About 1 year ago, I posted on BNC two important pieces by Peter Lang – “Does wind power reduce carbon emissions?” and a follow-up reply. Together, these stirred up considerable discussion (about 500 comments to date) and raised important questions about the ability of wind-energy to reduce emissions from burning fossil fuels, when natural gas usage for backup is properly factored. Below is a response sent to me by Michael Goggin, Manager, Transmission Policy, American Wind Energy Association. I look forward to the ongoing debate this will foment on this key topic — I certainly look forwards to joining in.
I’d also like to flag, for those in Adelaide, that #3 in my series “Thinking Critically About Sustainable Energy” is on tonight at the RiAus. Tonight’s topic is “Future Renewables“, covering engineered geothermal, ocean energy and next-generation biofuels. Hope to see some BNC readers there! And for those who can’t make it, there are always the videos.
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The Facts about Wind Energy’s Emissions Savings
Guest Post by Michael Goggin. Michael represents the wind industry on transmission matters, coordinates member input on the development of policy positions, facilitates the exchange of information between members, handles press inquiries on transmission-related issues, and advocates policy positions that advance wind industry interests. Through these activities, he works to promote transmission investment and advance changes in transmission rules and operations to better accommodate wind energy in the power system while maintaining system reliability. Prior to joining AWEA, he worked for two environmental advocacy groups and a consulting firm supporting the U.S. Department of Energy’s renewable energy programs. Michael holds a B.A. with honors in Social Studies from Harvard College.
Recent data and analyses have made it clear that the emissions savings from adding wind energy to the grid are even larger than had been commonly thought. In addition to each kWh of wind energy directly offsetting a kWh that would have been produced by a fossil-fired power plant, new analyses show that wind plants further reduce emissions by forcing the most polluting and inflexible power plants offline and causing them to be replaced by more efficient and flexible types of generation.
At the same time, and in spite of the overwhelming evidence to the contrary, the fossil fuel industry has launched an increasingly desperate misinformation campaign to convince the American public that wind energy does not actually reduce carbon dioxide emissions. As a result, we feel compelled to set the record straight on the matter, once and for all.
The Fossil Fuel Industry’s Desperate War Against Facts
Not to be deterred by indisputable data, numerous refutations, or the laws of physics, the fossil fuel lobby has doubled down on their desperate effort to muddy the waters about one of the universally recognized and uncontestable benefits of wind energy: that wind energy reduces the use of fossil fuels as well as the emissions and other environmental damage associated with producing and using these fuels.
For those who have not been following this misinformation campaign by the fossil fuel industry, here is a brief synopsis. Back in March 2010, AWEA heard public reports that the Independent Petroleum Association of Mountain States (IPAMS), a lobby group representing the oil and natural gas industry, was working on a report that would attempt to claim that adding wind energy to the grid had somehow increased power plant emissions in Colorado.
Perplexed at how anyone would attempt to make that claim, AWEA decided to take a look at the relevant data, namely the U.S. Department of Energy’s data tracking emissions from Colorado’s power plants over time. The government’s data, reproduced in the table below, show that as wind energy jumped from providing 2.5% of Colorado’s electricity in 2007 to 6.1% of the state’s electricity in 2008, carbon dioxide emissions fell by 4.4%, nitrogen oxide and sulfur dioxide emissions fell by 6%, coal use fell by 3% (571,000 tons), and electric sector natural gas use fell by 14% (Thorough DOE citations for each data point are listed in the hyperlink). Two conclusions were apparent from looking at this data: 1. the claim the fossil fuel industry was planning to make had no basis in fact, and 2. the fossil industry was understandably frustrated that they were losing market share to wind energy.
In early April 2010, AWEA publicly presented this government data, and when the fossil fuel lobbyists released their report later that month it was greeted with the skepticism it deserved and largely ignored. Case closed, right? We thought so too.
After the initial release of the report fell flat, the fossil fuel industry tried again a month later. John Andrews, founder of the Independence Institute, a group that has received hundreds of thousands of dollars in funding from the fossil fuel industry, penned an opinion article in the Denver Post parroting the claims of the original report. Fortunately, Frank Prager, a VP with Xcel Energy, the owner of the Colorado power plants in question, responded with an article entitled “Setting the record straight on wind energy” that pointed out the flaws in the fossil industry’s study and reconfirmed that wind in fact has significantly reduced fossil fuel use and emissions on their power system. Having been shot down twice, we thought that the fossil industry would surely put their report out to pasture.
Yet just a month later the report resurfaced, this time in Congressional testimony by the Institute for Energy Research, a DC-based group that receives a large amount of funding from many of the same fossil fuel companies that fund the Independence Institute. The group has continued trumpeting the report’s myths at public events around the country and on their website, and these myths are now beginning to spread through the pro-fossil fuel blogosphere. In recent days, these myths have re-appeared in columns by Robert Bryce, a senior fellow at the fossil-funded Manhattan Institute.
The fossil fuel industry’s desperate persistence and deep pockets make for a dangerous combination when it comes to distorting reality, so we’d like to once and for all clarify the facts about how wind energy reduces fossil fuel use and emissions.
The Truth about Wind and Emissions
The electricity produced by a wind plant must be matched by an equivalent decrease in electricity production at another power plant, as the laws of physics dictate that utility system operators must balance the total supply of electricity with the total demand for electricity at all times. Adding wind energy to the grid typically displaces output from the power plant with the highest marginal operating cost that is online at that time, which is almost always a fossil-fired plant because of their high fuel costs. Wind energy is also occasionally used to reduce the output of hydroelectric dams, which can store water to be used later to replace more expensive fossil fuel generation.
Let’s call this direct reduction in fossil fuel use and emissions Factor A. Factor A is by far the largest impact of adding wind energy to the power system, and the emissions reductions associated with Factor A are indisputable because they are dictated by the laws of physics.
In some instances, there may also be two other factors at play: a smaller one that can slightly increase emissions (let’s call it Factor B), and a counteracting much larger one that, when netted with B, will further add to the emissions reductions achieved under Factor A (let’s call this third one Factor C).
Factor B was discussed at length in an AWEA fact sheet published several years ago. This factor accounts for the fact that, in some instances, reducing the output of a fossil-powered plant to respond to the addition of wind energy to the grid can cause a very small reduction in the efficiency of that fossil-fueled power plant. It is important to note that this reduction in efficiency is on a per-unit-of-output basis, so because total output from the fossil plant has decreased the net effect is to decrease emissions.
As a conservative hypothetical example, adding 100 MW of wind energy output to the grid might cause a fossil plant to go from producing 500 MW at 1000 pounds of CO2/MWh (250 tons of CO2 per hour) to producing 400 MW at 1010 pounds of CO2/MWh (202 tons of CO2 per hour), so the net impact on emissions from adding 100 MW of wind would be CO2 emissions reductions of 48 tons per hour. Unfortunately, fossil-funded groups have focused nearly all of their attention on Factor B, which in this example accounts for 2 tons, while completely ignoring the 50 tons of initial emissions reductions associated with Factor A. A conservative estimate is that the impact of Factor B is at most a few percent of the emissions reductions achieved through factor A.
(Mr. Bryce’s recent Wall Street Journal article is the most creative in its effort to exaggerate Factor B and downplay factor A. In his article, Bryce exclaims about the “94,000 more pounds of carbon dioxide” that the IPAMS study claimed were emitted in Colorado due to Factor B. To be clear, 94,000 pounds is equivalent to the far less impressive-sounding 47 tons of carbon dioxide, or the amount emitted annually on average by two U.S. citizens. Yet just a few paragraphs later, Mr. Bryce speaks dismissively when noting a DOE report that found that, on net, wind energy would “only” reduce carbon dioxide by 306 million tons (enough to offset the emissions of about 15 million U.S. citizens.)
Factor C is rarely included in discussions of wind’s impact on the power system and emissions, but the impact of Factor C is far larger than that of Factor B, so that it completely negates any emissions increase associated with Factor B. Factor C is the decrease in emissions that occurs as utilities and grid operators respond to the addition of wind energy by decreasing their reliance on inflexible coal power plants and instead increase their use of more flexible – and less polluting – natural gas power plants. This occurs because coal plants are poorly suited for accommodating the incremental increase in overall power system variability associated with adding wind energy to the grid, while natural gas plants tend to be far more flexible.
(It is important to keep in mind that the supply of and demand for electricity on the power system have always been highly variable and uncertain, and that adding wind energy only marginally adds to that variability and uncertainty. Electric demand already varies greatly according to the weather and major fluctuations in power use at factories, while electricity supply can drop by 1000 MW or more in a fraction of a second when a large coal or nuclear plant experiences a “forced outage” and goes offline unexpectedly, as they all do from time to time. In contrast, wind output changes slowly and often predictably.)
To summarize, the net effect of Factors A, B, and C is to reduce emissions by even more than is directly offset from wind generation displacing fossil generation (Factor A).
Unsurprisingly, government studies and grid operator data show that this is exactly what has happened to the power system as wind energy has been added. A study by the National Renewable Energy Laboratory (NREL) released in January 2010 found drastic reductions in both fossil fuel use and carbon dioxide emissions as wind energy is added to the grid. The Eastern Wind Integration and Transmission Study (EWITS) used in-depth power system modeling to examine the impacts of integrating 20% or 30% wind power into the Eastern U.S. power grid.
The EWITS study found that carbon dioxide emissions would decrease by more than 25% in the 20% wind energy scenario and 37% in the 30% wind energy scenario, compared to a scenario in which our current generation mix was used to meet increasing electricity demand. The study also found that wind energy will drastically reduce coal generation, which declined by around 23% from the business-as-usual case to the 20% wind cases, and by 35% in the 30% wind case. These results were corroborated by the DOE’s 2008 technical report, “20% Wind Energy by 2030,” which also found that obtaining 20% of the nation’s electricity from wind energy would reduce carbon dioxide emissions by 25%.
