geothermal energy examples essay

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Mechanism and potential

Direct uses, geothermal heat pumps, electric power generation.

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geothermal energy

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• National Geographic - Geothermal Energy
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geothermal energy , a natural resource of heat energy from within Earth that can be captured and harnessed for cooking, bathing, space heating, electrical power generation, and other uses. The total amount of geothermal energy incident on Earth is vastly in excess of the world’s current energy requirements, but it can be difficult to harness for electricity production. Despite its challenges, geothermal energy stands in stark contrast to the combustion of greenhouse gas -emitting fossil fuels (namely coal , petroleum , and natural gas ) driving much of the climate crisis , and it has become increasingly attractive as a renewable energy source.

Temperatures increase below Earth ’s surface at a rate of about 30 °C per km in the first 10 km (roughly 90 °F per mile in the first 6 miles) below the surface. This internal heat of Earth is an immense store of energy and can manifest aboveground in phenomena such as volcanoes , lava flows, geysers , fumaroles , hot springs , and mud pots. The heat is produced mainly by the radioactive decay of potassium , thorium , and uranium in Earth’s crust and mantle and also by friction generated along the margins of continental plates.

Worldwide, the annual low-grade heat flow to the surface of Earth averages between 50 and 70 milliwatts (mW) per square meter. In contrast, incoming solar radiation striking Earth’s surface provides 342 watts per square meter annually ( see solar energy ). In the upper 10 km of rock beneath the contiguous United States alone, geothermal energy amounts to 3.3 × 10 25 joules, or about 6,000 times the energy contained in the world’s oil reserves. The estimated energy that can be recovered and utilized on the surface is 4.5 × 10 6 exajoules, or about 1.4 × 10 6 terawatt-years, which equates to roughly three times the world’s annual consumption of all types of energy.

Although geothermal energy is plentiful, geothermal power is not. The amount of usable energy from geothermal sources varies with depth and by extraction method. Normally, heat extraction requires a fluid (or steam ) to bring the energy to the surface. Locating and developing geothermal resources can be challenging. This is especially true for the high-temperature resources needed for generating electricity. Such resources are typically limited to parts of the world characterized by recent volcanic activity or located along plate boundaries (such as along the Pacific Ring of Fire ) or within crustal hot spots (such as Yellowstone National Park and the Hawaiian Islands ). Geothermal reservoirs associated with those regions must have a heat source, adequate water recharge, adequate permeability or faults that allow fluids to rise close to the surface, and an impermeable caprock to prevent the escape of the heat. In addition, such reservoirs must be economically accessible (that is, within the range of drills). The most economically efficient facilities are located close to the geothermal resource to minimize the expense of constructing long pipelines. In the case of electric power generation, costs can be kept down by locating the facility near electrical transmission lines to transmit the electricity to market. Even though there is a continuous source of heat within Earth, the extraction rate of the heated fluids and steam can exceed the replenishment rate, and, thus, use of the resource must be managed sustainably.

• Geothermal power
• Hydroelectric power
• Solar power
• Tidal power

Uses and history

Geothermal energy use can be divided into three categories: direct-use applications, geothermal heat pumps (GHPs), and electric power generation.

Probably the most widely used set of applications of geothermal energy involves the direct use of heated water from the ground without the need for any specialized equipment. All direct-use applications make use of low-temperature geothermal resources, which range between about 50 and 150 °C (122 and 302 °F). Such low-temperature geothermal water and steam have been used to warm single buildings, as well as whole districts where numerous buildings are heated from a central supply source. In addition, many swimming pools, balneological (therapeutic) facilities at spas , greenhouses , and aquaculture ponds around the world have been heated with geothermal resources.

Geothermal energy from natural pools and hot springs has long been used for cooking, bathing, and warmth. There is evidence that Native Americans used geothermal energy for cooking as early as 10,000 years ago. In ancient times, baths heated by hot springs were used by the Greeks and Romans. Such uses of geothermal energy were initially limited to sites where hot water and steam were accessible.

Other direct uses of geothermal energy include cooking, industrial applications (such as drying fruit , vegetables , and timber), milk pasteurization , and large-scale snow melting. For many of those activities, hot water is often used directly in the heating system, or it may be used in conjunction with a heat exchanger , which transfers heat when there are problematic minerals and gases such as hydrogen sulfide mixed in with the fluid. Early industrial direct-use applications included the extraction of borate compounds from geothermal fluids at Larderello, Italy , during the early 19th century.

Geothermal energy is also used for the heating and cooling of buildings. Examples of geothermal space heating date at least as far back as the Roman city of Pompeii during the 1st century ce . Although the world’s first district heating system was installed at Chaudes-Aigues, France , in the 14th century, it was not until the late 19th century that other cities, as well as industries, began to realize the economic potential of geothermal resources. Geothermal heat was delivered to the first residences in the United States in 1892, to Warm Springs Avenue in Boise , Idaho , and most of the city used geothermal heat by 1970. The largest and most-famous geothermal district heating system is in Reykjavík , Iceland , where 99 percent of the city received geothermal water for space heating by the mid-1970s after efforts began in the 1930s.

Beginning in the late 20th century, geothermal heat pumps gained popularity in many places as a greener alternative to traditional boilers , furnaces , and air conditioners . Utilizing pipes buried in the ground, these systems take advantage of the relatively stable moderate temperature conditions that occur within 6 meters (about 20 feet) of Earth’s surface, where the temperature of the ground maintains a near-constant temperature of 10 to 16 °C (50 to 60 °F). Consequently, geothermal heat can be used to help warm buildings when the air temperature falls below that of the ground, and GHPs can also help to cool buildings when the air temperature is greater than that of the ground by drawing warm air from a building and circulating it underground, where it loses much of its heat, before returning it. GHPs are very efficient, using 25–50 percent less electricity than comparable conventional heating and cooling systems, and they produce less pollution.

Depending upon the temperature and the fluid (steam) flow, geothermal energy can also be used to generate electricity . Geothermal power plants control the behavior of steam and use it to drive electrical generators . Some “dry steam” geothermal power plants simply collect rising steam from the ground and funnel it directly into a turbine . Other power plants, built around the flash steam and binary cycle designs, use a mixture of steam and heated water (“wet steam”) extracted from the ground to start the electrical generation process. Given that the excess water vapor at the end of each process is condensed and returned to the ground, where it is reheated for later use, geothermal power is considered a form of renewable energy .

The first geothermal electric power generation took place in Larderello , Italy, with the development of an experimental plant in 1904. The first commercial use of that technology occurred there in 1913 with the construction of a plant that produced 250 kilowatts (kW). Geothermal power plants were commissioned in New Zealand starting in 1958 and at the Geysers in northern California in 1960.

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Geothermal Energy

1. introduction.

Geothermal energy is an often overlooked and underappreciated alternative energy option. There are many myths and misunderstandings surrounding geothermal energy, and it is the goal of this paper to discover the truth about this alternative energy. This paper will explain in detail what geothermal energy is and the methods used to harness this energy. The paper will also compare geothermal energy with other alternative energy resources in terms of efficiency, cost, and environmental impact. Various studies have shown that geothermal energy is an available, affordable, and environmentally friendly option, but the public will not consider this energy source unless the myths and misconceptions are dispelled. This paper will examine the misconceptions and the studies that disprove them. The information in this paper will be targeted at the general public in order to inform them what geothermal energy is, and at policymakers in hopes to create a greater awareness of geothermal energy and its potential. The world is in dire need of alternative energy, and it is essential to take advantage of all options available. Geothermal energy is a relatively untapped energy resource and has great potential for helping to lessen the use of fossil fuels and the emission of greenhouse gases.

2. Benefits of Geothermal Energy

Today, there are many benefits to using geothermal energy. The first of these benefits is that geothermal energy is renewable. This means that the energy source is not one that can be used up, such as with oil or gas, but rather an energy source that can be sustained, such as with solar or wind power. This is due to the fact that the heat extraction process is natural and not dependent on injecting fluids, and the heat will be replenished by the Earth. Studies have shown that if the reservoir is used conservatively, it can provide a sustainable energy source for the long term. An example of this is the Blue Lagoon project in Iceland. The resort and spa use excess hot water from a nearby geothermal power plant to run its water heating systems and provide visitors with hot water straight from the ground. This is a clear demonstration of the way that geothermal heat can be used as a sustainable energy source to meet our needs. Another important benefit of geothermal energy that is relevant to the current environmental situation is that geothermal energy has low emissions of greenhouse gases and other pollutants. While not entirely free of greenhouse gas emissions, the carbon intensity of geothermal energy is very low when compared to fossil fuels. This means that the use of geothermal power in place of fossil fuels can be a method for reducing greenhouse gas emissions. A study conducted by the IPCC in 2006 estimated that the electricity generation costs of geothermal power were 0.2-0.3 times those of the benefits, and that the potential of reducing greenhouse gas emissions was greater than the increased cost, particularly for high-cost renewables such as solar and wind power. This is a very significant result for the environment, and given the current situation with climate change and the increasing pressure to reduce greenhouse gas emissions, this is a very important benefit of geothermal energy.

2.1. Renewable and Sustainable

Renewable energy sources are sources of power that are continuously replenished and exist in abundant supply on Earth. The two primary types of geothermal power are non-hydrothermal resources and high and moderate temperature resources. Non-hydrothermal resources are usually derived from the ground and can provide power and heat to small-scale direct-use applications. High and moderate temperature resources are mainly used to provide electricity. They are primarily found in tectonically active regions that host most of the Earth's volcanoes and geysers. The most readily available source of power is the vast reserve of steam and hot water found in the Earth's crust, which can be tapped to generate electricity. This power derived from the Earth is a result of the thermal energy contained in the rock and fluids at various depths. This energy is of primordial origin, largely deriving from the formation of the planet and from radioactive decay of minerals. Measures to harness this energy are equivalent to utilizing the Earth's stored sunlight. One of the most successful projects for direct-use application of geothermal energy can be found in Klamath Falls, where the Geothermal Greenhouse Corporation has developed greenhouse-drying systems that use geothermal water to heat the plants on wire mesh benches. This method can provide an efficient drying process for various products and holds great potential for future development. Due to the nature of geothermal resources and the technologies that harness them, geothermal power has long-term potential and can help to meet the needs of a growing population. These resources are sufficient to supply humanity with all the energy it will ever need. Steps to commercialize this energy will lead to its greater availability.

