

However as electricity prices are dropping fast this best case for the wind turbine owner will be significantly less. Based upon the difference between the Nordpool spot price average and the selling price you can calculate that there is a subsidy amounting to $0,01/kWh, which makes wind energy the least subsidized electricity production in Denmark with a very broad margin. No coal fueled power plant can ever produce electricity for $0,0402/kWh with the current market price for coal plus transport plus OPEX plus CAPEX – and most certainly not for 25 years.

I know most nuclear proponents would jump to the chance if you could sign a PPA for 25 year at four US cent per kWh.

The future wind LCOE is going to drop fast. Vestas is putting up a new 3,65 MW test wind turbine with 166 meter hub height to fetch stronger and steadier winds and the other Danish major wind power producer Siemens has announced that they expect to reduce the cost of wind by 40% within the next 10 years.

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@ Jens Stubbe

I have stated before that I find very few examples from Denmark relevant to the world problem of GHG emissions.

So, when is it forecast that Denmark will cease to burn any coal or gas for the purpose of electricity and heat generation?

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When will Denmark (with highest electricity prices in Europe) get it’s electricity prices down to those of France?

When will Denmark (with relatively high CO2 emissions intensity of electricity), get its CO2 emisisons of electricity down to the same as France (42 g/kWh in 2014 according to RTE figures)?

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@ Peter Lang

That is really a matter for the Danes and I really do not care what they charge for Electricity.

But there is one thing that should be clearly understood after the Paris talks on climate change. No longer is it good enough to embark upon GHG mitigation. What is required is GHG elimination.

At this stage GHG elimination is an impossible dream. There are a number of areas where there is no alternative but to burn fossil fuels e.g. Jet engines and Diesel engines. So in areas where the consumption of fossil fuels can be replaced by zero GHG emitting alternatives it should be done.

Jens Stubbe has told us how wonderful the Danish system using wind is hence my question of him or anyone for that matter.

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@ Tony Carden.
I suggest that Tony re-read the leading article on this thread. It concerns the limits to stability of grids operating with increasing proportions of weather-dependant wind power. It cites examples and statistical justifications for the proposition that current indications are that the practical limit is about the capacity factor of the generating plant. If this is correct, then it follows that major advances are necessary if wind power, in any configuration, is not to be limited in practice to much less than half of the total demand of the system, as measured in energy terms, not instantaneous.

It is not about whether there are unlimited pots of gold awaiting any project that claims to be potentially, but not quite yet, ghg-free. Nor, primarily about the cost of Danish electricity, although a significant tangential issue relates to whether and to what extent the Danish high wind turbine count and the highest or second-highest domestic electricity prices in the EU are cause and effect. Or whether fairies at the bottom of the garden are responsible for the high cost of Danish power.

Nobody has demonstrated that wind power in a grid can reliably be present at penetrations significantly above its capacity factor and, if so, how this can be achieved. Currently, and for reasons I can not fully explain, it certainly appears that the limitation is real and that thus efforts to reduce ghg emissions should recognise this as a limiting factor and which welcome the role of other, more reliable sources.

I’d very much like to read contributions that show where John’s conclusion is wrong and how additional wind penetration can be achieved reliably. Can it? How?

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My apologies to singletonengineer for cluttering up this thread, I was simply replying to earlier comments by others which I did not think were entirely on thread but I thought worth saying something about.

I do not need to re-read the lead article by John Morgan. I quite fully comprehend it.

In relation to your first paragraph I do not agree that
‘the practical limit is about the capacity factor of the generating plant’
The practical limit is the capacity factor of the wind.

John Morgan’s figures show that the capacity factor of the wind is 29 percent.

In relation to your second paragraph for many reasons which I intend to post in Open Thread 23 what happens in Denmark, in terms of the world’s efforts to reduce GHG emissions, is irrelevant. The production of Lego blocks is more relevant to the world certainly my grandchildren.

In relation to your third paragraph, I hope this extract from the above article assists.
‘As explained in detail by Jenkins and Trembath, it is increasingly difficult to build more wind or solar capacity as their market share approaches their capacity factor (CF) because they will then, at times, be producing energy in excess of demand. The economic drag incurred by dealing with surplus generation by storage, curtailment or demand reduction undermines the economics of building additional capacity. The capacity of wind and solar is thus limited to be roughly numerically equal to 100% of grid demand.’

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Mea culpa!

Apologies to Tony Carden. My comment a couple of posts upthread was not in response to his contribution(s). I am sorry for causing him to waste his time responding.

However, I do have a request for clarification of the final sentence of the Jenkins and Trembath quotation, “The capacity of wind and solar is thus limited to be roughly numerically equal to 100% of grid demand.”

The main point made by Jenkins & Trembath and supported by John Morgan is that the maximum practically achievable share of wind power in a grid will not exceed, over time, its capacity factor times the fleet capacity. I imagine that this could be true in the general case, eg coal, nuclear, renewables, although John’s work discussed only wind power.

