Geothermal gas turbine. View of a geothermal gas turbine at the geothermal power plant in Larderello, Italy. This region of Italy has high geothermal activity, that is there is an abundance of underground heat in the form of steam which can be exploited. Larderello and California, USA, are the only two locations in the world where high temperature geothermal steam can be directly used to turn electricity turbines.