The fact that this study found emissions savings to be even larger than the amount directly offset by adding wind energy is a powerful testament to the role of Factor C in producing bonus emissions savings. By running scenarios in which wind energy’s variability and uncertainty were removed, NREL’s EWITS study was able to determine that it was in fact these attributes of wind energy that were causing coal plants to be replaced by more flexible natural gas plants (see here page 174).
As further evidence, four of the seven major independent grid operators in the U.S. have studied the emissions impact of adding wind energy to their power grids, and all four have found that adding wind energy drastically reduces emissions of carbon dioxide and other harmful pollutants. While the emissions savings depend somewhat on the existing share of coal-fired versus gas-fired generation in the region, as one would expect, it is impossible to dispute the findings of these four independent grid operators that adding wind energy to their grids has significantly reduced emissions. The results of these studies are summarized below.
1 http://www.ercot.com/content/news/presentations/2009/Carbon_Study_Report.pdf
2 Transmission Expansion Plan, Vision Exploratory Study, Midwest ISO (2006), http://www.midwestiso.org/page/Expansion+Planning
3 http://www.state.nj.us/dep/cleanair/hearings/pdf/09_potential_effects.pdf
It is even more difficult to argue with empirical Department of Energy data showing that emissions have decreased in lockstep as various states have added wind energy to their grids. In addition and in almost perfect parallel to the Colorado data presented earlier, DOE data for the state of Texas show the same lockstep decrease when wind was added to its grid. This directly contradicts the Independent Petroleum Association of Mountain States report when it attempts to claim that wind has not in fact decreased emissions in Texas.
Specifically, DOE data show that wind and other renewables’ share of Texas’s electric mix increased from 1.3% in 2005 to 4.4% in 2008, an increase in share of 3.1 percentage points. During that period, electric sector carbon dioxide emissions declined by 3.3%, even though electricity use actually increased by 2% during that time (c.f. here). Because of wind energy, the state of Texas was able to turn what would have been a carbon emissions increase into a decrease of 8,690,000 metric tons per year, equal to the emissions savings of taking around 1.5 million cars off the road.
The fossil fuel industry’s latest misinformation campaign is reminiscent of scenes that played out in Washington in previous decades, as tobacco company lobbyists and their paid “experts” stubbornly stood before Congress and insisted that there was no causal link between tobacco use and cancer, despite reams of government data and peer-reviewed studies to the contrary. It’s time we enacted the strong policies we need to put our country’s tremendous wind energy resources to use, creating jobs, protecting our environment, savings consumers money, and improving our energy security, even if it means leaving a few fossil fuel lobbyists behind.
Brave New Climate 
134 replies on “Does wind power reduce carbon emissions? Counter-Response”
Kent Hawkins provides details of the emissions cuts (or lack of) due to wind power.
http://www.masterresource.org/2010/06/subsidizing-co2-emissions/#more-10349
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Regardless of fossil fuel propaganda it is a fact that wind and solar will require either massive storage capacity and /or fossil fuel,hydro or nuclear backup to accommodate base load demand reliably.
As nuclear and hydro are the only two of these three which are essentially non-polluting it would seem to me,innocent that I am,that nuclear would be a lay down misere to provide that backup as extra hydro is going nowhere in good old dry Australia.
So why,then,spend mega squillions on wind and solar to try and force them to do something they can’t,in practical terms,do?
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‘Inflexible’ seems to be wind/solar advocate newspeak for ‘baseload’.
In a certain sense, baseload power is the most flexible generation there is, as by definition it is capable of providing power whenever it is needed. Intermittent sources such as wind have the lowest flexibility, as they only operate under the correct weather conditions, or in the case of solar, during certain times of the day and year (once again, weather permitting).
OCGT natgas plants are highly flexible in the sense of being rapidly rampable, but they come at the cost of a high CO2 impost.
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This was a breathtakingly cynical effort, even for an industry hack.
Everyone, please note the absence of actual numbers in this post, except 2 tables of dubious relevance and that don’t support his contentions very well.
Take that first table: wind going from 2% to 6% caused everything to drop by 4% – except natural gas, which dropped 14%. This somehow supports the contention that wind makes the dirtiest plants turn off first?
Wait, wasn’t there a big recession in the timeframe that table discusses? Didn’t electrical consumption actually drop by more than the 4% claimed for CO2 and SO2 reductions? Wouldn’t that support the contention that the increased wind power caused more emissions that would otherwise have occurred?
As I said, breathtakingly cynical.
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Compare the cost of wind power and nuclear power on the basis that they must be able to provide baseload power:
Requirements:
Power is available on demand whenever we demand it – every instant of every day and all through the night.
Cost of nuclear power
Assumptions:
1. the first nuclear power station would cost the same or less than the first nuclear power station to be built in United Arab Republic (contract for four APR1400 units awarded to a Korean consortium a few months ago); i.e.
A$4,100/kW
2. The cost of further units would decrease over time, to say
$3,000/kW for the sixth unit.
Cost of wind power (to provide reliable, on demand power)
$2,600/kW for the Wind farms.
$1,000/kW cost for transmission and grid enhancements to manage the peak and fluctating wind power
$1,000/kW for gas generators to provide the power when the wind is not blowing at full power
$4,600/kW total
But wind power delivers, on average, only about 1/3 the energy of a nuclear power station of the same capacity. So we need 3 wind farms to produce the same average power per year as a nuclear power station. So the cost of the wind farms to provide the same energy as a nuclear power station would be:
$7,800/kWy/y of average power for the wind farms
$3,000/kWy/y of average power for the transmission and grid upgrades
$1,000/kW capital cost for gas generation for backup when there is no wind
$11,800/kWy/y total
An alternative to back up with gas generators is to use energy storage, such as pumped hydro, compressed air or batteries. Pumped hydro is the cheapest option where the appropriate topographic and geological conditions are available (Australia does not have much economic hydro potential near our major demand centres).
If we did have economic pumped hydro sites available the cost might be something like this:
$7,800/kWy/y of average power for the wind farms
$3,000/kWy/y of average power for the transmission and grid upgrades
$1,500/kWy/y for pumped hydro generating capacity
$100/kWh for energy storage capacity and we’d need say 50 days energy storage to get us through periods of below average wind generation; 50d x 24h/d = 1200h @ $100/kWh =
$120,000/kW of average power
$132,300/kW total (cost per KW average power)
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Wait, wasn’t there a big recession in the timeframe that table discusses? Didn’t electrical consumption actually drop by more than the 4% claimed for CO2 and SO2 reductions? Wouldn’t that support the contention that the increased wind power caused more emissions that would otherwise have occurred?
Yes, it’s kind of remeniscent of Carlo Ombello’s attempt to claim that the massive bargain-basement selloff of no-longer-viable PV panels in the wake of the scaled-back subsidies for PV solar in Germany and Spain somehow proves thar PV solar is becoming competitive in the market.
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Kent Hawkins study
Column Four – High efficiency gas plants only This shows the result of not implementing wind and using high efficiency gas plants to replace the same coal production.
If the assumption is that wind only provides 25% of power and the remaining 75% comes from high CO2 emitting coal is easy to see how 100% CCGT is going to provide lower CO2. Surely the comparisons should be 100% CCGT versus a specific wind % and the balance CCGT/OCGT and other storage options.
It like saying Denmark has higher CO2 emissions than France becasue it has 20% wind power, while ignoring where the 80% is coming from.
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The question of the net greenhouse benefit of wind within a grid is an interesting question and I’ll enjoy following the posts, but the more substantive question is whether investment in wind can offset, or in some way reduce the need for further investment in coal. Public policy debates seemed to have avoided addressing this directly, preferring to hide wind’s contribution within the obligation to purchase REC’s, with the implicit assumption that REC’s in themselves, somehow obviate the need to invest on fossil fuel generation.
The Electricity Supply Planning Council (South Australia) states
Click to access e400-0005.pdf
Further, actual output is below 18% of rated capacity for 50% of the time, during periods of peak demand (summer and winter). The use of “average capacity” or “capacity factor” hides the fact that the wind tends not to be blowing when the grid most needs the power, and therefore, at face value, has no prospect of displacing coal without massive overbuild or economical storage devices.
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Neil Howes,
I suggest you read the background! Follow the links from the Kent Hawkins article.
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As far as the discussion about the need for power system flexibility and how “baseload” and wind energy fit into that picture, I’ve written some on that topic as well:
Click to access Baseload_Factsheet.pdf
As far as the data in my article, if you follow the links and look at the DOE data yourself, I think you’ll find my conclusions are very well supported, about as well supported as any conclusions one can draw about any cause-and-effect relationship on a very complex system like the power grid.
The major downturn in gas use in Colorado in 2008 was almost certainly due to a shift away from gas and towards coal as natural gas prices peaked at over $14/MMBtu that summer. So if anything, the emissions savings that occurred as wind was added would have been even larger if that shift from gas to coal was not occurring simultaneously.
If you’d like even more data, let’s look at Denmark’s success in reducing electric sector carbon emissions by nearly 50% over the last two decades. (DOE data here: http://tonto.eia.doe.gov/country/country_energy_data.cfm?fips=DA)
Electricity consumption increased by 24% from 1991 to 2007, so we know that demand-side energy efficiency was not responsible for the decline in emissions over that time period. So, the solution must have come on the electricity supply side.
Wind energy output increased from 0.7 billion kWh in 1991 to 6.58 billion kWh in 2008, a nearly ten-fold increase of 6 billion kWh. Fossil fuel generation declined from 33 billion kWh in 1991 to 24 billion kWh in 2008, a decline of 9 billion kWh. Biomass power increased from .3 billion kWh to 3.67 billion kWh, accounting for the other 3 billion kWh of decrease in fossil generation. As a result of this increase in renewable energy output (2/3 wind, 1/3 biomass), coal consumption decreased from 15 million tons in 1991 to 7.8 million tons in 2008, a decline of nearly 50%, which explains why electric sector CO2 emissions also fell by nearly 50% over that period.