Maybe someone else can explain what that J&K mean by:
“The capacity of wind and solar is thus limited to be roughly numerically equal to 100% of grid demand.”

Is it only the trivial point that at any time in a stable grid without storage:
Generation (Supply) = Demand >= (Wind + Solar)

What have I missed?

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@ Roger Clifton, singletonengineer

“Installation of wind and solar is thus limited to a nameplate capacity roughly numerically equal to 100% of grid demand.”

That’s not true for the combined total of wind + solar when the two are anti-correlated with each other, as they appear to be in Europe. The economic losses for going above grid demand are not that big, even in the absence of storage.

Further, if the wind price is low enough compared with the alternatives (e.g. nuclear) it is not true even for wind alone when you have two completely independent regions generating wind power. e.g. North Africa (from the trade winds) and the North Sea (Northern Europe).

If the capacity factor of both areas was 50% then you can provide 75% demand coverage from wind. Curtailing or using the extra for something else when the total from both regions is more than demand is an economic calculation and depends on relative prices (which for wind power will only reduce).

The technical aspects of grid control powered only by wind require you to have advanced wind turbines which are generally run at slightly less than full capacity (blades slightly feathered) so you can ramp up capacity from some wind farms if necessary. Other short term cycle control equipment may also be required. The general trend is for the minimum generation from mechanical generators with high inertia to be lowered progressively as time goes on because there are other means of accomplishing the same thing.

However, for a system with no storage capability, the quoted constraint would be true for just North Sea wind generation. This isn’t a realistic scenario anywhere, however, as it will always be wind + solar.

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@Tony Garden

As I mentioned the subsidies for fossil fuel electricity generation is much higher than for wind electricity generation in Denmark and also locked by law that protect the right to supply district heating and natural gas for heating. The current energy minister was before the managing director of a powerful fossil lobby organization and the party he comes from was the same party that elevated Lomborg to fame. From what I read I think Australians also have to battle powerful fossil lobby groups to get rid of fossils.

Nordpool is the single largest electricity market in the world and very likely a model for other open electricity markets yet to come in the rest of the world.

Denmark is the birth place of modern wind turbine technology and a hot place for the development of the same, and since wind turbines are by far the cheapest new electricity generation it is also interesting.

Further and more to the point relative to the article that we are discussing the “capacity factor of wind” and how much wind that can be reliably integrated into the grid is also impacted by the way you build the infrastructure, which makes Denmark interesting.

Lastly more than 90% of all offshore wind turbines are from Denmark and the process of driving cost down is done in Denmark were the unsubsidized price seen over design lifetime is now around $0,06/kWh with capacity factors approaching 60%.

Closing the 50% price gap between on shore and off shore wind will be difficult and perhaps impossible but wind at sea is more steady making it easier to integrate in the grid and less intrusive making it more acceptable for the public.

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Perhaps it should read, “Installation of wind and solar is thus limited to a nameplate capacity roughly numerically equal to 100% of grid demand.”

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@Singleton Engineer

The post is not in the least bit wrong for a grid not focused upon handling intermittent electricity generation.

On the other hand it is feasible to focus attention on intermittent electricity generation and design an electric grid that can handle any percentage of intermittent electricity sources up to 100% but this will invariably become an economic question.

As John pointed out greater geographic spread reduce intermittence and so does higher capacity factor. John has also in other article made the case for producing Synfuels when electricity is in excess. Heating, transportation and industrial processes can be electrified and more demand can be time shifted by smart grid technologies and ultra cheap storage such as heat storage. Biomass and municipal waste can either be burnt to produce electricity or be converted into methane or Methanol – all of which adds some dispatchable power to balance the grid. Finally as is already the case a few hours every year in the Nordpool area you can curtail wind power and/or a small amount of electricity storage could be connected to the grid.

As for your theory then Denmark is part of Nordpool the worlds largest electricity market with an average cost of less than $0.03/kWh and new onshore wind currently sell for approximately including subsidies $0.04/kWh, which makes onshore wind the least subsidized electricity generation in Denmark.

The high taxation on electricity is simply a concealed fossil fuel subsidy and fossil fuels enjoys many other other direct and indirect subsidies.

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@singletonengineer

After just having praised the article I did find one example of less thoughtful extrapolation.

“As more wind is added, the flexibility of the rest of the grid will have to increase proportionately – double the wind energy would require about 40 MW/min ramp rate. But this additional ramping ability must be delivered by the shrinking dispatcheable generator sector. So the intrinsic flexibility of the rest of the grid must increase, and faster than in simple proportion to wind penetration. Practically that means increasingly strong pressure to shift from coal generation to gas as wind share grows.”

The capacity factor of wind has been ever growing and will continue to do so for a good deal of years to come simply because wind turbines scale and improve. Higher hub height means stronger and steadier winds. Higher capacity factor means less variation in output and slower variation in output, so despite the shrinking dispatcheable generator sector it won’t have to ramp more up and down.

