The growth potential for deep geothermal has been recognized just recently, but geothermal has been a source of energy to humankind since the dawn of civilization. For centuries, hot springs have been used for bathing, healing and heating. The early 20th century saw major advances in geothermal technology, with electricity generation in Larderello, Italy, and district heating in Reykjavik, Iceland. Since then, there has been no stop in technological innovations.