Method and apparatus for storing electrical energy

The invention relates to a method and an apparatus for storing electrical energy (1, 2), wherein in an electrolyzer (E) water cleaved with the aid of electric energy while hydrogen obtained (4) into a storage container (S) passed and when required removed therefrom and as fuel (7) of a fuel cell (B) for producing electrical energy (9) is supplied. In the process waste heat (WR1, WR5) (H), supplied to a hydrogen source to cover the existing there heat demand in a hydrogen-containing insert (5) in an endothermic reaction to produce hydrogen (6, 11) is implemented.