2.2. Reduced Greenhouse Gas Emissions

As previously mentioned in Section 1.1, the main by-product of geothermal power plants is virtually emission-free and therefore helps reduce the level of greenhouse gas emissions. It is estimated that a typical 10 MW binary-type geothermal power plant can reduce CO2 emissions by about 27,000 tonnes per annum in comparison to a natural gas-fired power plant. This is because the carbon in the geothermal fluids is released at the power plant and can be collected with no net release to the atmosphere. An analysis of the life-cycle of a geothermal plant has shown that emissions may be 122 times less than a comparably sized gas plant and twice that of a wind farm. The Lardarello dry steam field in Italy has been operating since 1913 and has saved an estimated 22 million tonnes of CO2 emissions when compared to a natural gas combined cycle power plant. Geothermal's ability to secure baseload power means that it can be a direct means to reduce emissions from the most common form of power generation, using baseload to ensure security of supply, coal-fired power plants. In the case of Indonesia, the conversion of diesel consumers in off-grid areas to geothermal power generation can contribute to a reduction in greenhouse gas emissions and a carbon market trade. Overall, the efficient conversion of geothermal energy and its low air emissions make it a suitable option for a sustainable energy future and a reduction of detrimental greenhouse gases.

2.3. Cost-Effective Energy Source

Geothermal energy is a cost-effective investment. This is due to the fact that it decreases the dependence on the volatile global markets and lessens the effects of inflation. The cost of geothermal energy is becoming more and more competitive with other energy sources. As the world market price of fuel continues to rise, the cost of geothermal energy is looking more and more attractive. After initially high construction costs, the long-term price of geothermal energy is found to be lower than the costs of other energy resources. This is due to the fact that once a geothermal power plant is built, it is capable of producing more energy on a consistent basis. In the New Zealand scenario, the cost of geothermal power is relatively low when compared to other countries as we have a unique situation where the government has granted us access to use the natural geothermal resources. This has led to the joint production of electricity and geothermal energy used for direct heating, resulting in a joint unique cost structure with the cost of electricity production being used as an opportunity cost for generating geothermal energy for direct use. With our ever-increasing concerns for the state of our planet, environmental and clean energy technologies need to become more mainstream in order to secure a positive future. Due to the fact that these energies often come at a higher cost than the more destructive and polluting energy sources, the provision of long-term price security and improved cost competitiveness is vital if they are to succeed. In New Zealand today, the opportunity to increase government core funding and to regulate the price of geothermal energy provides a bright future for the growth of this industry. This can only bring more positive results to an energy source that is already highly environmentally friendly and sustainable.

3. Geothermal Power Generation

Geothermal power generation is a renewable energy technology that uses the Earth's natural heat to produce electricity. Geothermal power is a sustainable and reliable energy source that is environmentally friendly. It is also the only form of renewable energy that is capable of providing continuous power. There are a number of power generation techniques and technologies that are used, and these largely depend on whether the resource is deemed high or low temperature. High temperature resources are generally required in order to generate electricity, while low temperature resources can be used for direct heating applications where the energy does not need to be converted to electricity. Most of the world's geothermal electricity is produced using dry steam and flash steam power plants. These are the most widely used systems and generate electricity by using high-pressure steam from deep within the Earth, which is used to drive turbines that power generators. Dry steam plants use steam from fractures in the ground, which is fed directly to the turbine. In flash steam plants, water is brought to the surface under pressure, and some of the pressure is relieved as the water is allowed to turn into steam. This steam is then fed to the turbines. Binary cycle power plants are the other main technology for generating geothermal power, and they are suited to low temperature resources. This technology is different from the steam systems in that the water or steam from the geothermal reservoir is used to heat another working fluid that has a lower boiling point. The fluid is vaporized in a heat exchanger, and the vapor then drives a turbine to produce electricity. The vapor is then condensed, and the process is repeated. Binary cycle plants release little to no emissions, and they have the added advantage of being able to generate electricity with fluid at lower temperatures (below 150°C), which is not hot enough to drive a steam turbine. This type of plant has the potential to open up vast areas of geothermal resources that are not suitable for the traditional steam systems and could add a significant amount of new capacity to the global geothermal industry.

3.1. Geothermal Heat Pumps

Heat pumps are machines that utilize a small amount of external power to transfer heat from a cool source to a warm source. This means that the heat pump will move warm air into a cool space and move cool air into a warm space. Many American homes have heat pumps as they are a very efficient form of heating and cooling. However, they are also a source of geothermal energy and have the potential to significantly reduce electricity use for heating. Currently, most geothermal heating comes from power plants, which very efficiently utilize a steam resource to generate electricity. Fewer than 1 million buildings use geothermal heat pumps. A geothermal heat pump is not limited to a specific size or location. It can be utilized in small residential areas as well as large-scale buildings. The size of the pump depends on the size of the structure it is heating and the desired temperature. With a series of pipes similar to a closed-loop system, a heat pump can move heat from the ground into a building and back down. Heat pumps have been proven to efficiently save energy and are considered the most environmentally friendly way to heat and cool a building.

3.2. Geothermal Power Plants

A geothermal power plant operates on a simple principle: heat is extracted from the earth and converted to electricity. The earth is a bountiful source of heat, thought to have originated from solar energy absorbed at the earth's surface. This is best exemplified by looking at solar energy conversion, in which intercepted solar radiation is absorbed by the earth and radiated back as heat. The temperature of the earth increases with depth, and the rate at which this occurs varies depending on regional factors. In some areas, the temperature of the earth at a depth of only a few meters is high enough to be used as a primary source of energy for direct-use applications. As mentioned earlier, it is the resources with higher temperatures that are most effectively used for power generation, as the potential to convert heat energy to mechanical and then electrical energy is far greater. The value of the temperature gradient of the resource, which is its rate of increase in temperature with increasing depth, determines the capability for heat extraction and thus power production. There are three main types of geothermal power plants: Dry-Steam, Flash-Steam, and Binary Cycle. These are differentiated based on the physical state of the fluid that comes into direct contact with the turbine, which is a result of varying fluid temperatures from the resource. The type of plant chosen is also contingent on reservoir characteristics and the extent of the resource. A) Dry-Steam Power Plants Dry-steam power plants are the simplest and oldest of all design types. The name "dry-steam" is somewhat misleading, as the fluid from the resource does not actually have to be in the vapor phase. The most common fluid is, in fact, saturated water which boils to produce steam as it encounters lower pressures at the surface or in a well. This simply involves the extraction of steam from the ground and its passage through a turbine on the surface. The most common plan-drawing is to drill a production well at the point of highest heat, optimal for higher temperature resources, and a second well several hundred feet away. This is then used to direct the steam to a turbine and manipulate the movement of the steam through the ground. This is the most marginal form of manipulation, as the direct extraction of steam is usually a natural occurrence for higher temperature resources. Well drilling costs and field development for this type of plant are generally very high, and as such, new dry-steam plants are not commonly being built in the developed world. However, it still presents an efficient and usually long-term means of energy production (e.g., the first plant built in Larderello, Italy, in 1904 still operates today).

4. Geothermal Energy Challenges

Resources with high levels of heat can be found in locations that have two of the three requirements for creating geothermal energy: high heat flow and an adequate water supply. Geothermal resources will be more abundant where tectonic or volcanic activity is present. These locations are mostly found in the continental plate boundaries, where earthquakes and volcanoes are a common occurrence. The greatest resources are found in regions that have active or geologically young tectonic systems, where volcanic activity and geothermal gradient are high. These resources are located deep within the earth, and sometimes getting access to them can prove more dangerous and costly than it is worth. In these cases, it is best to avoid these resources altogether. This is because drilling expense increases significantly as the depth of the resource increases, and attempts at tapping resources that are close to fault lines or other indicators of tectonic activity can pose considerable risk to the drilling crew and long-term damage to the plant. Overall, due to the specific location requirements, relative scarcity, and sometimes dangerous accessibility, exploitation of these resources can be quite limited. This ties in with the fact that geothermal energy only has a 0.4% share of global energy consumption.

4.1. Limited Geothermal Resources

Currently, the strongest argument against the large-scale development of geothermal energy is that resources are located only in certain areas, often in remote regions far from population centers. It is not economically feasible to pipe hot water or steam long distances. While geothermal development is possible in most countries, the potential is limited to a greater or lesser extent, depending on the regional geology. For example, it is estimated that Indonesia has 29,000 MWe of geothermal potential. The Philippines has less on a per capita basis, Costa Rica has slightly more. Other countries have prospects that are small in comparison. Developed nations may have the technology to utilize their geothermal resources, but many Third World countries could benefit significantly from this indigenous and renewable energy source. Unfortunately, they lack the capital for geothermal development, and they often have abundant, low-cost labor that makes geothermal power less attractive. While geothermal resources are renewable on a human time scale, they can be depleted. The fluid pressure and the temperature of the resource will drop over time if the fluid is removed faster than it is replaced. Three geothermal reservoirs in California's Geysers Field were "mined" to generate steam that was sold on a non-renewable contract; the power plants were shut down in the 1980s. These are now being used for injection and production, in essence to convert them to a hot dry rock reservoir energy storage. This emphasizes the need to manage the reservoir effectively, to ensure that it will be sustainable. Depending on the rate of extraction of heat, a reservoir may take thousands of years to tens of millions of years to reach a new equilibrium, assuming that it is recharged from greater depth. But most reservoirs will cool over time. The Hadean time scale is not of immediate concern to humanity, but depletion is an issue for current and future generations.

4.2. High Initial Investment

The expense of geothermal energy is justifiable given the long-term benefits. Although modest in its operation and maintenance charges, the upfront expenses of geothermal power are considerably more than the other conventional sources of energy. Power plants are rated by how many megawatts of power they can produce. They range in expense from 1 million to 2.5 million per megawatt, a significant increment from the 0.4 to 0.8 million per megawatt of a coal-fired plant. This is the same range of expenses for a wind or photovoltaic solar plant. The main reason for the high upfront expenses is the requirement for geothermal wells, which account for a significant part of the total plant cost. The wells are perhaps the most important part of a geothermal power plant since they are the access to the world's magma and the heat that is required for power production. After determining which type of well is suitable for the location and evaluating the number required, the cost of drilling should be considered. An average well can cost somewhere in the range of 1 to 4 million dollars inclusive of operations and maintenance. This places the total cost of a well somewhere in the range of 3 to 10 million dollars, making a considerably more significant expense per gigawatt than the originally estimated expenses. Building a geothermal power plant, due to the well costs, can mean ongoing spending spreading over many years until initial power is finally generated. On the bright side, once the power starts flowing, these plants have a fairly extensive lifespan compared to other types of power plants. This is mainly due to the fact that technological change can occur without any consequence on the heat under the earth and how hot it is. Therefore, the maintenance costs are mostly related to well issues or serious plant breakdown. Initial revenue is likely to be an issue for most small to medium-sized companies exploring geothermal power. This is due to the large long-term residual funding when comparing expected expenses and cash received from power sales. A way to alleviate this issue is usually to take a development loan on the expected future earnings from the geothermal reserve.