Solar and energy efficiency improvement also contribute to less ramp up and down ability. Solar generally tend to cater for the higher energy demand during working hours and for increased air condition usage and energy efficiency such as LED lighting caps the demand peaks.

The shift from coal to gas is not because coal power cannot ramp up and down but because coal power plants are most efficient when driven as base load. Gas power plants are cheaper to build and can thus make do with lesser utilization as long as there is high paying demand at least in some minimum time over a year.

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Peter Davies urges us to be reassured that sometimes wind and solar anti-correlate. However we’re not interested in when they do supply together, but when they don’t. We seem to the only people staring at the fact that most of the time wind and solar do not supply anywhere near capacity and indeed, sometimes they do not supply at all.

Why should the responsibility for the capacity factor of wind fall onto the grid operator? It is only the “must-take” provision that makes trouble for the people trying to provide a reliable power supply. If that provision were instead dismissed, and replaced with say, a hefty carbon tax, the problem of intermittency would fall on the wholesaler. It would be an engineering challenge, not a salesman’s pitch to an unwilling buyer.

In Australia, the grid operator accepts bids from a range of wholesalers to guarantee supply of 30 MWh across the next five minutes. It’s automated. In order to draw up their bid, a consortium of wind farms, solar farms and open cycle gas turbines could then negotiate among themselves as to their confidence to supply, the price they would pay each other, and when to shut down the spinning turbines and their capacity to bid during unfavourable weather. If the carbon efficiency of the wind+solar exceeds the carbon inefficiency of their backup, they might make a profit.

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@Roger Clifton

The “must take” provision makes sense at the moment when wind and solar penetration are low virtually everywhere. But as soon as you start getting solar and wind power exceeding demand at a particular time of day, then it makes sense to change the rules so that some wind / solar generation can be curtailed (after all fossil fuel generation sources, despatchable hydro etc.have first been curtailed).

It doesn’t really make sense to remove individual unit scheduling responsibility from the grid operator, purely because the grid operator is the the one party who knows everything that is going on and can make the best decision for the grid as a whole.

A bunch of generators of different types could get together to synthesise a type of generation which has different and more desirable characteristics than any of the individual generators. But to make better decisions than the grid operator on the use of the individual generating and storage plants they would have to duplicate all the grid operator data feeds. It’s possible, but does not seem to be a particularly efficient way to do it.

Further, smart grids will make significant use of demand response to flex demand up and down to offset as much of the variability of wind and solar as possible. It seems unlikely this would be used efficiently unless under the control of the single grid operator.

There are also problems with the most efficient use of storage. The problem with storage is self-cannibalisation. The ideal is that you have enough storage that the price of electricity does not vary very much between periods when there is plenty of wind and solar power and periods where there is a deficit. But if storage has to make money from arbitrage (selling when prices are high and buying when low), then it would be unprofitable if such price parity were close to being achieved.

One solution (not the only one) is that storage is contracted by the grid operator under completely different terms from generation, and the costs are then distributed across all electricity users.

It comes down to the regulations governing the monopoly grid operator. These are not set in stone and governments can change them if that is the right thing to do. At present the regulations tend to suit 20th century grids rather than mid 21st century smart grids. They will need significant changes at some point and there is a lot of work being done on this as well as on the technologies themselves.

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The “must take” provision makes sense at the moment when wind and solar penetration are low virtually everywhere.

Why? Why does it make sense to impose “must take” provisions for high-cost, low-value weather-dependent renewables? Wouldn’t it be far more rational and objectively justifiable, if the aim is to reduce global GHG emissions, to impose the “must-take” provision on nuclear instead? (as well remove the mass of impediments already imposed)?

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Peter Davies seems to argue against a regulated monopoly, AEMO, which basically runs a rational market via dispatch order for the various generators, based on price and within the physical constraints of availability, transmission capacity and ancillary services. He argues in favour of selected participants in that marketplace being granted priority entry to the market, regardless of price, due entirely to the fact that they are intermittent. Not because of the carbon savings that they represent, because his rules do not rely on carbon emission reduction, only that the sources be weather dependent and thus unreliable.

The argument is not that in operation they are zero carbon emitters – because that would necessarily result in support on equal terms for nuclear power.

Not on the basis price of avoided carbon emissions, because that would imply a carbon market and all that comes with it, winners and losers and the ability for cheaper external sources of carbon reduction to be utilised by those generators which are locked into carbon emitting fuels.

John Morgan’s discussion paper at the head of this thread demonstrates the inescapable practical limits of variable weather-dependant power sources. It has demonstrated that 100% market penetration is an unreachable dream, unless with mammoth (infinite?) overbuild.

It has demonstrated the futility of continuing a discussion which is repeatedly dragged back to an irrational starting point, one where the mathematics of atmospheric CO2 emissions and costs are ignored.

