Researchers at ETH Zurich have developed an innovative method to safely store hydrogen in iron for extended periods. Located at a pilot plant in Switzerland, the technology involves feeding hydrogen into a stainless steel reactor filled with natural iron ore at 400°C. The hydrogen then extracts oxygen from the iron ore, resulting in elemental iron and water. When energy is needed, the process is reversed by feeding hot steam into the reactor to convert iron and water back into iron oxide and hydrogen. This hydrogen can then be converted into electricity or heat in a gas turbine or fuel cell. The pilot plant has the capacity to store up to 10MWh of hydrogen, but up to 60% of the hydrogen's energy is lost during the process. Despite this, the technology is most beneficial as an energy storage medium when renewable energy sources such as wind or solar power are available and other options are limited. ETH Zurich plans to expand the pilot plant by 2026 to meet a significant portion of its winter electricity requirements using stored green hydrogen. This expansion will involve creating reactors with a volume of 2,000 cubic meters, capable of storing around 4GWh of green hydrogen. Wendelin Stark, Professor of Functional Materials at ETH Zurich, highlighted the ease of sourcing the raw material, iron ore, in large quantities for this technology, emphasizing its advantage. The project, part of ETH's Coalition for Green Energy and Storage, is aligned with Switzerland's Net Zero ambitions. The innovative iron-based hydrogen storage technology offers a promising solution for sustainable energy storage and could potentially contribute significantly to reducing carbon emissions.