Steel is one of the hardest industries to decarbonize, along with chemicals, cement and transportation. Converting all BF-BOF plants in the EU to hydrogen-based DRI/EAF would require up to 5.3 million tonnes of renewable hydrogen and up to 370 TWh of other renewable electricity. The challenge becomes even greater if variable renewable electricity is used and the electrolyzers cannot operate at constant full load. According to an analysis by the European Commission, the cost of producing hydrogen using solar photovoltaics will rise to almost 7 billion euros for a single average-capacity plant. In order to break even, the transport price of hydrogen must be less than 3 euros per kilo, with a high price, in another case less than 1.5 euros per kilo. Underground hydrogen storage in salt caverns offers a cost-effective solution, but they are not available across the EU.