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Here is a compilation of essays on ‘Geothermal Energy’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Geothermal Energy’ especially written for school and college students.
Essay on Geothermal Energy
Essay Contents:
- Essay on the Introduction to Geothermal Energy
- Essay on the History of Geothermal Energy Worldwide
- Essay on the Formation of Geothermal Resources
- Essay on the Types of Geothermal Resources
- Essay on the Geothermal Electricity
- Essay on the Geothermal Power Plants Technology
- Essay on the Other Applications of Geothermal Energy
- Essay on the Economics Related to Geothermal Energy Harnessing
- Essay on the Barriers in the Way of Geothermal Energy
- Essay on the Sustainability of Geothermal Energy
- Essay on the Effect of Geothermal Energy on Environment
Essay # 1. Introduction to Geothermal Energy:
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Geothermal energy is the earth’s natural heat available inside the earth. This thermal energy contained in the rock and fluid that filled up fractures and pores in the earth’s crust can profitably be used for various purposes. Heat from the Earth, or geothermal — Geo (Earth) + thermal (heat) — energy can be and is accessed by drilling water or steam wells in a process similar to drilling for oil.
Geothermal resources range from shallow ground to hot water and rock several miles below the Earth’s surface, and even farther down to the extremely hot molten rock called magma. Mile-or-more-deep wells can be drilled into underground reservoirs to tap steam and very hot water that can be brought to the surface for use in a variety of applications.
This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, from volcanic activity and from solar energy absorbed at the surface. It has been used for bathing since Paleolithic times and for space heating since ancient Roman times, but is now better known for generating electricity.
Worldwide, about 10,715 megawatts (MW) of geothermal power is online in 24 countries. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications.
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India has reasonably good potential for geothermal; the potential geothermal provinces can produce approximately 10,600 MW of power.
Geothermal power is cost effective, reliable, sustainable, and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation.
Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels. As a result, geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels.
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The earth’s geothermal resources are theoretically more than adequate to supply humanity’s energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, and interest rates.
Essay # 2. History of Geothermal Energy Worldwide:
The oldest known pool fed by a hot spring, built in the Qin dynasty in the 3rd century BC.
Hot springs have been used for bathing at least since Paleolithic times. The oldest known spa is a stone pool on China’s Lisan mountain built in the Qin dynasty in the 3rd century BC, at the same site where the Huaqing Chi palace was later built. In the first century AD, Romans conquered Aquae Sulis, now Bath, Somerset, England, and used the hot springs there to feed public baths and underfloor heating.
The admission fees for these baths probably represent the first commercial use of geothermal power. The world’s oldest geothermal district heating system in Chaudes-Aigues, France, has been operating since the 14th century. The earliest industrial exploitation began in 1827 with the use of geyser steam to extract boric acid from volcanic mud in Larderello, Italy.
In 1892, America’s first district heating system in Boise, Idaho was powered directly by geothermal energy, and was copied in Klamath Falls, Oregon in 1900. A deep geothermal well was used to heat greenhouses in Boise in 1926, and geysers were used to heat greenhouses in Iceland and Tuscany at about the same time. Charlie Lieb developed the first down-hole heat exchanger in 1930 to heat his house. Steam and hot water from geysers began heating homes in Iceland starting in 1943.
Global geothermal electric capacity. Upper red line is installed capacity; lower green line is realized production.
In the 20th century, demand for electricity led to the consideration of geothermal power as a generating source. Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the same Larderello dry steam field where geothermal acid extraction began.
It successfully lit four light bulbs. Later, in 1911, the world’s first commercial geothermal power plant was built there. It was the world’s only industrial producer of geothermal electricity until New Zealand built a plant in 1958.
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By this time, Lord Kelvin had already invented the heat pump in 1852, and Heinrich Zoelly had patented the idea of using it to draw heat from the ground in 1912. But it was not until the late 1940s that the geothermal heat pump was successfully implemented. The earliest one was probably Robert C. Webber’s home-made 2.2 kW direct-exchange system, but sources disagree as to the exact timeline of his invention.
