The Japanese power system has unique characteristics with regard to variable renewable energies (VREs), such as higher costs, lower potentials, and less flexibility with the grid connection compared to other major greenhouse-gas-emitting countries. We analyzed the role of renewable energies (REs) in the future Japanese power sector using the results from the model intercomparison project Energy Modeling Forum (EMF) 35 Japan Model Intercomparison Project (JMIP) using varying emission reduction targets and key technological conditions across scenarios. We considered the uncertainties for future capital costs of solar photovoltaics, wind turbines, and batteries in addition to the availability of nuclear and carbon dioxide capture and storage. The results show that REs supply more than 40% of electricity in most of the technology sensitivity scenarios (median 51.0%) when assuming an 80% emission reduction in 2050. The results (excluding scenarios that assume the continuous growth of nuclear power and/or the abundant availability of domestic biomass and carbon-free hydrogen) show that the median VRE shares reach 52.2% in 2050 in the 80% emission reduction scenario. On the contrary, the availability of newly constructed nuclear power, affordable biomass, and carbon-free hydrogen can reduce dependence on VREs to less than 20%. The policy costs were much more sensitive to the capital costs and resource potential of VREs than the battery cost uncertainties. Specifically, while the doubled capital costs of VRE resulted in a 13.0% (inter-model median) increase in the policy cost, the halved capital costs of VREs reduced 8.7% (inter-model median) of the total policy cost. These results imply that lowering the capital costs of VREs would be effective in achieving a long-term emission reduction target considering the current high Japanese VRE costs.

与其他主要温室气体排放国相比，日本电力系统在可变可再生能源（VRE）方面具有独特的特点，例如成本更高，潜力更低，电网连接的灵活性更低。我们使用模型比较项目能源模型论坛（EMF）35日本模型比较项目（JMIP）的结果分析了可再生能源（REs）在未来日本电力行业中的作用，该方案使用了不同的减排目标和跨方案的关键技术条件。我们考虑了太阳能光伏，风力涡轮机和电池未来资本成本的不确定性以及核和二氧化碳捕获和存储的可用性。结果表明，假设2050年减排80％，在大多数技术敏感性情景中，可再生能源可提供40％以上的电力（中位数为51.0％）。结果（不包括假设核电和/或核能持续增长的情景）丰富的家用生物质和无碳氢的供应）表明，在减排80％的情况下，2050年VRE的中位数份额将达到52.2％。相反，新建核电，可负担的生物质和无碳氢的可用性可以将对VRE的依赖性降低到不到20％。与电池成本的不确定性相比，政策成本对VRE的资本成本和资源潜力更为敏感。具体来说，虽然VRE的资本成本增加了一倍，导致保单成本增加了13.0％（模型间中位数），减半的VRE资本成本减少了总保单成本的8.7％（模型间中位数）。这些结果表明，考虑到目前日本高昂的VRE成本，降低VRE的资本成本将有效地实现长期减排目标。