Idaho’s state capitol building in Boise is heated by pumping up naturally hot water from 3,000 feet (914 m) below the Earth.
This form of energy is called geothermal.
The water is warmed by heat coming from underground chambers of magma, or molten rock.
Magma produces lava during a volcanic eruption.
In areas of volcanic activity, magma lies near the surface, making geothermal energy systems possible.
Many homes and businesses in Iceland, for example, depend on geothermal heat.