4.3. Environmental Concerns

The development of geothermal energy has the capacity to bring hazards of environmental pollution, subsidence, and depletion or contamination of the hydrogeological reservoir. Some of the environmental issues related to geothermal energy can be discussed below. Municipal solid waste (MSW) can also be a problem. MSW can be combusted to generate electrical power. The environmental issue is finding the right energy mix that will produce the least GHG. Phase out of certain conventional fossil-fueled plants and replacing them with more efficient plants can be an easier and cost-effective solution to mitigating climate change. Often, the destruction is done to build a reservoir for a hydroelectric station. This destroys the living environment of the previously existent flora and fauna, and often the terrain of surrounding land. The knowledge of the destruction can alter the ways in environmental conservation. The risk of depletion and contamination of the resource is higher for geothermal reservoirs, due to the requirement of direct utilization of the resource often leading to an unsustainable rate of exploitation. The stated hazards imposed by the development of geothermal energy are comparable to present fossil fuel generation and most modern-day energy resources. The probability/amplitude scale of the hazard and resource-specific mitigation measures are expected to differ. The likelihood that resource developers and/or a community will have the knowledge and dedication to employ the mitigation measures is uncertain. Environmental awareness, the preservation of natural resources, and cultural achievements are valued differently by distinct nationalities and cultures. The geographical occurrence of the geothermal resource is in areas of high natural or heritage value. Development of the resource in such areas will have higher resistance from the local populations and environmental organizations due to the clear impact on the environment and greater implications if things go wrong.

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Essay on Geothermal Energy

Introduction to Geothermal Energy

Geothermal energy, derived from the Earth’s heat, is a renewable and sustainable source of power with immense potential to meet our energy needs while reducing our carbon footprint. Unlike fossil fuels, which contribute to greenhouse gas emissions and climate change, geothermal energy offers a cleaner alternative. For example, Iceland has effectively harnessed its geothermal resources, generating nearly 75% of its electricity and providing heating for over 90% of its homes using geothermal energy. This success story showcases the viability and benefits of geothermal power, setting an inspiring example for other nations to follow suit. This essay will explore the principles of geothermal energy, its development, environmental impact, and future prospects.

History and Development of Geothermal Energy

Geothermal energy has a rich history dating back thousands of years, with early civilizations recognizing and utilizing the Earth’s heat for various purposes.

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• Ancient Utilization : Ancient cultures, such as the Romans, Greeks, and Chinese, recognized the therapeutic properties of hot springs and used them for bathing and healing purposes. These early civilizations also employed geothermal heat for cooking, heating, and space heating, demonstrating an early understanding of the benefits of geothermal energy.
• Modern Advancements : The modern development of geothermal energy began in the late 19th century with the construction of the first geothermal power plant in Italy in 1904. However, significant advancements in geothermal technology occurred in the mid-20th century. In the 1960s and 1970s, countries like the United States, New Zealand, and Iceland pioneered the development of geothermal power plants for electricity generation.
• Global Expansion : As technology improved and awareness of renewable energy grew, the global expansion of geothermal energy accelerated. Countries situated along tectonic plate boundaries, known as “geothermal hotspots,” such as Iceland, the Philippines, Indonesia, and Kenya, became leaders in geothermal power production. These regions benefit from the natural abundance of geothermal resources, making them ideal locations for geothermal development.
• Technological Innovations : Over the years, significant technological innovations have enhanced the efficiency and viability of geothermal energy. Enhanced geothermal systems (EGS) and binary cycle power plants are among the advancements that have expanded the reach of geothermal energy to regions previously considered unsuitable for traditional geothermal power generation.
• Research and Collaboration : Ongoing research and collaboration among governments, academia, and industry stakeholders continue to drive advancements in geothermal technology. Initiatives such as the International Renewable Energy Agency (IRENA) and the Geothermal Resources Council (GRC) facilitate knowledge sharing, promote best practices, and support the growth of geothermal energy worldwide.

Significance and Potential of Geothermal Energy

Geothermal energy holds significant promise as a renewable energy source due to its abundance, reliability, and minimal environmental impact. Its potential extends across various sectors, including electricity generation, heating, and industrial applications. Here are key aspects of its significance and potential:

• Renewable and Sustainable : Geothermal energy is renewable because it relies on the Earth’s internal heat, continuously generated by radioactive decay in the Earth’s core. Unlike fossil fuels, which are finite and contribute to greenhouse gas emissions, geothermal energy offers a sustainable alternative with minimal environmental impact.
• Reliable and Baseload Power : Geothermal power plants can provide reliable and consistent baseload power, unlike some other renewable sources like wind and solar, which are intermittent. This reliability makes geothermal energy valuable for meeting energy demand and enhancing grid stability.
• Low Emissions : Geothermal power generation produces fewer greenhouse gas emissions than fossil fuels. It can be crucial in reducing carbon dioxide emissions and mitigating climate change , making it an attractive option for countries seeking to transition to cleaner energy sources.
• Versatile Applications : Geothermal energy is helpful for a number of things, such as heating, cooling, and producing power. Direct use of geothermal energy for heating buildings, greenhouse cultivation, and industrial processes further enhances its versatility and economic viability.
• Job Creation and Economic Benefits : The development and operation of geothermal projects create job opportunities and stimulate economic growth in regions with geothermal resources. It can also reduce dependence on imported fuels, contributing to energy security and local economic development.
• Global Potential : Geothermal energy is abundant globally, with significant resources located in regions with high energy demand. Countries situated along tectonic plate boundaries, known as the “Ring of Fire,” and areas with volcanic activity have the most significant geothermal potential.
• Technology Advancements : Ongoing advancements in geothermal technology, such as enhanced geothermal systems (EGS) and binary cycle power plants, are expanding the reach of geothermal energy to regions previously considered unsuitable for traditional geothermal power generation.

How Geothermal Energy Works?

Geothermal energy harnesses heat from within the Earth to generate electricity and provide heating and cooling for various applications. The process involves accessing the Earth’s heat through natural geothermal reservoirs or by creating artificial reservoirs using advanced drilling techniques. Here’s how geothermal energy works:

• Heat Source : The Earth’s heat originates from its core, where temperatures reach several thousand degrees Celsius due to radioactive decay. This heat gradually transfers towards the Earth’s surface, creating geothermal gradients.
• Geothermal Reservoirs : Geothermal reservoirs are underground pockets of hot water or steam trapped in porous rock formations. Tectonic plate boundaries, volcanic activity, and geothermal hotspots are the usual locations for these reservoirs.
• Exploration and Drilling : Geologists use various techniques, including seismic surveys and exploration drilling, to locate and assess potential geothermal reservoirs. Once identifying a suitable site, operators drill production wells to access the hot water or steam within the reservoir.
• Fluid Extraction : Operators extract hot water or steam from the geothermal reservoir through production wells. The temperature and pressure of the fluid vary depending on the depth and characteristics of the reservoir.
• Power Generation : Production wells direct the extracted hot water or steam to the surface. In conventional geothermal power plants, the steam drives turbines connected to generators, producing electricity. In binary cycle power plants, the hot fluid vaporizes a working fluid with a lower boiling point, such as isobutane or pentane, which drives turbines to generate electricity.
• Heat Distribution : Direct heating and cooling applications can also utilize geothermal energy. District heating systems circulate hot water from geothermal wells through pipes to heat buildings, homes, and greenhouses. Similarly, geothermal heat pumps can extract heat from the ground during winter for heating and reject heat into the ground during summer for cooling.
• Reinjection and Sustainability : After extracting heat from the geothermal fluid, it is reinjected back into the reservoir through injection wells to maintain reservoir pressure and sustainability. This reinjection process replenishes the reservoir and ensures the long-term viability of geothermal energy production.

Environmental Impacts and Sustainability

Praise for geothermal energy’s low environmental impact compared to fossil fuels aside, it’s essential to consider its potential environmental effects and long-term sustainability. Here’s a look at both aspects:

• Low Greenhouse Gas Emissions : Geothermal energy produces minimal greenhouse gas emissions, primarily consisting of carbon dioxide and hydrogen sulfide, making it a cleaner alternative to fossil fuels.
• Reduced Air Pollution : Geothermal power plants emit low levels of air pollutants, such as sulfur dioxide and nitrogen oxides, compared to fossil fuel power plants, improving air quality and public health.
• Water Usage and Management : Geothermal power plants require water for steam production and cooling purposes. While water consumption per unit of electricity generated is relatively low compared to other power plants, sustainable water management practices are essential to mitigate potential impacts on local water resources.
• Land Use and Ecosystem Impact : Geothermal power plants require land for infrastructure, including well pads, pipelines, and power plant facilities. While the footprint of geothermal plants is relatively small compared to other energy developments, careful siting and environmental impact assessments are necessary to minimize impacts on local ecosystems and biodiversity .
• Induced Seismicity : In some cases, geothermal energy extraction, particularly from enhanced geothermal systems (EGS), can induce seismic activity. While most induced earthquakes are small and not felt at the surface, operators implement monitoring and mitigation measures to ensure safety and minimize risks.
• Subsurface Fluid Disposal : The reinjection of geothermal fluids into the reservoir after energy extraction is critical for sustaining reservoir pressure and preventing environmental impacts. Proper fluid disposal and management practices are essential to avoid contamination of groundwater and surface water sources.
• Noise Pollution : Geothermal power plants can generate noise from drilling activities, steam turbines, and cooling systems. Noise mitigation measures, such as sound barriers and equipment insulation, are implemented to minimize impacts on nearby communities and wildlife.
• Thermal Pollution : Discharging geothermal fluids, often hotter than the surrounding environment, can lead to thermal pollution in water bodies if not properly managed. Operators use cooling systems and environmental monitoring to mitigate thermal impacts on aquatic ecosystems.
• Lifecycle Assessment : Assessing the environmental impacts of geothermal energy involves considering the entire lifecycle of a geothermal project, including exploration, drilling, operation, and decommissioning. Lifecycle assessments help identify potential environmental risks and inform sustainable practices.
• Sustainability and Longevity : Considered a sustainable energy source, geothermal energy relies on maintaining a heat extraction rate that aligns with the natural rate of heat replenishment in the reservoir. Proper management and monitoring are essential to ensure the long-term sustainability of geothermal projects and minimize environmental impacts.