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@ Peter Davies,

“The problem with storage is self-cannibalisation. The ideal is that you have enough storage that the price of electricity does not vary very much between periods when there is plenty of wind and solar power and periods where there is a deficit. But if storage has to make money from arbitrage (selling when prices are high and buying when low), then it would be unprofitable if such price parity were close to being achieved.”

But that’s only a theoretical problem with storage, and will not become an issue until we have an extremely large amount of it (if ever). Self cannibalization’s far more likely to be a problem for renewable electricity generation (e.g. when the wind’s blowing it depresses the electricity price so it’s harder for wind turbines to be profitable) and storage can mitigate that problem.

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@singletonengineer

The issues with an all-renewable grid are not technical or economic, but regulatory – how to incentivise everyone correctly to get the required behaviour.

It is very clear how to put together a cost-effective grid using only wind and solar renewables plus pumped storage hydro for storage where geographically feasible and renewable hydrogen powering compatible CCGT generation for the rest of the backup.

You don’t need infinite renewables. You need the anti-correlation between (one load’s worth of capacity from each of) wind and solar to get you to around 70% time period coverage (50% + 30% CF’s respectively). Then pumped hydro (at 70% efficiency) and renewable hydrogen (45% efficiency) powering CCGT backup to cover the remaining 30% of the time.

To store into the pumped hydro capacity you need 1/0.7 = 1.4 times as much additional renewables energy as you will generate from pumped hydro. To store via renewable hydrogen it is 1/0.45 = 2.2 times as much as you need to fill the remaining gap.

For 100% renewable hydrogen backup (no pumped hydro) assume 50% wind and 30% solar CF, 70% direct load coverage with 10% spare generation available. The 30% gap x 2.2 = 66%. Subtract the 10% already going spare, and the storage need is for 56% extra renewables generation at a solar PV capacity factor of 30%. Assume a constant load, and we can generate all we need from 1 x wind and 3 x solar – each times the same nameplate capacity as the constant load needs. This can produce 50% + 3 x 30% = 140% renewable power compared with the 100% power the load consumes.

Thus an overconfiguration of solar nameplate capacity sufficient to produce 36% extra energy is adequate for an all-renewables system. i.e. wind + solar at 50% and 30% capacity factors have to deliver 136% of the load between them. The 36% comes directly from the extra factor of 1.2 (=2.2 – 1) you lose via the renewable hydrogen cycle times 30% gap. If you have some pumped hydro this overcapacity comes down because the efficiency is higher.

By 2030-2050 (at the point you will be switching residual natural gas CCGT to renewable hydrogen CCGT) the wind LCOE will be lower than current coal LCOE, and solar PV LCOE will be of the order of 2-3 US cents / kWh. Thus the direct renewable generation is very cheap and the 40% solar overconfiguration adds only 0.8 to 1.2 US cents / kWh. Electrolysis equipment and hydrogen storage costs very little by comparison with the rest (it doesn’t have to do very much). CCGT capital costs will be almost as low as they always have been (with a small uplift for hydrogen-compatible operation) as it is mainly CCGT fuel that dictates the cost.

Nuclear costs in western nations have always gone up with time, so it’s not at all clear it can compete with an all-renewable solution. See Joe Romm’s article as to why nuclear is not the complete solution – http://thinkprogress.org/climate/2016/01/07/3736243/nuclear-power-climate-change/ .

Once you do the sums, singletonengineer’s claim of infinite renewables capacity requirement comes down to just over a third of extra electrical energy generation required to support the storage / backup in one particular example of an all-renewables grid.

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The issues with an all-renewable grid are not technical or economic, but regulatory – how to incentivise everyone correctly to get the required behaviour.

What is the “required behaviour”, and why?

Is it to meet electricity system requirements or some people’s irrational, nonobjective, ideological belief?

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What an all-renewables grid would require in the US, if built to the projections of Mark Jacobson (per analysis by the Clean Air Task Force provided to James Hansen):

1,670 offshore wind farms the size of the 468 MW Cape Wind array (92 per coastal state)

2,400 Tehachapi-size wind farms (705 MW each ) onshore (or about 50 per state)

27,000 megawatts of wave machines (zero exist today)

227 Gigawatts of concentrated solar plants (or 580 Ivanpah-sized plants at 392 ME each, or 10 plus per state) to produce energy, and an additional 136 GW (7 per state) just for storage

2,300 GW of central solar PV plant, or 1,200 times more central PV capacity than exists today

Additional 469 GW of solar thermal storage, or roughly 1.5 times the capacity of US coal

http://csas.ei.columbia.edu/2015/12/29/wanning-workshop-beijing-charts-year-end-comments-2/

Some notes:

Transmission not included in the above analysis.
Renewable energy is not made using magic fairy dust. The Ivanpah solar facility, which displaced threatened species of desert tortoise, is a mega death trap for birds:

http://www.desertsun.com/story/news/environment/2014/04/07/birds-going-smoke-brightsource-energys-ivanpah-project/7448299/

A search engine search will enable you to watch solar power scorching birds on video.

