Overview of Geothermal Energy

Overview of Geothermal Energy

Geothermal energy is a form of energy that originates from the interior of the earth, actually the word geothermal means earth’s heat. The concentration of this energy increases as one goes deeper and closer to the crust that is the further one goes into the earth crust the higher is the temperature as compared to the surface. Actually, the global average for the earth’s geothermal gradient is approximately 30°C/km. A good example is if we removed 3 km of the earth surface the temperatures would rise to 5000°C enough to boil water on the surface. Large amounts of thermal energy are contained all over the globe.

Primordial heat and radioactive decay are the two known sources of geothermal energy. The result of creation of the earth about 4. 5billion years ago was by the ancient heat which is the heat retained in the side as the hot cosmic matter on the surface cooled. This is the reason why the earth supports life on the outside while the inside is composed of hot-rocks and metals.

Radioactive materials and elements formed the original composition of the earth. This element increases the amount of thermal energy as they slowly continue decay below us the heat generated continues to heat the interior of the earth. There is proof that some of the heat still manages to penetrate the insulation layer good examples of these sites are the volcanic features in Hawaii, New Zealand Japan and Italy.

Hot water is almost used in all power production processes across borders. Various methods are used to heat the water into steam( such include radioactive decay as in nuclear, combustion as in coal and natural gas). The steam is then used to turn turbines which in turn produces electricity. However, in geothermal; water is heated by the heat escaping from the earth’s core. This is achieved by the earth’s interior temperatures which are suitable for producing electricity.

During the drilling process, there are two possible cases that may arise, one we may find a porous rock where hot water has been collected. This water is extracted from beneath, using very specialized equipment. Case two is where we find no water but rocks, which are very hot in this case we form what is known as the enhanced geothermal system where cold water is pumped into the rocks, then the steam that return is collected. Geothermal is clean energy since there is no use of harmful products such as coal and nuclear, another advantage is that it’s sustainable as the only thing we need to ensure is that the water is injected back to the rocks after we exhaust the thermal energy in it.

Geothermal has other applications apart from production of power they include heating of pools, district heating, agriculture and laundries. These are applications are classified under the direct-use of geothermal.

Power generation via geothermal can be achieved by the use of either one of the two process. When the hot and pressured water is brought to the surface, it changes into a low-pressure chamber where it is turned into steam. The highly pressured steam is passed via a turbine which rotates to produce electricity, after the steam has been passed via the turbine it can either be released into the atmosphere or can be cooled into a liquid and injected back to the ground.

The binary geothermal is another method of power generation, which is mostly applicable in geothermal areas with low temperatures. The principle of operation is generally the same as it involves the use of hot water to drive a turbine but due to the low temperature, a working fluid (liquid with a lower boiling point as compared to water) is used. The hot geothermal water is pumped to the surface and then run via a heat exchanger where heat is transferred from water to the working fluid. Due to the low boiling the working fluid vaporizes faster under low temperatures thus producing enough pressure to drive the turbine.

The binary system operates as two close loops as neither the geothermal water nor the working fluid is exposed to the surface. Another thing that makes it unique is that there are no emissions in its cycle as water is re injected back and the working fluid is cooled and then reused again.

Geothermal energy exploitation is common across borders. Around the globe, the pioneers include United States, Mexico, Japan, Iceland and the Philippines, who are using it for power production. Although, geothermal is abundant one must drill to reach it, however, the cost of drilling is not cheap as it increases with depth. We are able to harvest the highest quality due to the advancement of the drilling technology.

The level of tectonic activity (interaction of the earth’s tectonic plates) affects the quality of geothermal energy within an area. The Pacific Ocean is encircled by a ring which is commonly known as the ring of fire where a lot of tectonic activity occurs. The area experiences volcanism due to large amounts of heat reaching the surface. Due to such factors the cost and technology required is quite expensive. However, researchers are working hard to ensure that cost of drilling comes down thus ensuring that geothermal is fully exploited.

Politics impedes the exploitation of geothermal energy in some countries. Government intervention is necessary because of the high cost, the state can support in terms of funding and policies. A good example is the Canadian federal government which in the past quarter century has not contributed anything to support geothermal science. Despite statics showing that western Canada has a lot of geothermal resources.

By disseminating news about the need and care of a sustainable energy through family members, friends, colleagues and becoming a member of CanGEA you bring us closer to the realization of geothermal power in Canada.

Comparison of low temperature (heat pumps) and high temperature geothermal resources

A lot of confusion has risen about the varied forms of geothermal energy that are associated with different geothermal resources. The perplexity is associated with the increase in geothermal awareness among the public.

People use different terms to describe the same thing. The term geo-exchange has helped in coming up with a definition of geothermal, as in the past geothermal was associated with high temperatures used for power production and direct heating. This is not the case anymore, as lower temperatures are used for recreational purposes.

The use of traditional oil, gas, coal fired heating ventilation and air-conditioning systems has been replaced using geo exchange systems.

Source: CanGEA

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RPN's contributed to this report.

Professional freelancer in Green Technology and Scientific Development. Educational background in the field of Human Resources Management.

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