The electrolysis and co-electrolysis processes allow to produce hydrogen through water-splitting and turn CO2 and water into organic fuels, such as methanol, ethanol, etc, respectively. Both hydrogen and methanol can be used as energy vectors or chemical feedstocks.
The electrolysis processes can be used for the storage of surplus energy coming from renewable sources or storing energy that cannot feed the grid, and for the balance of the grid itself. This is necessary because the energy system is mainly based on renewable sources, which are characterised by high intermittence.
The electrolysis and co-electrolysis systems can work at low (<150°C) or high (>600°C) temperature. There are polymeric electrolyte (PEMWE) and solid oxide (SOEC) electrolysis and co-electrolysis cells.