Nuclear Power and Carbon Neutrality
Spring and early summer brought unusually generous amounts of sunshine to the UK, with correspondingly high outputs from solar installations. However, calm weather in May resulted in a collapse of wind power on several days. These conditions prompted comment on the relationship between the generation of renewable power in the UK and imports of electricity from Europe (Watson, 2020). His article points out that some of the imported energy comes indirectly from coal-fired power stations, and much from nuclear power stations in France. This post considers some issues concerning the place of nuclear power in a decarbonising society.
In a chapter on the future of nuclear power, Dieter Helm wrote that its advocates claim that it provides zero carbon energy, is secure and competitive, and is the only way to “provide large-scale, low-carbon electricity generation” (2012, p.120). In view of the damage inflicted on the industry by low fossil-fuel prices in the 1980s and 1990s, the accidents at Three Mile Island in 1979 and at Chernobyl in 1986, he saw climate change as ‘heaven-sent for the nuclear industry”, since the drive to low carbon energy largely removed coal as a source of competition for nuclear power (2012, p.121). This advantage was undermined by the advent of low-cost shale-gas, and confidence in the industry was further undermined by the meltdowns and explosions at Fukushima in 2011. Nevertheless, nuclear power remained an option for large-scale electricity generation, though “no more of a silver bullet than current wind, current solar, or energy efficiency” (2012, p. 213).
More recently, David Elliott claimed that while “most see nuclear and renewables as clear rivals, the wider debate over nuclear continues”, and raised the issues of its role in grid balancing and possible hydrogen production, with heat supply to cities by small modular reactors (SMRs) as an option (2019, p. 246). He addressed the carbon footprint of nuclear plants, pointing out that they “do not directly generate carbon dioxide, but producing the fuel for them does” and that as reserves of high-grade uranium are depleted, producing nuclear fuel may eventually require so much energy that the process approaches the “point of futility” (2019, p. 248).
According to a 2006 paper from the Parliamentary Office of Science and Technology, most emissions occur during uranium mining, enrichment and fuel fabrication, with uranium extraction accounting for 40% of the total CO2 emissions, and decommissioning, including dismantling the nuclear plant and the construction and maintenance of waste storage facilities, accounting for a further 35%. Nuclear power generation overall was assigned a relatively small carbon footprint of approximately 5gCO2eq/kWh, a figure close to those estimated for run-of-river hydro schemes (<5gCO2eq/kWh), onshore wind (4.64gCO2eq/kWh) and offshore wind generation (5.25gCO2eq/kWh) (POSTnote, 2006).
Nuclear power is obviously free from the vagaries of sunshine and wind, but the claim that it is dispatchable needs to be examined. The output of electricity from a nuclear power station can be changed, but only slowly in comparison with many other sources; fast dispatch has been described as the ability to ramp up or shut down output from a power source in a matter of seconds, as for example in hydroelectric generation; natural gas turbines can reach full output from start up in minutes, putting them in the medium dispatch category, but nuclear power stations fall in the slow group, perhaps requiring hours for a major change in output, although they are capable of shutting down in seconds when safety is a consideration (Energy Education, 2020). Tatiana Salnikova discusses the need for flexible operation of nuclear power plants brought about by the growth of renewables, especially in France (Salnikova, 2017). She quotes figures for load-following capability (the rate at which output can be changed under normal circumstances): a quarter of the world’s nuclear power plants can operate flexibly, typically having the ability to change output by 2% per minute in the range from 100% to 40% of full load. (The limitations of flexible operation will be discussed further below).
Some of the perceived hazards of nuclear power are addressed by the World Nuclear Association (WNA, 2020). Regarding nuclear waste, it states that to the end of “2013, a total of about 370,000 tonnes of used fuel had been discharged from reactors worldwide, with about one-third of this (120,000 t) having been reprocessed”. Of this, 97% “is classified as low- or intermediate-level waste” and in France, where fuel is reprocessed, “just 0.2% of all radioactive waste by volume is classified as high-level waste (HLW)”. Plutonium, which is widely regarded as especially dangerous, is compared with other dangerous substances: “The effect of plutonium inhalation would be to increase the probability of a cancer developing in several years time, whilst most other strong toxins lead to more immediate death. Best comparisons indicate that, gram for gram, toxins such as ricin, some snake venoms, cyanide, and even caffeine are significantly more toxic than plutonium.” Radioactive substances generally are compared favourably with other hazardous materials, since “nuclear waste naturally decays, and has a finite radiotoxic lifetime. Within a period of 1,000-10,000 years, the radioactivity of HLW decays to that of the originally mined ore” whereas “other industrial wastes (e.g. heavy metals, such as cadmium and mercury) remain hazardous indefinitely.” The time scale referred to is presumably based on the average decay times of several waste products, since the half-life of plutonium-239, one of the fifteen isotopes of plutonium, is given elsewhere by the WNA as 24,000 years (WNA, 2018).
Helm lists the dangers of nuclear power under four headings: catastrophe, waste, weapons proliferation, and carbon emissions (which have been discussed above). By catastrophe he means something even worse than Chernobyl or Fukushima, perhaps the destruction of an entire city; this he considers highly unlikely, a risk which is “not so great as to rule the technology out” (2012, p. 130). Regarding nuclear waste he states the ethical position that “it is beholden upon those who create such waste to come up with a solution for dealing with it”, and discusses the main options, offering the hope that new reprocessing methods may yield waste with a much shorter half-life than at present. He accepts the link between civil nuclear power programs and the military use of plutonium, but makes the point that “military nuclear powers are not short of plutonium”, so that the fact that more will be produced from civil nuclear power is not a reason to abandon it (2012, p.132). Helm also looks at the future of nuclear power from the viewpoint of prospective investors, a perspective particularly relevant in democratic countries. In Germany, nuclear power stations which had been built under a system of monopoly provision were ordered to close without compensation following a change of government in 2000, after which further policy changes followed; Helm puts the question “If a democratic German government can behave in this way, then what protection can investors have elsewhere?” (2012, p. 135).