J. Donald Kroeker designed the first commercial geothermal heat pump to heat the Commonwealth Building (Portland, Oregon) and demonstrated it in 1946. Professor Carl Nielsen of Ohio State University built the first residential open loop version in his home in 1948. The technology became popular in Sweden as a result of the 1973 oil crisis, and has been growing slowly in worldwide acceptance since then.
In 1960, Pacific Gas and Electric began operation of the first successful geothermal electric power plant in the United States at The Geysers in California. The original turbine lasted for more than 30 years and produced 11 MW net power.
The binary cycle power plant was first demonstrated in 1967 in the U.S.S.R. and later introduced to the U.S. in 1981. This technology allows the generation of electricity from much lower temperature resources than previously. In 2006, a binary cycle plant in Chena Hot Springs, Alaska, came on-line, producing electricity from a record low fluid temperature of 57°C (135°F).
Installed geothermal electric capacity as of 2007 is around 10000 MW. The main countries having major electric generation installed capacities (as of 2007) are USA (3000MW), Philippines(2000MW), Indonesia (1000MW), Mexico (1000MW), Italy (900 MW), Japan(600MW), New Zealand (500MW), Iceland (450MW). The other region includes the Latin American countries, African countries and Russia.
Essay # 3. Formation of Geothermal Resources:
Geothermal energy is made up of heat from the earth. Underneath the earth’s relatively, thin crust, temperature range from 1000-4000°C and in some areas, pressures exceed 20,000 psi. Geothermal energy is most likely generated from radioactive, thorium, potassium and uranium dispersed evenly through the earth’s interior which produce heat as part of the decaying process. This process generates enough heat to keep the lose of the earth at temperature approaching 4000°C.
Composed primarily of molten Ni and Fe the core is surrounded by a layer of molten rock, the mantle at approx. 1000°C. Nine major crystal plates float on the mantle, and currents in the mantle cause the plates to drift, colliding in some areas and diverging in others.
When two continental plates coverage, a complex series of chemical reactions involving water and other substances combine to generate large bodies of molten rock called magna chamber that rise through the crust often resulting in volcanic activity. Molten rock also rises in the earth’s crust where the plates are moving away from each other and in other areas where the crust is thin.
Volcanoes, hot springs, geysers and fumaroles are natural clues as to the presence of geothermal resources near the surface and where economic drilling operations can tap their heat and pressure. Additional heat can be generated by friction as two plates converge and one moves on top of other.
Essay # 4. Types of Geothermal Resources:
There are following types of geothermal resources:
(i) Hydrothermal.
(ii) Geopressured.
(iii) Hot Dry Rock.
(iv) Active Volcanic Vents and Magna.
(i) Hydrothermal:
Hydrothermal resources contain superheated rock trapped by a layer of impermeable rock. The highest quality reserves with temperature over 240°C contain steam with little or no condensate (vapour dominated resources).
Some hydrothermal reserves are very hot ranging from 150-200°C, but roughly 2/3rd are of moderate temperature (100-180°C). Only two sizeable high quality dry steam reserves have been located to date on in the US and one in Italy. The geysers in northern California is perhaps the world’s largest dry steam field and could provide 2000 MWe capacity for upto 30 years.
(ii) Geopressured:
It contains moderate-temperature brines containing dissolved methane. They are trapped under high pressure in deep sedimentary formations sealed between impermeable layers of clay and shale. Pressures vary from 5000 to over 20,000 psi at depths of 1500 to 15000 metres. Temperature range from 90 to over 200°C, although they seldom exceed 150°C, each barrel of fluid at 10,000 psi and 150°C could contain between 20 and 50 standard cubic feed (SCF) of methane.
(iii) Hot Dry Rock:
It contains high temperature rocks, ranging from 90-650°C that may be fractured and contain little or no water. The rocks must be artificially fractured and heat transfer fluid circulated to extract their energy. Hot dry rock resources are much more extensive than hydrothermal or geo-pressured, but extracting their energy is more difficult.
