Geothermal energy has been used for centuries as natural heat in the form of hot springs for bathing. Some of that heat has also been used to keep greenhouses and some structures warm. A more recent innovation involves the use of shallow closed-loop systems that pump heat to and from structures by taking advantage of the constant temperature of soil around 10 feet deep. On a larger scale, some moderately deep closed-loop projects have also been installed to provide direct heat to heat large structures or campuses.
Since the first commercial geothermal plant was installed in Lardarello, Italy more than 100 years ago, geothermal energy is most often used for power generation. the. The world’s largest geothermal project – currently with about 750 MW of capacity – is located north of San Francisco, CA, U.S. Other projects have been developed in many regions including the western U.S., the Caribbean, El Salvador, Mexico, the Caribbean, Costa Rica, Australia, Japan, Indonesia, New Zealand, Philippines, Turkey, and parts of Europe. Geothermal electricity is generated in 26 countries and geothermal heating is used in 70 countries.
A potentially important use of geothermal energy is for hydrogen production. Hydrogen can be used to produce, store, move, and use energy. It is abundant but only in compound form so it must be produced through energy intensive processes. Most hydrogen today is produced using natural gas or coal which create CO2 emissions. Geothermal energy can be used to produce green hydrogen, with no CO2 emissions.