Climate change, energy, and Japan’s GX & fusion startups, part 4

Compared to fossil-fuel-based thermal power, nuclear power emits significantly less CO2, making it an valuable energy source in today’s pursuit of carbon neutrality. Looking ahead to the 2030s and beyond, expectations are rising for nuclear fusion as a next-generation stable energy option.

In previous parts of this “Climate Change and Energy” series, we explored Japan’s modern energy history in part 1 and part 2, and its initiatives in Green Transformation in part 3. In this final article, we turn our attention to Japan’s current nuclear power landscape and the progress of fusion energy research and development.

The Current State of Nuclear Power

The world’s first artificial nuclear reactor was completed in the United States in 1942. In Japan, frameworks and systems for nuclear power were developed in the mid-1950s, and in 1966, the Tokai Nuclear Power Plant became Japan’s first commercial reactor. Construction of additional nuclear power plants then expanded across Japan.

Today, the United States, France, and China account for nearly 60% of global nuclear generation capacity, followed by Russia, South Korea, and Japan.

Germany has pursued a policy of phasing out nuclear power generation. Although there were times when the country took a cautious stance toward this phase-out due to concerns over reducing greenhouse gas emissions, the Merkel administration accelerated the nuclear phase-out following the 2011 Great East Japan Earthquake, which caused an accident at the Fukushima Daiichi Nuclear Power Plant and led to the temporary shutdown of all reactors nationwide at the time. The Japanese government reviewed nuclear safety standards and introduced stricter operating conditions. Since then, reactors that have met these new standards have been gradually restarted. Nuclear power generation today is only about one-third of its pre-2011 level. Natural gas and renewable energy have since taken on a greater share of Japan’s energy mix.

Japan’s Nuclear Industry and Research Institutions

Nowadays, to maintain technical capabilities and secure talent, Japanese companies are stepping up recruitment and development for next-generation nuclear technologies.

The nuclear power sector consists of two main groups: utilities that own and operate nuclear plants, such as Tokyo Electric Power Company and other regional power firms, and manufacturers that design, produce, and maintain reactors and key components, including Mitsubishi Heavy Industries (MHI), Toshiba Energy Systems, and Hitachi. Companies such as Japan Nuclear Fuel Limited and Global Nuclear Fuel Japan (GNF-J) handle nuclear fuel production and the fuel cycle.

Current nuclear power plants rely on nuclear fission, a process in which heavy atomic nuclei such as uranium and plutonium split to release energy. This process produces high-level radioactive waste as a byproduct. By contrast, nuclear fusion combines light nuclei such as hydrogen or lithium to generate energy. While still experimental, fusion is considered safer than fission and has the potential to become a key energy source in the future. The ITER reactor uses the tokamak design, which confines high-temperature plasma inside a vacuum vessel to initiate fusion reactions.

MHI is deeply involved in nuclear fusion development as a participant in the ITER project, the world’s largest international fusion research initiative based in southern France. MHI manufactures Toroidal Field coils that generate the powerful magnetic fields needed to confine plasma, as well as critical components for the divertor system that handles plasma exhaust and heat removal.

Japan’s leading national research body in this field is the National Institutes for Quantum Science and Technology (QST). QST plays a central role in advancing fusion research and serves as Japan’s liaison for ITER, collaborating with domestic utilities and manufacturers.

Japan’s Nuclear Fusion Startups

Alongside major players like MHI and QST, a new wave of Japanese startups is driving fusion innovation. These companies often emerge from university or QST research, valuing speed, flexibility, and proprietary technology to compete globally.

・Kyoto Fusioneering: a Kyoto University spin-out focused on plant engineering and peripheral systems rather than the reactor core itself.

・Helical Fusion: founded in 2021 by researchers from the National Institute for Fusion Science, aiming to develop the world’s first steady-state helical fusion reactor by 2034.

・EX-Fusion: an Osaka University spin-out established in 2021, pursuing inertial confinement fusion using laser technology.

・Starlight Engine: a 2025 spin-out from Kyoto Fusioneering, working on a compact tokamak design under the FAST (Fusion by Advanced Superconducting Tokamak) concept.

・LINEA Innovations: established in 2022 by researchers from Nihon University and the University of Tsukuba, developing a fusion reactor using proton-boron (pB11) fuel for near-neutron-free reactions.

・MiRESSO: a QST spin-off specializing in low-cost, energy-efficient beryllium refining for use in fusion reactor blankets.

Japan’s experience with energy transitions, from its early modernization to today’s GX initiatives, highlights the growing urgency of decarbonization. The country aims for carbon neutrality by 2050, and progress is evident: greenhouse gas emissions have fallen from 1.41 billion tons in 2013 to 1.14 billion tons in 2022.

On the other hand, the dependence on imported fossil fuels still remains high. Geopolitical tensions and natural disaster risks underline the importance of improving energy security and self-sufficiency.

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