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EROEI PR
Energy Return on Energy Invested – Public Relations
During the research for my nuclear energy post, I came across this graph:
It shows a highly favorable EROEI for nuclear plants. Of course, as it comes from the World NuclearAssociation, hardly a neutral party, I took it with a grain of salt and chose not to include it in my post.
The funny thing is that I received the following press release yesterday:
The press release is from Vestas, the (Danish) largest manufacturer of wind turbines today (with more than a third of the world market):
A V90-3.0 MW offshore wind turbine has to produce electricity for just 6.8 months, before it has produced as much energy as used throughout its design lifetime. In other words this turbine model earns its own worth more than 35 times during its design lifetime.
Furthermore, compared to the V80-2.0 MW offshore wind turbine, the 6.8 months constitutes an improvement of approximately 2.2 months.
If installed on a good site, the V90-3.0 MW wind turbine will generate approximately 280,000 MWh in 20 years – thus sparing the environment the impact of a net volume of approximately 230,000 tons of CO2, as compared to the figures for energy generated by a coal-fired power station.
The above-mentioned are two of the results from a life cycle assessment (LCA), which Vestas completed of a V90-3.0 MW wind turbine in 2004. The calculations prove the environmental advantages of Vestas turbines also when taking the whole life cycle into consideration.
A life cycle assessment is both a mapping and an evaluation of the potential impact of the wind turbine on the external environment throughout its lifetime. The life cycle assessment for the V90-3.0 MW wind turbine is divided into four phases.
– The production phase, which covers the period from obtaining the raw materials to the completion of the wind turbine
– Transport of the wind turbine components and erection of the wind turbine
– Operation and maintenance throughout the 20-year design lifetime of the wind turbine
– Disposal of the wind turbine.
Vestas provides a more detailed summary of the life cycle assessments as well as more detailed reports (see the links in that page); I’ll just steal one graph:
But the nucleocrats also provide some detailed studies, summarised in this document which regroups a number of findings which I have no way to assess but which look well-researched. The graph above summarises the main finding, i.e. that nuclear energy supposedly has a great EROEI.
So, who will help me to make sense of these numbers?
Some more grist for the mill from the UK’s Prof David Elliott, Energy and Environment Research Unit, Open University:
“Nuclear plants do not generate any greenhouse gas emissions directly (except incidentally from the release of carbon dioxide coolant gas), but in general it does seem that the complete nuclear power fuel cycle, assessed from the start (mining) to the end (decommissioning and waste storage) and including the energy need for constructing and running the plants, does involve significant energy use, and hence emissions from the plant producing that energy. These emissions are probably more than for most renewable energy technologies – since the latter do not need any fuel or waste processing, although of course, like nuclear plants, they do need energy for the manufacture of the hardware and its materials.
“However the data is complex and sometimes disputed. The most reliable full life cycle energy assessment I’ve seen is from the team at Hydro Quebec in Canada, as reported in Energy Policy 30 (2002) pp 1267-1278. They put the overall energy output to input ratio for nuclear (in the N American context) at up to 16, compared to up to 80 for wind, i.e. over their useful lifetimes, nuclear plants only generate up to 16 times more energy than is needed to build and run/fuel them, while wind turbines generate up to 80 times more energy than is needed for their construction (no fuel needed to run them) [emphasis added]. For comparison, the energy output to input ratio for coal plants is up to 11, gas/ CCGT 14. These are all top of the range figures. On this measure then, wind is best (by about 5 times) but nuclear is only a bit better than gas and coal.
“It ought to be possible to link these energy ratios to the comparative emissions from each source (more energy = more emissions), but it’s not a simple relationship. … The data I’ve found generally has nuclear and renewables coming out similar, sometimes with wind being a bit better than nuclear, sometimes a bit worse, but both always being much better than fossil fuels. The reasons for the differences mainly seem to be because of (1) different assumptions about the fuel mix used to provide the electricity to manufacture the nuclear fuel (2) different assumptions used about the efficiency of the technology used for nuclear fuel fabrication/enrichment (3) different assumptions about how long nuclear plants, with their embedded energy/carbon, can be used. (4) This gets even more complicated when comparing with other sources with different technology life times and load factors. Here are some examples of the data.
“Joseph V. Spadaro, Lucille Langois, and Bruce Hamilton (2000) Assessing the Difference: Greenhouse Gas Emissions of Electricity Generation Chains (IAEA Bulletin 42 (2), 19-24) … contains a bar chart on page 21 which compares life-cycle emissions from different electricity gererators.
“Then of course … there is Nuclear Power: the Energy Balance [by] Jan-Willem Storm van Leeuwen and Philip Smith: ‘The use of nuclear power causes, at the end of the road and under the most favourable conditions, approximately one-third as much CO2-emission as gas-fired electricity production. The rich uranium ores required to achieve this reduction are, however, so limited that if the entire present world electricity demand were to be provided by nuclear power, these ores would be exhausted within three years. [emphasis added] Use of the remaining poorer ores in nuclear reactors would produce more CO2 emission than burning fossil fuels directly’. …
“This introduces an important factor into the debate – uranium reserves. They are usually said to be 50-100 years or so at current use rates in thermal/burner reactors. But that’s ‘currently economic reserves’. If we had a massive nuclear programme, more reserves would no doubt emerge but of gradually lower and lower quality. That in turn would increase the amount of energy needed for fuel production, as lower and lower grades of uranium ore have to be used. The assessment of when the so called ‘point of futility’ is reached, when more energy is needed to mine and process the fuel than is produced by the reactor, depends on a variety of complex factors, including the energy efficiency of the fuel fabrication and enrichment processes, and how this energy is provided. Centrifuge methods are much less energy intensive than the diffusion processes so far mostly used, but it’s hard to see how improvements in fabrication efficiency could continually compensate when lower and lower quality ores have to be used. The high grade ores currently used contain around 2% of uranium (20,000 parts per million), the lower grade ores only 01.%(1,000ppm). Granite contains just 4ppm and seawater 0.0003 ppm. If we had unlimited cheap carbon-free energy, then maybe we could extract some of this, but then we wouldn’t need to! Mind you the nuclear lobby would say that is what nuclear offers – and so we could have a self sustaining nuclear system[,] but with lots of waste to deal with. The debate continues.”
Posted by: Dismal Science | Apr 19 2005 16:19 utc | 51
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