For those who don’t believe the data, what do you make of the numerous government and independent grid operator studies I cited that have calculated major emissions savings from wind energy?
Michael Goggin,
American Wind Energy Association
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As far as the discussion about the need for power system flexibility and how “baseload” and wind energy fit into that picture, I’ve written some on that topic as well:
http://www.awea.org/pubs/factsheets/Baseload_Factsheet.pdf
OK then. Here’s Michael Goggin’s definition of flexibility from his report:
Flexibility is the ability of power output, or capacity, to change over a given period of time. One can speak about the flexibility of a single power plant or the combined flexibility of all power plants on the grid. Flexibility is critical for accommodating changes in electricity supply and demand that occur, often unexpectedly, as power plants go offline or as consumers turn appliances on and off. Demand for electricity can vary by a factor of three or more
depending on the weather and the time of day and year, which means that hundreds of gigawatts (GW)3 of flexibility must be built into the power system. Flexibility can be measured over different time periods: e.g., a power system might have the flexibility to increase generation by 1 GW over 1 hour and 3 GW over 5 hours, with each capability being important for reliable system operation.
Goggin is clearly conflating the concepts of intermittency and reliability under the term ‘flexibility’. Sure, the wind might pick up over a set of wind farms somewhere, and the power output will increase as a result. This increase might coincide with increased demand, or (more likely) it might not. The wind will also likely drop ar random intervals and the power output will drop. This may coincide with a drop in demand, or it may coincide with a great increase in demand (as during a breezeless heatwave).
This is unpredictability and unreliability, not flexibility. For a power generation technology to be truly flexible, the output must be controllable with respect to time, otherwise it’s just unreliable. It’s truly astonishing that Michael Goggin would pursue such a ludicrous line of reasoning, but I suppose that when you’re stuck defending a losing proposition, you’re forced into these absurd positions.
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I think a way to put these claims to the test would be to eliminate the subsidies for certain forms of generation and simply cap CO2 emissions at a predetermined level. The subsidies I believe are the production tax credit in the US, feed-in tariff in Europe and renewable energy certificate in Australia. Rather than the internal least cost combination the electricity seller may favour the mix with extra revenue. Take that away and the mix could favour less windpower, in which case the subsidy has created costs
1) cost to the taxpayer for PTCs
2) higher power bills than necessary.
I’d also like to see how hydro and interstate electricity import helped out with CO2 savings within a particular State like Colorado. Also the role if any of carbon credits.
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Your link is broken, and the site is broken when you fix the link. According to IEA figures, Denmark’s CO2 emissions per kWh of electricity reduced by 34% from 1990 to 2007.
Click to access CO2highlights.pdf
And also as a matter of some interest, the Danish Energy agency reports CO2 emissions per kWh much higher than the EIA at 517 grams/kWh which is pretty miserable.
http://www.ens.dk/en-us/info/factsandfigures/keyfigures/sider/danishkeyfigures.aspx
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Further on Denmark’s CO2 emissions, this chart tells most of the story with Denmark grouped with UK, Germany etc with emissions per capita around 50% higher than the France, Sweden and Switzerland who derive their electricity from nuclear or nuclear+hydro.
http://www.google.com/publicdata?ds=wb-wdi&met=en_atm_co2e_pc&idim=country:AUS&dl=en&hl=en&q=australia+co2+emissions+chart#met=en_atm_co2e_pc&idim=country:FRA:GBR:DEU:DNK:SWE:CHE:NLD
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Michael Goggin, you state in your fact sheet:
Is this Orwell-speak or are you suggesting that the feature of being able to readily reduce output is a significant asset of wind power – or is this a problem because when the wind blows harder at night when it is not needed, the spot price is forced negative, thereby costing wind operators to generate power?
When you say “difficult”, is this Orwell-speak for saying that when the wind is not blowing, the turbine does not produce power? (allowing for the fact that blade design can be optimised for a range of wind conditions)
The usual function of a generator is to produce power, not be required to sink an electrical load. If wind ramps up and down of its own accord, and makes network management more challenging, is the defect in the wind system or in the rest of the network? Is the problem simply that wind has marginal value within a grid requiring 99.998% reliability without an accompanying storage device allowing schedulability, but wind proponents are aware that storage would shift wind from a profitable economic proposition to a loss-making venture?
Can you provide evidence of instances in which the installation of a wind farm, or farms, has permitted the decommissioning of a baseload coal/gas/nuclear plant, or otherwise permitted a proposal for a plant to be abandoned?
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[…] Does wind power reduce carbon emissions? Counter-Response […]
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I don’t doubt that a wind farm can reduce CO2 emissions. However I don’t see it as a solution that is either scalable, or more to the point cost effective. If we want to reduce emissions cheaply then skip the wind and go for gas. Unless of course you enjoy burning money.
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Do I understand correctly that the argument is that wind variability is a good thing because it forces the substitution of gas for coal to cope with the intermittency?
Why not just build the gas and not the wind then? It would be a much cheaper way to reduce emissions.
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Neil Howes
You do not understand the basis of the comparison I make. The comparison is the combination of wind/CCGT/OCGT at 100% of wind’s capacity. This is the methodology correctly used by Katzenstein and Apt at Carnegie Mellon University. Although they did not show dramatic reductions from the theoretical one-to-one CO2 reductions for wind production they do (properly) acknowledge that their analyses were limited by (1) using CCGT alone versus wind/CCGT, and OCGT alone versus wind/OCGT, and should have included changing the CCGT/OCGT mix when adding wind, and (2) not having full operational data for gas plant fast ramping. See my post for the references.
The introduction of other storage means is not a realistic consideration for large-scale wind implementation.
I would always be careful in using Denmark as a example of beneficial wind use as it is a very unique situation involving relatively large (in electricity terms) Nordic neighbours who obtain 75% of their electricity from hydro generation. It is a well established fact that Denmark exports most of its wind power to the Nordic region. It could not survive its wind situation without such rare circumstances. The rest of us have to live in our own real world in this matter.
If I have missed anything in this response, please let me know.
Kent Hawkins
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I would always be careful in using Denmark as a example of beneficial wind use as it is a very unique situation involving relatively large (in electricity terms) Nordic neighbours who obtain 75% of their electricity from hydro generation. It is a well established fact that Denmark exports most of its wind power to the Nordic region. It could not survive its wind situation without such rare circumstances.
One might well begin to wonder if this was not all clear to the Danish wind protagonists at the outset of their program, knowing ir would be decades before the limitations of their approach would become obvious to observers.
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according to the IEA report referenced by quokka, denmark has reduced its coal use by 23 % since 1990; it has increased its use of natural gas by 129%.
I am confused about the numbers offered for denmark in grams CO2/kwh. From Mackay’s 881 to Brook’s revision somewhere around 600-625 (going on memory here) to 517 cited by quokka to the 342 or so in the IEA report.
Other countries don’t seem to show such variation.
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Quokka: the danish source you cite on emissions per kwh says 547 grams CO2/kwh, not 517.
Let’s not cut Denmark any slack!
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First off, I’d like to tip my hat to Barry for posting this article. It shows that he is interested in a serious, open debate and to look at all sides of the energy discussion, and give everyone a voice.
The information posted by qoukka was very revealing. On the google link, I suggest people try adding Australia and Spain (another nation aggressively persuading renewable energy) to this mix.
We can argue all day about the case in Denmark, but I don’t see how its relevant to most other industrialised nations. When I first came to this website and I was on the fence in the renewables/nuclear debate, I was told (I believe by finrod – cheers mate!) to compare a nation generating a large proportion of its KWhe from Nuclear (France) with one doing the same with Renewables (i.e. Denmark). Well I did, and this is what I learned:
A large Industrial Nation like France, in relative isolation managed to decarbonise ~90% of their electricity in around a decade or so. Electricity there is cheap.
Denmark, a much smaller nation (pop ~5 million) with good connections to its neighbours and on longer timescales, has not achieved anywhere near the same level of success.
Perhaps Denmark’s electricity emissions have reduced as a result of renewables, and I congratulate them for it. But my point remains that the we can not extract much relevant information from the Danish case, because they are in special circumstances. To do just what they have done in my own country (uk) would require a wind turbine build of epic proportions, and massive grid connections.
Its my personal opinion that we should stop the downplaying of renewable energy sources (the fossil fuel industries give them more than their share of flak already). Instead the pro-nukes an pro-renewables should see each other as natural allies, against a common opponent (fossil fuel industry).
I’d settle for even the small emissions savings described by Peter Lang in a previous post in this line, but only until the Nuclear build gets going in full swing. In other words, Renewables are going to be a short term tool, perhaps chopping off a few tonnes from peak load gas.
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I did notice that the Danish Energy Agency figure was for electricity sold in Denmark. Maybe others are derived in some other way?
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The Question of CO2 reduction is settled by looking at complete data. Yes carbon emissions did go down, but so did total generation. There is a major recession that accounts for that fact. The answer from AWEA does not include all data, in fact not any. Denmark has dismantled many of their offshore wind units, I believe due to the maintenance expense. To my knowledge NO fossil plants in Europe have been removed, with the possible exception old non-efficient units ready for retirement. No mention of continuous generation was made. No mention of the best solution ( if it is required at all) to carbon emissions, namely nuclear. No mention of nuclear at all. All wind energy requires a steady continuous source to support it. This is either a fossil plant or other continuous source, running at a low standby level to rapidly follow wind energy deviations.and supply the loss in energy rapidly. Hence
NO decrease in carbon emissions, except by fossil choice. The AWEA presented no data of comparison subsidies. LEN
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Always check the fine print:
Essentially the IEA is crediting the Danes for their extensive use of CHP. Without this, the ~600 g/kWh figure is probably valid, as you would expect from a country that gets 50% of its electricity from coal.
