Scientists at Osaka Metropolitan University have developed an artificial photosynthesis device that converts sunlight, water, and carbon dioxide into formic acid without using batteries. The self-regulating electrolyzer adjusts automatically to changing light levels, simplifying the process and cutting costs.
The system integrates a solid electrolyte into the electrolyzer, allowing it to perform maximum power point tracking through its own thermal and impedance properties. As sunlight increases, the device heats up and reduces electrical resistance, enabling stable fuel production throughout the day.
Professor Yutaka Amao explained the mechanism: "As sunlight increases, the electrolyzer naturally heats up. The system is designed so that this warming causes the electrical resistance to drop, allowing electricity to flow more freely." Tests under real outdoor conditions confirmed consistent formic acid output despite fluctuating sunlight.
Associate Professor Yasuo Matsubara noted prior demonstrations at the Osaka Kansai Expo 2025, where the technology powered a miniature diorama. The research, conducted with Iida Group Holdings Co., Ltd., was published in EES Solar.