Applications of Geothermal Energy

Geothermal energy has a wide range of applications, spanning from electricity generation to heating and cooling. Its versatility and sustainability make it a valuable resource for various sectors. Here are some key applications of geothermal energy:

• Electricity Generation : Geothermal power plants use steam or hot water from geothermal reservoirs to drive turbines and generate electricity. Binary cycle, flash steam, and dry steam are the three main types of geothermal power plants. These plants can provide baseload power, meaning they can operate continuously, unlike some other intermittent renewable energy sources.
• Direct Heating : Geothermal energy can be used directly for heating applications. In areas with accessible geothermal resources, operators can pump hot water from underground reservoirs directly into buildings for space heating, district heating systems, and greenhouse heating. This direct use of geothermal energy is efficient and cost-effective, reducing the need for traditional heating fuels.
• Cooling : Geothermal heat pumps use the Earth’s stable temperature below the surface to provide cooling in buildings during hot weather. The heat pump extracts heat from the building and transfers it to the ground, where the temperature is lower, providing efficient cooling without the need for traditional air conditioning systems.
• Industrial Processes : Various industrial processes requiring heat, such as food drying, lumber drying, and mineral processing, can utilize geothermal energy. The high temperatures available from geothermal sources make them suitable for these applications, reducing the reliance on fossil fuels for industrial heat.
• Agricultural Applications : Geothermal energy can benefit agriculture by heating greenhouses, extending the growing season, and improving crop yields. Geothermal heat can also be used for aquaculture, providing optimal water temperatures for fish farming.
• Desalination : Geothermal energy can be used in desalination plants to produce fresh water from seawater or brackish water. The heat from geothermal sources can drive the desalination process, reducing the energy required compared to traditional desalination methods.
• Spa and Wellness Tourism : Hot springs and geothermal spas are popular tourist attractions in many regions with geothermal activity. These natural hot springs offer relaxation and therapeutic benefits, attracting visitors and contributing to local economies.

Challenges and Limitations

Despite its many benefits, geothermal energy also faces several challenges and limitations that can hinder its widespread adoption and development. These challenges include:

• Resource Availability and Location : Geothermal resources exhibit uneven global distribution. Concentrated in regions with tectonic activity, geothermal resources are often found in volcanic areas or along tectonic plate boundaries. This limited geographical distribution can restrict the widespread deployment of geothermal energy.
• High Upfront Costs : The initial capital costs of geothermal projects, including drilling and infrastructure development, can be high. This can be a barrier to entry for developers, especially in regions with limited financial resources.
• Exploration Risks : Exploration for geothermal energy entails inherent risks, as the presence and quality of resources remain uncertain until drilling occurs. Failed exploration efforts can result in wasted resources and financial losses for developers.
• Technical Challenges : Geothermal energy production can be technically challenging, particularly in areas with low permeability or temperature gradients. Developing technologies like Enhanced Geothermal Systems (EGS) and other advanced methods aim to address these challenges, requiring additional research and development.
• Environmental Concerns : While geothermal energy is considered a clean and renewable energy source, its development can still have environmental impacts. These include land disturbance, water usage, induced seismicity, and the release of trace gases and minerals from geothermal fluids.
• Regulatory and Permitting Issues : Geothermal projects must navigate complex regulatory frameworks and obtain permits from multiple authorities. Delays in permitting can increase project costs and deter investment.
• Competition with Other Energy Sources : Geothermal energy must compete with other energy sources, such as fossil fuels, solar, wind, and hydropower. The availability and cost-effectiveness of these alternative sources can influence the development and competitiveness of geothermal projects.
• Limited Public Awareness and Support : Public awareness and support for geothermal energy are relatively low compared to other renewable energy sources. Education and outreach efforts are needed to increase awareness and promote the benefits of geothermal energy.

Case Studies

Here are a few case studies highlighting successful geothermal energy projects around the world:

• The Geysers, California, USA : The Geysers is the largest geothermal field in the world, located in California. The site has been producing electricity since the 1960s and currently has a capacity of over 700 megawatts (MW). The Geysers use steam from underground reservoirs to drive turbines and generate electricity, providing clean and renewable energy to thousands of homes in California.
• Hellisheiði Power Station, Iceland : The Hellisheiði Power Station is the second-largest geothermal power plant in the world, located near Reykjavik, Iceland. The plant has a capacity of 303 MW and utilizes a combination of steam and hot water to generate electricity. In addition to electricity generation, the plant provides hot water for district heating in Reykjavik, making it a highly efficient and sustainable energy source for the region.
• Wairakei Power Station, New Zealand : The Wairakei Power Station was the first geothermal power plant in New Zealand, commissioned in 1958. The plant has a capacity of 181 MW and has been instrumental in New Zealand’s transition to renewable energy . The Wairakei field also provides steam for the nearby Taupō District heating system, further demonstrating the versatility of geothermal energy.
• Kenya Rift Valley Geothermal Projects, Kenya : Kenya has rapidly expanded its geothermal energy capacity in the Rift Valley region. Projects like the Olkaria geothermal complex have significantly increased the country’s geothermal capacity, reducing reliance on fossil fuels and providing affordable and reliable electricity to millions of Kenyans.
• Soultz-sous-Forêts Geothermal Project, France : The Soultz-sous-Forêts project in France is an example of an enhanced geothermal system (EGS). This project involves injecting water into hot, dry rocks to create fractures and extract heat. While still in the experimental phase, EGS technology has the potential to unlock vast geothermal resources around the world.

Future Prospects

Geothermal energy holds significant promise for the future as a reliable, sustainable, and low-carbon energy source. Advancements in technology, increasing global energy demand, and the need to reduce greenhouse gas emissions are driving the growth of the geothermal energy sector. Here are some key future prospects for geothermal energy:

• Expansion of Geothermal Power Generation : The expansion of geothermal power generation is expected to continue as countries aim to meet their renewable energy targets and reduce dependence on fossil fuels. Technological advancements, such as enhanced geothermal systems (EGS) and binary cycle power plants, will enable the development of geothermal resources in regions previously considered unsuitable for traditional geothermal power generation.
• Integration with Other Renewable Energy Sources : Geothermal energy can complement other renewable energy sources, such as solar and wind, by providing reliable baseload power. Integrated energy systems that combine geothermal energy with other renewables and energy storage technologies can help ensure a stable and sustainable energy supply.
• Geothermal Heating and Cooling Solutions : The direct use of geothermal energy for heating and cooling applications is expected to grow, especially in urban areas and industries. District heating systems and geothermal heat pumps offer efficient and cost-effective heating and cooling solutions, reducing the reliance on fossil fuels and lowering carbon emissions.
• Increased Geothermal Exploration and Development : As technology improves and understanding of geothermal resources expands, exploration and development of geothermal projects will occur worldwide. Countries with high geothermal potential, such as those along the “Ring of Fire” and in geologically active regions, will likely see significant growth in geothermal energy development.
• Geothermal Energy in Developing Countries : Geothermal energy has the potential to provide reliable and sustainable energy access in developing countries with abundant geothermal resources. International cooperation and investment in geothermal projects can help these countries harness their geothermal potential and achieve energy security and economic development.
• Research and Innovation : Ongoing research and innovation in geothermal technology will drive further advancements in resource exploration, reservoir management, and energy conversion efficiency. This will help make geothermal energy more competitive with other energy sources and enhance its sustainability and environmental benefits.

Geothermal energy stands out as a reliable, sustainable, and low-carbon energy source with immense potential to meet global energy needs. Its versatility, from electricity generation to heating and cooling, makes it valuable in transitioning to a cleaner energy future. Despite facing challenges such as resource availability and upfront costs, ongoing advancements in technology and increasing global awareness are driving the growth of the geothermal energy sector. With continued support through policies, investments, and research, geothermal energy can be pivotal in reducing greenhouse gas emissions, enhancing energy security, and promoting sustainable development worldwide.

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Geothermal energy.

Geothermal energy is heat that is generated within Earth. It is a renewable resource that can be harvested for human use.

Earth Science, Geology, Engineering

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Geothermal energy  is heat that is generated within Earth. ( Geo  means “earth,” and  thermal  means “heat” in Greek.) It is a  renewable resource  that can be harvested for human use. About 2,900 kilometers (1,800 miles) below Earth’s crust, or surface, is the hottest part of our planet: the  core . A small portion of the core’s heat comes from the  friction  and  gravitational pull  formed when Earth was created more than four billion years ago. However, the vast majority of Earth’s heat is constantly generated by the decay of  radioactive   isotopes , such as potassium-40 and thorium-232. Isotopes are forms of an element that have a different number of  neutrons than the most common versions of the element’s atom.

Potassium, for instance, has 20 neutrons in its nucleus. Potassium-40, however, has 21 neutrons . As potassium-40 decays, its nucleus changes, emitting enormous amounts of energy (radiation). Potassium-40 most often decays to isotopes of calcium (calcium-40) and argon (argon-40). Radioactive decay is a continual process in the core . Temperatures there rise to more than 5,000° Celsius (about 9,000° Fahrenheit). Heat from the core is constantly radiating outward and warming rocks, water, gas, and other geological material. Earth’s temperature rises with depth from the surface to the core . This gradual change in temperature is known as the  geothermal gradient . In most parts of the world, the geothermal gradient is about 25° C per 1 kilometer of depth (1° F per 77 feet of depth). If underground rock formations are heated to about 700-1,300° C (1,300-2,400° F), they can become magma .  Magma  is molten (partly melted) rock permeated by gas and gas bubbles. Magma exists in the  mantle  and lower crust, and sometimes bubbles to the surface as  lava .

Magma heats nearby rocks and underground  aquifers . Hot water can be released through  geysers ,  hot springs , steam   vents , underwater  hydrothermal   vents , and  mud pots .

These are all sources of geothermal energy. Their heat can be captured and used directly for heat, or their steam can be used to generate  electricity . Geothermal energy can be used to heat structures such as buildings, parking lots, and sidewalks. Most of the Earth’s geothermal energy does not bubble out as magma, water, or steam. It remains in the mantle, emanating outward at a slow pace and collecting as pockets of high heat. This dry geothermal heat can be accessed by drilling, and enhanced with injected water to create steam. Many countries have developed methods of tapping into geothermal energy. Different types of geothermal energy are available in different parts of the world. In Iceland, abundant sources of hot, easily accessible underground water make it possible for most people to rely on geothermal sources as a safe, dependable, and inexpensive source of energy. Other countries, such as the U.S., must drill for geothermal energy at greater cost. Harvesting Geothermal Energy: Heating and Cooling Low-Temperature Geothermal Energy Almost anywhere in the world, geothermal heat can be accessed and used immediately as a source of heat. This heat energy is called low-temperature geothermal energy. Low-temperature geothermal energy is obtained from pockets of heat about 150° C (302° F). Most pockets of low-temperature geothermal energy are found just a few meters below ground. Low-temperature geothermal energy can be used for heating greenhouses, homes, fisheries, and industrial processes. Low-temperature energy is most efficient when used for heating, although it can sometimes be used to generate electricity. People have long used this type of geothermal energy for  engineering , comfort, healing, and cooking. Archaeological evidence shows that 10,000 years ago, groups of  Native Americans gathered around naturally occurring hot springs to  recuperate  or take  refuge  from conflict. In the third century BCE, scholars and leaders warmed themselves in a hot spring fed by a stone pool near Lishan, a mountain in central China. One of the most famous hot spring spas is in the appropriately named town of Bath, England. Starting construction in about 60 CE, Roman conquerors built an elaborate system of steam rooms and pools using heat from the region’s shallow pockets of low-temperature geothermal energy.

