A heat pump includes a first portion for evaporating a working fluid at a first pressure, for compressing the evaporated working fluid to a second, higher pressure, and for liquefying the compressed working fluid within a liquefier, and a second portion for compressing liquid working fluid to a third pressure, which is higher than the second pressure, for evaporating the working fluid compressed to the third pressure, for relaxing the evaporated working fluid to a pressure, which is lower than the third pressure, so as to generate electrical current, and for liquefying relaxed evaporated working fluid within the liquefier.