Hydrogen is the most abundant element in the Universe, but is not freely available in the ground. It is not a natural resource, in other words, it has to be produced, just like electricity, which is why use it is usually said that hydrogen is an energy vector. Hydrogen can be produced from a wide range of resources (water, fossil resources, biomass, microbes, etc.), following different transformation processes including electrolysis, gasification, reforming, photoelectrolysis and photobiolysis… By Carlos Fúnez Guerra. Head of the Open Innovation Unit at the Spanish National Hydrogen Centre.