Our paper focuses specifically on situations in which real-world constraints mean strategic choices must be made on resource allocation between nuclear or renewables-based electricity.

Our research explores this dilemma retrospectively, examining past patterns in the attachments (i.e. investments) of different countries to nuclear or renewable strategies. Our paper addresses three hypotheses:

A “nuclear climate mitigation” hypothesis: that countries with a greater attachment to nuclear power will tend to have lower overall carbon emissions.
A “renewables climate mitigation” hypothesis: that countries with a greater attachment to renewables will tend to have lower overall carbon emissions.
A “crowding out” hypothesis: that countries with a greater attachment to nuclear will tend to have a lesser attachment to renewables, and vice versa.
Across the study countries as a whole we found that the “nuclear climate mitigation” hypothesis is not sustained by the evidence at an appropriate level of statistical significance. The renewable climate mitigation hypothesis is confirmed with substantial significance. And the crowding out hypothesis is also significantly sustained.

Put plainly – if countries want to lower emissions as substantially, rapidly and cost-effectively as possible, they should prioritise support for renewables rather than nuclear power. Pursuit of nuclear strategies risks taking up resources that could be used more effectively and suppressing the uptake of renewable energy.

What might explain these patterns? Technologically, nuclear systems have been prone to greater construction cost overruns, delays, and longer lead times than similarly sized renewable energy projects. Thus, per dollar invested, the modularity of renewables projects offers quicker emissions reductions than large-scale, delay-prone, nuclear projects.

Furthermore, renewables tend to display higher rates of “positive learning” where increased deployment results in lower costs and improved performance, especially for wind farms and solar energy parks. This contrasts with the experience of nuclear power in France which has been prone to “negative learning,” rising costs or reduced performance with the next generation of technology.

In terms of policy, the incidents at Three Mile Island (1979), Chernobyl (1986), and Fukushima (2011), all resulted in significant tightening of regulatory requirements for nuclear reactors.