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 Production of Geothermal Energy
- Essay on the Applications of Geothermal Energy
- Essay on India Geothermal Energy Resources in India
- Essay on the Economics Related to Geothermal Energy Harnessing
- Essay on the Barriers of Geothermal Energy
- Essay on the Sustainability of Geothermal Energy
- Essay on the Effects of Geothermal Energy on Environment
Essay # 1. Introduction to Geothermal Energy:
Geothermal energy is the energy which lies embedded within the earth.
ADVERTISEMENTS:
Starting from the centre of the earth, it consists of the following zones:
(i) Solid metallic core
(ii) A molten core
(iii) A mantle of solid rock, 3,400 km thick, in layers
ADVERTISEMENTS:
(iv) A thin crust i.e., outer shell about 35 km thick.
Temperature ranges from 3,000 to 4,000°C in the core and the base of the mantle. Therefore, underfoot there is tremendous heat energy which makes its presence felt in the eruption of volcanoes and in the spouting of hot springs and geysers.
Four-fifth of this heat comes from the slow decay of radioactive isotopes within the earth and about one-fifth is heat of the dust and gas clouds which coalesced to form the planet about 5 billion years before.
There are at least seven types of geothermal resources namely:
ADVERTISEMENTS:
(i) Dry steam fields,
(ii) Wet steam fields,
(iii) Hot water,
(iv) Geo-pressure fields,
ADVERTISEMENTS:
(v) Magma deposits,
(vi) Hot dry rock, and
(vii) Volcanoes.
The first three are called hydrothermal reservoirs, owing to involvement of water in some form, and are the best resources for production of geothermal energy at present.
ADVERTISEMENTS:
Dry steam field is the most desirable form of geothermal energy. The steam is clean and easy to convert into electrical energy. Overall cost is considerably less than fossil or nuclear power. The geysers in California (USA) are good examples of dry steam fields. Steam from the well is collected, filtered to remove abrasive particles and passed through the steam-turbines coupled to electric generators. The capacity is 522 MW.
Similarly dry and slightly superheated steam from wells near Lardello in Italy has been used for generation of electrical energy since 1904. The present installed capacity of geothermal plants in Italy is more than 500 MW. Electrical energy is also being produced commercially in New Zealand, USA, Japan, Soviet Union and Mexico. However dry steam wells are rare.
There are about 300 known hot springs in India, located in the Himalayan Mobile belt, West coast region, and Narmada-Sone river region and in Bihar-Bengal belt region. There is a plan to utilise the geothermal energy for generation of electrical energy in Pugga Valley in Ladakh. The hot water under pressure is available at depths of 11-32 metres, at temperatures of 50-110°C.
The heat availability of this source is about 6,000 k calories/second i.e., equivalent of 25 MW of electric power. The temperature of the hot water at Manikaran near Kulu in HP is 69 – 93°C and that of Surajkund (Hazaribagh) is 87°. Wells can be drilled in the hot spring region and the saturated steam from them can be expanded in steam turbines to generate electric power.
In dry steam plants, the steam is directed onto a closed water flow which on external contact becomes steam which in turn is used to move the blades of turbine. The spent water steam is then condensed back into water by condenser and then exposed again to the heat of dry steam. So, this is a closed cycle system.
Dry steam plants are already in operation in Italy, California and Japan. Residential heating systems based on geothermal resources are in use in Iceland, USA etc. However, despite these successful instances the best use of this resource lies in the generation of electrical energy.
Wet steam fields are twenty times more than the dry steam fields in the world. They give wet steam—a mixture of hot water and steam under high pressure. The steam is separated and expanded in turbines to generate electricity. Such a plant of capacity of 75 MW has been set up in Mexico. The hot water is treated for removal of its minerals and then used for agricultural or municipal purposes.
Hot water can also be used for Desalination plants, air conditioning and refrigeration such as a 100 room hotel at Rotorua (NZ), heating of buildings, district heating, animal husbandry and industrial processes. In Iceland about 40% of the populations live in geo-thermally heated houses. The hot water can itself be used to generate electric power by transferring its heat to a secondary medium having boiling point lower than that of water e.g., butane and then expanding its vapour through vapour turbines.
Hot water gushing out from the earth’s interior can be used to evaporate butane or Freon to run vapour turbines and thereby generate electricity, or for other purposes.
In India, the hot springs of Vajreshwari and Ganeshpuri, Off Mumbai, and the sulphur hot springs in foothills of the Himalayas end elsewhere have been known since generations. Until recent times, these hot springs have been used only for bathing for some possible medicinal benefits and for cooking and heating by the local people. The potential of geothermal energy is the smallest among all other resources.
In Japan, geothermal power production was begun at Matsukawa in 1966 and at Otake in 1967. The capacity was 20 MW and 13 MW respectively in 1969, and later increased to about 60 MW. Japan has a total geothermal power production of about 215 MW. Many towns in United States heat some of their houses and commercial buildings with geothermal energy.
Essay # 2. History of Geothermal Energy Worldwide:
In the 20th century, demand for electrical energy led to the consideration of geothermal power as a generating source. Prince Piero Ginori Conti tested the first geothermal power generator on July 4, 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.
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 powers.
The binary cycle power plant was first demonstrated in 1967 in the USSR and later introduced to the US in 1981. 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 electrical power plant capacity as on 2007 was about 10,000 MW. The main countries having major electric generation installed capacities were USA (3,000 MW), Philippines (2,000 MW), Indonesia (1,000 MW), Mexico (1,000 MW), Italy (900 MW), Japan (600 MW), New Zealand (500 MW), Iceland (450 MW). The other region includes the Latin American countries, African countries and Russia.
