The energy transition is pushing towards a future powered by zero-emission energy systems, in which renewable energies can play a key role. Photovoltaic solar systems, wind power plants, wave energy converters are some of the protagonists involved in the energy revolution that humanity is experiencing. These systems are intermittent sources of energy due to the strict dependence on resource availability, such as solar radiation or wind. Electrolysers can help address the problem of intermittent energy production by making these systems more flexible and providing strength to electricity networks. Surplus renewable energy can be used to power electrolysers with the purpose of generating hydrogen, which can be stored as gas compressed, liquefied, or even absorbed/adsorbed and then converted directly to electricity, by means of fuel cells.