Geothermal Energy Essay

I. Introduction

            Geothermal energy is the heat energy that happens naturally within the Earth. The molten interior contains vast quantities of thermal energy; although some diffuses upward to the surface and is dissipated; temperatures within the Earth remain fairly constant, apparently maintained by the decay of radioactive material. Geothermal energy therefore represents a potentially inexhaustible source of energy, which has been tapped by humans for centuries but, until recent years, only a small scale. In some regions of the world, particularly in the zone of tectonic activity surrounding the Pacific Ocean, magma may occur at depths of only a few kilometers. Groundwater trickling down to the hot rocks overlying the magma chambers can be heated to temperatures as high as 205°-260 °C (400°- 500 °F). Where topography permits, the heated water may rise to the surface as hot springs. In a few areas where the water is prevented from reaching the surface, some of it may turn to steam. Energy also can be derived from heated rocks in the absence of groundwater.

            Moreover, water near the magma is heated high to high temperatures and will rise to the surface as steam or hot water through natural cracks or wells that have been drilled for that purpose. If enough steam is available, it can be used for generating electricity; hot water can be used for heating buildings. Most of the world’s geothermal resources are in areas where magma tends to rise close to the surface, such as in the earthquake zones and in regions of past or present volcanic activity (see Ostridge, Randy. “Geothermal Energy”. March 10, 1998). Geothermal areas often have geysers or hot springs. Geothermal energy is put to use in a number of locations. It drives electric generators at a northern California site called The Geysers, and a Wairakei, New Zealand. In Reykjavik, Iceland, almost every home is supplied with hot water for heating and washing by deep wells drilled under the city (see “Geothermal Energy—Energy from the Earth’s Core”).

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            The intents of this paper are to: (1) know the history of geothermal energy; (2) understand what geothermal energy really is; (3) learn the types of geothermal sources; (4) figure out how geothermal energy works; (5) discover the ways of conserving energy;(6) recognize the advantages and disadvantages and; (7) be knowledgeable about geothermal power technology.

II. Background

A. History of geothermal energy

            Several of the ancient people like the Chinese, Romans, and Native Americans had the chance to utilized hot mineral springs for their daily uses like cooking, bathing and heating. The water comes from hot spring are presently utilized globally in spas, for the industrial and agricultural uses and for heating buildings. A lot of individuals believe that hot springs have natural therapeutic powers. The use of geothermal energy to have electricity is the novel industry. During 1904, this concept was originated and started from a group of Italians who were able to make an electric generator at Lardarello. The said generator was generated through the natural steam bursting forth from the earth. By the year 1922, there was an attempt in making a geothermal power in the United States of America at The Geysers steam field in northern California. Recently, there are approximately 28 plants that have operations at the Geysers (see “History of Geothermal Energy”).

B. What is geothermal energy?

            The term geothermal is a Greek word. “Geo” pertains to “Earth” while “thermal” denotes “heat” (see “Geothermal Power”). It is a frequently identified as renewable energy. Moreover, geothermal energy denotes to “power generated by the harnessing of heat from the interior of the earth when it comes to -or close- the earth’s surface” (see “Groundsource heating”). This would mean that if a mass of rock or water below ground its surroundings, the heat can be recovered as geothermal energy. Drilling into the rock allows the hot water to flow to the surface. If the rock is dry, water is pumped down one hole, heated, and recovered from another. Moreover, geothermal energy is said to be proven indigenous energy source.

            Moreover, geothermal fluids may be used directly for heating homes and greenhouses and for industrial purposes if they occur near populated areas. Iceland is the most notable example. About 65 percent of its homes and much of its greenhouse produce depend on groundwater heat. Parts of Budapest, some Paris suburbs, and several communities in the Soviet Union are also heated in this way. In the United States most of Klamath Falls, Oregon, and parts of Boise, Idaho, depend on geothermal heating. Examples of the industrial use of geothermal fluids are found in Iceland and New Zealand (see “Energy from the earth”). In addition, such countries as Denmark and Sweden are experimenting with the use of geothermal fluids in heat-pump installations that also burn sewage. Furthermore, the greatest potential for large-scale use of geothermal energy is in the generation of electric power. Drilling into the steam pockets is a difficult process, however, and the steam itself is corrosive and contains dissolved gases, specifically hydrogen sulfide, that are difficult to remove. No other region in the United States of America is known to possess geothermal steam in sufficient quantities. Sources of geothermal hot water are much more numerous, particularly in such western states as California, Nevada, New Mexico and Utah. Much of this water has a temperature of only 95°- 150° C, too low for economic power generation by conventional methods.

