Energy Pros & Cons
Geothermal energy comes from the heat in the Earth’s core. In Iceland nearly all buildings are heated in this way. Geothermal power plants contribute significantly to electricity supply in El Salvador, the Philippines, Japan, Mexico, Italy, New Zealand and the western United States.
In some geothermally active regions, the heat from rock and water is near enough the surface to be accessed cost-effectively. Hot water or steam is pumped from underground. Steam can be used to turn turbines directly. Hot water can be pumped to the surface under pressure and turned to steam by suddenly decreasing the pressure. Alternatively, the heat can be used to vaporise a second liquid with a lower boiling point than water – the resulting gas is then used to turn turbines.
The volume of water taken out of the Earth can be re-injected, making geothermal power a sustainable energy source.