The hot springs of Chaudes Aigues, France, have provided a source of income and energy for the town since the 1300s. Tourists flock to the town for its elite  spas . The low-temperature geothermal energy also supplies heat to homes and businesses. The United States opened its first geothermal district heating system in 1892 in Boise, Idaho. This system still provides heat to about 450 homes. Co-Produced Geothermal Energy Co-produced geothermal energy   technology relies on other energy sources. This form of geothermal energy uses water that has been heated as a byproduct in oil and gas wells. In the United States, about 25 billion barrels of hot water are produced every year as a  byproduct . In the past, this hot water was simply discarded. Recently, it has been recognized as a potential source of even more energy: Its steam can be used to generate electricity to be used immediately or sold to the grid. One of the first co-produced geothermal energy projects was initiated at the Rocky Mountain Oilfield Testing Center in the U.S. state of Wyoming.

Newer technology has allowed co-produced geothermal energy facilities to be  portable . Although still in experimental stages, mobile power plants hold tremendous potential for isolated or impoverished communities. Geothermal Heat Pumps Geothermal heat pumps (GHPs) take advantage of Earth’s heat, and can be used almost anywhere in the world. GHPs are drilled about three to 90 meters (10 to 300 feet) deep, much shallower than most oil and natural gas wells. GHPs do not require fracturing  bedrock  to reach their energy source.

A pipe connected to a GHP is arranged in a continuous loop—called a "slinky loop"—that circles underground and above ground, usually throughout a building. The loop can also be contained entirely underground, to heat a parking lot or landscaped area. In this system, water or other liquids (such as glycerol, similar to a car’s  antifreeze ) move through the pipe. During the cold season, the liquid absorbs underground geothermal heat. It carries the heat upward through the building and gives off warmth through a duct system. These heated pipes can also run through hot water tanks and offset water-heating costs. During the summer, the GHP system works the opposite way: The liquid in the pipes is warmed from the heat in the building or parking lot, and carries the heat to be cooled underground. The U.S. Environmental Protection Agency has called geothermal heating the most energy-efficient and environmentally safe heating and cooling system. The largest GHP system was completed in 2012 at Ball State University in Indiana. The system replaced a coal -fired boiler system, and experts estimate the university will save about two million dollars a year in heating costs. Harvesting Geothermal Energy: Electricity In order to obtain enough energy to generate electricity, geothermal power plants rely on heat that exists a few kilometers below the surface of Earth. In some areas, the heat can naturally exist underground as pockets steam or hot water. However, most areas need to be “enhanced” with injected water to create steam. Dry-Steam Power Plants Dry-steam power plants take advantage of natural underground sources of steam. The steam is piped directly to a power plant, where it is used to fuel  turbines and generate electricity. Dry steam is the oldest type of power plant to generate electricity using geothermal energy. The first dry-steam power plant was constructed in Larderello, Italy, in 1911. Today, the dry-steam power plants at Larderello continue to supply electricity to more than a million residents of the area. There are only two known sources of underground steam in the United States: Yellowstone National Park in Wyoming and The Geysers in California. Since Yellowstone is a protected area, The Geysers is the only place where a dry-steam power plant is in use. It is one of the largest geothermal energy complexes in the world, and provides about a fifth of all renewable energy in the U.S. state of California.

Flash-Steam Power Plant

Flash- steam power plants use naturally occurring sources of underground hot water and steam . Water that is hotter than 182° C (360° F) is pumped into a low-pressure area. Some of the water “flashes,” or evaporates rapidly into steam , and is funneled out to power a turbine and generate electricity . Any remaining water can be flashed in a separate tank to extract more energy.

Flash-steam power plants are the most common type of geothermal power plants. The volcanically active island nation of Iceland supplies nearly all its electrical needs through a series of flash-steam geothermal power plants. The steam and excess warm water produced by the flash-steam process heat icy sidewalks and parking lots in the  frigid  Arctic winter. The islands of the Philippines also sit over a tectonically active area, the " Ring of Fire " that rims the Pacific Ocean. Government and industry in the Philippines have invested in flash-steam power plants, and today the nation is second only to the United States in its use of geothermal energy. In fact, the largest single geothermal power plant is a flash-steam facility in Malitbog, Philippines. Binary Cycle Power Plants Binary cycle power plants use a unique process to conserve water and generate heat. Water is heated underground to about 107°-182° C (225°-360° F). The hot water is contained in a pipe, which cycles above ground. The hot water heats a liquid organic compound that has a lower boiling point than water. The organic liquid creates steam, which flows through a turbine and powers a generator to create electricity. The only emission in this process is steam. The water in the pipe is recycled back to the ground, to be reheated by Earth and provide heat for the organic compound again. The Beowawe Geothermal Facility in the U.S. state of Nevada uses the binary cycle to generate electricity. The organic compound used at the facility is an industrial refrigerant (tetrafluoroethane, a  greenhouse gas ). This refrigerant has a much lower boiling point than water, meaning it is converted into gas at low temperatures. The gas fuels the turbines, which are connected to electrical generators. Enhanced Geothermal Systems Earth has virtually endless amounts of energy and heat beneath its surface. However, it is not possible to use it as energy unless the underground areas are "hydrothermal." This means the underground areas are not only hot, but also contain liquid and are  permeable . Many areas do not have all three of these components. An  enhanced geothermal system (EGS)  uses drilling, fracturing, and injection to provide fluid and permeability in areas that have hot—but dry—underground rock. To develop an EGS, an “injection well” is drilled vertically into the ground. Depending on the type of rock, this can be as shallow as one kilometer (0.6 mile) to as deep as 4.5 kilometers (2.8 miles). High-pressure cold water is injected into the drilled space, which forces the rock to create new fractures, expand existing fractures, or dissolve. This creates a reservoir of underground fluid.

Water is pumped through the injection well and absorbs the rocks’ heat as it flows through the reservoir. This hot water, called  brine , is then piped back up to Earth’s surface through a “production well.” The heated brine is contained in a pipe. It warms a secondary fluid that has a low boiling point, which evaporates to steam and powers a turbine. The brine cools off, and cycles back down through the injection well to absorb underground heat again. There are no gaseous emissions besides the water vapor from the evaporated liquid. Pumping water into the ground for EGSs can cause seismic activity, or small  earthquakes . In Basel, Switzerland, the injection process caused hundreds of tiny earthquakes that grew to more significant seismic activity even after the water injection was halted. This led to the geothermal project being canceled in 2009. Geothermal Energy and the Environment Geothermal energy is a renewable resource. Earth has been emitting heat for about 4.5 billion years, and will continue to emit heat for billions of years into the future because of the ongoing radioactive decay in Earth’s core. However, most wells that extract the heat will eventually cool, especially if heat is extracted more quickly than it is given time to replenish. Larderello, Italy, site of the world’s first electrical plant supplied by geothermal energy, has seen its steam pressure fall by more than 25 percent since the 1950s. Reinjecting water can sometimes help a cooling geothermal site last longer. However, this process can cause “micro-earthquakes.” Although most of these are too small to be felt by people or register on a scale of magnitude, sometimes the ground can quake at more threatening levels and cause the geothermal project to shut down, as it did in Basel, Switzerland.

Geothermal systems do not require enormous amounts of freshwater. In binary systems, water is only used as a heating agent, and is not exposed or evaporated. It can be recycled, used for other purposes, or released into the atmosphere as non toxic steam. However, if the geothermal fluid is not contained and recycled in a pipe, it can absorb harmful substances such as arsenic, boron, and fluoride. These toxic substances can be carried to the surface and released when the water evaporates. In addition, if the fluid leaks to other underground water systems, it can contaminate clean sources of drinking water and aquatic  habitats .

Advantages There are many advantages to using geothermal energy either directly or indirectly:

• Geothermal energy is renewable; it is not a fossil fuel that will be eventually used up. Earth is continuously radiating heat out from its core, and will continue to do so for billions of years.
• Some form of geothermal energy can be accessed and harvested anywhere in the world.
• Using geothermal energy is relatively clean. Most systems only emit water vapor, although some emit very small amounts of sulfur dioxide, nitrous oxides, and particulates.
• Geothermal power plants can last for decades and possibly centuries. If a reservoir is managed properly, the amount of extracted energy can be balanced with the rock’s rate of renewing its heat.
• Unlike other renewable energy sources, geothermal systems are “ baseload .” This means they can work in the summer or winter, and are not dependent on changing factors such as the presence of wind or sun. Geothermal power plants produce electricity or heat 24 hours a day, seven days a week.
• The space it takes to build a geothermal facility is much more  compact  than other power plants. To produce a GWh (a gigawatt hour, or one million kilowatts of energy for one hour, an enormous amount of energy), a geothermal plant uses the equivalent of about 1,046 square kilometers (404 square miles) of land. To produce the same GWh,  wind energy  requires 3,458 square kilometers (1,335 square miles), a solar  photovoltaic  center requires 8,384 square kilometers (3,237 square miles), and  coal  plants use about 9,433 square kilometers (3,642 square miles).
• Geothermal energy systems are adaptable to many different conditions.

They can be used to heat, cool, or power individual homes, whole districts, or industrial processes.

Disadvantages Harvesting geothermal energy still poses many challenges:

• The process of injecting high-pressure streams of water into the planet can result in minor seismic activity, or small earthquakes.
• Geothermal plants have been linked to  subsidence , or the slow sinking of land. This happens as the underground fractures collapse upon themselves. This can lead to damaged pipelines, roadways, buildings, and natural drainage systems.
• Geothermal plants can release small amounts of greenhouse gases such as hydrogen sulfide and carbon dioxide.
• Water that flows through underground reservoirs can pick up trace amounts of toxic elements such as arsenic, mercury, and selenium. These harmful substances can be leaked to water sources if the geothermal system is not properly insulated.
• Although the process requires almost no fuel to run, the initial cost of installing geothermal technology is expensive. Developing countries may not have the sophisticated infrastructure or start-up costs to invest in a geothermal power plant. Several facilities in the Philippines, for example, were made possible by investments from U.S. industry and government agencies. Today, the plants are Philippine-owned and operated.

Geothermal Energy and People Geothermal energy exists in different forms all over Earth (by steam vents, lava, geysers, or simply dry heat), and there are different possibilities for extracting and using this heat. In New Zealand, natural geysers and steam vents heat swimming pools, homes, greenhouses, and prawn farms. New Zealanders also use dry geothermal heat to dry timber and feedstock. Other countries, such as Iceland, have taken advantage of molten rock and magma resources from volcanic activity to provide heat for homes and buildings. In Iceland, almost 90 percent of the country’s people use geothermal heating resources. Iceland also relies on its natural geysers to melt snow, warm fisheries, and heat greenhouses. The United States generates the most amount of geothermal energy of any other country. Every year, the U.S. generates at least 15 billion kilowatt-hours, or the equivalent of burning about 25 million barrels of oil. Industrial geothermal technologies have been concentrated in the western U.S. In 2012, Nevada had 59 geothermal projects either operational or in development, followed by California with 31 projects, and Oregon with 16 projects. The cost of geothermal energy technology has gone down in the last decade, and is becoming more economically possible for individuals and companies.

