Hydrogen internal combustion engines (H2-ICEs), as a lower-cost alternative to fuel cells, are gaining industry attention. Kawasaki Heavy Industries is developing a compact hydrogen-powered generator called "O'Cuvoid," which integrates a hydrogen internal combustion engine driving a generator. The unit targets an output of 35 kW per system and occupies approximately one square meter of space. Designed for mobility and outdoor applications, the device can power large vehicles—such as passenger cars and train carriages—by linking multiple units in parallel. The hydrogen engine leverages Kawasaki’s motorcycle technology and incorporates a supercharger identical to those used in sport motorcycles to enhance hydrogen compression and combustion efficiency. Kawasaki also plans to deploy this engine in its Corleo quadrupedal humanoid robot, a manned robotic platform expected to enter service by 2035. Hydrogen internal combustion engines are significantly cheaper to manufacture than fuel cells, primarily using materials like iron and aluminum without requiring expensive platinum-group catalysts. The total system cost is less than one-tenth that of a fuel cell system and can utilize existing internal combustion engine maintenance infrastructure. Additionally, H2-ICEs tolerate lower-purity hydrogen and can even run on hydrogen-natural gas blends, whereas fuel cells require hydrogen purity exceeding 99%. Hydrogen ICEs offer faster power response, making them suitable for high-power-demand scenarios, though their energy conversion efficiency is around 40%—lower than the 60% efficiency of fuel cells—and they produce nitrogen oxides during combustion. Toyota has already deployed hydrogen internal combustion engines in its GR Corolla race cars, competing in Japan’s Super Taikyu endurance racing series, where real-world performance closely matches that of conventional gasoline-powered race cars. Since 2023, Toyota has been conducting trials with liquid hydrogen technologies and integrating superconducting motors into hydrogen storage tanks. Meanwhile, Mitsubishi Fuso Truck and Bus Corporation is developing hydrogen ICEs for heavy-duty trucks, reusing 80% of existing diesel truck components to control costs. India has also designated hydrogen as a national strategic priority, with Tata Motors advancing parallel development of hydrogen-powered heavy trucks. The Japanese government aims to increase annual hydrogen supply to 20 million tons by 2050—roughly ten times current levels. However, widespread hydrogen adoption still faces significant hurdles, including an underdeveloped industrial ecosystem, a declining number of hydrogen refueling stations (down from 179 in fiscal year 2022 to around 150), high costs of green hydrogen, and competition from electric vehicle technologies. Currently, most industrial hydrogen production relies on fossil fuels, and market prices stand at approximately ¥100 per normal cubic meter (Nm³)—far above the government’s 2050 target of ¥20/Nm³.