BraveNewClimate

How can we compare the cost, performance and value-for-money of alternative large-scale clean energy projects? Actually, it’s pretty tough to try and avoid apples-and-oranges comparisons. Still, some adjustments can be made, such as for capacity factor, to partially levelise comparisons.

Below is a simplified comparison of four recent real-world projects. All can be considered first-of-a-kind installations, except for the wind farm.

1. A large proposed wind farm in South Australia (600 MWe peak)

The wind project will use 180 of the 3.4 MWe Suzlon turbines and “generate enough electricity to power 225,000 homes“. It includes a biomass plant that could produce up to 120 MWe of backup power to cover low-wind periods, and might offset up to 2.5 million tonnes of CO2 per year. At average 8m/s winds the capacity factor is estimated to be about 35%. A 60 km undersea high voltage direct current cable will connect it with Adelaide. Cost is $1.3 billion for the generating infrastructure and $0.2 billion for the cable.

2. A large Generation III+ nuclear power plant in Finland (1600 MWe peak)

The in(famous) Olkiluoto 3 NP unit, a European Pressurised Reactor (EPR) being built by the French (AREVA). The project has seen significant delays (first electricity now expected in 2014), and a cost blowout from the original € 3.7 billion to a new figure of € 6.4 billion. Despite this, the Fins have ordered two more EPR units. Assume it runs at the average Finnish capacity factor of 86%. 

3. A large solar PV plant under construction in New South Wales (150 MWe peak)

To be built in Moree, this will cover 3.4 km squared with 645,000 multi-crystalline PV panels, and is forecast to output 404 GWh per year (enough for 45,000 households). Part of the “Solar Flagships” programme, the cost is $A 923 million. Estimated to abate 364,000 tonnes of CO2 per year (based on NSW emission factor 0f 0.9 tCO2/MWh). Estimated capacity factor is 30.7% (based on peak power and GWh forecasts) — this seems high compared to typical PV performance.
(more…)

Filed under: Nuclear, Renewables, TCASE | 150 Comments »

The concept of energy return on investment (EROI), often called energy returned on energy invested (EROEI), is a simple and familiar one. Here is the short definition, from the Encyclopedia of Earth. To cite:

———————————————–

Energy return on investment (EROI) is the ratio of the energy delivered by a process to the energy used directly and indirectly in that process.

For example given a process with an EROI of 5, expending 1 unit of energy yields a net energy gain of 4 units. The break-even point happens with an EROI of 1 or a net energy gain of 0.

A common related concept is the energy payback period. Every energy system has initial investments of energy in the construction of facilities. The facility then produced an energy out for a number of years until it reaches the end of its effective lifetime. Along the way, additional energy costs are incurred in the operation and maintenance of the facility, including any self use of energy. The energy payback period is the time it takes a facility “pay back” or produce an amount of energy equivalent to that invested in its start-up.

———————————————–

Wiki also has a decent article about it, and it’s a source of much discussion on websites like The Oil Drum. In short, a simple concept, but fraught with debate. It is not my intention here to wade into the arguments on EROEI of individual energy sources — that would require many TCASE posts, and even after that, I’d be unlikely to get consensus. But feel free to hammer away on the ins and outs of EROEI in the comments.

What I want to do here is propose a simple method for estimating EREOI based on a life-cycle assessment of greenhouse gas emissions. This requires some assumptions, but is useful, I think, because LCA studies are readily available and widely cited, whereas explicit EREOIs via net energy analysis are harder to find and compare in a consistent way.

There have been many well-researched peer-reviewed studies looking at the life-cycle emissions of different energy technologies, expressed in terms of kilograms of CO2-e/MWh (commonly). For non-fossil fuel energy technologies, this is a useful benchmark for calculating EROEI, because their inputs mostly come from fossil fuels, yet they produce no CO2 when generating. So, let’s consider ‘clean energy’ EROEIs on this basis.

(more…)

Filed under: Nuclear, Renewables, TCASE | 20 Comments »

Heat engines require cooling, to turn heat energy into mechanical energy (and then, via a turbine-connected generator, to electrical energy). This is an unavoidable physical principle, and is typically exploited via the Carnot cycle. Usually, this cooling requirement uses water.

