My memories of thermodynamics are old and full of gaps, but from what I remember both steps, if performed at "normal temperatures, necessarily produce a waste o

My memories of thermodynamics are old and full of gaps, but from what I remember both steps, if performed at "normal temperatures, necessarily produce a waste of energy. The first step, i.e. using electricity to drive a heat pump, is efficient only if the temperature differential between the cold body and the hot one is small. On the other side, conversion of thermal energy into electricity is efficient only if the temperature differential is large. How does Malta overcome this problem?