Fuel cells that work with the enzyme hydrogenase are, in principle, just as efficient as those that contain the expensive precious metal platinum as a catalyst. However, the enzymes need an aqueous environment, which makes it difficult for the starting material for the reaction – hydrogen – to reach the enzyme-loaded electrode. Researchers solved this problem by combining previously developed concepts for packaging the enzymes with gas diffusion electrode technology. The system developed in this way achieved significantly higher current densities than previously achieved with hydrogenase fuel cells.