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.

Pathway to a land-neutral expansion of Brazilian renewable fuel production

L. R. Camargo, G. Castro, K. Gruber, J. Jewell & M. Klingler. (2022). Pathway to a land-neutral expansion of Brazilian renewable fuel production. Nature Communications 13, 3157. Open Access. DOI: https://doi.org/10.1038/s41467-022-30850-2

Biofuels are currently the only available bulk renewable fuel. They have, however, limited expansion potential due to high land requirements and associated risks for biodiversity, food security, and land conflicts. We therefore propose to increase output from ethanol refineries in a land-neutral methanol pathway: surplus CO2-streams from fermentation are combined with H2 from renewably powered electrolysis to synthesize methanol. We illustrate this pathway with the Brazilian sugarcane ethanol industry using a spatio-temporal model. The fuel output of existing ethanol generation facilities can be increased by 43%–49% or ~100 TWh without using additional land. This amount is sufficient to cover projected growth in Brazilian biofuel demand in 2030. We identify a trade-off between renewable energy generation technologies: wind power requires the least amount of land whereas a mix of wind and solar costs the least. In the cheapest scenario, green methanol is competitive to fossil methanol at an average carbon price of 95 €/tCO2.

Quitting fossil fuels: how fast can the world do it?

J. Jewell, M. Vetier, V. Vinichenko, O.M. Lægreid, S. Pai, A. Cherp, H. Brauers, I. Braunger, L. Nacke, H. Zerriffi. (2022). Quitting fossil fuels: how fast can the world do it? Policy brief.

To meet climate targets, fossil fuel use needs to rapidly decline. Has anything similar happened in the past? Do current coal phase-out efforts put us on the path to save the climate? And how would such radical fossil fuel decline affect fossil fuel workers? To answer these questions, we analyzed historical precedents of fossil fuel decline, current efforts to phase-out coal and future pathways to reach climate targets.

We find surprising precedents of decline in the 1970s and 80s when industrialized wealthy economies responded to the oil crises. At the same time, the current pledges of coal phase-out are insufficient to deliver on the 1.5°C targets and are limited to countries with low costs and high enough capacity to overcome those costs. Nevertheless, in spite of the opposition from fossil fuel workers to transitions, we identify opportunities for low-carbon jobs to replace fossil fuel jobs.

Download and read the policy brief from the Contractions project.

Societal transformations in models for energy and climate policy: the ambitious next step

E. Trutnevyte, L.F. Hirt, N. Bauer, A. Cherp, A. Hawkes, O.Y. Edelenbosch, S. Pedde, & D.P. van Vuuren. (2020). Societal transformations in models for energy and climate policy: The Ambitious Next Step. One Earth, 1 (4), 423-433. Open Access. DOI: https://doi.org/10.1016/j.oneear.2019.12.002.

Whether and how long-term energy and climate targets can be reached depend on a range of interlinked factors: technology, economy, environment, policy, and society at large. Integrated assessment models of climate change or energy-system models have limited representations of societal transformations, such as behavior of various actors, transformation dynamics in time, and heterogeneity across and within societies. After reviewing the state of the art, we propose a research agenda to guide experiments to integrate more insights from social sciences into models: (1) map and assess societal assumptions in existing models, (2) conduct empirical research on generalizable and quantifiable patterns to be integrated into models, and (3) build and extensively validate modified or new models. Our proposed agenda offers three benefits: interdisciplinary learning between modelers and social scientists, improved models with a more complete representation of multifaceted reality, and identification of new and more effective solutions to energy and climate challenges.

On the political feasibility of climate change mitigation pathways: Is it too late to keep warming below 1.5°C?

J. Jewell. & A. Cherp. (2020). On the political feasibility of climate change mitigation pathways: Is it too late to keep warming below 1.5°C? Wiley Interdisciplinary Rev (WIRE) Climate Change, 11 (621). Open Access. DOI: 10.1002/wcc.621.

Keeping global warming below 1.5°C is technically possible but is it politically feasible? Understanding political feasibility requires answering three questions: (a) “Feasibility of what?,” (b) “Feasibility when and where?,” and (c) “Feasibility for whom?.” In relation to the 1.5°C target, these questions translate into (a) identifying specific actions comprising the 1.5°C pathways; (b) assessing the economic and political costs of these actions in different socioeconomic and political contexts; and (c) assessing the economic and institutional capacity of relevant social actors to bear these costs. This view of political feasibility stresses costs and capacities in contrast to the prevailing focus on benefits and motivations which mistakes desirability for feasibility. The evidence on the political feasibility of required climate actions is not systematic, but clearly indicates that the costs of required actions are too high in relation to capacities to bear these costs in relevant contexts. In the future, costs may decline and capacities may increase which would reduce political constraints for at least some solutions. However, this is unlikely to happen in time to avoid a temperature overshoot. Further research should focus on exploring the “dynamic political feasibility space” constrained by costs and capacities in order to find more feasible pathways to climate stabilization. This article is categorized under: The Carbon Economy and Climate Mitigation > Decarbonizing Energy and/or Reducing Demand

Prospects for powering past coal

J. Jewell, V. Vinichenko, L. Nacke, & A. Cherp. (2019). Prospects for powering past coal. Nature Climate Change, 9(8), 592–597. Gated. DOI: https://doi.org/10.1038/s41558-019-0509-6. Preprint.

