The Many Shades of Green
How Green is Nuclear Energy?" I developed this article in response to their request, and it was published as the lead article in their special issue, "Focus on Nuclear Energy."
The online version of the article at the link above attracted a number of interesting comments. Several of the comments addressed areas that I hadn't covered in the article. These were valid criticisms, but I was dealing with a strict word limit, and as I have observed many times, energy is a very complex area. Any analysis of energy alternatives must address multiple dimensions, including economics, health and safety, environmental impacts, resource availability, and reliability. And each of these areas has multiple dimensions as well. For example, environmental considerations include impacts on air, water, and land. To say nothing of the fact that some elements of the picture change over time--new technology developments, new resource discoveries, changing international political alliances, and other factors all affect the comparison of different energy supply alternatives.
So, when I undertook this assignment, the editor and I agreed that I should focus a lot on greenhouse gases (GHGs), since that is a major concern around the world today. The editor also wanted me to address the issue of waste, as that is an issue that is often regarded as the Achilles heel for nuclear power.
Even covering those areas proved quite a challenge, and in the end, I would characterize what I wrote as an overview of the topic. I tried to mention other elements that could affect the comparison of energy technologies, but did not have the space to explain them.
Thus, some of the comments picked up on areas that I had only mentioned in passing. For example, one comment noted that the impact of nuclear accidents on the environment might trump the benefits of nuclear energy. This topic alone is a huge one, and to address it properly, one would have to compare region impacts versus global ones, short-term impacts versus long-term ones, the costs and potential for cleaning up from accidents versus dealing with climate change, and much more. And, while the impacts of an event at a solar or wind farm may be small, one should then consider the whole life cycle of other technologies. To cite just one recent example that crossed my desk, solar panels and wind farms use materials that are, to date, in limited supply. However, some people believe that there are large untapped resources at the bottom of the sea--but mining materials for solar panels in the oceans can carry risks to the environment in case of accident that could be widespread and significant.
Other comments legitimately noted areas that I hadn't addressed. One commenter, for example, spoke to the fact that we should reduce our use of energy. I agree that conservation should be part of the equation (although the author of the comment may have had more in mind than the type of conservation I am thinking about), but trying to evaluate how much we could save was beyond my mandate. Furthermore, globally, there are huge numbers of people who live in severe energy poverty, so the calculus of how much energy the world really "needs" quickly becomes very complicated. My focus was limited to addressing nuclear power as one option to meet whatever energy needs society has, and to assessing nuclear power in terms of its effects on the environment, i.e., it's "greenness."
Another commenter observed that we may not really know how good or bad different pollutants are. Can increased levels of CO2 be a good thing? Can radioactivity lead to mostly good genetic changes? And the author of that comment wonders if mankind will even be around forever, so what difference does it make? Again, my mandate stopped far short of such apocalyptic musings. The author of that comment does make a good point that perhaps there may be ways to recycle CO2 and use it, and indeed, there are researchers looking at just such things. But, unless you feel that the fate of mankind is already determined and there is nothing we can do, I feel that our role is to plan the best we can for the world as we know it. It is a delicate balance, I know. You can't totally ignore the fact that we are working on improved ways to store energy, cheaper and more efficient solar cells, advanced nuclear reactors, nuclear fusion, etc. I do not doubt that, 100 years from now, the conversation about the greenness of one source of energy or another might be very different. But today, we can only operate on the best knowledge we have, and my comparisons are made in that spirit.
Finally, one commenter noted that I hadn't covered all the materials issues associated with power production. In particular, that author mentioned the large amount of cement needed for nuclear power plants. This one was of particular interest to me, because I have seen a lot of discussion of the materials requirements for different energy sources, and while current nuclear power plants are large structures and clearly require a lot of cement, most sources I've read point to wind and solar energy as the major culprits for large use of construction materials. While a single windmill is, of course, much smaller than a nuclear power plant, the diffuse nature of the wind and sun creates a requirement for many windmills or solar panel structures, and the resulting use of materials is much higher, per unit of energy generated, for solar and wind plants than for nuclear plants. One example of the comparisons I have seen is provided in a table by Breakthrough, that is based on data from a report by the University of Sydney, in Australia.
My one brief article was not intended to address all the issues. Nor was it intended to "prove" that nuclear power is the best of all options. As I said in the article, there are clearly shades of green. And there are shades of any other element of energy production we may care to examine. The whole point of my writing the article is that we need to move away from the simplistic views of energy technology that regard wind and solar as green because it is natural, and everything else as bad. Wind and solar power do have impacts on the environment, and a fair comparison of energy technologies has to look at multiple dimensions. Each will excel in some areas and fall short in others, and finding the right balance is, and will remain, a difficult and imperfect process.
Update May 5, 2017: The graph below, from a Department of Energy report (Table 10.4, DOE Quadrennial Technology Review 2015), came to my attention after I posted this article. I add it here as a further example of the materials requirements for different energy technologies: