What is geothermal
energy? How do people exploit such resources?
How is this alternative energy better
than what we are using now?
Is geothermal energy perfect?
What is geothermal energy? How do people exploit such resources?
Geothermal energy is the heat contained within the
earth. It is estimated that the temperature in the core of the
earth is at least 6650 o C. Yet, the earth is cooling
down very slowly: at the rate of 300 to 350 o C within
three billion years. There is 42X1012 W of heat in the
earth, of which 2% is in the crust and 98% in the mantle and
core. With today's technology, it would be impossible to access
the energy that reside too deep within the earth, but the 840 000
000 000 W (2%) of geothermal energy that is accessible is
sufficient for humans to use for a long period of
time.1
Areas around the plate margins make for the best geothermal
energy extraction sites - that is because the crusts in those
areas are much thinner. There are two main methods of utilizing
geothermal energy: direct heat usage and electricity generation.
Direct heat usage is the most commonly used form because it is
the simplest. A reasonable comparison would be boiling eggs in
hot springs. Direct heat usage is very commonly used in some high
latitude places on plate boundaries like Iceland and Japan.
People consume the energy by exploiting wells deep into the earth
with water pipelines. The hot water from the pipelines is then
used for many purposes like melting ice on the road, greenhouse
warming, drying clothes, or maintaining the heating system in
residential areas. Generating electricity with geothermal energy
is similar to the direct use method. The only difference is that
the temperature requirement is a lot higher (> 150
o C) so that the steam can push the turbine to produce
electricity.
How is this alternative energy better than what we are using now?
Geothermal energy is localized and no fuel is
required. This makes geothermal energy economical and eliminates
the chance of damaging the environment during transportation,
storage and usage. Also, the supply of geothermal energy is
continuous and will not be fluctuated by any political or
economical factors.
Although the utilization of geothermal energy has existed for more than a century, it has yet to be perfected. Many environmental impacts take place during the building of a geothermal plant. At the beginning of each project, roads and working platforms have to be built so that exploratory and production equipment can be brought in. These changes to the environment can damage local plants and wildlife. Further, the drilling process can also damage the environment, as the deep well will unavoidably pass through some underground water bodies, which the drilling fluid can contaminate. The increased temperature of the area can kill life forms in the water. Moreover, the disposal of mud bored out with the drill is a potential environmental problem. Problems can continue to occur when the plant is in operation. The geothermal fluid usually contains gases and dissolved substances that can pollute the environment. Some of them are carbon dioxide, hydrogen sulfide, methane, sodium chloride (salt), boron, arsenic and mercury. Likewise, if the plant is not maintained properly, hot wastewater can leak into surrounding areas and damage the ecosystem (thermal pollution.)2
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