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90 comments on ASPO VII - first day
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90 comments on ASPO VII - first day
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Here is the result of the most comprehensive study of the EROI that has been done:
http://nuclearinfo.net/Nuclearpower/WebHomeEnergyLifecycleOfNuclear_Power
Whilst an immense number of quibbles may be made about details, and have been by those who are entirely opposed to nuclear energy in the first place, the broad picture is that the EROI of nuclear is just fine, just as it is for solar power, certainly for the thin film versions including thin-film silicon.
Wind power is a little more doubtful, and that is one reason why it is best to consider it as part of a total energy system.
Where EROI is doubtful is in oil sands, and it reaches absurd levels in ethanol from corn.
Here we go again with the EROEI numbers being widely and wildly at variance...3:1, 8:1 and if my eyes do not deceive me 93:1!!! We cannot have a serious discussion of alternative energy sources without numbers of EROEI we can trust. Is it not possible for intelligent people to sit down and devise a methodology of arriving at a EROEI framework that has putative validity and utility that we can use to formulate policy and useful discussion?
Not whilst some who have an ideological objection to nuclear power are deliberately trying to stuff the figures up you can't.
Precision in EROI calculations is anyway difficult, and provide immense opportunities to fiddle the figures.
There are also real difficulties, like the fact that your figures are very different if you assume reprocessing or if you don't, and that by itself would account for a substantial amount of the difference between the Swedish figures and the US figures where they don't reprocess.
If they are using old processes to make the initial uranium into fuel in the US figures, that might account for most of the rest.
Except where it is a plainly daft situation, such as in ethanol from corn, you don't usually have to bother as the dollar figure gives you a good estimate of whether something is worthwhile.
Just about everyone here on the site aside from David has acknowledged that the 93:1 number is completely bogus.
Chris
"Is it not possible for intelligent people to sit down and devise a methodology of arriving at a EROEI framework that has putative validity and utility that we can use to formulate policy and useful discussion?"
No, it is not possible. Intelligent people disagree widely regarding what inputs to include and how to value externalities & opportunity costs. There is no non-arbitrary way to arrive at such valuations. Hence, EROEI analytic methodology can't be agreed upon & hence isn't very meaningful.
If the 93X return were true, utility companies would be immensely profitable and would be building nuclear reactors as fast as possible. The fact that there are only occasional new ones built suggests a number closer to 8X.
Almost all the cost of nuclear is in building it, and fuel costs make up only a fraction of total cost.
Interest rates as almost all the cost is upfront and the cost of fossil fuel as a competitor are the significant factors, and the EROI of nuclear power had nothing to do with it.
Like Darwinsdog, I feel that boundary conditions are too difficult to specify to make most EROI calculations very useful, and they have chiefly been used for polemical purposes because they are so imponderable.
Given that these exact same calculations are performed daily by most competent chemical engineers and that any sort of chemical plant is terribly expensive including simpler ones such as refineries and yes believe it or not refineries are fairly simply as far as chemical plant go.
And further given these are horribly expensive and tough to build profitably I'd suspect that Nuclear Power plants suffer all the same problems as any other chemical plant. The fact the final reaction is a nuclear transformation just makes them different.
You have countries like Iran that are unable to build refineries to support their own internal needs for example yet claim to be building nuclear power for independence. A fairly trivial blocked would render them in serious trouble in short order as they ran out of gasoline.
Mexico is another example of a country that does not have enough refining capacity.
The point is Nuclear power plants fit in well with other complex chemical plants and have all the same issues and more.
Embedded energy is useful when talking about materials that have been shipped in but in all the cases a very well defined process was used at each step and all thats needed is a fairly strait forward analysis to determine the overall energy embedded in a given product.
Surprisingly or I suspect not so surprisingly these calculations are not made public.
Try and find the real embedded energy in steel and concrete.
http://www.csmonitor.com/2008/0312/p14s01-stgn.html
Thus done correctly it should be fairly trivial to determine the embedded energy in any chemical plant and if its for energy production calculate the break even point.
We can do quite well for costs the energy calculation is almost identical.
http://www.cera.com/aspx/cda/public1/news/pressReleases/pressReleaseDeta...
I have no doubt that calculations are possible, and indeed have quoted the Vattenfall figures which were done under the sort of conditions you describe.
However, it is always possible to argue against any given set of boundary conditions, and that is the usual approach by those who don't like the results of this actual, detailed breakdown.