Scaling brings resistance. The Cape Wind facility has gone approximately nowhere after 15 years of effort; the promoters put a brave face on it by noting it is mired in litigation:

http://www.nawindpower.com/e107_plugins/content/content.php?content.14675

More analysis of Jacobson’s plan is slated for release late this winter or in the spring (N. Hemisphere).

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@Frank Jablonski

What you don’t say, but should, is that Mark Jacobson’s proposed US electricity grid would replace all energy use in the USA by 2050, not just supplying the current electricity grid demand.

Here’s the Jacobson source article : https://web.stanford.edu/group/efmh/jacobson/Articles/I/USStatesWWS.pdf

For that reason my rough calculation spreadsheet above shows it generates each year considerably more than four times the 2013 US annual TWh electricity consumption of 4,066 TWh from http://www.eia.gov/electricity/annual/html/epa_01_02.html .

It would require about 0.5% of the USA surface area for machinery and facilities and another 2.4% for spacing between wind turbines which could be used for other purposes. That’s total land use, not additional land use, since energy.

The question the US states citizens will ask themselves is whether they would prefer to live close to a nuclear plant, of which there would be a number in each state, or whether they wish to devote 2.9% of the land area of the USA to an all-renewable energy solution.

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Greg Davies,
A number of us have already discussed Mark Jacobson’s report on Open Thread 23. In short he has not completed the report. The storage element has not been finalized and is due for completion in 2016. Then I am an anticipating a cost estimate for this project. Until that is done his report is speculative as will be a lot of the comments.

I will re-post this comment on Open thread 23 where it is appropriate to discuss off thread topics.

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@ Peter Davis.

After a very long string of assumptions and guesses, Peter arrived at a situation where the most variable of the variable supplies are presumed to be able to be absorbed into storage such as pumped hydro (Where? What cost?) and hydrogen.

I just happens that I have some experience with electrolytically produced hydrogen and with H2 storage… and with three hydrogen fires, one of which blew apart the cladding off the building which contained it.

First, electrolytic H2 production does not lenditself readily to spikes and troughs in electicity supply – it works best on steady load. There may be techniques foradapting to fluctuating loads, combined with either none or little power at all, but I have not seem them described. These bones need to be fleshed out.

Second, current H2 economics are very much in favour of production by stripping hydrogen from a feedstock of natural gas. If I really want hydrogen in large quantities, as is the case for existing power turbines, the cheapest method is not to manufacture on-site by electrolysis even when the marginal cost of electricity is essentially equal to the cost of coal, ie 2 or 3 cents per kWh. Thus, on the basis of reduced cost and reliability and even safety, bottled hydrogen is frequently preferred even when almost-free power is available and an existing facility is on site.

Third, given the safety implications of hydrogen storage, I would far prefer to live adjacent to a nuclear power station than next to a hydrogen production and storage facility at a scale of hundreds of MW average.

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As so often happens, the (interesting) discussion has drifted far from the topic of this thread. At least the moderator and I would appreciate continuing on the latest open thread.

Where, by the way, various commenters may find some value in what I have contributed…

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Moderator,

Can we have a thread entitled something like “Discussions on all renewables versus all nuclear grids” please? That seems to be the scope of the topic we all wish to discuss, but the information gets very diluted with other stuff on the open thread 23.

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Would Peter D bring more than hopes and wishes?I’d appreciate some facts. Meanwhile, John M’s excellent, factual and substantiated article cannot be discussed on its merits?

Someone’s joking.

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@singletonengineer

I’d appreciate some facts.

I have neither the time nor the patience to read in detail…..

Make up your mind. Do you want blow by blow refutations with factual links to put you right on those things on which you are misinformed, or would you prefer to conduct the debate at a summary level?

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Step 1: Agree the topic for discussion

Step 2: Can you answer ‘yes’ to the first three boxes here? http://twentytwowords.com/a-flowchart-to-help-you-determine-if-youre-having-a-rational-discussion/

Step 3: if you answer ‘yes’ to the questions in those three boxes, then we can agree to have a discussion about the topic, provided the following rules are obeyed:

Do not introduce new arguments while another arguments has yet to be resolved
Do no move onto another argument if it is shown that a fact you have relied upon is inaccurate
Provide evidence for your position or arguments
Do not argue that you do not need evidence

I’d suggest your suggested topic is too poorly defined. I’d suggest one of the following:

Which electricity system would supply cheaper electricity: all nuclear or all renewables generation?
Which is the cheaper option to reduce GHG emissions intensity of the electricity system: All nuclear or all renewables

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@Jens Stubbe

You state that “The capacity factor of wind has been ever growing and will continue to do so for a good deal of years to come simply because wind turbines scale and improve. Higher hub height means stronger and steadier winds. Higher capacity factor means less variation in output and slower variation in output, so despite the shrinking dispatcheable generator sector it won’t have to ramp more up and down.”

