Renewable hydrogen production by water electrolysis

The global energy demand is mainly met by fossil fuels, so new sustainable fuels need to be produced based on renewable energy sources. However, their inherent dependence on weather conditions causes them to be intermittent. In order to solve this problem, it is necessary to have storage systems. In this regard, hydrogen and fuel cells offer a promising solution as energy carriers. Nowadays, water electrolysis is one of the most environment-friendly ways to produce hydrogen from renewable sources. The hydrogen produced can be used in transport, industry, residential applications, or stationary power generation, carrying out a gradual decarbonization of these sectors. In this context, this chapter shows the theoretical bases, the most important characteristics, and the main technologies of water electrolysis (alkaline, proton exchange membrane, and solid oxide) to produce hydrogen. Also, a review of commercial electrolyzers and the main projects regarding their integration with renewable energy sources are discussed.