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quokka: what you say just above makes some sense.
the exported electricity (mostly or all wind) would be emissions free because uncontaminated by back up generation, as that backup is coming from another country and is itself clean (hydro from Norway, etc.). If 10 percent of their generated electricity (exports) is largely emissions free, that would bring the number down quite a bit.
but then the number is very misleading, pointing directly to the very peculiar situation of denmark referred to by Kent Hawkins and others.
does this make sense? (I ask myself as well)
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I feel a bit of sympathy for Michael – it must be difficult for a guy who earned his BA in Social Studies to get tangled in a technical discussion. It must feel sort of like bringing a penknife to Fallujah.
There are certain things that one needs to understand when it comes to maintaining a reliable grid with millions of energy sinks and thousands of energy sources. Even with “smart” grids that have a good deal of automation, the key is the ability to CONTROL the output of at least some of the generators – unless you want a command driven system that refuses to send power to certain unpopular loads when demand exceeds supply. One part of the control that is absolutely invisible to most consumers – unless the grid operator goofs up – is the need to control reactive loads by adjusting voltage regulators on some of the supplying generators.
I will grant that many very large nuclear and coal fired power plants were not designed to provide rapidly varying power, but I will not concede that either nuclear or coal is inherently inflexible. The rate of power changes is largely limited by thermal inertia and unit specific fuel system limitations. Both energy sources have been used as the single source in highly maneuverable large ship engines with exceptional ability to provide EXACTLY the amount of power demanded at the time it is demanded.
Certainly, it is true to say that all machines fail unexpectedly from time to time, but it is also true that the RATE at which those machines fail can be controlled by the operators / maintainers . People who are good to their machines and understand the maintenance requirements can ensure a very impressive reliability record. In the US, for example, I believe that the average number of unplanned shutdowns in nuclear power plants per unit per year is 0.25. In most years, 75-90% of the fleet will not experience a single unplanned shutdown, with the remaining part of the fleet experiencing one or a few more. In 2009, 13 units in the US nuclear fleet had capacity factors for the entire year that were greater than 100% and the record for a breaker to breaker run without a single shutdown is about 700 days.
Michael, I am sorry if it offends you for me to remind people that you earned your Bachelor of Arts (with honors) in Social Studies and you have been a political lobbyist for most of your career. You are obviously a smart guy who can express yourself, but you have little to no experience in the importance of numbers or understanding engineering topics.
I earned my undergraduate degree in English, but it happened to have been a BS with enough math, science and engineering courses to convince Admiral Rickover to hire me and train me to serve as an engineering officer on his nuclear powered submarines. To this day, I still have some folks in the technical world who look down at my degree, but that is a cross I have to bear.
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Comparing CO2 emissions from electricity at the 2 time points that Goggins uses, 1991 and 2007, doesn’t tell us much about wind, since that was significantly added only between the middle 1990s and 2003. Nor does it tell us much about CO2. Because of Denmark’s large interconnectors, its CO2 production varies quite a bit from year to year, so anyone can pick a low year and a high year to illustrate a rise or a fall. The overall trend (all CO2, not just electricity) since 1995 has been essentially flat.
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Two of my favorite charts when talking about wind power, are these:
Click to access DKELEC.pdf
Click to access FRELEC.pdf
Don’t forget to look at the numbers on the left, GWh.
Are there still any questions?
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oh, those charts are quite nice.
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Kaj,
Those charts should make the choice for Australia absolutely clear. But why can’t the RE advocates see the bleeding obvious?
To other BNC contributors I say:
Our goal should be the fuel mix that France has adopted. Convincing the oponents of that is where we should put our energies, not into arguing about more symbols like a price on carbon. We did the Kyoto symbol, surely it should be plain that these symbols are not the way forward. I realise I am a lone voice amongst the BNC contributors, but surely you would have to accpet that there is now, and always will be, enormous oppostion to anything that is raising the price of energy when there is next to no evidence it will have the desired effect. But we can see the effect that going to the French energy mix will have.
And surely most can see that if we allow nuclear to be low cost, then low cost clean electricity will displace fossil fuels for transport and heating more quickly than if it is high cost. So we will cut our emissions, in Australia, faster if clean electricity is low cost. More importantly, if celan electricity is low cost, it will displace fossil fuels faster in the developing world.
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Has anybody else followed Mr. Goggin’s references to see where he (and the EIA) got their emissions numbers? Take his first chart, the Colorado emissions change from 2007 to 2008. His reference initially goes to AWEA, at
Click to access 04_05_2010_Colorado_emissions_response.pdf
That in turn points to a couple of spreadsheets from the EIA, the emissions spreadsheet is at
http://www.eia.doe.gov/cneaf/electricity/st_profiles/sept07co.xls
If you look at that spreadsheet, upper left corner, there’s one word that Mr. Goggin doesn’t mention. The one word? Estimates. The EIA hasn’t measured anything, compared with Bentek, who did. The EIA details how they calculate the emissions in http://www.eia.doe.gov/oiaf/1605/ggrpt/documentation/pdf/0638%282006%29.pdf. They essentially take the fuel burned times a fixed carbon coefficient.
Since Colorado and Texas both apparently have emissions measuring equipment on their stacks, why hasn’t the government made use of that data, instead of estimating?
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These graphs are even better:
Click to access DKTPES.pdf
Click to access FRTPES.pdf
Note the thin red line which is Denmark’s Wind Energy – a tiny fraction of Total Primary Energy supply. And about 1/2 of that is exported.
When you realize that Denmark commonly uses District Heating from CHP power plants, they could easily utilize the waste heat from Nuclear, to supply heat loads, thus Primary Energy Supply is a relevant comparison.
Considering the discrepancy in Denmark’s CO2 per kwh numbers, I would point out that Denmark and the EU declare all biomass energy CO2 neutral, which of course is a ridiculous assumption. Since Denmark produces a large portion of their Electricity from Peat & Biomass, some are ignoring a large amount of CO2 production. So I would go with Mackay’s 881 gms/kwh.
Waste Biomass like Wood and Plant Fibers, could easily be recycled into building materials, trapping the carbon for many decades. Agricultural Waste should be plowed into the soil for soil remediation or it can be converted to Biochar & sequestered in the soil. Of course, eventually some of the buried biomass will eventually return to the atmosphere, after many decades, however the desperate need is to reduce CO2 emissions over the next 20 yrs – it just ain’t going to help if carbon dumped into the atmosphere today is returned to plants & trees 70 yrs from now.
There may also be some discrepancy in terms of how CHP is accounted for. If a CHP power plant produces ½ Electrical Energy and ½ EFFECTIVELY UTILIZED Heat, do you declare ½ the CO2 output to Electricity and ½ to Heat?
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Wayne Gulden,
Thank you for that. Isn’t it amazing what can be found when we dig into the assumptions and the sources.
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Kent Hawkins
I was taking issue with comparing wind plus coal versus CCGT instead of wind plus CCGT/OCGT versus CCGT. I would also take issue with only having wind capacity at 100% of average demand, using 25% capacity factor( for US or Australia) and not using existing hydro. Your comments on ERCOT curtailment ignored the fact that most of this is due to transmission constrains from the McCamey region to major demand not excess supply.
Why is Denmark a special case because it balances wind with hydro? This is what will be done almost everywhere wind is used and is presently being done for nuclear and coal-fired power in many countries.
The introduction of other storage means is not a realistic consideration for large-scale wind implementation.
Certainly North and South America, Africa and Asia all have very large hydro resources for storage. Australia the driest continent has up to 22,000GWh of hydro storage and certainly potential to install very considerable additional pumped hydro storage or to increase present hydro capacity and run at a lower capacity factor.
The rest of us have to live in our own real world in this matter.
Not sure who you are referring to as “the rest of us” who dont have access to hydro storage?
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dwbd,
Thank you for those two charts.
I’d like to use the French chart to highlight the point I’ve been making that the world can cut GHG emissions faster with low-cost, clean electricity.
Other BNC readers: please look at the chart of France’s total primary energy consumption by fuel. Notice the proportion of oil. Electricity’s share of total energy consumption is increasing. That is good everywhere, but especially so when electricity is near carbon free as it is in France. So we want to accelerate that trend. We want electricity to replace fossil fuels faster (especially oil and gas in France’s case).
How can we do that?
Clearly, we need to reduce the cost of electricity if we want it to more rapidly replace fossil fuels for heat and transport.
So, in case you missed it earlier, we need to put our emphasis on getting low cost clean electricity.
A price on carbon for electricity generation, therefore, is exactly the wrong policy intervention.
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Neil Howes says:
Australia certainly will not be building massive pumped storage sites to try to make wind power baseload capable. You know that full well, so I wonder why you keep repeating such total nonsense.
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Peter Lang
I’d like to use the French chart to highlight the point I’ve been making that the world can cut GHG emissions faster with low-cost, clean electricity.
You should be sure what the graph is showing; France uses 160Mtoe of oil and NG and produces 37 Mtoe(430,000GWh) of nuclear power, but in this graph this appears to have been “corrected” to a FF equivalent of about 110Mtoe( comparable to the coal or oil used to generate electricity). Countries like Australia and Denmark are generating 80% of electricity from coal so this is the biggest source of GHG. So you are right that countries that use low CO2 emitting electricity (France, Canada, Norway) have lower GHG emissions than countries that use mainly coal and oil(Australia, US and China).
Australia certainly will not be building massive pumped storage sites to try to make wind power baseload capable.
Australia really doesn’t have to build massive pumped hydro sites, to use a very significant (>50% electricity generation) wind power, just a modest pumping capacity at existing dams that can give very large storage, and using present hydro storage as you outlined in a previous BNC post on pumped hydro.
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Interesting link below:
http://www.slate.com/id/2264111/
No doubt written by someone on the coal industry payroll :)
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The description of Michael Goggin’s expertise ie “Michael holds a B.A. with honors in Social Studies from Harvard College.”. Amazing. When I seek information on power generation I look to the views of a qualified engineer with experience in the power generation industry and not someone who has expertise in social studies. I am not surprised the AWEA think this is credible expertise for their front man.