Why do I raise this point? Because it seems to be a source of much confusion (innocent and deliberate) amongst the energy illiterate, especially when mounted as an argument against nuclear energy generation (and, implicitly, as a reason for adopting renewable energy). For instance, Friends of the Earth have decried:

Nuclear power plants consume large amounts of water –35-65 million litres daily. Indeed nuclear power is the thirstiest of all energy sources. A December 2006 report by the Commonwealth Department of Parliamentary Services states: “Per megawatt existing nuclear power stations use and consume more water than power stations using other fuel sources. Depending on the cooling technology utilised, the water requirements for a nuclear power station can vary between 20 to 83 per cent more than for other power stations.” Global warming and water shortages are likely to exacerbate problems experienced by the nuclear power industry during heatwaves in recent years. Nuclear power plants in several countries, including France and the US, have had to operate at reduced capacity, or to shut down temporarily, because of reduced water supply or to avoid breaching regulations limiting the heat of expelled water.

So what’s the story? Are water limitations and discharge regulations destined to be a major limiting factor for nuclear power, especially for places that are experiences increasing water shortages, such as Australia? The short answer is no — this is classic FUD. For the longer answer, read on.

All thermal power plants, by definition, make use of heat engines with heat exchangers, and so require cooling (although this need can be reduced in various ways, as explained below). This includes coal-fired, nuclear fission, oil-fired, conventional gas-fired, solar thermal and geothermal power stations. The renewable energy sources that don’t have this cooling requirement are hydropower, wind, wave, tidal and solar photovoltaic power.

Water is used in two ways in thermal power plants: (a) Internal steam cycle: to create steam via the energy source (fossil fuel combustion, fission chain reaction, heat exchange with deep rocks [hot dry rock geothermal] or a heat transfer fluid [concentrating solar power]) and convey it to an electricity-generating turbine, and (b) Cooling cycle: to cool and condense the after-turbine steam (this condensation dramatically decreases the volume of the expanded steam,creating a suction vacuum which draws it through the turbine blades), and then to discharge surplus heat to the environment.

(more…)

Filed under: Nuclear, Renewables, TCASE | 49 Comments »

In TCASE 3 – The energy demand equation to 2050, I concluded the following:

The world in 2050 will demand ~700 EJ of thermal energy, or roughly 300 EJ of electrical energy. This will require ~10,000 GWe (10 TWe) of generating capacity, which is a 5-fold increase in electricity generating capacity, or 680 MWe, every day, for the next 40 years (2010 to 2050).

Given the large uncertainties associated with this forecast, the actual value could easily be as high as 15 TWe, which would up the daily built-out rate to a little over 1 GWe per day. But let’s stick with 680 MWe rate for this post.

What would that mean in terms of today’s zero-carbon (when generating) energy sources? Consider three technologies that are potentially (i.e., theoretically) able to be scaled up sufficiently to do this job (wind, solar thermal and nuclear fission), and then look at the limit analysis (what would be needed for any one technology to do the whole job — accepting that in reality, there will always be some diversity of energy technologies that are deployed worldwide). I will, for simplicity, use US capacity factors for these energy sources (solar thermal from Spain), based on the latest (2008) data. We can assume the US situation would be reflective of global conditions if the technologies are properly deployed worldwide (with due expertise and siting considerations).

——————————————————-

1. Wind turbines. Wind power collects ~2 W/m² (or 2 MWe per km²), and this figure is not really dependent on the turbine size. (If you have larger turbines, you need to space them further apart. If you build large turbines with tall towers, the increased hub height does access stronger winds, increasing the yield by ~30%). The 2008 US capacity factor for wind was 23.5%. For our unit, let’s choose a widely deployed turbine, the 2.5 MWe (peak), the GE 2.5xl (rotor diameter = 100 m, hub height = 75 – 100 m, cut-in windspeed of 3.5 m/s, peak at 12.5 m/s, cut-out at 25 m/s).

To get 680 MWe average power, 680/0.235  = 2900/2.5 =  1,160 GE 2.5xl turbines per day, worldwide, spread over 340 km² of land area (a square 18.4 x 18.4 km). Based on the University of Sydney ISA report (p145), which also agrees with Prof Per Peterson’s figures, this will consume ~1,250,000 tonnes of concrete and 335,000 tonnes of steel per day. Every day, from 2010 to 2050. Adding 1 day’s energy storage using NaS batteries (to make it equivalent to the solar thermal example below), increases the mass of steel required to 455,000 tonnes per day (see chart at bottom of the post).

(more…)

Filed under: Nuclear, Renewables, TCASE | 181 Comments »

Updated 13/10/2009, based on post comments. Bottom line: 2050 power demand will be ~10 TWe of electrical generating power — a 5-fold increase on today’s levels, requiring the construction of ~680 MWe per day from 2010 to 2050.

Before we look in detail at the various low-carbon energy technologies that may provide the means to move away from fossil fuels, it is worthwhile considering what our future energy targets are likely to be. That is, what are plausible energy demand scenarios?

