Although hydrogen is one of the most commonly-found elements in the universe, it rarely exists as an independent molecule on our planet. Most of the time, it is bound to other elements or molecules to form compounds like water, carbohydrates, hydrocarbons and DNA acids. Obtaining hydrogen is not easy and usually requires a certain amount of energy to break the bonds connecting hydrogen to other elements. One process is water electrolysis in which electric energy is used to split water into hydrogen and oxygen. To regain the potential chemical energy stored in the hydrogen molecule, hydrogen and oxygen are combined to yield energy and water in the fuel cell which works in the reaction opposite to the electrolysis. This chapter discusses these two processes occurring in the electrolyser and in the fuel cell, two fundamental components of the solar hydrogen energy system.
KeywordsFuel Cell Concentration Polarisation Electromotive Force Electrolytic Cell Activation Polarisation
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