In context: As humanity moves toward building permanent habitats off-Earth, researchers are developing reliable energy systems to support life in extreme environments. They’ve long studied electrolysis to generate oxygen and hydrogen in space, but low gravity reduces its efficiency. Honda plans to tackle this problem by testing its system aboard the International Space Station.

Honda is aiming beyond Earth with plans to test its high-differential pressure water electrolysis system aboard the International Space Station. In partnership with Sierra Space and Tec-Masters, the company hopes the technology will support a regenerative fuel cell system for sustaining life on the Moon – and potentially offering scalable energy solutions on Earth.

The centerpiece of Honda’s effort is a circulative renewable energy system designed to continuously generate oxygen, hydrogen, and electricity. Drawing on decades of fuel cell expertise, the company plans to build infrastructure that uses lunar resources – like sunlight and water – to support long-term human presence on the Moon.

The system operates in a closed loop. During the lunar day, solar panels power the electrolysis process to split water into hydrogen and oxygen. The generated oxygen provides astronauts with breathable air. Meanwhile, the electrolysis plant uses hydrogen and excess oxygen reserves as fuel for electricity. The approach is not unlike closed-loop home solar systems that store excess energy in batteries for nighttime use. Meanwhile, the only byproduct of the process is water, which is recycled back into the system.

Honda’s high-differential pressure water electrolysis system is compact and lightweight, helping cut transportation costs – a key concern for lunar missions. It also stores high-pressure gas in smaller containers to reduce bulk, and by removing mechanical compression, it lowers maintenance needs and boosts reliability for long-term use.

Honda plans to test its system’s core components in the microgravity aboard the ISS. Sierra Space will lead mission integration, coordinating with NASA to transport materials aboard its Dream Chaser spaceplane. Tec-Masters will provide expertise on ISS technology during the testing phase.

Honda formed a Space Development Division within American Honda late last year to strengthen ties between the US space industry and Honda R&D’s Space Strategy Office in Japan. By refining its regenerative fuel cell system under extreme conditions, the company aims to demonstrate its potential as a clean, renewable energy source for lunar missions and Earth-based infrastructure. Honda envisions scalable applications that support global decarbonization.