A sensor (1) for selectively detecting liquids in apparatuses for storing energy, comprises at least one porous absorption layer (3) for absorbing liquids. Independent claims are: (1) an apparatus (6) for storing energy, comprising at least one store for e...

A fuel cell system of the present invention has a separation unit for separating gas-liquid mixed fluid discharged from the fuel cell stack. The separation unit has a tank for storing the separated liquid. A pair of metal electrodes is disposed on the side...