The ways in which geothermal energy functions can be well understood if one gets an idea about the uses to which it is put to.
To begin with geothermal energy essentially refers to the heat energy that is sourced from the interiors of the Earth. Primary usage of geothermal energy is as an environmentally clean substitute for fossil fuels.
It is a renewable energy source and is sustainable and affordable.
Geothermal energy functions as an electricity generating medium. Western United States and some other countries of the world possess geothermal energy based electricity generating plants. As per an estimate, geothermal energy meets five percent of the electricity demand of California. The comparable figure for El Salvador is 25 percent.
Iceland and Idaho use geothermal heat for warming up buildings among other things.
Homes across United States make use of geothermal heat pumps for heating or cooling buildings as the case might be. It is an environmentally clean and inexpensive procedure.
Geothermal heat pumps make use of the constant temperature that exists just under the Earth's surface.
It may be noted that a layer of molten rock (magma) exists under the Earth's crust. This layer is a steady source of heat. Mostly the heat is generated from the decay of some naturally occurring radioactive materials.
Areas in the Earth with the highest recorded underground temperatures are referred to as "hot spots". These hot spots are found in regions possessing geologically young volcanoes or active volcanoes. The
Pacific Rim also referred to as 'Ring of Fire' possesses a large number of hot spots.
Geothermal energy, as already mentioned functions as a source of electricity generation. Power plants use geothermal springs for this purpose.
One way of doing this is to tap a naturally existing "hydrothermal convection". Here the steam generating from the heated up water is captured for driving electric generators.
Geothermal power plants themselves drill holes into the rock surface to efficiently capture the rising steam.
Geothermal power plants take out steam and hot water from within the Earth for power generation and subsequently sends it back into the earth's surface. This is done to increase the longevity of the source of the heat.
The simplest form of geothermal power plants drives the steam directly into the turbine. Subsequently the steam passes into the condenser, which condenses it back to water.
In some geothermal power plants extremely hot water is "flashed" into steam (or depressurized) for driving the turbine.
Again some other geothermal power plants make use of what is known as the binary system. Here the hot water passes via a heat exchanger. There it heats up another liquid (like isobutane) within a close loop.
Since isobutane has a lower boiling point than water it can be more effortlessly turned into steam. This steam now runs the turbine.
It may be noted that the three kinds of systems used in geothermal power plants as described above are referred to as Dry steam system, Flash steam system and Binary cycle respectively.