(iv) Active Volcanic Vents and Magma:
It occurs in many parts of the world. Magma is molten rock at temperature ranging from 700°C to 1600°C, lying under the earth crust, the molten rock is part of the mantle and in approx. 24 to 28 km thick. Magma chambers represent a huge energy source, the largest of all geothermal resources but they rarely occur near the surface of the earth and extracting their energy is difficult.
Essay # 5. Geothermal Electricity:
As per the International Geothermal Association (IGA) sources, about 10,715 MW of geothermal power in 24 countries is online. In 2010, the United States led the world in geothermal electricity production with 3,086 MW of installed capacity from 77 power plants.
The largest group of geothermal power plants in the world is located at the Geysers, a geothermal field in California. The Philippines is the second highest producer, with 1,904 MW of capacity online. Geothermal power makes up approximately 18% of the country’s electricity generation.
Geothermal electric plants were traditionally built exclusively on the edges of tectonic plates where high temperature geothermal resources are available near the surface. The development of binary cycle power plants and improvements in drilling and extraction technology enable enhanced geothermal systems over a much greater geographical range.
Demonstration projects are operational in Landau-Pfalz, Germany, and Soultz-sous-Forest, France, while an earlier effort in Basel, Switzerland was shut down after it triggered earthquakes. Other demonstration projects are under construction in Australia, the United Kingdom, and the United States of America.
The thermal efficiency of geothermal electric plants is low, around 10-23%, because geothermal fluids do not reach the high temperatures of steam from boilers. The laws of thermodynamics limits the efficiency of heat engines in extracting useful energy. Exhaust heat is wasted, unless it can be used directly and locally, for example in greenhouses, timber mills, and district heating.
System efficiency does not materially affect operational costs as it would for plants that use fuel, but it does affect return on the capital used to build the plant. In order to produce more energy than the pumps consume, electricity generation requires relatively hot fields and specialized heat cycles. Because geothermal power does not rely on variable sources of energy, unlike, for example, wind or solar, its capacity factor can be quite large – up to 96% has been demonstrated. The global average was 73% in 2005.
Essay # 6. Geothermal Power Plants Technology:
To convert geothermal energy into electrical energy, heat must be extracted first to convert it into useable form. Mile-or-more-deep wells can be drilled into underground reservoirs to tap steam and very hot water that drive turbines that drive electricity generators.
There are basically four types of geothermal power plants which are operating today. The description of these power plants is as follows:
(i) Flashed Steam Plant:
The extremely hot water from drill holes when released from the deep reservoirs high pressure steam (termed as flashed steam) is released. This force of steam is used to rotate turbines. The steam gets condensed and is converted into water again, which is returned to the reservoir. Flashed steam plants are widely distributed throughout the world.
(ii) Dry Steam Plant:
Usually geysers are the main source of dry steam. Those geothermal reservoirs which mostly produce steam and little water are used in electricity production systems. As steam from the reservoir shoots out, it is used to rotate a turbine, after sending the steam through a rock-catcher. The rock-catcher protects the turbine from rocks which come along with the steam.
(iii) Binary Power Plant:
In this type of power plant, the geothermal water is passed through a heat exchanger where its heat is transferred to a secondary liquid, namely isobutene, isopentane or ammonia-water mixture present in an adjacent, separate pipe. Due to this double-liquid heat exchanger system, it is called a binary power plant.
The secondary liquid which is also called as working fluid should have lower boiling point than water. It turns into vapour on getting required heat from the hot water. The vapour from the working fluid is used to rotate turbines.
The binary system is therefore useful in geothermal reservoirs which are relatively low in temperature gradient. Since the system is a completely closed one, there is minimum chance of heat loss. Hot water is immediately recycled back into the reservoir. The working fluid is also condensed back to the liquid and used over and over again.
(iv) Hybrid Power Plant:
Some geothermal fields produce boiling water as well as steam, which are also used in power generation. In this system of power generation, the flashed and binary systems are combined to make use of both steam and hot water. Efficiency of hybrid power plants is however less than that of the dry steam plants.
Enhanced Geothermal System:
The term enhanced geothermal systems (EGS), also known as engineered geothermal systems (formerly hot dry rock geothermal), refers to a variety of engineering techniques used to artificially create hydrothermal resources (underground steam and hot water) that can be used to generate electricity.
