GEOTHERMAL ENERGY

The word geothermal comes from the Greek words geo (earth) and therme (heat). So, geothermal en­ergy is heat from within the earth. We can use the steam and hot water produced inside the earth to heat buildings or gen­erate electricity. Geothermal energy is a renewable energy source because the wa­ter is replenished by rainfall and the heat is continuously produced inside the earth.

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Energy inside the earth
Geothermal energy is generated in the earth's core, about 4,000 miles below the surface. 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 which 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 three to five miles thick under the oceans and 15 to 35 miles thick on the continents.
The earth's crust is broken into pieces called plates. Magma comes close to the earth's surface near the edges of these plates. This is where volcanoes occur. The lava..that erupts from volcanoes is partly magma. Deep underground, the rocks and water absorb the heat from this magma. The temperature of the rocks and water get hotter and hotter as you go deeper underground.
People around the world use geother­mal Where is geothermal
energy found?
Most geothermal reservoirs are deep un­derground with no visible clues showing above ground.
Geothermal energy can sometimes find its way to the surface in the form of:
. volcanoes and fumaroles (holes where
volcanic gases and steam are released) . hot springs and
· geysers
are usually found along major plate bound­aries where earthquakes and volcanoes are concentrated.When magma comes close to the sur­face it heats ground water found trapped in porous rock or water running along frac­tured rock surfaces and faults. Naturally occurring large areas of hydrothermal re­sources are called geothermal reservoirs. Geologists use different methods to look for geothermal reservoirs. Drilling a well and testing the temperature deep under­
Uses of geothermal energy
Some applications of geothermal energy use the earth's temperatures near the surface, while others require drilling miles into the earth. The three main uses of geo­thermal energy are:
1) Direct Use and District Heating Systems which use hot water from springs or reservoirs near the surface.
2) Electricity generation in a power part requires water or steam at very high temperature (300 to 700 degrees Farr­enheit). Geothermal power plants are generally built where geothermal reser­voirs are located within a mile or two Of the surface.
3) Geothermal heat pumps use stable ground or water temperatures near the earth's surface to control building tem­peratures above ground.