Essay # 3. Production of Geothermal Electricity:
According to 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 worlds is located at the Geysers, a geothermal field in California. The Philippines is the second highest producer, with 1,904 MW of capacity on line. Geothermal power makes up about 18% of the country electricity generation.
Geothermal electric power 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 enhanced geothermal systems over a much greater geographical range. Demonstration projects are operational in Landau-Pfolz, Germany and Soultz-sous-Forets, France. Other demonstration projects are under construction in Australia, UK and USA.
The thermal efficiency of geothermal electric power plants is low, about 10.23% because geothermal fluids do not attain the high temperatures of steam from boilers. The thermodynamic laws restrict 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.
Though system efficiency does not materially affect operational cost as it would for plants using fuels, but it does affect return on the capital cost of the plant. In order to generate more energy than the pumps consume, electricity generation needs 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.
Enhanced Geothermal System:
The term enhanced geothermal systems (EGS), also called the engineered geothermal systems (formerly known as 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 for generation of 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 natural occurring hydrothermal resources.
Given the costs and limited full-scale system research to date, EGS remains in its fancy, 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 wide spread.
Essay # 4. Applications of Geothermal Energy:
Low-temperature (300°F or 149°C) geothermal resources are typically used in direct-use applications like district heating, greenhouses, fisheries, mineral recovery, and industrial process heating. However, some low-temperature resources can be used for generation of electricity using binary cycle electricity generating technology.
Direct heating is far more efficient than electric power generation and places less demanding temperature requirements on the heat resource. Heat may come from cogeneration via, a geothermal electrical plant, or from smaller wells or heat exchangers buried in shallow ground. Geothermal heat pumps can be used for space heating essentially anywhere.
Essay # 5. India Geothermal Energy Resources in India:
India’s geothermal energy capacity have been estimated to produce 10,000 MW of power- a figure which is much higher than the combined power being produced from non-conventional energy sources like wind, solar and biomass. But yet geothermal power has not been explored. With the existing open economic policies of the Govt., and large incentives given to non-conventional energy sectors, the future of geothermal energy sector in India appears to be bright.
Several geothermal provinces in India characterized by heat flow (78-468 mW/m2) and thermal gradients (47-100°C/km) discharge about 400 thermal springs. After the oil crisis in 1970s, the Geological Survey of India conducted lot of survey to explore the possibilities of geothermal power harnessing. The investigations carried out in the past have identified several sites which are suitable for power generation as well as for direct use.
These provinces are capable of generating 10,000 MW of power. Though geothermal power production in Asian countries like Indonesia, Philippines has gone up, India with it’s around 10,000 MW geothermal power potential is yet to harness to its full capacity. However, with the growing environmental problems associated with thermal power plants, future for geothermal power in India appears to be bright.
Essay # 6. 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 account for over half the costs, and exploration of deep resources entails significant risks.
Unlike conventional power plants that run on fuel that is to be purchased over the life of the plant, geothermal power plants use a renewable source that is not susceptible to price fluctuations. The price of geothermal is within range of other electricity choices available today when the costs of 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 drilling geothermal has decreased during last two decades, exploration and drilling remain expensive and risky. Drilling costs alone account for as much as one-third to one-half of the total cost of a geothermal project. Location of best resources can be difficult, and developers may drill many dry wells before they discover a viable source.
Because rocks in geothermal areas are usually extremely hard and hot, replacement of drilling equipment is required. Individual productive geothermal wells generally yield between 2 MW and 5 MW of electricity; each may cost $1 million to $5 million to drill. A few highly productive wells are capable of producing 25 MW or more power.
Transmission:
Geothermal power plants are to be located near specific areas near a reservoir because it is not practical to transport steam or hot water over distances exceeding about 3 km. Since many of the best geothermal resources are located in the rural areas, developers may be limited by their ability to supply electricity to the power 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 upgrading. 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.
Essay # 7. Barriers of Geothermal Energy:
1. Energy sources like wind, solar and hydro are more popular and better established; these factors could make developers decided against geothermal.
2. Main disadvantages of building a geothermal energy plant mainly lie in the exploration stage, which can be capital intensive and high-risk; many companies, whose commission surveys are often disappointed, as quite often, the land they were interested in, cannot support a geothermal energy plant.
3. 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.
4. Finding a suitable build location.
5. 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 gas can be very tricky to do safely.
Essay # 8. 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 × 1018 MWh). About 20% of this 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 Lorderello, 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 re-injected, these wells could their theoretically recover their full potential. Such mitigation strategies have already been implemented at some sites. The extraction of several geyser fields has also been attributed to geothermal power development.
Essay # 9. Effects 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 power plants emit an average of 122 kg of CO2 per MWh of electrical energy, a small fraction of the emission intensity of conventional fossil fuel plants. Plants that experience high level 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 like 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 instance, a geothermal heat pump powered by electricity from a combine 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 emission intensity of the neighbouring electric power grid.
Plant construction can adversely affect land stability. Enhanced geothermal system can trigger earthquakes as part of hydraulic fracturing.
Geothermal has minimal land and fresh water requirements. Geothermal plant use 3.5 km2 per GW of electric generation (not capacity) versus 32 and 12 km2 for coal facilities and wind form respectively. They use 20 litres of fresh water per MWh versus over 1,000 litres per MWh for nuclear, coal, or oil.