GEOTHERMAL ENERGY

Types of Geothermal Plants

There are three basic types of geothermal power plants:

* Dry steam plants use steam piped directly from a geothermal reservoir to turn the generator turbines. The first geothermal power plant was built in 1904 in Tuscany, Italy, where natural steam erupted from the Earth.
* Flash steam plants take high-pressure hot water from deep inside the Earth and convert it to steam to drive the generator turbines. When the steam cools, it condenses to water and is injected back into the ground to be used over and over again. Most geothermal power plants are flash steam plants.
* Binary cycle power plants transfer the heat from geothermal hot water to another liquid. The heat causes the second liquid to turn to steam which is used to drive a generator turbine.




Geothermal Energy Is Generated Deep Inside the Earth
Image of the earth's interior, from the outside to the inside, with the crust, the mantle of magma and rock, the outer core of magma, and the innermost core of iron.


Geothermal energy is generated in the Earth's core. Temperatures hotter than the sun's surface are continuously produced inside the Earth by the slow decay of radioactive particles, a process that happens in all rocks. The Earth has a number of different layers:

* The core itself has two layers: a solid iron core and an outer core made of very hot melted rock, called magma.
* The mantle surrounds the core and is about 1,800 miles thick. It is made up of magma and rock.
* The crust is the outermost layer of the Earth, the land that forms the continents and ocean floors. It can be 3 to 5 miles thick under the oceans and 15 to 35 miles thick on the continents.