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One other thing, notice that about 10% of French electricity is coming from Coal and Gas. Imagine how low the already negligible figure of 83gco2/kwh for them could be if they got rid of this bit of Fossil fuel – It may even account for the entire figure.
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Sorry I’m a bit late in this discussion but when Michael is talking about “flexibility” he is really talking about load following and fast start. Coal and nuclear can do load following but are not great at fast start.
The only renewable energy source that I know of that can do fast start is hydro. Batteries can do it as well but they are just not cost effective today.
In most networks, baseload makes up more than 60% of the energy demand. In Australia it is closer to 75%. So we cannot dismiss baseload lightly and it will make sense to have generators that specialise in baseload cost effectively for many decades to come.
But Michael is right that we need a mix of generators to handle fast start (generally for peak load). Wind won’t help here unless we curtail the turbines when the wind is blowing which is unlikely to be attractive to the wind farm owners.
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I puzzled over why large hydro in Australia doesn’t get the REC subsidy. The get out clause is renewable generation built since 1997 so it excludes anything bigger than a couple of MW. Large hydro doesn’t need subsidies since customers can get it when they want it, not when it is ‘available’.
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Sorry I’m a bit late in this discussion but when Michael is talking about “flexibility” he is really talking about load following and fast start. Coal and nuclear can do load following but are not great at fast start.
I got the distinct impression that Michael Goggin was claiming wind power to be a flexible power source itself, rather than making the far more defensible claim that significant wind power generation increased the requirement for flexibility from the other generators on the grid… which is the opposite of the meaning of his claim.
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Neil Howes,
What on earth are you talking about? Are you trying to say that the IEA is using the wrong conversion factors and distorting all their energy figures? If so, perhaps you should let them know. I am sure they’d be interested to hear your opinion.
On the pumped hydro points you continually repeat, I’ve shown you over and over again that you don’t understand what you are talking about. But you keep repeating the same rubbish.
On many occasions I’ve suggested you describe your concept, define your assumptions and estimate the cost of the system. But you never have done so. You run away and hide each time I suggest it. So, instead of continually repeating the same nonsense, why don’t you do as I suggested? Then perhaps you will see how totally ludicrous it is.
For others reading this, Australia is a dry continent with low topographic relief. We have very little hydro potential. Our Snowy Mountains Scheme has little water inflows so the capacity factor of the whole system is as low as 14% (2007). We need the storage to collect and store water during multi-decadal periods of above average rainfall so we can maximise our hydro generation through multi-decadal periods of below average rainfall. That is why the storage was built. If we want to divert it to other uses then we reduce the capacity factor of the scheme.
The hydro energy we do have is highly valuable for balancing the grid and for emergency generation. The larger our demand grows the more valuable will be our hydro for what it was always intended for. There is no way it will be handed over to firm wind power – to try to make wind power look more economically viable than it is. It would be a ludicrous waste of our highly valuable, but severely limited, hydro resources.
There is also no way that our existing storages could be turned into viable pumped storage for firming wind power. There may be some existing reservoirs that can be made into economically viable pumped hydro for charging (pumping) using reliable, low cost baseload power supplies, but certainly not for unreliable, high-cost power supplies like wind.
I’ve explained all this numerous times in detail, so there is not point in me doing so again. Neil either doesn’t understand or doesn’t want to. So it is up to Neil to document his concept, document the assumptions and estimate the cost. Then it would be worth going into details to explain the flaws in his argument.
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Further to my previous comment, it seems to me that the essence of Goggin’s argument is to note that ‘flexibility’ is an important issue when it comes to pumping wind power into the grid (without mentioning that it’s the backup to wind which <absolutely must possess this trait), examining the mental imagery which people have when ‘flexibility’ is mentioned (something which can be bent out of shape and made to be twisty or curvey), noting that the output from wind kinda looks twisty and curvey when plotted on a graph, conflating all these ideas into a generous mess of Word Soup, and serving said soup up, hoping no-one’s going to look too closely at the ingredients.
This is an approach which likely works very well on Michael Goggin’s usual pro-wind audience, and we have to understand that it is those people he is writing for, not the regular BNC audience. It is probable that Goggin does not really care about any of the criticism he has recieved here, because he has delivered his true audience exactly what they want and what they expect… comforting sounds from their chosen shaman to be digested whole rather than carefully chewed over.
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Finrod, I was basing my assessment (perhaps naively) on Michael’s definition of flexibility (ability to “turn up” or “turn down” electricity generation as needed). This is done two ways. You either have the generator running part loaded so the load on the generator can be increased or decreased or you cold start a new generator or shut down a generator.
Given that, I did find his table 1 difficult to reconcile. It is certainly true that wind can turn down quickly but can only turn up with the wind blowing and the blades feathered so it is part loaded. It would seem hard to argue that wind was flexible based on that table.
It could be that Michael is including load following in the Capacity definition but this is not clear. It can be a problem when an author introduces new terms into a well established lexicon for power generation.
I am surprised at the Federal Energy Regulatory Commission’s comment. I hope it wasn’t taken out of context. The NY Times article quoted did say “Wellinghoff’s view also goes beyond the consensus outlook in the electric power industry about future sources of electricity.”
I tend to put my money on the guys that have to make it all work.
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Michael’s statements regarding co2 emissions and wind power in Denmark are to a large extent irrelevant. Some of the reasons have already been summarized here, but I find it especially misleading to split the energy sectors
into smaller pieces and then claim that one sector emits certain amount without accounting for the changes this sector induces elsewhere. Denmark like other Nordic countries use CHP plants to generate both electricity and heat and since the demand for heating doesn’t correlate with wind speed (in isolation) an ample supply of wind power lowers the efficiencies of the CHP plants with higher Co2 emissions for each kWh produced. Wind powers role in reducing Denmarks (high) CO2 emissions has been marginal. The changes in building codes and district heating have been far more important. In fact it could not be any other way, since wind power produces only few percentage points of their total primary energy supply (since electricity is only one component of PES). The actual importance if wind power as a tool in tackling climate change is in no relation to the huge noise it produces in public discussions.
Advocates of wind power understandably wish to split the energy sector
into multiple pieces since then it easier to shift the blame outside their own sector while labeling themselves as “ethical”, but that is just silly. In terms of climate change, it is the overall CO2 emissions from all sources that matter and then one cannot just brush away the fact that wind power is in most places build on top of the fossil fuel based energy infrastructure.
Another observation from the Nordic electricity markets, is that using public subsidies (paid by Danes) Danes have created an engine that transfers wealth from the less wealthy nation of Denmark into a more wealthy nation of Norway. To see this, visit the nordpool web site and check out the electricity flows and spot prices in the region, especially the flow between “Denmark West” and “Norway 2”. As you can see, the Danes export during the night time (and on Sunday) when the spot prices are low and import during the day time when the spot prices are higher. If I were Norwegian, I would be all in favor of more wind power…in Denmark. (http://www.nordpoolspot.com/reports/flow)
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Neil Howes
My analyses do not compare wind plus coal to CCGT. Most of them compare wind plus gas (CCGT and OCGT) to CCGT. I did introduce coal by request and performed some coal/gas/wind combinations to coal which showed the coal/gas performed better compared to coal than coal/wind/gas. To take the view that you do is misunderstanding my analyses.
Introducing hydro is a special case as most jurisdictions do not have the luxury of having sufficient hydro available to be diverted to wind balancing. Not all available hydro can typically be used in this way. A consideration is the dispatch merit order of the different generation types which varies by jurisdiction. In some cases hydro can be baseload, intermediate or peaking, and coal can be baseload or intermediate for example. It makes a difference in terms of what is used to balance wind, or in other words what wind is displacing. In most cases this will be gas, which is a mid-merit, or intermediate, generation source. In the event of high wind production at night baseload generation can be impacted by wind. In most cases using hydro to balance wind does not reduce CO2 emissions.
The analysis of using hydro to balance wind is complicated and depends on the hydro type, run-of-river or impounded. For example in Ontario Canada there is considerably more baseload run-of-river hydro (an unusual case) than most jurisdictions, but gas is going to be used to balance wind. I teamed with Don Hertzmark at MasterResource to analyze the Northwest US (a relatively impounded hydro-rich jurisdiction) use of hydro to balance wind, which illustrates the complexity and shows that the hydro is not necessarily available for wind balancing.
In Denmark’s case, the hydro production in Norway and Sweden, at a total of 200,000 GWh, where most of the Danish wind production goes is almost thirty times as large as Denmark’s total wind production. I’m not saying that you need this ratio but you do need a lot of hydro to balance wind. Again in Denmark’s case they take less Danish wind in wet years.
As far as hydro development potential is concerned there are other considerations, for example (1) in most jurisdictions permitting could be a difficult process because of environmentalists’ concerns, and (2) given the hydro potential why not develop it alone without the additional cost of wind, including the additional transmissions costs (and required permitting of transmission lines) to collect wind’s additional widely dispersed energy availability. Denmark would be better off just importing Nordic hydro than force fitting wind into the system.
Finally on the issue of storage, there are no storage technologies available for the foreseeable future to handle large utility-scale use of wind power, including pumped hydro which is more suited to diurnal variations in demand, not constant balancing as in the case of wind. There is considerable information available on pumped hydro, and other storage schemes. For starters look to David MacKay’s book, which does a good job analyzing this. It can be downloaded at http://www.withouthotair.com/download.html
You touch on a very complex subject and this short discussion only begins to cover all the considerations realistically. I don’t know your background or where you are coming from on this, but you have a lot of work to do to support your claims.
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Thanks to Michael for the post and Barry for giving him a voice. But the post
didn’t really target the tough questions and dealt with the easy questions
in a obscure way … as can be seen from criticisms already. When I see
people talk about percentages of different things I immediately ask about
the absolute numbers. Wind up 3.6% of total energy and coal down 3% can mean really different things depending on the modality of the energy mix,
particularly when you add in the Gas down 14%. So I was immediately
thinking “what the hell does that mean?”. But that’s a minor issue. The
big issue is scalability.
