Implications of Japan’s long term climate mitigation target and the relevance of uncertain nuclear policy

Abstract

Achieving long-term climate mitigation goals in Japan faces several challenges, starting with the uncertain nuclear power policy after the 2011 earthquake, the uncertain availability and progress of energy technologies, as well as energy security concerns in light of a high dependency on fuel imports. The combined weight of these challenges needs to be clarified in terms of the energy system and macroeconomic impacts. We applied a general equilibrium energy economic model to assess these impacts on an 80% emission reduction target by 2050 considering several alternative scenarios for nuclear power deployment, technology availability, end use energy efficiency, and the price of fossil fuels. We found that achieving the mitigation target was feasible for all scenarios, with considerable reductions in total energy consumption (39-50%), higher shares of lowcarbon sources (43-72% compared to 15%), and larger shares of electricity in the final energy supply (51-58% compared to 42%). The economic impacts of limiting nuclear power by 2050 (3.5% GDP loss) were small compared to the lack of carbon capture and storage (CCS) (6.4% GDP loss). Mitigation scenarios led to an improvement in energy security indicators (trade dependency and diversity of primary energy sources) even in the absence of nuclear power. Moreover, preliminary analysis indicates that expanding the range of renewable energy resources can lower the macroeconomic impacts of the long term target considerably, and thus further in depth analysis is needed on this aspect. Key policy insights• For Japan, an emissions reduction target of 80% by 2050 is feasible without nuclear power or CCS.• The macroeconomic impact of such a 2050 target was largest without CCS, and smallest without nuclear power.• Energy security indicators improved in mitigation scenarios compared to the baseline.

The role of renewables in the Japanese power sector: implications from the EMF35 JMIP

“…Shiraki et al (2016) estimated the future siting and scale of power plants under CO 2 emission reduction targets using a dynamic multiregional optimalgeneration planning model. Along with the above studies using power dispatch models, studies using energy system models and integrated assessment models (IAMs) also provided the impact of emission reduction targets on the power sector (Silva Herran et al 2019;Kato and Kurosawa 2019;. However, all of these studies implemented by a single model or a single-model framework.…”

A framework for national scenarios with varying emission reductions

“…Concerning variations in technological availability and cost, there are well-known examples in the global study carried out under EMF27 and the Assessment of Climate Change Mitigation Pathways and Evaluation of the Robustness of Mitigation Cost Estimates (AMPERE) projects 46,50 (for example, non-CCS scenarios). Furthermore, there are similar national or regional implementations [51][52][53] . These scenario variations can be added to the standard set as supplementary (extended) scenarios in a similar way to those proposed in the SSPs 54 .…”

Demand-side decarbonization and electrification: EMF 35 JMIP study

“…This study employs scenarios from five energy-economic and integrated assessment models: AIM/Enduse-Japan (Oshiro and Masui 2015;Fujimori et al 2019;Kainuma et al 2003), AIM/Hub-Japan (Fujimori et al 2017a, b, c;Silva et al 2019), DNE21 (Hosoya and Fujii 2011;Fujii and Komiyama 2015), IEEJ_Japan 2017 (Matsuo et al 2013(Matsuo et al , 2020, and TIMES-Japan (Kato and Kurosawa 2019;Kurosawa and Hagiwara 2012;Loulou et al 2005;Sato 2005). Hereafter, each model is called AIM/Enduse, AIM/Hub, DNE21, IEEJ, and TIMES-Japan.…”