III. Discussion

            Energy from fossil fuels makes many industries run. These fossil fuels become a source power responsible for the operation of some industrial plants and factories. Almost all our means of transportation like buses and cars use gasoline and diesel. Airplanes and ships are also dependent on oil. With the rising prices of oil in the world market, our government has explored the possibility of using alternate or non-conventional sources of energy such as geothermal energy. As of today, a number of geothermal plants are being developed in different parts of the country specifically in California called The Geysers (see “Geothermal Energy—Energy from the Earth’s Core”). Geothermal energy is used mainly for generating electricity.

            In the home, electrical energy is used for cooking, air conditioning, and lighting, and for other electrical appliances. For entertainment, the radio, television, and video-cassette recorder need electrical power. In order to survive the high price of gasoline, motorists must practice a number of energy-saving techniques such as putting off the engine when caught in heavy traffic, avoiding jack-rabbit start, and closing the windows during long drives to reduce drag. Regular checkup of the engine can result in efficient run.

            A nationwide campaign for conserving energy must be undertaken. Everyone must maximize the use of electrical energy in both public agencies and in private homes. At certain times, lights in parks must be alternately put off. Public buildings must not be lighted in the meantime that natural lighting is sufficiently available. Street lights and those outside buildings must be put off during the day. Lights for billboard advertisements must not be allowed during energy crisis. At home, every individual can save on electrical consumption by putting off appliances such as lamps, fans and cleaners when not in use. A well-planned schedule o continuous ironing or cooking at one time is economical.

A.  Types of Geothermal Sources

            Geothermal power is powered by extracting the heat of the earth. In some parts that have high temperature groundwater at shallow depths like wells, they are “drilled into natural fractures in basement rock or into permeable sedimentary rocks”. Either the hot water or the steam passes through the wells using the pump or boiling. The researches are moving forward to identify if the fourth method used, which are the deep wells into “hot dry rocks”, can be utilize economically to heat up the water “pumped down from the surface”. During 1989, the hot dry rock plan of the United Kingdom is discarded when it is promulgated economically that it is impractical and useless. The hot dry rock programs are presently being established in France, Germany, Australia and Switzerland.  Magma resources give a very high-temperature geothermal opportunities, however, exist technology does not permit recuperation of heat from the said resources. Below is a graph that shows geothermal energy sources (see “Geothermal Power” Wikipedia, the free encyclopedia. November 23, 2006).

B. How geothermal energy works

            In a geothermal power plant, hot water and steam are directly drawn from the underground reservoirs using an elaborate system of valves and pipes. The hot water taken out is under pressure. Once it reaches the earth’s surface where pressure is lesser, the water boils and one fifth of the volume of water turns to steam. The hot water steam mixture goes to a separator where water and other impurities such as mud are removed and directed to a disposal canal. Some of the excess water is pumped back to the underground reservoirs. The steam causes the turbine to turn and as it does, electricity is produced. After doing work on the turbine blades, the steam goes to a condenser and into a discharge tank. In addition, fossil fuels like coal, oil, diesel, or natural gas are burned in the fossil fuel-fired thermal power plants to generate heat. The heat generates steam which drives high-speed steam turbines. From the boiler, the steam goes to the turbine through pipes (see “Geothermal Power: How it works”). At the turbine, the steam expands and turns the blades. The generator’s rotor which is connected to the turbine also rotates along with the turbine, thus producing current. With its useful energy spent, the steam goes to the condenser. There it is cooled, liquefied and afterwards, returned to the boiler. Below is an illustration of the geothermal power plant (see “Geothermal Energy—Energy from the Earth’s Core”).

C. The ways of conserving energy

            Everyone needs energy all the time. Energy is costly. Every individual should help to conserve it. How?

            ð use flourescent lights instead of incandescent bulbs

            ð Turn off unnecessary lights. Clean the bullbs regularly to get more light.

            ð Before cooking, thaw or melt frozen foods. This will help reduce the time needed to cook them

            ð In cooking, switch the stove to „low“ when the food starts to boil. Use the least amount of water necessary to cook food to hasten boiling. Do not use a large stove for a small pan.

            ð Do not open or close the refrigerator frequently to reduce the amount of energy used.

            ð Use your electric iron efficiently. A flat iron consumes more power than a color television set. When you are almost through ironing your clothes, unplug the iron. There will be enough stored heat in the iron to press a few remaining clothes.

            ð Television and radio sets can waste a large amount of energy when not used properly. Turn off your sets if no one is viewing or listening.

            ð Use the washing machine when you have a full load. However, care must be taken not to overload the machine. Overloading will only make it work harder, thereby consuming more energy.