Traditional geothermal plants exploit naturally occurring hydrothermal reservoirs and are limited by the size and location of such natural reservoirs. EGS reduces these constraints by allowing for the creation of hydrothermal reservoirs in deep, hot but naturally dry geological formations. EGS techniques can also extend the lifespan of naturally occurring hydrothermal resources.
Given the costs and limited full-scale system research to date, EGS remains in its infancy, with only a few research and pilot projects existing around the world and no commercial-scale EGS plants to date. The technology is so promising, however, that a number of studies have found that EGS could quickly become widespread.
Essay # 7. Other Applications of Geothermal Energy:
In the geothermal industry, low temperature means temperatures of 300°F (149°C) or less. Low-temperature geothermal resources are typically used in direct-use applications, such as district heating, greenhouses, fisheries, mineral recovery, and industrial process heating. However, some low-temperature resources can generate electricity using binary cycle electricity generating technology.
Direct heating is far more efficient than electricity generation and places less demanding temperature requirements on the heat resource. Heat may come from co-generation via., a geothermal electrical plant or from smaller wells or heat exchangers buried in shallow ground.
As a result, geothermal heating is economic at many more sites than geothermal electricity generation. Where natural hot springs are available, the heated water can be piped directly into radiators. If the ground is hot but dry, earth tubes or down-hole heat exchangers can collect the heat.
But even in areas where the ground is colder than room temperature, heat can still be extracted with a geothermal heat pump more cost-effectively and cleanly than by conventional furnaces.
These devices draw on much shallower and colder resources than traditional geothermal techniques, and they frequently combine a variety of functions, including air conditioning, seasonal energy storage, solar energy collection, and electric heating. Geothermal heat pumps can be used for space heating essentially anywhere.
Geothermal heat supports many applications. District heating applications use networks of piped hot water to heat many buildings across entire communities. In Reykjavik, Iceland, spent water from the district heating system is piped below pavement and sidewalks to melt snow.
Essay # 8. Economics Related to Geothermal Energy Harnessing:
Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations, but capital costs are significant. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks.
Unlike traditional power plants that run on fuel that must be purchased over the life of the plant, geothermal power plants use a renewable resource that is not susceptible to price fluctuations. The price of geothermal is within range of other electricity choices available today when the costs of the lifetime of the plant are considered.
Most of the costs related to geothermal power plants are related to resource exploration and plant construction. Like oil and gas exploration, it is expensive and because only one in five wells yield a reservoir suitable for development. Geothermal developers must prove that they have reliable resource before they can secure millions of dollar required to develop geothermal resources.
Drilling:
Although the cost of generating geothermal has decreased during the last two decades, exploration and drilling remain expensive and risky. Drilling Costs alone account for as much as one-third to one-half to the total cost of a geothermal project. Locating the best resources can be difficult; and developers may drill many dry wells before they discover a viable resource.
Because rocks in geothermal areas are usually extremely hard and hot, developers must frequently replace drilling equipment. Individual productive geothermal wells generally yield between 2 MW and 5 MW of electricity; each may cost from $1 million to $5 million to drill. A few highly productive wells are capable of producing 25 MW or more of electricity.
Transmission:
Geothermal power plants must be located near specific areas near a reservoir because it is not practical to transport steam or hot water over distances greater than two miles. Since many of the best geothermal resources are located in rural areas, developers may be limited by their ability to supply electricity to the grid. New power lines are expensive to construct and difficult to site.
Many existing transmission lines are operating near capacity and may not be able to transmit electricity without significant upgrades. Consequently, any significant increase in the number of geothermal power plants will be limited by those plants ability to connect, upgrade or build new lines to access to the power grid and whether the grid is able to deliver additional power to the market.
Direct heating applications can use much shallower wells with lower temperatures, so smaller systems with lower costs and risks are feasible. Residential geothermal heat pumps with a capacity of 10 kilowatt (kW) are routinely installed.