Even if what you are saying is true, the over CF of wind installations will only marginally increase unless existing installations are “repowered” and/or the overall capacity of wind installations for a grid are greatly expanded (which then leads to over capacity further leading to REDUCED capacity factor due to the need to curtail). In either case, there would seem to be considerable cost involved, especially if existing nameplate wind capacity is close to the average grid demand.

BTW Can you please provide a source that gives some indication of how capacity factor of a turbine scales with hub height? If the increased tower costs were also available, that would be a great help.

Also, can anyone advise how you are able to create a post “in reply”?

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Hi Greg, I can help with your request of estimating the effect of hub height on capacity factor. It will vary from site to site, and from turbine to turbine, but the following rule of thumb gives a very approximate estimate. A 10% increase in hub height will yield approximately a 2% increase in energy. A 20% increase will yield approximately a 4% increase in energy, etc.

So if a turbine has a capacity factor of 30% at a hub height of 80m, then at a hub height of 112m it will have a CF ~ 32.4% (ie, a 40% increase in height will increase energy by about 8%).

The following may help you make your own estimate. Many wind turbine manufacturers show graphs of annual energy production (AEP), vs site average wind speed. I’ve copied a link to one from Vestas at the link below. This is based on an assumption of the wind speed distribution, which varies from site to site, but the assumed Rayleigh distribution is as good an assumption as any if you don’t have measurement data.

To convert AEP to capacity factor, divide by 8766 and again by the turbine capacity (in MW).

Next you need to estimate how the wind speed changes with hub height. The wiki link below will help with this.

https://www.vestas.com/en/products_and_services/turbines/v117-3_3_mw#!power-curve-and-aep
https://en.wikipedia.org/wiki/Wind_profile_power_law

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Greg
To reply to a post simply click on the reply button at the bottom of the email you receive with the comment in it.

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@dos74

Thanks Dave Osmond.

I checked your links but using the most favourable assumption about the atmospheric stability (alpha = 1/7), I only get a 1.37% increase in wind speed with each 10% of height increase and the AEP for the turbines appear to increase in a slightly less than linear manner with wind speed, making 1.37% increase in CF the outer limit for each 10% of hub height increase. The Wikipedia article suggests that offshore wind farms would only see a 1.05% output (and hence CF) improvement per 10% increase in hub height.

Is there something I am not factoring in to fall so far short of the 2% that you provided?

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Hi Gred, the main reason for the discrepancy is that alpha=1/7 is not the most favourable assumption about atmospheric stability. As soon as you introduce stability (common at night), then the shear is likely to increase. In many sites, average measured shear exponents exceed 0.2, and even levels above 0.3 are not that rare. Moreover, if the ground is rough due to nearby forests or complex terrain, then this can also increase shear levels.

However I agree that off-shore shear levels are much lower, and my approximate rule-of-thumb was meant for on-shore sites only.

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Hi Greg, I just re-read your comment and realised that there is a larger reason for the discrepancy. You said that the speed-AEP relationship was slighly less than linear. This is wrong. Have a look again. In going from 6 to 7.7m/s, the Vestas AEP goes from 8,000 to 12,000 MWh. ie, a 28% increase in speed gives a 50% increase in energy. The relationship is steeper than linear.

That’s the main reason for your estimate not matching my rule of thumb.

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@Greg Khan

BTW Can you please provide a source that gives some indication of how capacity factor of a turbine scales with hub height? If the increased tower costs were also available, that would be a great help.

Greg,

The Capacity Factor (CF) is actually to do with project economics, rather than a straight technical issue to do with hub height, as should become clear if you read below.

There is a very simple law about wind power output. Power output is proportional to the cube of the wind speed and to the square of the rotor diameter.

The following charts gives an indication of the increase in wind speed with height due to less interference from surface friction and other effects :

The wind speed on the simple top chart is generally too high for most sites.

Using the top chart, as an example, the wind speed at 40m height is 16.2 m/s, but at 100m height is 18.5 m/s. The factor of the two wind speeds is 1.14, and the difference in power output is the cube of this, which is 1.48. So at 100m instead of 40m height you get almost 50% more power.

Translating this to a capacity factor is complicated because other factors come into it.

The wind is more consistent higher up, but the choice of turbine is going to make a huge difference to capacity factor.

If you increase the ratio of rotor area to generator capacity, then you increase the capacity factor. This is often referred to as Specific Area Ratio (=Su in the PDF below) measured in m2 / kW. The higher the ratio for the turbine selected for a given site then the higher the capacity factor. See the last slide of this link – http://cf01.erneuerbareenergien.schluetersche.de/files/smfiledata/4/7/8/6/3/2/114bSWRcaseUSA.pdf .

To get from hours of operation to capacity factor divide the Nh figure on the chart by 8,760 hours in a year.

You can also think of it as reducing the generator capacity for a given hub height and rotor diameter, in which case you can see this reduces the cost, and reduces the maximum power output and average power output. But the capacity factor is higher because the generator is operating at a higher capacity and at maximum capacity for a higher proportion of the time, even though that maximum capacity is lower!

