> There are also heat pump cycles that can be driven directly with heat. They are called https://en.wikipedia.org/wiki/Absorption_heat_pump https://en.wikipedi

> There are also heat pump cycles that can be driven directly with heat. They are called https://en.wikipedia.org/wiki/Absorption_heat_pump https://en.wikipedia.org/wiki/Absorption_heat_pump But they are much less efficient that electrical ones, adding even a small amount of electricity to the cycle (even if the primary energy is heat) can dramatically improve efficiency.