“Limits To Growth fallacy”

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(Photo credit: RaeA)

I was reading an analysis at the Oil Drum about nuclear power use and scaling in France. As usual on TOD, the comments are brimming with insight and impassioned discourse. As a rebuttal to the modest conclusion of the article, one commenter linked to UIC Nuclear Issues Briefing Paper # 75, entitled Supply of Uranium. It looked like the start of a fine analysis, but then alarm bells sounded.

(Before I dive into details I just want to say that, based on my current understanding, I think fission should be much more widely employed as a power source than we have seen to date. But I firmly claim that I am neither a nutty nuclear zealot nor an anti-nuke hippie :P)

Now, as an appetizer to the main rant, let me start with this passage:

Changes in costs or prices […] may alter measured resource figures markedly. At ten times the current price, seawater might become a potential source of vast amounts of uranium.

There’s nothing terribly wrong there, but when the viability of producing an energy resource is measured in “cost”, that’s a danger sign. Instead, (or in addition), I prefer to see some consideration given to Energy Returned on Energy Invested (EROEI). Stated simply, EROEI is the net energy returned from an operation, rather than the net profit/loss. The reason this is important is that the P/L can be misleading in the short term– fortunes can be made while performing operations that make no sense in terms of energy production.

Looking at the EROEI instead gives an indication of the long term viability of an energy operation. At “ten times the cost” to extract, how much energy is being put into the endeavor? Are we still going to turn an energy-profit in the end and come out ahead? If not, then we’ve just converted some amount of energy (x) into some amount less than (x), which on its face seems a bit wasteful.

There are a lot of important details I’m omitting. Sometimes it makes sense to do a net-negative energy conversion, if for example your output energy is in a more useful form. There are also a lot more inputs to consider than the cost of pulling uranium out of the ground (e.g. cost of scaling out plants, keeping radioactive waste from creating a generation of atomic supermen, etc.) Here’s one essay at TOD addressing “peak uranium”, but on all fronts there’s plenty of contention. Even though I have done a very loose treatment of this issue, I hope it is sufficient to show that EROEI is a calculation that merits consideration.

What piqued my interest was not in the above passage, however, but the following (my emphasis):

From time to time concerns are raised that the known resources might be insufficient when judged as a multiple of present rate of use. But this is the Limits to Growth fallacy, a major intellectual blunder recycled from the 1970s, which takes no account of the very limited nature of the knowledge we have at any time of what is actually in the Earth’s crust. Our knowledge of geology is such that we can be confident that identified resources of metal minerals are a small fraction of what is there.

“A logical fallacy regarding growth?”, I thought. “Hot dog, I’m hooked!” I immediately tabbed out to google to learn all I could, only to find that there’s no such fallacy. This was certainly a bit deflating, but also reassuring in a significant sense: if logic supports boundless growth then it would come into conflict with Physics; a situation that can only end paradoxically.

After reading the rest of the relevant passages and the Appendix that expands on them, I came to understand that the author didn’t precisely mean there was a logical fallacy at play, but rather to malign the work Limits to Growth (and to be fashionable, the even-more-oft-maligned work of Malthus).

Neither work’s specific predictions about imminent doom came to pass; a fact that this author then leverages to refute all limited-growth hypotheses. But this is a fallacy of faulty generalization. It’s true that we didn’t run out of energy in the past, but not necessarily because a limit doesn’t exist. COR and Malthus’ predicted limits were incorrect– practically usable energy reserves often get revised upward due to new data, new technology, and new resource types becoming practical. So far, we have always found ways to bump up the limit faster than we have burned through it. Logically speaking, though, those past events make no prediction about whether this will continue to be the case. (Thermodynamically speaking, it cannot forever remain the case)

The paper’s author claims there is enough uranium in the crust and the ocean that we will always have bunches available, which is very likely true. However the paper refers to availability as the amount existing on earth, but then equivocates it to mean the amount practically recoverable by us, two very different things.

Scarcity of cheap uranium will indeed lead to higher prices, but not in an unbounded fashion. Once the real value that can be derived from the stuff is less than the market price, you’ve hit your limit to growth. Where is that limit? This is what I chiefly want to learn. It depends on a staggering number of factors, but it’s frankly idiotic to claim that something can’t occur simply because it has not yet done so.

Aside: I wonder if I can get DepletedCranium‘s input on this. He has a demonstrated facility for debunking the alleged feasibility of many kinds of green energy, and he’s also all about the nuclear. Perfect combo IMO for this issue.

4 responses to ““Limits To Growth fallacy””

  1. Well how about me instead?

    Uranium is ubiquitous on the Earth. It is a metal approximately as common as tin or zinc. Talk of uranium scarcity by those opposed to nuclear power is really nonsensical – it’s all around us. It just needs a commercial incentive to exploit it. This is at the root of talk about uranium shortages; the market, despite some speculative pressure of late, is not there to support all but the most economic deposits. In fact the current bump in prices were the result of the existing refined inventory surpluses being drawn down, not a drop in production.

