Geothermal Energy Industry Workers

Hot springs and underground reservoirs, products of geothermal energy, have long been used as sources of heat. Paleo-Indians in North America used hot springs more than 10,000 years ago as a source of warmth and cleansing. They also used the minerals in the springs as a source of healing. Geothermal water was used by the ancient Romans to treat skin and eye diseases. In the town of Pompeii, it was used to heat buildings. Ancient Japanese, Chinese, and other cultures also recognized the restorative and practical uses of geothermal energy.

In 1322, French villages began using hot springs for home heating. In 1326, the first "health spa" at a natural hot springs was established in Belgium. Spas set up around hot springs became popular in the 1800s in the United States.

In the late 1800s, scientists and engineers began to study the practical uses of geothermal energy as it related to the production of electricity. According to the Geothermal Energy Association (GEA), "major district-wide heating and individual use geothermal energy projects have been in continuous, successful long-term operation at Boise, Idaho, since 1892 … and the first large-scale geothermal electricity plant opened at Larderello, Italy, in 1904."

The U.S. Department of Energy reports the following geothermal energy firsts in the United States in the first half of the 20th century: the first geothermal power plant goes into operation, but it does not produce enough energy to remain viable (1921); the first commercial greenhouse use of geothermal energy is undertaken in Boise, Idaho (1930); and the first commercial building use of a groundwater heat pump in Portland, Oregon (1948).

In 1960, the first large-scale geothermal electricity-generating plant began to operate at The Geysers in Northern California. By the 1980s, geothermal power plants were built in several western U.S. states. By 1985, U.S. geothermal power plants produced about 2,000 megawatts (MWs) of electricity. Today, there are approximately 2.5 GWs of geothermal power online in the United States. Plants in the U.S. produce about 28 percent of all geothermal-generated electricity in the world.

The United States produces more geothermal energy than any other country, yet geothermal energy generates less than 0.5 percent of total U.S. electricity. In 2018, geothermal energy fueled only 0.4 percent of all elecricity generation in the United States, according to the Energy Information Administration.