In the developed world (US, Europe, Japan, Australia and so on), we’ve enjoyed a high standard of living, linked to a readily available supply of cheap energy, based mostly on fossil fuels. Indeed, it can be argued that this has encouraged energy profligacy, and we really could be more efficient in the mileage we get out of our cars, the power usage of our fridges, lights and electrical appliances, and in the design of our buildings to reduce demands for heating and cooling. There is clearly room for improvement, and sensible energy efficiency measures should be actively pursued. More on that in later posts.

In the bigger, global picture, however, there is no realistic prospect that we can use less energy in the future. There are three obvious reasons for this.

1) Most of the world’s population – collectively, the developing world – is extremely energy poor. Over a third of all humanity, some 2.5 billion people, have no access to electricity whatsoever. For those that do, their long-term aspirations for energy growth, to achieve something equating that used today by the developed world, is a powerful motivation for development. For a nation like India, with over 1 billion people, that would mean a twenty-fold increase in per capita energy use.

2) As the oil runs out, we need to replace it if we are to keep our vehicles going. Oil is both a convenient energy carrier, and an energy source (we ‘mine’ it). In the future, we’ll have to create our new energy carriers, be they chemical batteries or oil-substitutes like methanol or hydrogen. On a grand scale, that’s going to take a lot of extra electrical energy! This counts for all countries.

3) With a growing human population (which we hope will stabilise by mid-century at less than 10 billion) and the burgeoning impacts of climate change and other forms of environmental damage, there will be escalating future demands for clean water (at least in part supplied artificially, through desalination and waste water treatment), more intensive agriculture which is not based on ongoing displacement of natural landscapes like rainforests, and perhaps, direct geo-engineering to cool the planet, which might be needed if global warming proceeds at the upper end of current forecasts.

(more…)

Filed under: Nuclear, Renewables, TCASE | 101 Comments »

Before getting entangled in the thorny bramble of sustainable energy options, I thought it helpful to arm you with a set of terminological secateurs. So TCASE #2 (recalling that TCASE = the Thinking Critically About Sustainable Energy series) is a brief primer and glossary on energy terms. This is not meant to be anything comprehensive, but it’s enough to get your technical feet wet and to understand some of the units and concepts that are liberally thrown around by those who are used to talking in the energy jargon. (If readers feel I have missed something important [no doubt], please feel free to add this to the comments, and I will also update this post to reflect the important suggestions.)

Anyway, first up, we need to understand the difference between power and energy. Let’s say you have a jug of water. It has some volume, which is the amount of water the jug holds. Now, let’s say you gradually tip out the water — the flow of water (the amount of water being poured per unit time) is a rate. Well, in caricature, the volume of water is like energy, and the flow of water is like power. Not a perfect analogy, but they never are…

Now, when measuring anything, you could use any manner of units. I’m going to consistently stick to SI (Système Internationale) units. If you want to translate back and forth (imperial, metric, nonsensic, etc.), look up the tables here. The basic SI unit of energy is the Joule. The basic unit of power is the Watt (W), which has units of Joules per second (J/s). So, a 60 W incandescent light globe uses up energy at a rate of 60 J/s, or 216,000 J per hour (60 x 3,600 = 216 kilojoules, kJ). Or, to express it another way, in one hour (h) that light would use up 60 Wh worth of energy, and in a day, it’d use 60 x 24 = 1,440 Wh, or 1.44 kWh. So, kWh are a unit of energy.

(more…)

Filed under: Nuclear, Renewables, TCASE | 47 Comments »

This is the first post in what is planned to be an extended series, ‘Thinking critically about sustainable energy‘ (henceforth TCASE #). As explained in my previous blog entry, A necessary interlude, this series will look in detail at the issues confronting renewable and nuclear energy, with an aim to break down the often complex and multifaceted critiques and promotions being made about various energy generation technologies into simpler, single-issue chunks, which can be more readily pinned down and understood.

I will also profile some of the less well-developed low-carbon technologies, such as tidal, wave, microalgae, and geothermal, as well as nuclear fusion, fusion-fission hybrids, travelling wave reactors etc. and speculate on their possible future roles. I hope in this way that I’ll be able to reinforce people’s understanding of why I no longer hold renewable energy to be a primary solution — and yet, by the same yardstick of maintaining intellectual honesty, acknowledging that I’ll also keep an open mind to unconsidered possibilities and caveats that are raised by commenters (be these against nuclear energy, and/or for renewables). Indeed, I’ll also discuss critically the social and technical impediments facing nuclear power adoption and the Generation III/IV synergy.

First up, a little history of the evolution of my thought on this topic, as documented my professional research and in the archives of this blog.

(more…)

Filed under: Nuclear, Renewables, TCASE | 94 Comments »