In increasing the capacity factor by reducing the generator like this, you also collect less energy than you could for the land or sea area you use and for the rotor area. The recommendation is to site wind turbines 6 rotor diameters apart (in two dimensions) on land. Thus the energy available for a given land (or sea) area is independent on the rotor size, though it is still dependent on the hub height and turbine type chosen.

So you can increase the capacity factor if you wish, and increasing the hub height makes the trade off between energy output and capacity factor easier, because there is more energy available at the increased height.

However, the aim of the wind project is to make the best rate of return on the capital investment, not to maximise the capacity factor, so it is a question of balancing specific power ratio against project income and cost, and for a given hub height and turbine type (specific power ratio) there will be an optimum balance leading to a particular capacity factor. If governments gave a subsidy for higher capacity factors then you would suddenly find the capacity factor of new wind farms taking a jump, though the total power output might reduce.

The expectation for offshore wind turbines in good locations is a CF of around 50% for maximum energy extraction, and as high as 60% with smaller generators. But offshore wind is expensive anyway and you might stick with 50% but more output.

By contrast onshore wind turbines are cheaper to build and install. There is an expectation that the windiest sites in the USA could achieve 60% capacity factor with tall turbines with high area/ gen capacity ratios, and that there is enough very windy land in the USA to put them on (even though the power output per unit area reduces with the increase in capacity factor). See the presentation link above.

There’s a lot more data in Bernard Chabot’s presentation (link above) as to how the onshore wind market in the USA is shifting to these taller, higher specific power ratio and therefore higher CF turbines. He’s a cross between an engineer and an economist, so well suited to discuss issues such as capacity factor, though the presentation can get a bit heavy in places.

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Greg
There are also mechanical limits to the maximum speed at which a wind turbine can operate i.e. they stop in gale force winds.

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“a 28% increase in speed gives a 50% increase in” power.

Well, yes. Theoretical power delivered is proportional to the sideways lift on the blade, which is proportional to the square of the relative airspeed. Eg, 1.25^2 = 1.56

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Yes, theoretically the power increases in proportion to the cube of the wind speed. In practice, the turbine efficiency changes with wind speed. For example, once a wind turbine reaches rated power, any increase in wind speed does not increase power. And thus total energy (over a year, for example) is more likely to vary in proportion to annual average wind speed to a power of somewhere between 1.2 and 2.

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@dos74

” For example, once a wind turbine reaches rated power, any increase in wind speed does not increase power. And thus total energy (over a year, for example) is more likely to vary in proportion to annual average wind speed to a power of somewhere between 1.2 and 2.”

That is the year by year behaviour after you have selected the wind turbine to install, when the wind varies each year from the multi-year average.

With correct turbine selection you would expect the multi-year average of power output on different sites to correlate with the rotor swept area and cube of their multi-year average wind speeds, provided the wind farm economics rewards maximum annual energy and not a higher capacity factor.

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Hi Peter,

the key to the issue is your last sentence: “provided the wind farm economics rewards maximum annual energy and not a higher capacity factor”.

A turbine manufacturer could put an absolutely massive generator on the back of the wind turbine just so that it could continue to generate power efficiently during a 1 in 50 year wind storm event. They would also have to massively over-engineer the strength of the blades, gearbox, tower and foundations to cope with the huge loads that this would impose. In practice, they look at the wind statistics of the site, and decide that it is more economic to design the wind turbine so that it is most efficient at the most common wind speeds, and feather the blades to reduce loading at higher wind speeds with a resultant drop in efficiency. Google “wind turbine power coefficient Cp” to see what the efficiency of wind turbines look like as a function of wind speed.

As a result, annual energy production is not proportional to annual average wind speed to the power of 3, instead the coefficient is generally somewhere between 1.2 and 2.

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Thanks to all those helping me fill my knowledge gaps.

But some of the claims still do not seem to add up.

The AEP graphs supplied by Siemens show that AEP increase with yearly average wind speed is clearly slightly less than linear in the region where they have plotted figures. For the Vestas V117 turbine linked, I assume that the graph is bounded because below an average wind speed of 6m/s, the capacity factor is so poor that the turbine would be uneconomical while above 8.75m/s, there would be too much time where the maximum operational wind speed of 25m/s would be exceeded. In both cases, I would assume Vestas would recommend a different turbine which would be similarly bounded but have its operating yearly average wind speed range shifted down or up to better suit the prevailing conditions.

Now the power may well increase somewhere between the square and the cube of the wind speed but the AEP graphs supplied by Siemens are for average yearly windspeed. And since any decrease in wind speed would reduce the power by the same proportional amount (assuming the aerodynamic behavior of the blades does not change). So while the rate of increase in AEP from 0m/s to 6m/s is 1333MWh/(m/s) and from 0 to 8m/s is 1500MWh/(m/s), in the region of interest, the behavior is approximately linear with an offset: 2000MWh/(m/s) – 4000MWh

If we take the case where the yearly average wind speed is 7m/s and the hub height is raised by 10% from the specified 80m to 88m, then the yearly average wind speed increases to 7.059m/s (assuming an alpha of 1/7) so the AEP rises from about 10000MWh to 10137Mwh which seems a trivial improvement.

