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Energy storage

Energy storage is the storage of a quantity of energy in an easily usable form for future use. This part focus on energy storage by the molecule of hydrogen.

The hydrogen building

Hydrogen is extracted from molecules that contain it, as is the case with water. One of the solutions is to implement a hydrolysis reaction of the water. It takes place in an electrolyzer that uses electricity produced by photovoltaic panels, for example. The electric current will “break” the molecule of water in two, and consequently forming oxygen and hydrogen. 

The energy can then be stored as hydrogen rather than in batteries.

In the majority of projects that already use this technology, electricity is produced by a photovoltaic system and then used directly to cover the needs of the household. On the other hand, if production exceeds demand, the excess electricity activates the electrolyzer to produce hydrogen. It is then stored under pressure or in solid form in suitable tanks. When the electricity production can no longer meet the needs of the household, the hydrogen feeds a generator set equipped with a fuel cell to perform the reverse reaction and produce energy. The yield is between 31% and 39%. 


Strong points

  • Lifetime and maintenance of hydrogen storage
  • Low environmental impact (the reaction in the electrolyzer does not emit any CO2)
  • Fuel cells take up little space
  • Makes it possible to develop renewable energies produced locally


  • Hydrogen storage requires significant amounts of energy
  • Risks of flammability and detonation with existing air
  • The cost of water electrolysis is quite high
  • Lower efficiency than a battery system