To keep global warming within 1.5 °C of pre-industrial levels, there needs to be a substantial decline in the use of coal power by 2030 and in most scenarios, complete cessation by 2050. The members of the Powering Past Coal Alliance (PPCA), launched in 2017 at the UNFCCC Conference of the Parties, are committed to “phasing out existing unabated coal power generation and a moratorium on new coal power generation without operational carbon capture and storage”. The alliance has been hailed as a ‘political watershed’ and a new ‘anti-fossil fuel norm’. Here we estimate that the premature retirement of power plants pledged by PPCA members would cut emissions by 1.6 GtCO2, which is 150 times less than globally committed emissions from existing coal power plants. We also investigated the prospect of major coal consumers joining the PPCA by systematically comparing members to non-members. PPCA members extract and use less coal and have older power plants, but this alone does not fully explain their pledges to phase out coal power. The members of the alliance are also wealthier and have more transparent and independent governments. Thus, what sets them aside from major coal consumers, such as China and India, are both lower costs of coal phase-out and a higher capacity to bear these costs. To limit warming, a rapid reduction in coal use is needed. Early retirement of coal power plants by members of the Powering Past Coal Alliance, which includes mainly wealthy countries that use little coal, would have a modest climate impact. Prospects for expanding the Alliance are examined.

Limited emission reductions from fuel subsidy removal except in energy-exporting regions

J. Jewell, D. McCollum, J. Emmerling, C. Bertram, D.E.H.J. Gernaat, V. Krey, L. Paroussos, L. Berger, K. Fragkiadakis, I. Keppo, N. Saadi, M. Tavoni, D.P. van Vuuren, V. Vinichenko, & K. Riahi. (2018). Limited emission reductions from fuel subsidy removal except in energy-exporting regions. Nature. Gated. DOI: https://doi.org/10.1038/nature25467. PrePrint.

Many governments use subsidies for fossil fuels to reduce the cost of energy for domestic consumption. This has led to the frequent argument that removing subsidies could play an important part in mitigating climate change. Now, Jessica Jewel and colleagues show that subsidy removal would indeed substantially lower emissions in fossil-fuel-exporting countries, but would reduce global carbon dioxide emissions by only a few per cent by 2030. This small reduction would largely be due to offsetting effects from international trade and fuel substitution. The authors also find that subsidy removal would not dramatically increase the use of renewable energy, adding to the suggestion that extensive revisions of subsidy policies would not produce a major benefit for climate mitigation.

Quantifying uncertainties influencing the long-term impacts of oil prices on energy markets and carbon emissions

D.L. McCollum, J. Jewell, V. Krey, M. Bazilian, M. Fay & K. Riahi. (2016). Quantifying uncertainties influencing the long-term impacts of oil prices on energy markets and carbon emissions. Nature Energy, 1 (7), 16077. Gated. DOI: https://doi.org/10.1038/nenergy.2016.77. Preprint.

Oil prices have fluctuated remarkably in recent years. Previous studies have analysed the impacts of future oil prices on the energy system and greenhouse gas emissions, but none have quantitatively assessed how the broader, energy-systemwide impacts of diverging oil price futures depend on a suite of critical uncertainties. Here we use the MESSAGE integrated assessment model to study several factors potentially influencing this interaction, thereby shedding light on which future unknowns hold the most importance. We find that sustained low or high oil prices could have a major impact on the global energy system over the next several decades; and depending on how the fuel substitution dynamics play out, the carbon dioxide consequences could be significant (for example, between 5 and 20% of the budget for staying below the internationally agreed 2 C target). Whether or not oil and gas prices decouple going forward is found to be the biggest uncertainty.

Comparison and interactions between the long-term pursuit of energy independence and climate policies

J. Jewell, V. Vinichenko, D. McCollum, N. Bauer, K. Riahi, T. Aboumahboub, O. Fricko, M. Harmsen, T. Kober, V. Krey, G. Marangoni, M. Tavoni, D.P. Van Vuuren, B. Van Der Zwaan & A. Cherp. (2016). Comparison and interactions between the long-term pursuit of energy independence and climate policies. Nature Energy 1, 1-9. Gated. DOI: https://dx.doi.org/10.1038/nenergy.2016.73.

