Historical diffusion of nuclear, wind and solar power in different national contexts: implications for climate mitigation pathways

V. Vinichenko, J. Jewell, J. Jacobsson, A. Cherp. (2023). Historical diffusion of nuclear, wind and solar power in different national contexts: implications for climate mitigation pathways. Environmental Research Letters 18, 094066. Open Access. DOI: https://doi.org/10.1088/1748-9326/acf47a

Climate change mitigation requires rapid expansion of low-carbon electricity but there is a disagreement on whether available technologies such as renewables and nuclear power can be scaled up sufficiently fast. Here we analyze the diffusion of nuclear (from the 1960s), as well as wind and solar (from the 1980–90s) power. We show that all these technologies have been adopted in most large economies except major energy exporters, but solar and wind have diffused across countries faster and wider than nuclear. After the initial adoption, the maximum annual growth for nuclear power has been 2.6% of national electricity supply (IQR 1.3%–6%), for wind − 1.1% (0.6%–1.7%), and for solar − 0.8% (0.5%–1.3%). The fastest growth of nuclear power occurred in Western Europe in the 1980s, a response by industrialized democracies to the energy supply crises of the 1970s. The European Union (EU), currently experiencing a similar energy supply shock, is planning to expand wind and solar at similarly fast rates. This illustrates that national contexts can impact the speed of technology diffusion at least as much as technology characteristics like cost, granularity, and complexity. In the Intergovernmental Panel on Climate Change mitigation pathways, renewables grow much faster than nuclear due to their lower projected costs, though empirical evidence does not show that the cost is the sole factor determining the speed of diffusion. We demonstrate that expanding low-carbon electricity in Asia in line with the 1.5 °C target requires growth of nuclear power even if renewables increase as fast as in the most ambitious EU's plans. 2 °C-consistent pathways in Asia are compatible with replicating China's nuclear power plans in the whole region, while simultaneously expanding renewables as fast as in the near-term projections for the EU. Our analysis demonstrates the usefulness of empirically-benchmarked feasibility spaces for future technology projections.

Phasing out coal for 2 °C target requires worldwide replication of most ambitious national plans despite security and fairness concerns

V. Vinichenko, M. Vetier, J. Jewell, L. Nacke  & A. Cherp.  (2023). Phasing out coal for 2 °C target requires worldwide replication of most ambitious national plans despite security and fairness concerns. Environmental Research Letters 18, 014031. Open Access. DOI: https://doi.org/10.1088/1748-9326/acadf6

Ending the use of unabated coal power is a key climate change mitigation measure. However, we do not know how fast it is feasible to phase-out coal on the global scale. Historical experience of individual countries indicates feasible coal phase-out rates, but can these be upscaled to the global level and accelerated by deliberate action? To answer this question, we analyse 72 national coal power phase-out pledges and show that these pledges have diffused to more challenging socio-economic contexts and now cover 17% of the global coal power fleet, but their impact on emissions (up to 4.8 Gt CO2 avoided by 2050) remains small compared to what is needed for achieving Paris climate targets. We also show that the ambition of pledges is similar across countries and broadly in line with historical precedents of coal power decline. While some pledges strengthen over time, up to 10% have been weakened by the energy crisis caused by the Russo-Ukrainian war. We construct scenarios of coal power decline based on empirically-grounded assumptions about future diffusion and ambition of coal phase-out policies. We show that under these assumptions unabated coal power generation in 2022–2050 would be between the median generation in 2 °C-consistent IPCC AR6 pathways and the third quartile in 2.5 °C-consistent pathways. More ambitious coal phase-out scenarios require much stronger effort in Asia than in OECD countries, which raises fairness and equity concerns. The majority of the 1.5 °C- and 2 °C-consistent IPCC pathways envision even more unequal distribution of effort and faster coal power decline in India and China than has ever been historically observed in individual countries or pledged by climate leaders.