Geothermal

Geothermal's advantage is that it doesn't pollute the air and it is sustainable. And its disadvantage is that the [|thermal efficiency] of geothermal electric plants is low, around 10-23%, because geothermal fluids are at a low temperature compared with steam from boilers. By the laws of [|thermodynamics] this low temperature limits the efficiency of [|heat engines] in extracting useful energy during the generation of electricity.