Ensuring energy security and mitigating climate change are key energy policy priorities. The recent Intergovernmental Panel on Climate Change Working Group III report emphasized that climate policies can deliver energy security as a co-benefit, in large part through reducing energy imports. Using five state-of-the-art global energy-economy models and eight long- term scenarios, we show that although deep cuts in greenhouse gas emissions would reduce energy imports, the reverse is not true: ambitious policies constraining energy imports would have an insignificant impact on climate change. Restricting imports of all fuels would lower twenty-first-century emissions by only 2–15% against the Baseline scenario as compared with a 70%reduction in a 450 stabilization scenario. Restricting only oil imports would have virtually no impact on emissions. The modelled energy independence targets could be achieved at policy costs comparable to those of existing climate pledges but a fraction of the cost of limiting global warming to 2 ◦ C.

Global energy security under different climate policies, GDP growth rates and fossil resource availabilities

A. Cherp, J. Jewell, V. Vinichenko, N. Bauer & E. D. Cian. (2016). Global energy security under different climate policies, GDP growth rates and fossil resource availabilities. Climatic Change, 136 (1), 83-94. Open Access. DOI: https://doi.org/10.1007/s10584-013-0950-x.

Energy security is one of the main drivers of energy policies. Understanding energy security implications of long-term scenarios is crucial for informed policy making, especially with respect to transformations of energy systems required to stabilize climate change. This paper evaluates energy security under several global energy scenarios, modeled in the REMIND and WITCH integrated assessment models. The paper examines the effects of long-term climate policies on energy security under different assumptions about GDP growth and fossil fuel availability. It uses a systematic energy security assessment framework and a set of global and regional indicators for risks associated with energy trade and resilience associated with diversity of energy options. The analysis shows that climate policies significantly reduce the risks and increase the resilience of energy systems in the first half of the century. Climate policies also make energy supply, energy mix, and energy trade less dependent upon assumptions of fossil resource availability and GDP growth, and thus more predictable than in the baseline scenarios.

2°C and SDGs: united they stand, divided they fall?

C. von Stechow, J. C. Minx, K. Riahi, J. Jewell, D. L. McCollum, M. W. Callaghan, C. Bertram, G. Luderer & G. Baiocchi. (2016). 2°C and SDGs: united they stand, divided they fall? Environmental Research Letters, 11 (3), 034022. Open Access. DOI: https://doi.org/10.1088/1748-9326/11/3/034022.

The adoption of the Sustainable Development Goals (SDGs) and the new international climate treaty could put 2015 into the history books as a defining year for setting human development on a more sustainable pathway. The global climate policy and SDG agendas are highly interconnected: the way that the climate problem is addressed strongly affects the prospects of meeting numerous other SDGs and vice versa. Drawing on existing scenario results from a recent energy-economy-climate model inter-comparison project, this letter analyses these synergies and (risk) trade-offs of alternative 2 °C pathways across indicators relevant for energy-related SDGs and sustainable energy objectives. We find that limiting the availability of key mitigation technologies yields some co-benefits and decreases risks specific to these technologies but greatly increases many others. Fewer synergies and substantial trade-offs across SDGs are locked into the system for weak short-term climate policies that are broadly in line with current Intended Nationally Determined Contributions (INDCs), particularly when combined with constraints on technologies. Lowering energy demand growth is key to managing these trade-offs and creating synergies across multiple energy-related SD dimensions. We argue that SD considerations are central for choosing socially acceptable 2 °C pathways: the prospects of meeting other SDGs need not dwindle and can even be enhanced for some goals if appropriate climate policy choices are made. Progress on the climate policy and SDG agendas should therefore be tracked within a unified framework.

Post-2020 climate agreements in the major economies assessed in the light of global models

M. Tavoni, E. Kriegler, K. Riahi, D. P. van Vuuren, T. Aboumahboub, A. Bowen, K. Calvin, E. Campiglio, T. Kober, J. Jewell, G. Luderer, G. Marangoni, D. McCollum, M. van Sluisveld, A. Zimmer & B. van der Zwaan. (2014). Post-2020 climate agreements in the major economies assessed in the light of global models. Nature Climate Change, 5 (2), 119-126. Open Access. DOI: https://doi.org/10.1038/nclimate2475.

Integrated assessment models can help in quantifying the implications of international climate agreements and regional climate action. This paper reviews scenario results from model intercomparison projects to explore different possible outcomes of post-2020 climate negotiations, recently announced pledges and their relation to the 2 °C target. We provide key information for all the major economies, such as the year of emission peaking, regional carbon budgets and emissions allowances. We highlight the distributional consequences of climate policies, and discuss the role of carbon markets for financing clean energy investments, and achieving efficiency and equity.