    From the outset the basic attraction of nuclear energy has been its low fuel costs compared with coal, oil and gas fired plants. About half of the cost at the current price of UO2 is due to enrichment and fabrication of fuel pellets, and these costs will remain stable even if the price of U3O8 rises. Thus the fuel’s contribution to the overall cost of the electricity produced is relatively small, so even a large fuel price escalation will have relatively little effect. For instance, typically a doubling of the uranium market price would increase the fuel cost for a light water reactor by 26% and the electricity cost about 7% whereas doubling the gas price would typically add 75% to the price of electricity from that source.

    However even if raw uranium prices increased by orders of magnitude and currently unexploited known deposits were not able to meet demand, there is still a huge amount of fissile material left in so called ‘spent fuel’ that can be extracted by reprocessing. This is a well known process, practiced all over the world particularly by countries like France, Britain, and Japan which do not have secure domestic supplies of yellowcake.

    Thorium, which is much more abundant than uranium can also be use a fuel in some existing reactors like the CANDU-6 without modification. Breeder reactors too are existing technology that can produce unlimited amounts of plutonium that can be burnt as reactor fuel in existing designs. In fact the reason attempts to commercialize these two cycles have failed was that uranium was just too cheap.

    The point here is that fuel cost and availability now or in the long term, is the least of the problems faced by nuclear energy. The arguments put forward that this source of energy should not be exploited because it is not sustainable into the future are without factual or logical foundation.

  2. DV82XL thanks for taking the time to reply. I am keenly interested in a deeper understanding of nuclear’s sustainability; particularly breeder reactors.

    After my limited meta-research several months ago I noted breeder reaction as a sound, experimentally-validated theory, but with some significant obstacles between now and when we can have it in widespread production. I’m going to have to go back and refresh my info.

    Regarding the viability of scaling up uranium (or thorium) extraction, I still wish there were studies discussing it in quantitative lifecycle (energy ROI) terms. Without something tangible to point at, it could just be pro-nuke propaganda that has as little foundation as the “50 years left” anti-nuke crowd. I don’t doubt that the elements are plentiful, I just want to know how the economics and energy return changes when we run out of low-hanging fruit.

    Thank you again for your thoughts!

  3. “Regarding the viability of scaling up uranium (or thorium) extraction, I still wish there were studies discussing it in quantitative lifecycle (energy ROI) terms.”

    Specifically, at today’s price of ~$40/kG of uranium, the ore costs amount to only ~0.1 cents/kW-hr (i.e., only ~2-3% of nuclear’s total power cost). The ore cost could increase by a factor of 10 (to ~$400/kg) and nuclear’s power cost would only increase by ~1 cent.

    However the problem with your question is that it depends on which fuel cycle that is assumed and what model you use to estimate unknown reserves.

    Currently the once-through cycle only uses a fraction of the fissile material in it. Thus spent nuclear fuel still has from 95 percent to 99 percent of unused uranium in it, and this can be recycled. As a consequence at current consumption we have about 600 years of burnable fuel above ground already.

    Now your next question will be is reprocessing viable from the energy ROI perspective, and the answer is yes. What it is not is economically viable and that is because current prices for new uranium are too low.

    And this is not all. The most popular types of reactors require the fuel to be enriched to increase the concentration of the key isotope U235. Right now as it stands a good deal of this is left in the tailings but again at the cost of fresh uranium it is not cost effective to extract it.

    The low price of uranium has also means that exploration has not been given the priority that it would be if prices were higher.

    In fact Uranium resources from conventional sources compare very favourably with most other resources. Virtually no exploration for conventional uranium sources has been undertaken during the last 30 years. Most of the world’s land surface has yet to be explored for uranium. It is economically possible to extract uranium and thorium from phosphate ore and mine tailings, but this is not done because of the abundance of conventional supplies. This source alone amounts to millions of tons of both uranium and thorium.

    As well there are a number of placer deposits of both ores that have been identified but at the moment are not economically viable, again because of low prices. Also the Japanese have demonstrated that it is technically economically possible to extract Uranium from sea water using low energy techniques, but again it’s sill cheaper to buy on the open market.

    Breeder reactors have been maligned as an unproven technology. The fact is they have been in regular use for decades breeding plutonium for nuclear weapons. It is a mature technology that simply isn’t worth the cost at this point. Construction of the Clinch River Commercial Breeder Reactor was abandoned simply because it was not economically viable. not because of technical problems.

    Currently uranium market prices are depressed by the effort of the US government to burn up the U235 and Pu239 left over from cold war weapons. Until that stock is drawn down their is virtually no need for new uranium. The only US uranium enrichment plant currently in operation, operates at far less than full capacity. In fact. it only operates at all because a US government owned utility, TVA buys enriched U235 from it. This arrangement has probably been made for national defense purposes. Until the weapons stockpiles are burned up, there is no incentive for more uranium or thorium explorations, reprocessing, or breeding.

    The argument that we are running out of Uranium/Thorium resources, amounts to an appeal to ignorance, since it is arguing in effect that undiscovered resources do not exist, and that other fuel cycles cannot be used.

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