From electricity to hydrogen and back again

Water can be split into oxygen and hydrogen by passing an electrical current through it, in a process known as electrolysis. This process effectively stores most of the initial electrical energy in the form of a gas that has chemical energy content.  

Fuel cells allow this stored hydrogen to be converted back into electricity. Hydrogen and oxygen are fed into the cell in such a way that the two gases react with each other, thus generating electricity, heat, and water.

But how practical is all this when it comes to daily use?
Hydrogen is the optimal storage medium for energy that cannot be used immediately, thanks to the extremely low energy loss entailed in producing hydrogen via electrolysis. Solar arrays and wind turbines are the best examples of this phenomenon. At night, or when there is no wind, such facilities produce no electricity. To compensate for this, the excess energy that these solar arrays and wind turbines produce can be stored via electrolysis and used later on – a complete hydrogen cycle that produces no environmental pollution.