Where does the electricity come from that we use in our homes? Most power plants make electricity by heating water to make steam. The steam rises and turns turbines, which make electricity. Many power plants burn coal to heat the water. Coal is a major cause of air pollution. Burning fossil fuels like coal is also thought to cause global warming. Geothermal energy is a cleaner source of energy. Geothermal means natural heat that comes from inside the Earth.
Much of the Earth's heat comes from its core. It is still hot from when the Earth formed over four billion years ago. Heat from the core spreads outward through the Earth's mantle, or middle layer. Inside the mantle, rocks are mostly in liquid form, called magma, melted by the Earth's internal heat. Magma heats the water under the ground. In some places, the hot water shoots to the surface in hot springs and geysers. This hot water can power geothermal energy systems.
Making electricity at a geothermal power plant is easier. Most of them use water that is already hot. Wells are drilled one to two miles down through the Earth's rocks. Hot water or steam is pumped to the power plant.