Geothermal power plants are one of the most efficient energy sources on Earth today. It works by tapping into steam or hot water reservoirs underground to drive an electrical generator to produce electricity. However, even if geothermal power plants are not renewable at all, researches tell that they are capable of providing heat for a number of decades. The are depleted as the ground cools eventually. Thus, hydroelectric is a more stable source of energy compared to it.