Balneotherapy Balneotherapy is the treatment of disease by spa waters, usually by bathing and drinking. Some famous spas in the United States that offer balneotherapy include Hot Springs, Arkansas, and Warm Springs, Georgia. The most famous balneotheraputic spa in the world, Iceland's Blue Lagoon, is not a natural hot spring. It is an artificial feature where water from a local geothermal power plant is pumped over a lava bed rich in silica and sulfur. These elements react with the warm water to create a bright blue lake with alleged healing properties.

Geothermal Powers

Since 2015 the three countries with the greatest capacity for geothermal energy use have included the United States, Indonesia, and the Philippines. Turkey and Kenya have been steadily building geothermal energy capacity as well.

Ring of Geothermal Geothermal energy sources are often located on plate boundaries, where Earth's crust is constantly interacting with the hot mantle below. The Pacific's so-called Ring of Fire and East Africa's Rift Valley are volcanically active areas that hold enormous potential for geothermal power generation.

The Fumaroles There are no geysers at The Geysers, one of the most productive geothermal plants in the world. The California facility sits on fumarolesvents in Earth's crust where steam and other gases (not liquids) escape from Earth's interior.

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Geothermal Energy: What Is It and How Does It Work? Report

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Throughout the history of its existence, humankind has been increasingly using energy for the purposes of industrial development of civilizations. Natural resources, such as gas, coal, and oil have so far been the key sources of energy. However, as the aforementioned resources are non-renewable, the issue of using alternative sources of energy has emerged.

Among the many options investigated nowadays by the scientists, geothermal energy occupies not the last place, possessing a number of both advantages and disadvantages that make it a point of debate in the energy-seeking society.

As such, geothermal energy can be defined as the energy of the Earth (in Greek, “geo” means “earth”, and “therme” means “heat”) (California Energy Commission, 2010). Deep underneath the Earth surface, there is a thick layer of magma, liquid rock so hot that at the depth of ten thousand feet its heat would be enough to boil water.

Underground water reservoirs are sometimes situated close enough to the magma layer and warm up to over 300 degrees Fahrenheit. Nowadays people use those natural hot water reservoirs either directly, when hot water springs are located close to the surface, or indirectly, by pumping hot water and steams to the electricity generation power plants or geothermal heat pumps controlling temperature of buildings above ground (California Energy Commission, 2010).

Employing geothermal energy as an alternative to traditional energy sources is attractive due to a number of advantages. For one thing, geothermal energy is characterized by renewability and sustainability (Geothermal Education Office, 2009).

Heat radiation is emitted continuously from within the Earth, and annual precipitation regularly refills the underground reservoirs with huge amounts of water. Therefore, it is possible to sustain the production of geothermal bases for at least centuries on end. For another thing, using the renewable and sustainable geothermal energy allows for considerable saving of exhaustible and polluting resources, such as fossil fuels and nuclear materials.

Environmental impacts are thus lowered by eliminating the necessity for mining, processing and transporting fossil fuels (Geothermal Energy Association, 2010). In addition, using geothermal energy considerably reduces the risks of global warming compared to other energy sources. Geothermal energy plants have been found to emit a sufficiently low amount of the key greenhouse gas, carbon dioxide, which makes this type of energy plants an attractive environmentally friendly alternative (Geothermal Energy Association, 2010).

Along with the aforementioned attractive characteristics, the rosy prospects of geothermal energy are marred by a number of disadvantages. Firstly, due to geographical locations, geothermal sources are not universally available and are concentrated mainly along the sites with high volcanic activity.

Secondly, drilling necessary for geothermal development may be seriously hampered by peculiarities of landscape. Thus, for example, there is no question of developing geothermal energy sites in national parks which are, however, full of geysers. Thirdly, due to high concentration of silica in hot-water reservoirs, the pipes used in geothermal industry suffer high rates of corrosion and therefore require costly scaling.

In the modern world struggling to preserve the remaining exhaustible resources and satisfy the ever-growing need for energy by employing alternative sources of energy, geothermal energy appears to be one of the best solutions. Despite certain disadvantageous features like unevenness in location and costliness, geothermal energy possesses valuable characteristics of renewability and sustainability that make it an attractive alternative to fossil fuels and nuclear energy.

California Energy Commission. (2010). Geothermal Energy . Web.

Geothermal Education Office. (2009). Geothermal Energy . Retrieved from http://geothermaleducation.org/

Geothermal Energy Association. (2010). Geothermal Basics . Retrieved from http://www.geo-energy.org/geo_basics.aspx

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What Is Geothermal Energy? Definition, Examples, and How It Works

Learn all about the process of creating electricity from geothermal sources.

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• Renewable Energy
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How Does Geothermal Energy Work

Cost of geothermal energy.

• Types of Power Plants

Enhanced Geothermal Systems (EGS)

• Pros and Cons

Geothermal Energy in Iceland

Geothermal energy is power produced through the conversion of geothermal steam or water to electricity that can be used by consumers. Because this source of electricity doesn’t rely on nonrenewable resources like coal or petroleum, it can continue to provide a more sustainable source of energy into the future.

While there are some negative impacts, the process of harnessing geothermal energy is renewable and results in less environmental degradation than other traditional power sources.

Geothermal Energy Definition

Coming from the heat of the Earth’s core, geothermal energy can be used to generate electricity in geothermal power plants or to heat homes and provide hot water via geothermal heating. This heat can come from hot water that is converted into steam via a flash tank—or in rare cases, directly from geothermal steam.

Regardless of its source, it’s estimated that heat located within the first 33,000 feet, or 6.25 miles, of the Earth’s surface contains 50,000 times more energy than the world’s oil and natural gas supplies, according to the Union of Concerned Scientists.

To produce electricity from geothermal energy, an area must have three major characteristics: enough fluid, sufficient heat from the Earth’s core, and permeability that enables the fluid to interface with heated rock. Temperatures should be at least 300 degrees Fahrenheit to produce electricity, but need only exceed 68 degrees for use in geothermal heating.

Fluid can be naturally occurring or pumped into a reservoir, and permeability can be created through stimulation—both through a technology known as enhanced geothermal systems (EGS).

Naturally occurring geothermal reservoirs are areas of the Earth’s crust from which energy can be harnessed and used to produce electricity. These reservoirs occur at various depths throughout the Earth’s crust, can be either vapor- or liquid-dominated, and are formed where magma travels close enough to the surface to heat groundwater located in fractures or porous rocks. Reservoirs that are within one or two miles of the Earth’s surface can then be accessed via drilling. To exploit them, engineers and geologists must first locate them, often by drilling test wells.

First Geothermal Power Plant in the US

The first geothermal wells were drilled in the U.S. in 1921, eventually leading to the construction of the first large-scale geothermal electricity-generating power plant in the same location, The Geysers , in California. The plant, operated by Pacific Gas and Electric, opened its doors in 1960.

The process of capturing geothermal energy involves using geothermal power plants or geothermal heat pumps to extract high-pressure water from the underground. After reaching the surface, the pressure is lowered and the water converts to steam. The steam rotates turbines that are connected to a power generator, thereby creating electricity. Ultimately, cooled steam condenses into water that is pumped underground via injection wells. 

Treehugger / Hilary Allison

Here’s how geothermal energy capture works in greater detail:

1. Heat From the Earth’s Crust Creates Steam

Geothermal energy comes from the steam and high-pressure hot water that exist in the Earth’s crust. To capture the hot water necessary to power geothermal power plants, wells extend as deep as 2 miles under Earth’s surface. Hot water is transported to the surface under high pressure until the pressure is dropped above ground—converting the water into steam.

Under more limited circumstances, steam comes directly out of the ground, rather than first being converted from water, as is the case at The Geysers in California.

2. Steam Rotates Turbine

Once the geothermal water is converted to steam above the Earth’s surface, the steam rotates a turbine. The turning of the turbine creates mechanical energy that can ultimately be converted to useful electricity. The turbine of a geothermal power plant is connected to a geothermal generator so that when it rotates, energy is produced.

Because geothermal steam typically includes high concentrations of corrosive chemicals like chloride, sulfate, hydrogen sulfide, and carbon dioxide, turbines must be made of materials that resist corrosion.

3. Generator Produces Electricity

The rotors of a turbine are connected to the rotor shaft of a generator. When the steam turns the turbines, the rotor shaft rotates and the geothermal generator converts the kinetic—or mechanical—energy of the turbine into electrical energy that can be used by consumers.

4. Water Is Injected Back Into the Ground

When the steam used in hydrothermal energy production cools, it condenses back into water. Likewise, there may be leftover water that isn’t converted into steam during energy generation. To improve the efficiency and sustainability of geothermal energy production, excess water is treated and then pumped back into the underground reservoir via deep well injection. 

Depending on the geology of the region, this may take high pressure or none at all, as in the case of The Geysers, where water simply falls down the injection well.   Once there, the water is reheated and may be used again.

Geothermal energy plants require high initial costs, often about $2,500 per installed kilowatt (kW) in the United States. That said, once a geothermal energy plant is complete, operation and maintenance costs are between $0.01 and $0.03 per kilowatt-hour (kWh)—relatively low compared to coal plants, which tend to cost between $0.02 and $0.04 per kWh.

What’s more, geothermal plants can produce energy more than 90% of the time, so the cost of operation can be covered easily, especially if consumer power costs are high.

Types of Geothermal Power Plants

Geothermal power plants are the aboveground and underground components by which geothermal energy is converted to useful energy—or electricity. There are three major types of geothermal plants: 

In a traditional dry steam geothermal power plant, steam travels directly from the underground production well to the aboveground turbine, which turns and generates power with the help of a generator. Water is then returned underground via an injection well.

Notably, The Geysers in northern California and Yellowstone National Park in Wyoming are the only two known sources of underground steam in the United States.  

The Geysers, located along the border of Sonoma and Lake County in California, was the first geothermal power plant in the U.S. and covers an area of about 45 square miles. The plant is one of just two dry steam plants in the world, and actually consists of 13 individual plants with a combined generating capacity of 725 megawatts of electricity.

Flash Steam

Flash steam geothermal plants are the most common in operation, and involve extracting high-pressure hot water from underground and converting it to steam in a flash tank. The steam is then used to power generator turbines; cooled steam condenses and is injected via injection wells. Water must be over 360 degrees Fahrenheit for this type of plant to operate.  

Binary Cycle

The third type of geothermal power plant, binary cycle power plants, rely on heat exchangers that transfer the heat from underground water to another fluid, known as the working fluid, thereby turning the working fluid into steam. Working fluid is typically an organic compound like a hydrocarbon or a refrigerant that has a low boiling point. The steam from the heat exchanger fluid is then used to power the generator turbine, as in other geothermal plants.

