The argument in favor of nuclear power at this point is pretty obvious: global warming is bad news, so a major power source that doesn't emit greenhouse gasses sounds good, right? An odd counter-argument has emerged from the anti-nuclear side: they claim nuclear power actually is a source of CO2 emissions. They say that if you look at the full life cycle of a nuclear power plant, so much work is done in mining, transport and decommissioning and so much concrete is used in its construction that nukes shouldn't be considered a low-emissions power source.
Fortunately, quite a few studies have been completed doing full-cycle analysis of the CO2 emissions for different power sources. From a report published in July 2011, a meta-study summarizing 21 such studies:
Full Lifecycle GHG Emissions Intensity of Electricity Generation Methods, WNA July, 2011
But, there's more to say about this, of course...
The results pretty clearly split in half, where burning hydrocarbons is the worst thing you can do, and anything else is much better. Coal remains public enemy number one among the hydrocarbons, and natural gas looks like the best of them-- though there's a gotcha here that's often ignored: methane is itself a worse greenhouse gas than CO2, so any leaks of natural gas are a bad problem in themselves. The graph here is intended to show the "Greenhouse Gas Emissions Intensity" so the y-axis is not just CO2 (per unit of power), but rather CO2e, the "equivalent CO2": so some effort has been made here to track other GHG besides CO2. But unfortunately, there's been some more recent work (see here or perhaps here) on this that I suspect means the number for Natural Gas from this report is too low.
There's another problem with figuring the numbers for Solar and Wind, in that many of the actual solar/wind plants built are designed to use Natural Gas burning as a backup. I presume that what they've done here is try to separate out the emissions from hybrid power sources into different categories, but if what's under discussion is should we build another plant like that, that point of view is less useful. (In other words, the labels "Solar" and "Wind" shouldn't be used to greenwash fracking.)
Anyway, just using the data as presented, among the low CO2 emitters, we can split them into three ranks, where oddly enough solar power is the worst, and nuclear power is one of the cleanest, tied with hydropower and wind.
Now, this particular meta-study was done by the "World Nuclear Association", an industry support group, so it's inevitable that someone will raise the possibility of bias. But the list of studies they've examined seems fairly impressive, with a wide range of sources, and their stated methodology for choosing which studies to include makes some sense. And the overall result is similar to things I've seen from other sources.
Interestingly enough, this WNA report also includes an analysis that looks for biases in it's own sources. They break them down according to categories such as government, industry or universities, and compare the results from the different sets. There's no very clear pattern that emerges, except that the analysis done by "nuclear specialists" show a lower estimate of CO2 emissions, but not just for nuclear power, they're consistently lower for all power sources.
I once asked some anti-nuclear folks at the dailykos for references to explain where they got the impression that GHG emissions for nuclear were high-- I was pointed to an article up on the nature.com site, which relied entirely on a meta-study (pdf) by Benjamin K. Sovacool.
As it happens this particular study apparently has quite a few very bad methodological problems. On this subject, allow me to quote the rationalwiki (just like wikipedia except snarkier, and I always seem to agree with it... clearly I'm another a member of Rat Nation):
... he was left with 19 studies that satisfied his criteria. He did not evaluate the soundness of methodology at all, or consider whether there was any peer review before publication, he just considered whether it was described in enough detail. ... He also did not remove superseded versions of the same analysis from the same authors. This led him to include 3 versions of the Leeuwen and Smith nonsense, as well as 3 different studies by Dones et al. Finally, to arrive at a "true" value of CO2 emissions, he calculated a mean of all results. He arrived at a value of 66 g/kWh, which he then compared to emissions from other sources, with each value selected from a single analysis.
This all sounds pretty damning (and for what it's worth, a similar take on this subject seems to have survived the rough-and-tumble of wikipedia: Life-cycle greenhouse-gas emissions of energy sources. I've got a slightly different take on this though: why is Sovacool under the impression that 66g CO2e/kWh is such a big number?
The WNA chart uses different units, "tons CO2e/GWh", but the conversion factor to get from Sovacool's numbers to those works out to 1.1023, just a 10% increase. So even if you decided not to quibble with Sovacool's methodology, you get a number of 72.8 tons CO2e/GWh, which remains over on the right side of the WNA chart. And using Sovacool's numbers for the dirtiest form of coal, you'd get 1157.4 tons CO2e/GWh, comparable to the WNA figure, though also a larger number.
So, even using Sovacool's number's I'd be left with the same overall conclusion: we need to use as much of the non-hydrocarbon power sources as we can get, including nuclear. Sovacool's own (somewhat innumerate) conclusions about how you get more "bang-for-buck" out of renewables than nuclear seems almost besides the point-- they're all so much better than coal, why argue about it?
(By the way: both wikis cite different studies with lower GHG figures for nuclear than this WNA study I'm using.)
Now, the "Leeuwen and Smith nonsense" (as our level-headed friends at the rationalwiki put it) despite being very popular with anti-nuclear folks really has been thoroughly shot down by many sources. Here's one discussion. The wikipedia article on Jan Willem Storm van Leeuwen quotes some others if you're interested.
So what we have here is a case where a handful of not-very-reputable researchers have been seized on by the anti-nuclear side, and quoted repeatedly as the source of truth (as opposed to those terribly biased members of the great conspiracy, who were cited by the WNA study).
If there was any serious question about GHG emissions from nuclear plants, you would think it would be settled by now, since there are multiple high-quality studies on the subject that have been out for well over 5 years. Instead, many people of the anti-nuclear persuasion seem to have seized upon the few studies that agree with them (despite being of evident low quality).
This seems like a very familiar syndrome, much like what we've seen with the climate change denialists, whose reliance on a few cranks has been documented well in the book (and now documentary) Merchants of Doubt: How Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming (2010) by Naomi Oreskes and Erik M. Conway.
But then, Naomi Oreskes herself has no trouble rejecting the vast majority of expert technical opinion on nuclear power (not to mention on GMOs)... the irony is so thick there you could spread it at L1 as a solar screen.
In this piece, I'm just trying to discuss one aspect of the Great Nuclear debate. The first impulse of the anti-nuclear folks is always to play hopscotch, so I expect responses that jump to other issues like "but what about nuclear waste?" and "but why do we need nuclear if we have solar & wind?" and so on, but for the present just try to focus on this one sub-issue... I throw out some questions to the anti-nuclear adherents: there's a widespread belief on your side that seems to be thoroughly, demonstrably wrong. How did this happen? What are you doing to keep it from happening again? If you can be wrong about this, what else might you be wrong about?
Some follow-up work for me, if I keep going with this:
- Do some spot checks of the studies cited as sources by the WNA study. Pay particular attention to the University sources (on the theory that an anti-nuclear person would feel more comfortable with those).
- Find some additional studies that weren't included in the WNA study. Again, pay attention to university studies. Similarly look for remarks made in recent IPCC reports.
- Determine precisely what they mean by Solar and Wind. Are these hybrid installations with some Natural Gas included in the figures, or is that broken out under the Natural Gas numbers?
- Examine the studies linked to from the wikipedia page. How are they getting a lower figure for nuclear GHG emissions than from the WNA report?
- Study the discussion page (and the main page's history) to get an idea of how it converged on what I would call the truth (rather than the well-represented anti-nuclear side on this).