ALKALINE ELECTROLYSER (AEL)
They use a liquid electrolyte solution and the resulting hydrogen is of medium purity. It requires very bulky equipment.
SOLID OXIDE ELECTROLYSER (SOEC)
It uses a solid ceramic material as electrolyte and obtains high-purity hydrogen. The process is highly efficient but requires temperatures of between 500ºC and 850ºC, which makes the operation very expensive.