These plants can operate at a much lower temperature than required by flash steam plants—just 225 degrees to 360 degrees Fahrenheit.

Also referred to as engineered geothermal systems, enhanced geothermal systems make it possible to access energy resources beyond what’s available through traditional geothermal power generation.

EGS extracts heat from the Earth by drilling into bedrock and creating a subsurface system of fractures that can be pumped full of water via injection wells.

With this technology in place, the geographic availability of geothermal energy can be extended beyond the Western United States. In fact, EGS may help the U.S. increase geothermal energy generation to 40 times current levels. This means that EGS technology can provide around 10% of the current electric capacity in the U.S.

• Geothermal Energy Pros and Cons

Geothermal energy has huge potential for creating cleaner, more renewable energy than is available with more traditional sources of power like coal and petroleum. However, as with most forms of alternative energy, there are both pros and cons of geothermal energy that must be acknowledged. 

Some advantages of geothermal energy include:

• Cleaner and more sustainable. Geothermal energy is not only cleaner, but more renewable than traditional sources of energy like coal. This means that electricity can be generated from geothermal reservoirs for longer and with a more limited impact on the environment. 
• Small footprint. Harnessing geothermal energy requires only a small footprint of land, making it easier to find suitable locations for geothermal plants.
• Output is increasing. Continuing innovation in the industry will result in higher output over the next 25 years. In fact, production is likely to increase from 17 billion kWh in 2020 to 49.8 billion kWh in 2050.  

Disadvantages include:

• Initial investment is high. Geothermal power plants require a high initial investment of around $2,500 per installed kW, compared to about $1,600 per kW for wind turbines. That said, the initial cost of a new coal power plant may be as high as $3,500 per kW.
• Can lead to increased seismic activity. Geothermal drilling has been linked to increased earthquake activity, especially when EGS is used to increase energy production.
• Results in air pollution. Due to the corrosive chemicals often found in geothermal water and steam, like hydrogen sulfide, the process of producing geothermal energy can cause air pollution.

A pioneer in the generation of geothermal and hydrothermal energy, Iceland’s first geothermal plants went online in 1970. Iceland’s success with geothermal energy is due in large part to the country’s high number of heat sources, including numerous hot springs and more than 200 volcanoes.  

Geothermal energy currently constitutes about 25% of Iceland’s total production of energy. In fact, alternative energy sources account for almost 100% of the nation’s electricity. Beyond dedicated geothermal plants, Iceland also relies on geothermal heating to help heat homes and domestic water, with geothermal heating servicing about 87% of buildings in the country.  

Some of Iceland’s largest geothermal power plants are:

• Hellisheiði Power Station. The Hellisheiði power plant generates both electricity and hot water for heating in Reykjavik, enabling the plant to use water resources more economically. Located in southwest Iceland, the flash steam plant is the largest combined heat and power plant in the country and one of the largest geothermal power plants in the world, with a capacity of 303 MWe (megawatt electrical) and 133 MWth (megawatt thermal) of hot water. The plant also features a reinjection system for non-condensable gases to help reduce hydrogen sulfide pollution.  
• Nesjavellir Geothermal Power Station. Located on the Mid-Atlantic Rift, the Nesjavellir Geothermal Power Station produces about 120 MW of electrical power and about 293 gallons of hot water (176 degrees to 185 degrees Fahrenheit) per second. Commissioned in 1998, the plant is the second-largest in the country.
• Svartsengi Power Station. With an installed capacity of 75 MW for electricity production and 190 MW for heat, the Svartsengi plant was the first plant in Iceland to combine electricity and heat production. Coming online in 1976, the plant has continued to grow, with expansions in 1999, 2007, and 2015.

To ensure the economic sustainability of geothermal power, Iceland employs an approach called stepwise development. This involves evaluating the conditions of individual geothermal systems in order to minimize the long-term cost of producing energy. Once the first productive wells are drilled, the production of the reservoir is evaluated and future development steps are based on that revenue.

From an environmental standpoint, Iceland has taken steps to reduce the impacts of geothermal energy development through use of environmental impact assessments that evaluate criteria like air quality, drinking water protection, and aquatic life protection when choosing plant locations.

Air pollution concerns related to hydrogen-sulfide emissions have also risen considerably as a result of geothermal energy production. Plants have addressed this by installing gas capture systems and injecting acid gases underground.  

Iceland’s commitment to geothermal energy extends beyond its borders to Eastern Africa, where the country has partnered with the United Nations Environment Programme (UNEP) to expand access to geothermal energy.

Sitting on top of the Great East African Rift System—and all of the associated tectonic activity—the area is particularly well-suited to geothermal energy. More specifically, the UN agency estimates that the region, which is often subject to serious energy shortages, could produce 20 gigawatts of electricity from geothermal reservoirs.

“ How Geothermal Energy Works .” Union of Concerned Scientists .

“ Electricity Generation .” U.S. Department of Energy.

" Geothermal Basics ." U.S. Department of Energy .

" Use of Geothermal Energy ." U.S. Energy Information Agency .

“ A History of Geothermal Energy in America .” U.S. Department of Energy.

“ Geothermal Explained: Geothermal Power Plants .” U.S. Energy Information Administration .

Sakai, Yoshihiro, et al. “ The Latest Geothermal Steam Turbines .” Fuji Electric Systems Co., Ltd .

National Research Council. Induced Seismicity Potential in Energy Technologies . The National Academies Press. 2013.

“ Geothermal FAQs .” U.S. Department of Energy.

“ U.S. Coal Plant Retirements Linked to Plants with Higher Operating Costs .” U.S. Energy Information Administration .

“ Geothermal Electricity Production Basics .” National Renewable Energy Laboratory.

“ About Geothermal Energy .” Calpine .

" How an Enhanced Geothermal System Works ." U.S. Department of Energy .

“ Geothermal Energy Factsheet .” University of Michigan .

“ Construction Costs for Most Power Plant Types Have Fallen in Recent Years .” U.S. Energy Information Agency .

“ Coal-Fired Power Plant Construction Costs .” Synapse Energy Economics .

" Protocol for Addressing Induced Seismicity Associated with Enhanced Geothermal Systems ." U.S. Department of Energy .

“ Iceland, a World Leader in Clean Energy, Supports Africa's Push for Geothermal Power .” U.N. Environment Programme .

“ Geothermal .” Orkustofnun National Energy Authority.

“ The World's Largest Geothermal Heating System Saves up to 4M Tons CO2 Annually .” C40 Cities .

Hallgrímsdóttir, Elin, et al. “ The Geothermal Power Plant at Hellisheiði, Iceland .” GRC Transactions , vol. 36, 2012, pp. 1067-1072.

Ballzus, Claus, et al. “ The Geothermal Power Plant at Nesjavellir, Iceland .” Proceedings World Geothermal Congress 2000, pp. 3109-3114.

“ Svartsengi Power Plant. ” HS Orka .

“ Sustainable Utilisation .” Orkustofnun National Energy Authority .

Wanqing, Cheng. “ Environmental Impact of Geothermal Development in the Ísafjardarbaer Area, NW-Iceland .” The United Nations University, reports 2001, no. 2.

Berstad, David, and Lars O. Nord. “ Acid Gas Removal in Geothermal Power Plant in Iceland .” Energy Procedia , vol. 86, 2016, pp. 32-40., doi:10.1016/j.egypro.2016.01.004

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The debates around renewable sources of energy have been going on at least a decade. After more than a century of relying on fossil fuels almost entirely, changing this paradigm in favor of the renewable energy sources may seem difficult and unjustified for some people. However, the situation when fossil fuel was the most efficient and the cheapest source of energy has been left far in the past; nowadays, it is obvious that using oil or gas is not only expensive, but also causes tremendous damage to the planet we live on. Many countries such as Germany or Sweden have already made significant efforts to fix this situation, employing numerous power plants working on the renewable sources of energy; the most effective among these sources is geothermal energy. Using it has a number of benefits which should be considered by governments globally. Geothermal energy—and in particular, the prices of it—does not depend on the world’s economic and political situation as strongly as fossil fuels do. Besides, extracting and transporting fossil fuel adds up to the price of energy produced from it. In its turn, geothermal energy is much cheaper than conventional ones, involving low-running costs and saving up to 80% of costs over fossil fuels ( CEF ).

Environmental friendliness is another benefit of geothermal energy. Being a renewable source, it definitely produces less waste and pollution than conventional energy sources; the exact indexes, however, depend on the systems used for producing geothermal energy. In open-loop geothermal systems, carbon dioxide makes up about 10% of air emissions; an even smaller percentage of emissions is methane. Overall, open-loop geothermal systems produce 0.1 pounds of carbon dioxide and other harmful gases per kilowatt-hour of the energy produced. In closed-loop systems, the greenhouse gases are not released into the atmosphere, although a relatively small amount of such emissions can be produced during a geothermal power plant’s construction. For a comparison, a power plant producing electricity from gas releases up to 2 pounds of carbon dioxide per kilowatt-hour into the atmosphere, and those power plants that work on coal produce an astonishing 3.6 pounds of greenhouse gases per kilowatt-hour of energy produced. As it can be seen, even less advanced open-loop geothermal systems are much cleaner and safer for ecology than the power plants working on conventional energy sources ( UCS ).

Low maintenance costs make yet another reason why using geothermal power plants should be a priority for many countries. Geothermal heat pump systems require 25% to 50% less energy for work compared to the conventional systems for heating or cooling. Besides, geothermal equipment is less bulky, so it requires less space: due to the very nature of geothermal energy (which is extracted from the bowels of the planet), geothermal power plants have only a few moving parts, all of which can be easily sheltered inside a relatively small building. This is not to mention that the life span of geothermal equipment is rather long: up to 50 years for pipes, and up to 20 years for pumps ( GreenMatch ). All this makes geothermal power stations easy to build and maintain.

As it can be seen, using geothermal energy is more effective than energy produced from conventional sources of energy. Geothermal energy is cheaper, less harmful for the environment, and power plants producing it are easier to build and maintain. These factors make geothermal energy a reasonable and effective alternative to energy produced from fossil fuels, so the governments of the world should consider converting their industries to work on geothermal energy.

Works Cited

• “Advantages of Geothermal Energy.” ConserveEnergyFuture . N.p., 20 Jan. 2013. Web. 26 Sept. 2016.
• “Environmental Impacts of Geothermal Energy.” Union of Concerned Scientists . N.p., n.d. Web. 26 Sept. 2016.
• “Advantages and Disadvantages of Geothermal Energy.” GreenMatch . N.p., n.d. Web. 26 Sept. 2016.

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Essay on geothermal energy: top 11 essays | energy management.

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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 Effect of Geothermal Energy on Environment

Essay # 1. Introduction to Geothermal Energy:

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.

