地域再エネ共同研究プロジェクト

Introduction

In response to global climate change and the pursuit of a sustainable society, countries around the world are accelerating the adoption of renewable energy. In recent years, with continuous technological advancements in solar and wind power and a significant reduction in generation costs, renewable energy has gradually established itself as a primary source of electricity worldwide. Internationally, the annual newly installed capacity of renewable energy continues to reach record highs, and its economic competitiveness has surpassed that of traditional fossil fuels. In Japan, the government is also actively promoting the spread of renewable energy to achieve a “decarbonized society.” Since the Great East Japan Earthquake in 2011, Japan has re-evaluated its reliance on nuclear power and accelerated its transition toward decarbonization, leading to significant changes in renewable energy-related policies and systems. The Japanese government has set a target to increase the share of renewable energy to 36–38% by 2030, and is vigorously developing diverse energy sources such as solar and wind power. At the same time, efforts are being made to advance technological development, improve electricity transmission infrastructure, and promote coexistence policies with local communities, positioning renewable energy as a central pillar of Japan’s energy policy. In terms of development potential, Japan possesses solar and offshore wind resources equivalent to 14 times the amount needed to achieve 100% renewable electricity supply, along with substantial potential for large-scale off-river pumped hydro energy storage (Cheng et al., 2022). From a technical perspective, Esteban & Portugal-Pereira (2014) simulated Japan’s hourly electricity demand in 2030 and analyzed meteorological data for wind and solar energy. Their results indicate that Japan’s power system is technically capable of increasing the share of renewable energy to 100%, with stable and reliable electricity supply achievable through the use of pumped hydro and battery storage to balance daily supply-demand fluctuations. Even in the Kanto region, which has the highest electricity demand, the offshore wind power potential along the coast is estimated at 287 terawatt-hours (TWh) annually—slightly exceeding the annual supply capacity of Tokyo Electric Power Company (Yamaguchi & Ishihara, 2014)—when economic and social factors are excluded. This demonstrates that Japan has sufficient and abundant natural resource potential for renewable energy development. However, at the current stage, Japan still faces challenges in terms of renewable energy adoption rates, cost competitiveness, and stable power supply, and lags behind leading countries in these areas.