“The pilot plant can store around 10 megawatt hours of hydrogen over long periods. Depending on how you convert the hydrogen into electricity, that’ll give you somewhere between 4 and 6 megawatt hours of power.”
ETH Zurich stores summer hydrogen as iron in plain steel reactors with 6 millimetre walls, at normal pressure, using untreated iron ore. The catch is up to 60 percent of the energy gone in the round trip. Three reactors cover the winter needs of three to five Swiss homes, and the pilot still runs on grid power. Cheap storage is easy when you throw away more than half of what you store.