The sustainability of nuclear power in terms of continued uranium extraction from various sources is discussed by MacKay, (2009) together with issues of land use and construction costs.
The financial aspects of nuclear power are relevant to the question of flexible operation, touched on briefly above, and discussed by Elliott in his sections on renewables and nuclear balancing (2019, pp. 246-8). As mentioned earlier, nuclear power might have a future role in heat and hydrogen supply, but also in grid balancing, where it could offset the variability of electricity supply from renewables. Elliott however points out that even given the technical solutions needed to obtain adequate flexibility from nuclear power stations, “this undermines their economics. Nuclear plants are usually run flat out, 24/7, to recoup their large capital costs”. He puts this in the perspective of the UK, where summer night electricity demand can fall to around 20GW, and may fall as low as 17GW in the near future, making it difficult to see how renewables and nuclear power can work together in an economical way.
There has been much discussion of the future of small modular reactors in the UK. Promotional literature from the nuclear industry has claimed that one SMR could produce 440MWe of electricity, enough to supply a city the size of Leeds (present population about 830,000), and anticipates around 40 GWe of installed nuclear capacity in the UK by 2050 (Rolls-Royce, 2017). A later publication describes the SMR technology envisaged by the Rolls-Royce-led UK SMR consortium as able to produce nuclear power in a new way anywhere in the world, and capable of solving “the conundrum of how to create affordable energy, and more of it, with a lower carbon footprint”. Further, factory production of modules “removes all the cost and schedule risks of on-site manufacture on large-scale projects. Modules can be transported to site on a truck exactly when they're required” (Rolls-Royce, 2020). The portability of small nuclear reactors has of course been proved in their application to nuclear submarines, and the concept of floating nuclear power stations has existed for some time. Russia’s Rosatom project is intended for mass production, and the first floating nuclear power plant, Akademik Lomonosov, started operation in December 2019. The intention is to provide combined heat and power to locations near ports, “providing up to 70 MW of electricity or 300 MW of heat, or cogeneration of electricity and heat for district heating, enough for a city with a population of 200,000 people.” (Wikipedia, 2020).
A recent article in The Engineer (2020) reports that the UK government has announced £40m of funding to develop next generation nuclear energy technology, in an effort to drive economic growth, create new jobs and support its ambition to achieve net zero emissions by 2050. Much of the funding is targeted at three advanced modular reactor (AMR) projects focussed on the development of power station reactors that can be built in factories and transported to remote locations. Comments on the article cover a wide range of opinion and topics such as the problems of planning permission for sites and regulatory approval, but several note that the sum of £40m is several orders of magnitude below what is needed for a realistic program of nuclear power station development. The viewpoint of prospective investors in nuclear power may prove more influential in determining its future, at least in the UK, than issues of ethics, risk or utility.
References
Elliott, D. (2019) Renewable Energy in the UK. London: Palgrave Macmillan
Energy Education, (2020) ‘Dispatchable source of electricity’, Stenhouse, K., Hanania, J., Donev, J., University of Calgary, April 28, 2020
https://energyeducation.ca/encyclopedia/Dispatchable_source_of_electricity
Helm, D. (2012) The Carbon Crunch. New Haven and London: Yale University Press
MacKay, David J. C., (2009) chapter: ‘Nuclear?’ in Sustainable Energy - Without the Hot Air. Cambridge: Green Books
Available as a free publication at https://www.withouthotair.com/
POSTnote (2006) ‘Carbon Footprint of Electricity Generation’, Parliamentary Office of Science and Technology, Number 268, October 2006.
https://www.parliament.uk/documents/post/postpn268.pdf
Rolls-Royce, (2017) ‘UK SMR: A National Endeavour’, Rolls-Royce plc, 06/09/2017.
https://www.uknuclearsmr.org/wp-content/uploads/2017/09/V2088-Rolls-Royce-SMR-Report-Artwork-Web.pdf
Rolls-Royce, (2020) ‘UK small modular reactor: pioneering intelligent power’ Rolls-Royce plc, 2020.
https://www.rolls-royce.com/products-and-services/nuclear/small-modular-reactors.aspx#/
Salnikova, T. (2017) ‘Flexible operation of nuclear power plants – first steps for paradigm change worldwide?’ VGB PowerTech 5, 2017
The Engineer (2020) ‘UK government nuclear funding targets small modular reactors’, The Engineer, 14th July 2020
https://www.theengineer.co.uk/uk-government-modular-reactors/
Watson, D. (2020) ‘Renewables: Let’s address reality’, Engineering and Technology, June 15, 2020
https://eandt.theiet.org/content/articles/2020/06/renewables-let-s-address-reality/
Wikipedia, (2020) ‘Russian floating nuclear power station’
https://en.wikipedia.org/wiki/Russian_floating_nuclear_power_station
WNA (2018) ‘Plutonium’, World Nuclear Association, (Updated December 2018)
https://world-nuclear.org/information-library/nuclear-fuel-cycle/fuel-recycling/plutonium.aspx#
WNA (2020) ‘Radioactive Waste - Myths and Realities’, World Nuclear Association, (Updated February 2020)
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