Any mode of energy should reduce emissions when used to supplement
a base supply, the issue that this blog has been concerned with
on and off for quite some time is what happens when you try to build
the entire power supply with intermittent sources like wind/solar. I’d
suggest you focus on that issue if you wish to write a second piece.
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Last May I wrote a blog post where I looked at energy production and CO2-emissions from sixteen countries. It could be usefull now. It’s in Finnish, but a (poor) Google- translation is available.
Click on the charts to see them in English.
You will see how nuclear power has affected emissions. I don’t say there are always a causality, but there coud be. You tell me what you think.
Thank’s to Jari-Petri for an informative comment. The CHP + district heating is (IMHO) commonly not wery good understood. I don’t get the idea of David MacKay in this case.
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Michael opposes flexible power to inflexible power.
I think FInrod is correct that M engages in rhetorical manipulation of these terms.
M seems to equate baseload and “inflexible.” Is this misleading?
I have read some material on load following in French nuclear plants. It takes some time for the power adjustments to take place, so ramping up and down is not instantaneous. That said, when French nukes are load following, and thus showing some flexibility, are they no longer providing baseload, as the equation of baseload and inflexible implies?
I hope I have asked my question correctly. It all comes down to whether there is something misleading (over and above the negative connotations around “lack of flexibility) in equating baseload with “inflexible.”
g
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How exactly can power ‘on all the time’ be a disadvantage? I’d take that over ‘flexible’ i.e. unreliable renewables anyday.
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on my question above, I suspect Kent Hawkins implicitly answers it in his reply to Neil. I’d still like to hear people’s thoughts on my question.
Kent, by the way, offers us a model combination of rigor and respectful tone. It is an interesting comparison with Peter Lang. In substance, they are saying virtually the same thing. But Peter comes across as angry, and perhaps as a much different person.
Peter may of course be way nicer than Kent; but that’s not what “comes across” in respective rhetorics.
That said, there’s a place for anger. Still, just as a point, John B I’ll bet has a much easier time with Kent than with Peter, even though P and K share very similar points of view on energy and economy.
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I should say, in partial qualification to my comments on rhetoric, that anger is often a function of commenter’s sense of urgency combined with a commenter’s sense of who the real enemy or enemies are.
Is it a good idea to piss off people like Neil or John?
for me, that’s hardly where the fight ought to be.
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“Nor does it tell us much about CO2. Because of Denmark’s large interconnectors, its CO2 production varies quite a bit from year to year, so anyone can pick a low year and a high year to illustrate a rise or a fall.”
T Ricotta: this is an interesting comment, but I don’t understand it. what are the large interconnectors and how do they relate to varying CO2? Just asking for some layperson’s clarification.
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In part answer to Greg’s question, I think there may be some misunderstanding about the term baseload. Baseload is just the minimum amount of power needed in a network to meet demand. There is really nothing special about baseload it’s just the part of demand that is always there morning, noon and night.
The demand varies continuously day and night so all generators need to be able to respond to changing demand to some degree. Sufficient baseload generators need to handle the night time variability which is generally less than during the day. These generators are supplying both baseload and load following. Of course any “baseload” generator doing load following is not running at full capacity all the time.
From about 6 am the demand starts to ramp up in a reasonably predictable way and additional generators are cold started to handle the rising load. Clearly these “intermediate” generators as they are called need to be good at load following because they ramp up with the load over around 2-3 hours plus handle the shorter term ups and downs in demand. Similarly around 4 pm the demand starts to fall and these intermediate generators ramp down and around 8-9 pm they are shut down.
Peak load is much less predictable but happens somewhere between 9 am and 6 pm depending on the weather. In summer there is typically one peak with its apex in early afternoon caused by building cooling. In winter in some countries there can be two peaks, one mid-morning and one mid-afternoon – usually caused by building heating.
Clearly during the day, there is less requirement for baseload generators (which just means those generators that run all the time) to do load following. They are typically the lowest cost generators so they will run fully loaded and the intermediate and peaking plant will handle the load variability.
Greg, I’m not sure this answers your question but it might clarify the situation (or not).
On Ricotta’s point about interconnectors and CO2, I think what he is saying is that a country like Denmark may buy electricity from a neighbour over the country interconnecting grid but not account for the CO2 generated to produce that electricity. If the electricity came from a German coal plant then Germany would report the CO2 generated not Denmark even though Denmark used the electricity.
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Too much comparison of elephant shrews with elephants.
Denmark, around 20% wind, is backed by NOrway’s hydro. Around here, BPA has stated flat out that not more than 20% of rated total capacity can be wind backed by hydro; we have quite aways to go to reach this figure and already the 143 or so utility companies are having gris balancing problems.
I conclude that even with massive hydro (which we have in this region), wind can only be a minority player, although one part in five is, of course, significant.
Oz, it seems, have rather different constraints and the discussions on PNC certainly suggest that for Oz wind can only be a boutique player.
But it can be that, every grid can accomidate a small portion of intrmittent sources of electirc power.
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actually martin: that was really helpful.
walking a reader through a day’s typical electricity output, with attention to when the different loads occur and what power sources handle those loads is a good idea. Thanks.
So baseload power sources can often load follow, but typically it is less efficient for them to do so during the day for I and P loads.
In France, what power source handles typical I and P?
Thanks for clarification on the interconnectors.
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It seems that even France wnats to have a substantial portion of nameplate generation in wind: 3 GW is about 8% of typical daytime maximum loads.
http://blog.cleantechies.com/2010/08/30/france-to-have-3000-mw-of-offshore-wind-by-2015/
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greg meyerson, on 3 September 2010 at 22.31 — The French do load following with their NPPs. They also export less power during the day than during the night. There are also some natgas units and a modest amount of pumped hydro. This last is primarily for peak shaving, although other generators are going to have to cick in as well.
Every grid is different.
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I believe France has a legal obligation under the EU directive on renewable energy to increase renewables by 2020:
http://ec.europa.eu/energy/renewables/index_en.htm
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[…] Goggin since utilized the content of the link referred in his comment at the Brave New Climate blog. as response to two previous posts carried at the BNC authored by Mr. Peter Lang, a retired […]
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Tom Williams,
You said: https://bravenewclimate.com/2010/09/01/wind-power-emissions-counter/#comment-95434:
“But my point remains that the we can not extract much relevant information from the Danish case, because they are in special circumstances. To do just what they have done in my own country (UK) would require a wind turbine build of epic proportions, and massive grid connections.”
Although I spent my first 40 years in the UK, I seldom go there any more. During my last visit I was astounded by the number of wind turbines so I looked up their contribution to electric power in the UK. For wind power to replace coal requires 50 times more windmills than exist today. That would indeed be a build of “epic proportions”!
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There is a little black face in the grey area on the right hand side of the page. Is this a concern?
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Lynne, Mr Smiley is there for a reason…
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Folks, ‘fast start’. My initial reply is ‘so what?’. One might ask why in the past…say before 1990, ‘fast start’ never passed the lips of a System Operator? This is because ‘fast start’ is not a category that is *intrinsic* to the grid, any well built grid.
During the pre-1990 period there was simply an abundance of capacity. Each *steam* driven unit was collectivized in the overall grid to rate the system capacity. The fastest ‘fast start’ is simply a good old fashioned steam turbine with a ‘governor’ that can respond *instantly* to variation in the system speed..and that is, the load, up or down. This is why generally, you cannot, ever, have a system that is built solely on gas turbines: no governor. However, steam plants, be they nat. gas fired ones, coal driven or nuclear, can do that IF they are designed that way. Plants that can change load at 10, 30 or even 50MWs a minute are WAY faster than *any* Gas Turbine from a cold start, even one on turning gear.
When we look at a *serious* nuclearized grid, say, taking Australia totally nuclear, we look at at *minimum* at what France has done. But we make the Australian one far better, with complete load changing, slightly over capacity nuclear plants of a *variety of sizes* and capability.
*Any* high temperature reactor can *easily* “store” power by diverting it to desalination. I understand that water is a big issue for much of that continent. ALL nuclear plants can divert a portion of their primary heat and / or their waste heat at the low end of their turbines to desal and then the ‘problem’ of overcapacity is solved and I mean solved completely. No pump storage is needed *at all*. But that is why *planning* is needed.
Wind, as Rod Adams noted is not ‘plannable’, it can not be ‘controlled’, so you need a bigger and bigger integrated Smart Grid to pull something like this off with a BIG MAYBE it can even be done. And…what would be the point, in any event? The *only* point to this utiopia would be NOT to go nuclear. And that would be quite backward, for any area of the globe today.
David Walters
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The *only* point to this utiopia would be NOT to go nuclear.
And, by extension, to maintain the primacy of coal and gas in power generation. This is the true goal of organisations such as the American Wind Energy Association.
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Finrod, on 7 September 2010 at 5.36 — It might be a unintended consequence, but no, not a goal of AWEA.
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Finrod, on 7 September 2010 at 5.36 — It might be a unintended consequence, but no, not a goal of AWEA.
I assert that the protection of the privileges of the established FF industries is indeed the goal of the AWEA and similar organisations, although they would never openly state it.
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Finrod, on 7 September 2010 at 6.01 — I already knew that you assert that, but you need to be open to the possibility (nay, high probability) that you are dead wrong.
So far you have shown no evidence whatsoever for your stance.
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Test only
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Finrod, on 7 September 2010 at 6.01 — I already knew that you assert that, but you need to be open to the possibility (nay, high probability) that you are dead wrong.
So far you have shown no evidence whatsoever for your stance.
I could be wrong. I have no unequivocal evidence to back up my claim. But if I am wrong, this implies a non-trivial degree of delusion on the part of the luminaries of such organisations.