District heating (Cities etc.) systems may benefit from economies of scale if demand is geographically dense, as in cities, but otherwise piping installation dominates capital costs. Direct systems of any size are much simpler than electric generators and have lower maintenance costs per kW.h, but they must consume electricity to run pumps and compressors.
Essay # 9. Barriers in the Way of Geothermal Energy:
i. Finding a suitable build location.
ii. Energy source such as wind, solar and hydro are more popular and better established; these factors could make developers decided against geothermal.
iii. Main disadvantages of building a geothermal energy plant mainly lie in the exploration stage, which can be extremely capital intensive and high-risk; many companies who commission surveys are often disappointed, as quite often, the land they were interested in, cannot support a geothermal energy plant.
iv. Some areas of land may have the sufficient hot rocks to supply hot water to a power station, but many of these areas are located in harsh areas of the world (near the poles), or high up in mountains.
v. Harmful gases can escape from deep within the earth, through the holes drilled by the constructors. The plant must be able to contain any leaked gases, but disposing of the gas can be very tricky to do safely.
Essay # 10. Sustainability of Geothermal Energy:
Geothermal power is considered to be sustainable because any projected heat extraction is small compared to the Earth’s heat content. The Earth has an internal heat content of 1031 joules (3. 1015 TW.hr). About 20% of this is residual heat from planetary accretion, and the remainder is attributed to higher radioactive decay rates that existed in the past.
Natural heat flows are not in equilibrium, and the planet is slowly cooling down on geologic timescales. Human extraction taps a minute fraction of the natural outflow, often without accelerating it.
Even though geothermal power is globally sustainable, extraction must still be monitored to avoid local depletion. Over the course of decades, individual wells draw down local temperatures and water levels until a new equilibrium is reached with natural flows. The three oldest sites, at Larderello, Wairakei, and the Geysers have experienced reduced output because of local depletion.
Heat and water, in uncertain proportions, were extracted faster than they were replenished. If production is reduced and water is re injected, these wells could theoretically recover their full potential. Such mitigation strategies have already been implemented at some sites. The extinction of several geyser fields has also been attributed to geothermal power development.
Essay # 11. Effect of Geothermal Energy on Environment:
Fluids drawn from the deep earth carry a mixture of gases, notably carbon dioxide (CO2), hydrogen sulphide (H2S), methane (CH4) and ammonia (NH3). These pollutants contribute to global warming, acid rain, and noxious smells if released.
Existing geothermal electric plants emit an average of 122 kilograms (269 lb) of CO2 per megawatt-hour (MW-h) of electricity, a small fraction of the emission intensity of conventional fossil fuel plants. Plants that experience high levels of acids and volatile chemicals are usually equipped with emission-control systems to reduce the exhaust.
In addition to dissolved gases, hot water from geothermal sources may hold in solution trace amounts of toxic chemicals such as mercury, arsenic, boron, and antimony. These chemicals precipitate as the water cools, and can cause environmental damage if released. The modern practice of injecting cooled geothermal fluids back into the Earth to stimulate production has the side benefit of reducing this environmental risk.
Direct geothermal heating systems contain pumps and compressors, which may consume energy from a polluting source. This parasitic load is normally a fraction of the heat output, so it is always less polluting than electric heating. However, if the electricity is produced by burning fossil fuels, then the net emissions of geothermal heating may be comparable to directly burning the fuel for heat.
For example, a geothermal heat pump powered by electricity from a combined cycle natural gas plant would produce about as much pollution as a natural gas condensing furnace of the same size. Therefore the environmental value of direct geothermal heating applications is highly dependent on the emissions intensity of the neighbouring electric grid.
Plant construction can adversely affect land stability Enhanced geothermal systems can trigger earthquakes as part of hydraulic fracturing.
Geothermal has minimal land and freshwater requirements. Geothermal plants use 3.5 square kilometres (1.4 sq mi) per gigawatt of electrical production (not capacity) versus 32 and 12 square kilometres (4.6 sq mi) for coal facilities and wind farms respectively. They use 20 litres (5.3 US gal) of freshwater per MW-h versus over 1,000 litres (260 US gal) per MW-h for nuclear, coal, or oil.