Hydrogen can be used as an energy carrier, whose potential lies in the possibility of storing and transporting it for later use and recovering the energy it contains by recombining it. The production of hydrogen, however, involves the use of a certain amount of energy.
The cleanest way to produce free hydrogen is by separating the water into its two constituent elements: hydrogen and oxygen. This separation is carried out by the contribution of energy in the form of electric current, in a process called electrolysis.
Under normal conditions, hydrogen is in a gaseous state with a very low density, which means that it takes up a large amount of space, too much to be useful. For this reason, it is stored in tanks or bottles as a gas at very high pressure.
To recover the energy from the hydrogen, the process of its production is reversed in a fuel cell, where the hydrogen recombines with oxygen to form water and returns a large part of the energy previously supplied in the form of electricity.
One of the main applications and interests for this technology is the possibility of using the surplus energy from a renewable facility (e.g., solar photovoltaic energy) to generate hydrogen. In this way, it is possible to store this energy -that would otherwise be lost- for a period of time and to be able to use it later for other applications, for example, in a hydrogen vehicle. In this way, by using 100% renewable energy for the production and use of 100% clean hydrogen, it can be said that the hydrogen vehicle operates with zero emissions.