They’ve been rolling out wind power for a while now. It’s not as if we have no data on the actual effects it has. I suppose it remains possible that the leadership of the AWEA is innocently misinterpreting the accumulated data.
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Finrod, on 7 September 2010 at 9.03 — In the USA, the primary reason for cancelling new coal burners is the uncertainty of the potential of future CO2 emissions costs. Old coal plants are scheduled for closure primarily due to the (other) emissions control requirements the EPA now insists upon. Maybe the Sierrra Club cmpaign against dirty coal also contributes to this.
At last count, only 8 new coal plants are still scheduled to the constructed (and further uncertainties and so on may but an end to those). Plans are afoot (dunno are far these will go) to construct 26 new NPPs. At the same time, old coal burners are be planned to be shut down or converted to wood burners by many untilities, mostly across the southeast.
In the USA, wind continues to be a small player so far.
What’s your beef?
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David B. Benson,
As you point out, the USA is in a funk about building coal power plants. Also the nuclear program is minimal. Somehow, we seem to believe that “Conservation” is the answer. Lunacy!
It is pretty obvious what will happen if the construction of fossil fuel and nuclear power plants is unreasonably curtailed. California has provided a preview. The lights go out and then neighboring states charge extortionate fees for electricity. It reminds me of Denmark and Germany.
he USA
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gallopingcamel, on 7 September 2010 at 13.00 — Here in the Pacific Northweest, energy conservation is expected to enable foregoing about 30% of otherwise required new power generation. It is, by far, the least expensive alternative.
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Oh yes, its called “energy efficiency”.
Same works everywhere, with the UK being one of the more notorious in using energy inefficiently; up to 50% savings are possible there, according to reliable sources (David McKay, etc.)
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FAZ in Germany carries an interview today with Andreas Nauen, ex-head of wind energy at Siemens and now CEO of Repower, a wind turbine maker. This is 90% owned by the Indian Suzlon group.
He alleges in answer to the question of when wind power will no longer need subsidies: “in some countries this is no longer the case, eg in New Zealand.”
Is this lack of subsidies true for NZ overall ? or is he referring to some specific high-wind location with no intermittency?
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[…] one of Mr. Goggin’s rebuttals myself. He also posted a more substantive rebuttal at bravenewclimate. That may have been a mistake – the readers and commentators there include many of the […]
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David B. Benson,
I wish you luck with that “energy efficiency” thing. However, as long as you folks continue to defy reality your troubles will compound. You need to build oil refineries and power plants (NPPs or coal). Failing that you need to be very careful about picking fights with your neighbors.
If LA wants to impose sanctions on Arizona it needs to consider which state controls the Hoover dam that affects so much of the water and electricity in the region.
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See the first of a four part response to Goggins/AWEA article here:
http://www.masterresource.org/
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I recall reading an article in the WSJ a few months back describing the huge gains made by wind in Texas. The surprising finding in the article was that the gains made by wind power came not at the expense of old, inflexible coal power, but actually at the expense of natural gas generation. This would seem to contradict Mr Goggin’s point about Factor C, so I’d be curious to learn how he would respond to this report (link below).
http://online.wsj.com/article/SB10001424052748704188104575083982637451248.html
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David Walters and Michael Goggin,
I have a question regarding gas generation in wind firming. I’d also like to hear others’ input on this question.
To answer the question you will need a good understanding of how the Kent Hawkins Calculator works. You can get it by asking him to send it to you. His email address is: kenthawkins@rogers.com
The web site is: http://www.masterresource.org/2010/02/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-v-calculator-update/
And a summary paper showing the comparison of the calculator outputs with the results of recent studies is here: http://www.masterresource.org/2010/06/subsidizing-co2-emissions/#more-10349
My questions are:
1. How can the CCGT and OCGT gas generators be dispatched so they come on line to firm wind power when the wind power is fluctuating wildly?
2. How much duplication of gas generation capacity would this cause?
I understand there is a limit to how often a gas turbine can be started and stopped per day (I understand the maximum is 3 times per day).
Let’s assume we have a low wind season (say 6 months) and a high wind season also of six months.
In each season, the wind power can fluctuate between zero and full power.
I suspect the Ken Hawkins calculator is overestimating the emissions produced by gas turbines when wind firming because I suspect the amount of OCGT has been overestimated and the amount of CCGT has been underestimated, especially in the low wind period. I imagine that CCGT should provide most of the power during the low wind period. But that means say 80% of the installed capacity must be CCGT.
During the high wind period we’d need more OCGT. The total gas capacity required would total more than 100% of the wind capacity.
If the wind power is fluctuating wildly how are the OCGT’s dispatched during falling wind power? Once all the OCGT’s are on-line, there are no more left to bring on-line as the wind drops further. I am having trouble understanding why we wouldn’t need almost 100% OCGT and say 80% CCGT to allow us to firm wind power.
Can someone please explain, in a system that is only wind and gas (exaggeration to make the explanation simple), how would the dispatching of the OCGT and CCGT’s be managed?
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I didn’t know this. Do you (or anyone) have any insight into the reason?
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John,
This is from memory. I think David Walters told us this some time ago. I understand it is a manufacturers constraint, and it is written into contracts. If breached, then warranty can be void. That is my memory of what someone said, I think it was David Walters.
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I think we need to quantify ‘fluctuating wildly’ before looking at how to cope with it. This report
http://books.google.co.uk/books?id=nIk9orBL1fMC&lpg=PP1&pg=PA14#v=onepage&q&f=false
seems rather pro-wind, but at least has some statistics in it. Averaging over many windfarms does give some smoothing of the short-timescale fluctuations, so you need to be able to cope with a ramp rate of ~20% full power/hour, rather than ~100% for a single farm. So at first sight , if it takes H hours to get a CCGT plant started, you will need ~(Wind capacity)*H/5 of OCGT capacity to cope until the CCGTs come online, but can then shut the OCGTs down again. To the extent that next-few-hours wind forecasts can be trusted, actual use of OCGTs can be reduced by scheduling CCGTs to begin startup in anticipation of being needed, but the capacity has to be there for when the forecast is wrong.
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Peter you have done some good studies on this it seems “does wind reduce carbon emissions”. According to ‘some’ there soes seem to be a net reduction of CO2 emissions. But it’s a decieving number.
A few things to consider. No wind farm has ever shutdown a coal plant or a gas plant.
If one’s system is based on a steam cycle with governors on turbines to regulate speed of the system and load, then the steam has to be available. I’m excluding here the growing new builds to all GTs (both simple and combined cycle). But tthe fact is that most of the worlds advanced grids are run off of steam, not GTs. Thus…
While every KW of wind in theory reducing the generation of KWs from steam, thus from gas and oil, it also *institutionalizes* these steaming plants (and that actually includes nuclear) for back up.
Every KW of wind needs a KW of on-demand power back up. BTW….GTs unless they are already online at lower loads or Combined Cycle GTs with governors on the turbines and quick firing again, ON LINE, are not instant power, albeit the system rarely needs true instantaneous generation unless a major source trips off line.
So there are these general things to consider: As Peter pointed out in his studies, one has to include either *new build* GTs with the cost of new wind or, the maintaning of older, dirtier conventional steam plants remaining instutionalized and steaming away for every KW of penetration into the market for power.
Germany, for example, has to keep coal plants firing away when relying on wind. *Coal plants!*. As my son says, “how whacked is THAT?!!?”.
The “Windies” look to a future of ALL wind, HVDC lines chris-crossing the land, the world, whatever and THEN they believe everything would be well with the world. It’s BS of course, but there you have it, from an operrators POV.
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I can see that there would be a restriction on the number of times you can stop and restart a CCGT because of the steam cycle. I’m much less sure about OCGT. As I understood OCGT technology it is similar to an aero jet engine. To my knowledge there is no restriction on starting and stopping aero turbines – a short-haul domestic aircraft must start and stop engines at least 10 times a day.
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Martin, it is not true. Frame units in particular…like the GE F6 and F7 of which there are very many, are restricted between starts and stops by *contractual* agreements between the operator and GE. Units are often rated based on how many starts and start are allowed before their warranty runs out.
Mostly this bigger, 170 MW (per unit, simple cycle) doesn’t start and stop more than two cycles.
The smaller aeroderivative units are far more forgiving but they don’t like to run them in the ‘start and stop’ mode constantly. Some companies put limits how many starts and *minimum* run time the smaller units can be utilized.
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Luke_UK,
You are getting to the substance of the question I am trying to get explained to me. I’ll come back to your poast. First let me deal with your opening sentence:
I agree. My question was not very well put. I am having a discusion with some US engineers by email about this same question. I’ve clarified my question for one of them and post it here.
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Luke_UK,
I don’t get this bit. If the wind power continues to drop and all the OCGT’s are already operating, even though we are bringing CCGT’s on line, I don’t see how we have any more OCGT’s availabe to continue to come on line as the wind power continues to drop.
Consider a real NEM excample, but imagine it is scaled up for the situation where wind power and gas backup have to provide all our power. This is an exaggeration, I agree, but it helps to clarify the question and the explanation. The situation occurs on August 12, 2010. The NEMs total wind power dropped from CF 60% to 20% in about 4 hours (reading from a monthly graph here: http://windfarmperformance.info/documents/analysis/monthly/aemo_wind_201008_hhour.pdf )
Let’s say this amounts to a drop of 800MW in 4 hours or 200MW per hour. Scale this up for the case with higher capacity penetration to say 2000MW per hour for a total drop of 8000MW in 4 hours. How do we handle that. How much OCGT and how much CCGT capacity do we need?
What about for the case on August 27 when the wind power dropped from 70% to near zero in just over 24 hours, say 1400MW in 30 hours. Scale up to 14,000MW in 30 hours. How much OCGT and how much CCGT is needed? At the moment I am thinking we need nearly 14,000MW of OCGT to handle this, and this is not the worst case we could encounter.
