Geothermal
energy is a very interesting energy source that has garnered a lot of
attentions today because of the immense need to global dependence on fossil
fuel and the resultant negative consequences. As the name implies geothermal
energy is simply energy that is contained in intense heat which continuously
flows deep within the earth. Studies show that deep in the energy contained
deep within the earth crust, some 10000 meters down the surface of the earth,
is 50,000 greater than all the oils and natural gases in the world put
together. Such tremendous amount of energy can be interestingly utilized and
tapped to supply the energy requirements of the world.
Interestingly,
geothermal energy is already being tapped in many regions of the world
especially in the United States of America. The United States make use of
geothermal facilities to provide up to 68 billion KWh electricity which is
enough to serve more than 6 million household per annum. Most of the U.S
geothermal facilities are located in California.
Capturing Geothermal Energy
The
techniques involved in capturing geothermal energy are very interesting. Basically
geothermal energy is obtained from naturally occurring hydrothermal
convections. This technique involves allowing cooler water to seep into to the
Earth’s crust. The water is heated up by the intensive heat taking place in the
core and then it rises to the surface. The heat can then be tapped when it rise
to the surface and used to drive steam engine or used as desired. Once the heat
is captured, it can be used in various ways to generate electricity. How it is
used depends on a number of variables which will be discussed shortly.
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Dry Steam: One of the ways of capturing and using geothermal
power is known as dry steam. In this process, the steam captured from the core
is directed directly to the turbine where it is condensed into water in a
condenser. This is a relatively simple design and a very easy process of
capturing and using the energy. The energy tapped can be used to drive the
turbine and the water directed back to the core to continue the cycle.
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In the second
process, the hot water obtained from the earth’s core can be depressurized. The
process of depressurizing the hot water can also be referred to as flashing.
When depressurized, the hot water becomes steam and this can be used in driving
the turbine for generating electricity and the resultant warm water can then be
channeled back to the core to continue the process.
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Thirdly, we have
the Binary cycle system which is
commonly used but is actually the most complicated of the three. The binary
cycle system involves the passing of the hot water obtained from the geothermal
reservoir through a heat exchanger. Here in the heat exchanger, the hot water
heats up a liquid, in most cases isobutane can be chosen as the choice liquid.
The major property to consider when choosing the liquid is its low boiling
point. The liquid should be easily converted into steam which is then used to
drive the turbine and generate electricity.
