The first geothermal heat utilization is impossible to estimate exactly. Yet, in the 16th century Georgius Agricola observed that temperature in mines generally increased with their depth. Later on, Alexander Von Humboldt calculates an approximation of 3.8 deg Celsius increase for every 100 meters of depth, and so we have our first study of the Earth’s thermal gradient.
First modern measurements were performed in 1740, in a mine near Belfort, France. Since the 1950’s, worldwide geothermal heat research have been conducted.
By the end of the 19th Century, Prince Piero Conti proposed an idea to harness natural steam from the Larderello geothermal field in Italy to produce electric power. He started by conducting technical experiments in 1903, and a year later, the first geothermal power experiment produced enough energy to illuminate five incandescent light bulbs.
By 1913, Conti had completed the construction of a 250 kW commercial power plant fed by pure steam, and in 1916, two more power units of 3.5 MW each. And this is how geothermal power production was born.