I know I am exaggerating a bit. But please someone explain to me how much OCGT and CCGT do we need to give us low emissions throughout both high wind and low wind periods of the year and also to be able to handle the highest possible ramp rates over the full range of wind farm outputs that can be experienced.
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Peter I was out at the 442 MW Strathgordon hydro on Saturday with some Adelaide visitors. It looked about 60% full despite torrential rain. I’d say wind heavy places like SA are importing a lot of interstate power for smoothing of lulls. It would be good if AEMO could do a Java animation to prove or disprove this.
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Peter,
Your NEM example is actually less severe than the worst case example in the above linked report (taken from German total wind output) of 20% of rated capacity per hour drop, or 400 Mw/hr for your scaled up system. Without downloading all the data, it’s hard to tell if that is the steepest drop, the eye picks out the big drops, 60%-20% in 4 hours, better than the steep ones, 50% to 30% in an hour then back up to 40%. I suspect that it is the steep drops that are the most severe test, however, even if they don’t last long. There was only 1 hour of 20% fall in the German data, so I’ll assume the drop profile goes 10%, 20%, 10% 10%….
I’ll give a sketched example as my guess as to what might happen in such a situation.
1) I agree with your estimate that to cope with long low-wind periods, we want 70-80% of the wind farm nameplate capacity as CCGT capacity.
2) Start with the system steady and the wind farms at 80% capacity. Wind is meeting most of the system demand, the rest is mostly CCGT, perhaps with a bit of OCCT. On top of the plant needed to meet demand, there is a few % of spinning reserve, needed to cope with unexpected demand spikes. tripping out plant etc. This will be composed of some combination of CCGTs being run a bit below 100%, and able to ramp up a few % each quickly, OCGTs run at mid load, and OCGTs running at zero load. I don’t know the optimum mix. Do two OCGTs running at 50% rated burn more or less gas than 1 at 100% and one running grid-synced but doing nothing useful?
3) The wind decides to do it’s once-a-year-event drop out, falling from 80% CF to 75%CF in 30 minutes and continuing down. The shortage is initially met from the spinning reserve – but now there is no reserve, so the next block of OCGTs that is on standby but not burning gas is told to fire up, the block after that told to stand by, etc.
4) 30 minutes in, wind at 75%CF and falling fast, the grid controllers watching the wind power plots – and the prediction software that helps them – decide this is not a blip. They call enough CCGTs to balance the system at 70% wind CF – i.e. guessing that the drop-off will continue – and tell them to fire up. As the fall continues, further CCGTs are called, as the controllers try to get ahead of the game but without starting up more generators than necessary, as well as OCGTs to meet the immediate shortage
5) 1 hour in, wind at 70% CF and dropping faster, 10% of wind nameplate being met by OCGTs and rising.
6) 2 hours in, wind at 50% CF, ‘lost’ 30% met by OCGTs. Fastest drop over, but still falling 10%/hour
7) How long does it take a CCGT to come online? Suppose it to be 3 hours, and the first ones will become available 31/2 hours in. At that point, wind is at 35% CF, the original CCGTs are running, and OCGTs are providing for the 45% of wind capacity that has been lost. As the ‘new’ CCGTs arrive, they make up for continuing wind drop, then start taking the load off the OCGTs
8) 4 hours in, wind at 30% CF, ‘new’ CCGTs make up for 10% wind CF lost, OCGTs for 40%. From now on, CCGTs whose start-up was initiated in the steepest part of the drop arrive faster than the continuing wind drop, and the OCGTs are ramped down, then stopped
9) 5 hours – 8 hours, wind steadies at 20% CF, all available CCGTs are brought online, so we end up at 20% wind, 75% CCGT, 5% OCGT + some for spinning reserve.
There may be a further complication that some CCGT plants can operate in OCGT mode for fast response, then start heating the boiler and transition to full CCGT mode when steam is available. I think I saw a reference to this on the Siemens site, but now can’t find it. This reduces the need for rarely-used backup equipment, and reduces the need to call up CCGTs in anticipation of needing them, which will sometimes result in unnecessary start/stops.
There is also Siemens new CCGT plant designed for wind integration, claiming 40 minute startup and 59% efficiency, good for 250 start/stop cycles/year.
http://www.energynews24.com/2010/05/siemens-eon-inaugurate-efficient-ccgt-at-germanys-irsching-5
Nice work for them, selling wind turbines that create a load following problem and fancy CCGTs that solve it.
All of this post needs reviewing by someone who knows what is really done in the industry, in case much of the above story is just fiction.
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Luke, just on start up time, a CCGT is…because it is ‘combined’ means that the GT part comes up and parallels to the system way in front on the HRSG’s steam turbine. If my memory serves me correctly, the F7 from GE parallels in about 5 minutes and reaches full 170 MWs in 18 minutes.
People should understand that GTs are *everything* their manufacturers say they are. They are amazing pieces of technology. Their only draw back: they burn fricken natural gas. They get about a 50% thermal efficiency (which means in the real world about 44% or less depending on age (HRSGs are amazing for tube leaks).
They can generally run at half-load and idle there…still pumping out CO2 and burning gas.
Interesting….250 start/stop cycles? That’s less than GE versions. Meaning only Monday-Friday, nothing on Week ends, no room for trips. Bummer.
David
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Luke_UK and David Walters,
I’ll come back to your comments. Sorry for the delay, I had a computer hicup.
I am having a discussion with Kent Hawkins and two other US engineerrs who were involved in the development of the calculator. I”ll post here the substance of my latest email as it may be of interest to BNC contribuitors.
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Luke_UK,
Thank you for that great explanation. Love it!
Now I want to get a bit picky.
1. You have assumed a less than worst case scenario because you assume the operator will get a strong signal at the beginning (you assume the fastest rate of wind drop is at the beginning). However, eye-balling the wind output chart for 12 August, suggests the fastest rate of power drop is in the middle part of the drop; i.e. a typical S-shaped curve like a cumulative distribution curve. The middle part is where the drop off is fastest, long, and without warning. The operators need to be able to allow for this. I suspect, the operators would frequently have to assume the event they are dealing with right now could turn into being a worst case event. Therefore, often they act with proper caution and decide to start more turbines than actually turns out to be needed. If I am correct, it means, if wind capacity is connected to the grid, we are running excess turbines part loaded or in spinning reserve much of the time.
2. Totalling the maximum CCGT and the maximum OCGT capacity I get 110% (80% CCGT and 30% OCGT). That seems reasonable to me, but I expect it might be even higher. I accept what David Walters says that CCGT’s can operate as OCGTs and so can start up as fast as an OCGT. However, the reality seems to be that most of the gas build is OCGT not CCGT. In that case we are not saving much in emissions. The more I think about all this the more I tend to believe that the Kent Hawkins Calcluator is probably not too far off the mark. That is, wind power is not saving any emissions, especially in a system that is mostly coal and coal power stations have to participate in the firming of wind – as is the case in Australia, in the Bentek study and in the Netherlands.
4. I wonder if you would be able to produce a chart and short explanation (perhaps it could be posted on BNC) showing time on the horoizontal axis, power on the vertical axis and:
a. Which CCGT’s and OCGTs are running and at what percentage of full power before the wind suddenly and unexpectedly begins to drop (and with no indication of how much the wind might drop)
b. wind power drops from 1GW to 100MW at 20%per hour (assumed worst case)
c. when each CCGT and OCGT is instructed to start up
d. When each CCGT an OCGT is generating and at what percentage of its full power
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David Walters,
Thank you for your comments. This is good information for me.
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Peter, your welcome. I suspect we are all looking forward to your next ‘digestion of the facts’.
We need a lot more information…like real time operating figures and the stuff Luke wrote about. Instead of speculation, we need to see systems and what they are doing.
You asked a good question or poised one, in passing: The rate of starts and total MWhrs for OCGT vs CCGTs.
Just so you know, the bigger Frame units can often run as OCGTs and are, *if configured as such* to do just that. They have diverter dampers, called ‘diverter valves’ that bypass the HRSG. It’s also called ‘condenser bypass’. i never worked at one of those.
A few things to consider. OCGTs (or as I’m used to calling them “Simply Cycle GTs*) are usually smaller in MW output not just because they are not CCGTs but as per GTs itself. They run, usually, in the 50 to 100MW range. So, of you fly into Kennedy Airport, you can see some rather artistically covered LM6000 that are neither OCGTs or CCGTs but Co-Gens…where the there IS a HRSG but used to create steam and *some* power off of that steam. so there is a lot of that too.
David
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David Walters,
Thank you. I am digesting all this. As you say, we really need some good data. The electricity generation data is easy to get. But I haven’t managed to get the gas consumption data yet. The generators hold it as a closely guarded secret. But I still believe we shluld be able to get it some how.
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Peter,
To answer your questions where I can:-
1)My assumed profile was approximately ‘S’ shaped. As I stated at the top of the story, the wind dropped 10% in the first hour (80% CF to 70%CF), then 20% in the 2nd hour (to 50%), then 10%, 10%. There will indeed be false alarms, as you suggest, when you get a large rapid drop followed by steady or even rising wind. Thorough analysis of the detailed wind output data should allow some reasonable guidelines to be put in place, but they will never be perfect.
2)Worst case is at point 7, 45% of total wind capacity as OCGTs, so the capacity is 80% + 45% = 125%
3)????
4)Please remember I ‘m just guessing – I was hoping someone would come by and correct the story, so we could all learn something. The suggested 20%/hr all the way down from 100% to 10% is beyond worst case, as there is only one hour in which the drop was that steep in the German data, according to that report I linked to, not a whole series of them. 10%/hour looks like the worst sustained drop in the Australian data as well.
Another thing we don’t know yet is the relative cost of shutting down equipment only to have to start it up again vs the cost of extended part-load operation for several plants. If the stop/start cost is low, most plants will be running at optimum almost all the time, with only a few plants ramping as fast as possible at any given time. If it is high, many plants will be kept at part load rather than optimum load, and the net fuel saving from the wind will be small.
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