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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