A method of and apparatus for desalinating sea water using geothermal energy. A low voltage (such as less than 0.9V) is applied to a hydrogen generating catalysts to generate hydrogen and oxygen, wherein geothermal heat is used as a heat source. The hydrogen and oxygen are used to drive a gas turbine to generate electricity. The oxygen and hydrogen are transported away and combusted to generate heat and pure water, as such salt are separated from the pure water.