I use an alpha of 1/7 because according to the following Wikipedia page, a larger value would only apply if turbines were to be built in areas that had a high amount of obstruction (where the average wind speed would be worse than for clear areas). In fact, from the following page, 1/7 seem generous for on shore wind.
https://en.wikipedia.org/wiki/Wind_gradient

Peter Davies, you say “provided the wind farm economics rewards maximum annual energy and not a higher capacity factor”.

Shouldn’t capacity factor be a baseline for assessing how a wind farm is built, given that most of the cost appears to be in the generator rather than the tower and base (not that those costs should be ignored). Or are the other costs, like of setting up transmission lines and maintenance, a greater factor so the AEP is given priority?

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Greg,

I forgot to reply to your comment about using a wind shear exponent of 1/7. Although this is fine for many sites, there are undoubtedly many wind farm sites with a shear exponent greater than this. As I mentioned previously, stability greatly affects the shear exponent. The wiki page you linked to quotes an exponent of 0.4 for stable air above flat open coast. The wiki page below mentions the exponent can be above 1. Stable air is quite common during the night.

Similarly, many wind farms are located in regions with forested areas nearby, and this can also increase shear exponent levels above 1/7 even without stability effects.

https://en.wikipedia.org/wiki/Wind_engineering

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Hi Greg,

Your assumption about Vestas recommending a different turbine if the average wind speed is below 6m/s or above 8.75m/s is partly on the money. I’d just add that if the site average wind speed was above 8.75m/s, then it may present loading on the turbine greater than what the turbine (blade/gearbox/tower/foundation) was designed for. The fraction of the time the wind speed is above 25m/s is likely to be trivial, and would only be a minor consideration.

Although you haven’t linked to the Siemen’s AEP curve, I believe you may have made some minor miscalcs. The 10% increase in hub-height should increase the wind speed by 1.37%, or from 7m/s to 7.10 m/s. You quote a slope for the AEP curve as being 2000MWh/(m/s), so that increase in speed should boost the AEP by 192 MWh, a 1.91% increase. Thus the 1.37% increase in wind speed increases energy by 1.9% (ie, greater than linear, an exponent of approximately 1.4).

Finally, turbines are generally designed to maximise project economics, which roughly speaking means maximising (generation/CAPEX). In practise, this means neither capacity factor nor generation is maximised, but the optimum lies somewhere in between.

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@Peter Davies and Greg Kaan,

Peter’s closing comment is very significant and lies at the root of the primary misunderstanding about the economics of wind power.
“…provided the wind farm economics rewards maximum annual energy and not a higher capacity factor.”

In some markets, the following happens:
(1) Priority. Wind power may receive priority access to the market, ahead of other sources. Whenever wind can generate, it is permitted to do so.
(2) Price. Wind power may receive preference over other sources, regardless of price – this might be in the form of a pre-set wholesale energy price which retailers must pay, regardless of lower bids from competing producers, which are typically either FF or nuclear.
(3) Avoidance of paying for risks. Wind power providers may not be responsible for the costs attributable for “ancillary services”, primarily frequency control, which match the system output to demand. This generally involves a mixture of hydro and/or “spinning reserve”, which can be thought of as baseload style gas, oil, coal or fission fuelled plant operating at below their full capacity. The reserve capacity is typically at least equal to the largest generating unit in the system.

Thus, in an unfair market, wind gets the benefits of “maximum annual energy” without any penalty for having low capacity factors.

In a fair energy market wind power providers would bid for day-ahead supply like others and either provide at the bid price or pay someone else to do so in the event of inability to supply as bid.. Wind would carry the financial risks that arise from unplanned inability to supply, either via a direct market mechanism or by arranging, progressively through the day, for others to do so on their behalf.

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Returning to the capacity factor of wind farms, the following report from Greenmarkets reports that the average capacity factor for wind farms on the NEM was 31.8 per cent in 2015, up from 30.9 per cent in 2014. Bearing in mind that WA’s large-scale wind farms have far higher CFs than the national average, this further supports that the average CF of wind farm CFs in Australia is generally in the range 31%-37%, with some variation from year to year. Indeed, using data from 2007 onwards, I have 2010 being the worst year, and 2007 the best year.

http://greenmarkets.com.au/resources/review-of-the-nem-2015

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Now for the bad news, taken from the same report and regarding the NEM market:

Carbon emissions intensity increased from 0.809 to 0.817 t/MWh last year.

Greenhouse emissions increased by 2.2% in 2015.

Despite the hype from the renewables sector, we are losing the emissions race despite 1% reduction in overall energy sent out in the NEM market.

There is nothing at all to celebrate yet, despite claims of increasing CF for wind turbines.

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