Hydrogen will play an increasingly important role in replacing fossil fuels and it can be sustainably produced by using solar energy to split water molecules. The resulting clean energy can be stored, used to fuel cars or converted into electricity on demand. But making it reliably on a large scale and at an affordable cost is a challenge for researchers. Efficient solar hydrogen production requires rare and expensive materials — for both the solar cells and the catalyst — in order to collect energy and then convert it.

Scientists at EPFL’s Laboratory of Renewable Energy Science and Engineering (LRESE) came up with the idea of concentrating solar irradiation to produce a larger amount of hydrogen over a given area at a lower cost. They developed an enhanced photo-electrochemical system that, when used in conjunction with concentrated solar irradiation and smart thermal management, can turn solar power into hydrogen with a 17% conversion rate and unprecedented power and current density. What’s more, their technology is stable and can handle the stochastic dynamics of daily solar irradiation.

The scientists estimate that their system can run for over 30,000 hours — or nearly four years — without any part replacements, and up to 20 years if some parts are replaced every four years. Their solar concentrator turns and follows the sun across the sky in order to maximize its yield. Sophia Haussener, the head of the LRESE and the project lead, explains: “In sunny weather, our system can generate up to 1 kilogram of hydrogen per day, which is enough fuel for a hydrogen-powered car to travel 100 to 150 kilometers.”

Thanks to an open interface, it will be possible to monitor the instantaneous performance of the system.