Geology And Geophysics

Geothermics an Introduction



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Four billion years ago, which is considered to be the most initial period of earth's formation, our planet was nothing but a hot globe of gas and dust. After such a long period of earth's continual transformation, still the core of the earth that is 4000miles below the surface experiences a heat of 9000 degrees Fahrenheit, hotter than the surface of the sun. Geothermic or Geothermal is the term that stands for Earth's heat. We all know that the interior of the earth is very hot. The radioactive decomposition of rocks found inside the core adds to this internal heating. The Earth is made of different layers, though no one knows the accurate structure of the layers. The core of the earth is divided into inner core and outer core. The inner core is solid iron and the outer core, which is known as magma is filled with hot molten metals. Mantle is the next layer that is 1800 miles deep and is a mixture of hot magma and rock. The upper surface of the earth, where we can find our continents has uneven thickness. Under the sea, this thickness varies between 3 to 5 miles and around 15 to 30 miles on the landscapes. So, wherever there is a thin layer of crust and more proximity towards the heated magma there is an instant source of natural geothermal energy. In other words, volcanic vents or hot reservoirs of water underneath the surface or steam generated due to heated bottom provide us the scope to utilize and exploit geothermal energy.

Geothermal energy is a clean source of energy and is considered to be renewable. It is a great source for electricity generation. The hot water from the geothermal reservoir is used to rotate turbine to generate electricity. The heated steam underground can also be used for the same purpose. A number of geothermic power plants have been installed in around twenty countries all over the world. United state is the largest producer of geothermal energy. The geothermal power plants fall into three category according to the varying attributes of temperature and pressure of the underground fluid.
Dry steam power plant utilizes the heated steam with minimum or no water associated with it. The dry steam has the temperature as hot as 455 degrees F. This dry steam rotates the turbine to generate electricity. This is the oldest type of power plant. The Geyser, which is the largest production plant of geothermal energy, is of this type.
Flash type plants use hot water of temperature more than 360 degrees F from the underground reservoir. Water underneath the surface in a high pressure and temperature condition converts into gaseous state when pumped to the power plant. Due to high pressure drop steam is formed and helped to generate electricity.
In binary geothermic plants underground water below 360 degrees F that is not able to produce enough steam is used. The hot water is passed through a heat exchanger pipe, where it transfers the heat to fluids like iso-butane and iso-pentane having lower boiling point than water. The fluids vaporize and power the turbine to produce electrical power. In contrast to the other two types of power plants, binary plants do not emit residual gases to the atmosphere. Hence, it is cleanest in nature and also considered to be the most economical and efficient plant.

Besides providing electrical power supplements, geothermal energy can be used in many other useful ways.

Geothermal heat pumps(GHP) are used worldwide to maintain a stable temperature condition in residential areas and offices. During winter GHP is used to keep the buildings warm and during hot summer it spreads cool vibes. GHP is very economical as it requires very less electricity to run. GHP that is buried under the ground has number of horizontal or vertical pipes to carry the water or any other liquids. These fluids absorb the excess heat from the building in the summer and transfer it to the underground, which keeps the building cool in hot days. On the other hand, the liquids in the GHP to provide warmth during winter carry the temperature difference between the underground and outside cold air.
The most direct use of geothermal energy can be witnessed in its centuries old usage for warm bath both by humans and animals. The natural hot springs have always been believed to have health benefits. Now a days, this energy is enjoyed in the swimming pools and through many of the health spas, engaged to ease up muscle strains.
Geothermal energy is also used in pasteurizing milk, improving vegetation in the green houses, drying up timber and wool, manufacturing of paper, speeding up the growth of fishes and other sea creatures' lives, animal husbandry etc.

Advantages of geothermal power plants are many.
They are a clean substitute to fossil fuels. They do not cause any environmental hazards. Though dry and flash type of geothermic plants emit little amount of polluted gases, it is considered to be negligible.
Geothermal plants can run 24 hours a day and is independent of weather condition. They require less space than other type of plants and can be installed easily without much concern regarding agricultural and residential areas.
A small plant can provide enough electricity to be used in villages. It debars the use of expensive fossil fuel and hence can enhance people's standard of living.

After a lot of advantages that we get from geothermic energy, a few specks of disadvantages are also to be endured. Geothermic power plants may disturb the nearby locality. Some geothermic plants are being manufactured larger as compared to the availability of geothermic source. It can cause the source to deplete and run out. So the process of drawing up continuous energy has to be halted and the site should be given sufficient time to heat up naturally.

Geothermal energy is a wonderful alternative to fossil fuels and cleaner as compared to other renewable sources like wind energy, because it does not require any other fuels to produce the power. The environmental friendliness of this energy has become the reason for its worldwide popularity, acceptance and exploration.

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