Geothermal energy is considered renewable, because it is replenished in nature by rainfall, but the process is very complex. The basic thing one must know is that the heat (geothermal energy) is produced inside and around the earth’s core. Energy is harnessed from heat within the earth. Technically it is the steam and hot water created inside the earth, which can be used to heat buildings or produce electricity.
The heat from the earth’s core flows outward and then transfers into the surrounding layers of rock, when temperatures and pressures become high enough, rocks become magma. Magma’s density is less than the density of the surrounding rocks, so it rises slowly towards the earth’s surface, bringing the heat with it and producing the steam. Not all magma reaches earth’s surface, but when it does, it comes to the surface in a liquid form which is known as lava. The magma, that stays under is heating it’s surroundings: rocks, underground streams of water, rainwater, etc.) – the temperature reaches 700 degrees F. These heated streams sometimes reach the surface in the form of hot springs or geysers, though mostly they stay buried underground, forming natural thermal reservoirs.
The geothermal energy was used from earliest times to heat buildings, cook and cure diseases.
In France geothermal waters have been used to heat up homes since 1960s.
Nowadays, the use of this type of energy is more effective and with the help of geology, geochemistry and complicated engineering most of the underground reservoirs can be reached and the potential of these sources can be used to its fullest.
First stage is finding a perfect site to drill a geothermal production well. The second stage is the drilling and construction of the well itself. The third stage is building a power plant or a collection plant around. So when the hot water reaches the surface through the well, it is used to either generate electricity via a power plant or is saved for non-electrical purposes.
The power plant uses the steam to spin its turbine generators which then convert this power to electricity. The “used” water from the turbine is then returned to the natural reservoir via an injection well and is reheated, so that the pressure in the reservoir remains unaltered.
This is the basic principle of how the geothermal collection works. Next time we will talk about the types of geothermal plants, where on earth they can be used and what is the energy potential of geothermal sources worldwide.