Study claims nuclear plays minor role in cutting emissions

Published in Nature Energy, the paper - titled Differences in carbon emissions reduction between countries pursuing renewable electricity versus nuclear power - was written by Benjamin Sovacool of the University of Sussex Business School and Andy Stirling of Germany's ISM International School of Management, among others. It presents conclusions of an analysis of World Bank and International Energy Agency data for 123 countries over two 25-year periods: 1990-2004 and 2000-2014.

The authors say the study found that in countries with a high GDP per capita, nuclear electricity production does associate with a small drop in CO2 emissions. But in comparative terms, this drop is smaller than that associated with investments in renewable energy. Also, in countries with a low GDP per capita, nuclear electricity production clearly associates with CO2 emissions that tend to be higher.

"One core finding is that countries with nuclear power attachments do not tend to have lower levels of national carbon emissions," the paper says. "A second core finding is that lower levels of carbon emissions do associate more strongly with the relative scales of national attachments to renewable energy than with nuclear attachments. In other words, it is renewable (more than nuclear) attachments that tend to be associated in practice with significantly lower levels of carbon emissions ... A third core finding is that the scales of nuclear and renewable attachments do tend to vary negatively with each other."

A combined nuclear and renewable energy mix is incompatible for a number of reasons, the paper says. These include the configuration of electricity transmission and distribution systems where a grid structure optimised for larger scale centralised power production such as conventional nuclear, will make it more challenging, time-consuming and costly to introduce small-scale distributed renewable power. Similarly, finance markets, regulatory institutions and employment practices structured around large-scale, base-load, long-lead time construction projects for centralised thermal generating plant are not well designed to also facilitate a multiplicity of much smaller short-term distributed initiatives.

"The evidence clearly points to nuclear being the least effective of the two broad carbon emissions abatement strategies, and coupled with its tendency not to co-exist well with its renewable alternative, this raises serious doubts about the wisdom of prioritising investment in nuclear over renewable energy," Sovacool said. "Countries planning large-scale investments in new nuclear power are risking suppression of greater climate benefits from alternative renewable energy investments."

In their paper Sovacool et al explicitly state that they are not proposing a causal relationship between a country's share of nuclear or renewable generation and the CO2 emissions per GDP per capita, only a correlation according to the timeframe and other assumptions they make.

"The specific historic correlation proposed by Sovacool et al [is not] a useful contribution to discussion of future energy and environmental policy," said World Nuclear Association Director General Agneta Rising.

She noted that the study includes hydro among renewables, and that it is the leading source of renewable energy. "Thus the historic effects proposed in terms of CO2 per GDP per capita are dominated by correlation with the share of hydropower in the generation mix, rather than giving an indication of the role played by wind turbines or solar panels, or the potential for them to do so in the future," she said. "Hydropower installations could be said to have more practical similarities with nuclear than with other renewables."

The authors' final conclusion is that "diverse renewables are generally proving in the real world to be significantly more effective than nuclear power at reducing climate disruption." Rising said: "We do not believe that this study provides evidence to support that conclusion, primarily because it reports finding that relate to hydropower, not to the broad sweep of diverse renewables now being deployed."

Many issues need to be considered when determining the optimal mix of technologies that will allow a much greater level of decarbonisation of energy supply, Rising said. "We believe it will involve a much larger role for all low-carbon technologies, including a very significant expansion of nuclear generation."