For engineering purposes this will be the type of breakdown used.
The public domain things put out by opponents to nuclear power area very different kettle of fish, as the ones I have seen contain laughable inacuracies - see the quotes and links I have already given.
Other techniques to demonstrate a low EROI include specifying old, energy intensive methods of refining the fuel, assuming no reprocessing etc.
I don't have anything against EROI calculations when used for engineering purposes and where the boundaries are clearly stated, but I dislike it when they are used for fundamentally polemical purposes.
It is easy to see that the 93:1 number is not an EROEI estimate from the link. They ignore the energy needed to enrich the fuel. What they are trying to do is to hide associated carbon emissions, but a few people who have very little notion of how energy works have interpreted one form of dishonesty to be something even more incredible, that energy invested can be ingored in an EROEI estimate. It is really very silly that this even comes up.
Chris
Interesting. They claim 0.026g uranium consumed per kWh electricity generated; they don't tell us whether this is yellowcake, enriched uranium, or just U-235. Since 1kWh = 3.6 x 106J, we find that they achieve at best
3.6 x 106J / 0.026g
or Energy out = 1.38 x 108J/g
Their spreadsheet gives interesting values for extraction, conversion, enrichment and so on of "uranium in ore": 0. That seems a bit low.
They tell us that "some" of their uranium comes from Olympic Dam - they don't say how much or where the rest comes from, except that some comes from another mine in Namibia - presumably if the rest came from mines which produce uranium more efficiently, they'd want us to know?
Anyway, Olympic Dam tells us that their operations go through,
fossil fuels, 5.477 x 1015J
uranium ore, 8.887 million tonnes, but producing only
yellowcake, "up to" 4,500 tonnes [source], which is 4.5 x 109 grams
Thus the energy going into producing yellowcake is,
5.477 x 1015J / 4.5 x 109g
or Energy in = 1.217 x 106 J/g
Energy out / Energy in = 1.38 x 108J/g / 1.217 x 106 J/g = 113:1
That is, the fossil fuel energy used in mining and refining, not accounting for shipping and transportation, is paid back 113 times over in electricity from the plant. I suppose the other 21 ratio must come from the other stuff.
The equation becomes worse for the plant if the 0.026g of "uranium" per kWh refers to U-235, to enriched uranium, rather than to yellowcake.
When you turn yellowcake into enriched uranium fuel rods, you lose about 90% of the material, so if the "0.026g uranium consumed" refers to fuel rods, the EROEI would drop from 113 to about 11 or so.
U-235 is about 0.7% of yellowcake, so if they were only talking about that then the EROEI would be... 0.8:1.
That's the difficulty with the EROEI figures - or anything else - for nuclear. More than any other energy source it seems to attract partisan work. People begin by loving or hating it, and making assumptions which will give them the conclusions they want, and they're deliberately vague about areas which could give less than the impression they want.
Something about nuclear, for both supporters and detractors, attracts a load of old bollocks.
I agree that proper EROI calculations are difficult, depend critically on what assumptions are made, and provide ample opportunities to fiddle them.
They are not unlike company accounts in that respect, of which we have recent experience of the figures given being there to deceive, with junk rated as AAA assets.
If many of these calculations were serious, the least I would expect when for instance a figure is givn for 'nuclear EROI' is a range statement to take account of whether re-processing is used.
Many of the calculations floating around also assume that the old-fashioned process is used to refine the fuel in the first place, which is far more energy intensive.
That is fine and can be justified on the grounds that it expresses historic ratios, but these blanket figures are then used to counter arguments for more nuclear build, when anyone in their right mind will use the far less energy intensive modern refining processes.
Overall they make about as much sense as statements of bank solvency, and it would be a full time job to sort out all the misrepresentations involved, with some of the stupid assumptions which have been laid bare I can only conclude that they mostly represent polemics, rather than serious attempts to calculate EROI.
Unlike many other forms of energy, the potential is certainly there in nuclear at least on the technical level to greatly increase energy efficiency, and that is by huge amounts, which also makes it more unwise to draw conclusions about the advisability of future nuclear build from these calculations.
BTW, my remarks should be taken as applying to pro nuclear calculations to nearly the same extent, although I much prefer an approach which looks in detail at a single plant rather than attempts to make sweeping statements for the whole nuclear industry.