            ð Water us the most abundant natural resource that everyone has, but it would be good to conserve water, It takes a lot of energy just to pump, purify and deliver water to individual’s home. Never leave a faucet dripping. Spending a small amount of time in fixing the faucet will save yoy gallons of precious water.

D. The Advantages and Disadvantages

            ª Advantages

            Ø Geothermal energy does not give pollution and does not affect the greenhouse effect (see “Geothermal Power: Advantages”).

            Ø The power stations do not occupy an ample room that is why there is no great effect on the environment (see “Geothermal Power: Advantages”).

            Ø There is no fuel involve (see “Geothermal Power: Advantages”).

            Ø When you create a geothermal power station, it inclines that you are almost free in energy. Geothermal power station may require a small amount of energy in order to run however it is been taken through the energy that is being generated (see “Geothermal Power: Advantages”).

            ª Disadvantages

            Ø The major dilemma is that there are no enough places where an individual create a geothermal power station (see “Geothermal Power: Disadvantages”).

            Ø There are times that the geothermal site may possibly “run out of steam” and maybe for many years “Geothermal Power: Disadvantages”

            Ø The risky gases and minerals might come from underground and not easy to dispose safely (“Geothermal Power: Disadvantages”).

E. Geothermal Power Technology

            Utility-scale geothermal power production uses three major technologies. These technologies are generally identified as dry steam, flash steam and binary cycle steams.  The technology is used depending on the temperature and pressure of the geothermal reservoir. In comparison to wind, solar and hydro-based renewable energy, geothermal energy plant operation is autonomous of variability everyday and during seasoned weather (see “Geothermal Power Technology”).

©Dry Steam

            In the dry steam power plants, they use extremely hot steam and small amount of water from the geothermal reservoir. The steam proceeds immediately by means of a pipe to a turbine in order to rotate a generator that gives electricity. Dry Steam power plant is the type geothermal power plant that is initially utilized in Italy in 1904 and the oldest geothermal power plant amongst the three (“Geothermal Power Technology”).

© Flash steam

            Flash steam power plants utilize hot water from the geothermal tank. As soon as the water is pumped to the generator, it is discharged from the pressure of the deep tank. The rapid drop in pressure produces an amount of the water to evaporate which rotates a turbine to generate electricity. The flash steam and dry steam power plants releases little amounts of nitric oxide, sulfur and carbon dioxide but usually 50 times below conventional fossil-fuel power plants (“Geothermal Power Technology”).

© Binary Cycle

            Binary-cycle power plants utilize average-temperature water that come from geothermal reservoir. In this power plant, hot geothermal fluids go through on a side of a heat converter in order to heat up “working fluid in a separate adjacent pipe”.  The working fluid–normally an organic element have a minimal boiling point like the Iso-pentane or Iso-butane—is evaporated and go through a turbine in order to generate electric power. Below is an illustration of Binary Cycle (“Geothermal Power Technology”).

IV. Conclusion

            In many places, water is found below the earth’s surface. In some places, heat inside the earth changes this water to steam. This geothermal energy can be used to make electricity. The geyser formed where a crack in the earth’s crust allows hot gases and steam to rise to the surface. Wells drilled in certain places also allow hot gases and steam to rush to the surface. Wells were drilled into the ground. Steam rushes up through the wells. Pipes carry the steam to turbines inside the geothermal power plants. The turbines run generators that make electricity. Geothermal energy might one day be used in places where water is not found below the surface. Wells could be forced down to the hot spot. Then water could be forced down the well and changed to steam. The steam would then rise to the surface and turn turbines.

References

“Geothermal Power”. http://home.clara.net/darvill/altenerg/geothermal.htm
“Groundsource heating”. www.climatechangenorth.ca/H1_Glossary.html
“History of Geothermal Energy”. http://lsa.colorado.edu/essence/texts/geothermal.htm
Ostridge, Randy. “Geothermal Energy”. March 10, 1998. University of Prince Edward Island. http://www.upei.ca/~physics/p261/projects/geothermal1/geothermal1.htm
“Energy from the earth”. http://zebu.uoregon.edu/1996/ph162/l18.html
“Geothermal Energy—Energy from the Earth’s Core”. http://www.eia.doe.gov/kids/energyfacts/sources/renewable/geothermal.html
“Geothermal Power: Advantages”. http://home.clara.net/darvill/altenerg/geothermal.htm
“Geothermal Power: Disadvantages”. http://home.clara.net/darvill/altenerg/geothermal.htm
“Geothermal Power” Wikipedia, the free encyclopedia. November 23, 2006. http://en.wikipedia.org/wiki/Geothermal_power
“Geothermal Power Technology”. http://www.repp.org/geothermal/geothermal_brief_power_technologyandgeneration.html

 

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