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.

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.

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.

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 10 31 joules (3. 10 15 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 (CO 2 ), hydrogen sulphide (H 2 S), methane (CH 4 ) and ammonia (NH 3 ). 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 CO 2 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.

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Geothermal Energy as The Solution to The 21st Century Problem of Energy

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Geothermal Energy: A Review

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7 Examples of Geothermal Energy

Geothermal, the word has been derived from two words ‘geo’ and ‘thermal’. Geo refers to the earth, while thermal is related to heat. Therefore, geothermal energy is the heat or the thermal energy extracted from the earth. The radioactive decay and the late heavy bombardment period is responsible for the development and confinement of heat into the earth’s core. The earth’s core is estimated to be present about 6,427 km below the ground and has a temperature of about 4200 degrees Celcius. Since the earth is located in a free space that serves to be a vacuum, the cooling down of this trapped heat energy will take a lot of time. Therefore, ensuring energy generation for billions of years. Geothermal energy can be extracted from solid rocks or from molten magma. It is a reliable, renewable, and clean source of energy generation. Geothermal energy has a minimum contribution to air pollution because it does not involve any combustion of fossil fuels. Therefore, no toxic gases are released into the environment. In comparison to other sources of energy generation, geothermal energy produces 6 times less carbon dioxide into the environment. However, greenhouse emissions, adverse environmental effects, generation setup cost, etc. are some of the disadvantages of using geothermal energy. The depletion of geothermal energy is unpredictable, hence it is considered as one of the greatest disadvantages. Geothermal energy has great potential and is considered to be a technology of the future. Hence, it guarantees employment generation and development of the nation.

1. Geothermal Heated Homes

Geothermal energy finds its prime application in heating homes. An ideal geothermal heat pump is connected to a large system of coils that extracts the heat from the ground. This heat is then circulated inside the home with the help of traditional ducts. This system is established in such a way that this process can be modified according to the seasons. During summers, this large system of coils is filled with water and an antifreeze solution. The heat present inside a house is transferred to the earth, thereby cooling down the environment inside the house.

2. Geothermal Power Plants

Thermal energy present beneath the earth’s surface can be used to generate electricity. Geothermal power systems make use of steam from the earth to generate electrical energy. This steam is used to rotate the turbines at a high speed. Setting these turbines in motion, i.e. after causing the turbines to develop mechanical energy, the mechanical energy is fed to the electricity generation system. The electricity generating system mainly comprises a generator, which converts mechanical energy into electrical energy with the help of electromagnetic induction. This process is very reliable and eco-friendly as it does not release any toxic or carbon-rich gases into the environment. Also, it does not leave any residue behind. Therefore, there exists no land pollution, which further avoids waste management. Geothermal energy is advantageous as it provides consistency, stability, and renewability.

3. Hot Springs

There are a number of natural hot springs present on the earth. Hot springs are formed when the water present underground comes in contact with a hot rock. The water gets heated up and geological heat emerges out. These springs serve to be places of great interest to the tourists. Therefore, geothermal energy can be used to generate economic benefits and to generate employment for the youth. Hot springs are one of the most easily accessible applications of geothermal energy. People often take a bath in hot springs as recreational activities. The only inconvenience is the pungent smell of sulfur present in or near an open hot spring.

4. Geothermal Geysers

Geothermal geysers are very much similar to geothermal hot springs. The only difference is that in a geothermal geyser the water flows in the form of a vertical column that is several feet high. The most popular geothermal geyser is known as Old Faithful located in Yellowstone National Park in the United States. The Old Faithful geyser erupts every 60-90 minutes. The requirements for the existence of a geothermal geyser are a water source present under the earth’s surface, a vent present on the surface of the earth, and hot underground rocks.

5. Green Houses

If a lake is present near a greenhouse, it is of most important use. A heating coil network is established under the lake, and the water is added with the anti-freezing solution. The steam or the gas generated due to this internal heat is then fed to the greenhouses. This heat produced by the earth is responsible for the maintenance of temperature inside the greenhouse. The main requirements of a greenhouse are proper heat and temperature, both of which are easily supplied by employing geothermal energy.

6. Fumarole

When the water present underground comes in contact with hot rock or magma, it gets heated up and emerges out through a vent. This vent is called a fumarole. Fumaroles can be formed when there exists a crack or opening on the surface of the earth. Therefore, a fumarole is basically an opening near a volcano or hot spring. This is yet another example of geothermal energy as the heat or the thermal energy required for the generation of a fumarole is extracted from the earth’s surface only. The extraction of heat energy, however, does not require any pump because it follows a natural process of genesis. Hence, it is directly accessible and only requires a little modification. The disadvantage is that sometimes fumaroles arbitrarily go missing. However, they might reappear as per the earth’s self clock. Hence, causes instability to properly utilize energy.

Health and wellness related activities make use of geothermal energy. Spas and other related services make use of hot springs and fumaroles to generate heat and steam. Geothermal energy has been used in this manner for a long time. This method serves to be an inexpensive, natural, and effective way to achieve personal care benefits. A geothermal opening present near a spa serves to be the greatest asset because it is an infinitely available and easily accessible source of energy.

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Geothermal Energy

Geothermal energy is heat energy from the earth—geo (earth) + thermal (heat).

Geothermal resources are reservoirs of hot water that exist or are human-made at varying temperatures and depths below the earth's surface. Wells, ranging from a few feet to several miles deep, 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, including: 

Deep underground, the presence of hot rocks, fluid, and permeability (the ability for that fluid to move among the rocks) offer conditions from which electricity can be generated. Using natural or human-made permeability and fractures, the fluid flows through the hot rocks, absorbing heat from the rocks that can be drawn up through wells to Earth’s surface. That heat energy is then converted to steam, which drives turbines that produce electricity. Learn more about geothermal electricity generation .

Heating and Cooling  

Geothermal resources such as naturally occurring underground reservoirs of hot water or the stable temperature of the subsurface can be used to heat and cool buildings. Geothermal heat pumps provide heating and cooling using the ground as a heat sink , absorbing excess heat when the aboveground temperatures are warmer, and as a heat source when aboveground temperatures are cooler. District heating and cooling systems use one or more types of geothermal systems, such as a  series of geothermal heat pumps, in order to heat and cool groups of buildings, campuses, and even entire communities. Learn more about geothermal heating and cooling . 

Geothermal direct use applications  use wells—usually deeper than those for heat pumps—to draw hot water from the subsurface to directly provide hot water to buildings, space heating, or heat for industrial processes ranging from fish farming and greenhouses to drying pulp, paper, lumber, and other materials. Learn more about direct use .

Benefits of Geothermal Energy

Renewable —The heat flowing from Earth’s interior is continually replenished by the decay of naturally occurring radioactive elements and will remain available for billions of years.

Firm and Flexible —Geothermal power plants produce electricity consistently and can run essentially 24 hours per day/7 days per week, regardless of weather conditions. They can also ramp generation up or down to respond to changes in electricity demand.

Domestic —U.S. geothermal resources can be harnessed for power production and heating and cooling without importing fuel.

Small footprint —Geothermal power plants and geothermal heat pumps are compact. Geothermal power plants use less land per gigawatt-hour (404 m 2 ) than comparable-capacity coal (3,642 m 2 ), wind (1,335 m 2 ), and solar photovoltaic (PV) power stations (3,237 m 2 ) ( source ). GHPs can be retrofitted or integrated in new buildings.

Clean —Modern geothermal power plants emit no greenhouse gasses and have life cycle emissions four times lower than solar PV, and six to 20 times lower than natural gas. Geothermal power plants consume less water on average over the lifetime energy output than most conventional electricity-generation technologies ( source ). 

See how we can generate clean, renewable energy from hot water sources deep beneath the Earth's surface. The video highlights the basic principles at work in geothermal energy production and illustrates three different ways the earth's heat can be converted into electricity.

U.S. Geothermal Growth Potential

The 2019 GeoVision analysis indicates potential for up to 60 gigawatts of electricity-generating capacity, more than 17,000 district heating systems, and up to 28 million geothermal heat pumps by 2050. If we realize those maximum projections across sectors, it would be the emissions reduction equivalent of taking 26 million cars off U.S. roads every year . 

In 2022, the Enhanced Geothermal Shot™ analysis confirmed the potential for even more geothermal electricity-generating capacity— 90 gigawatts by 2050 —if we can achieve aggressive cost reductions in enhanced geothermal systems. Next-Generation Geothermal Power report even identified the potential for up to 300 GW of next-generation geothermal electricity generation, depending on the development of storage capabilities and other emerging technologies. 

Resources and Initiatives:

Geothermal Everywhere Initiatives

Geothermal Glossary

U.S. Department of Energy Geothermal Technologies Office

The U.S. Department of Energy (DOE) Geothermal Technologies Office (GTO) focuses on realizing the potential to generate electricity and produce heating and cooling for U.S. homes from clean, domestic geothermal resources. To do so, GTO works in partnership with industry, academia, DOE's  national laboratories , and others on research, development, and demonstration activities focused on these areas:

• Enhanced Geothermal Systems (EGS) – Advancing the commercial viability of EGS (human-made geothermal energy).
• Hydrothermal Resources – Advancing technologies to expand electricity generation using naturally occurring geothermal resources and value-added opportunities like lithium extraction. 
• Low-Temperature and Coproduced Resources - Improving the efficiency and expanding the utility of low-temperature (<300° F) geothermal systems such as geothermal heat pumps and district heating and cooling systems. 
• Data, Modeling, and Analysis - Addressing nontechnical barriers to geothermal deployment through environmental and resource assessments, data stewardship, and analytical tools.

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Geothermal Energy

These underground reservoirs of steam and hot water can be tapped to generate electricity or to heat and cool buildings directly.

Geothermal energy has been used for thousands of years in some countries for cooking and heating. It is simply power derived from the Earth’s internal heat.

This thermal energy is contained in the rock and fluids beneath Earth’s crust . It can be found from shallow ground to several miles below the surface, and even farther down to the extremely hot molten rock called magma .

How Is It Used?

A geothermal heat pump system can take advantage of the constant temperature of the upper ten feet (three meters) of the Earth’s surface to heat a home in the winter, while extracting heat from the building and transferring it back to the relatively cooler ground in the summer.

Geothermal water from deeper in the Earth can be used directly for heating homes and offices, or for growing plants in greenhouses. Some U.S. cities pipe geothermal hot water under roads and sidewalks to melt snow.

Production of Geothermal Energy

To produce geothermal-generated electricity, wells, sometimes a mile (1.6 kilometers) deep or more, are drilled into underground reservoirs to tap steam and very hot water that drive turbines linked to electricity generators. The first geothermally generated electricity was produced in Larderello, Italy, in 1904.

There are three types of geothermal power plants: dry steam, flash, and binary. Dry steam, the oldest geothermal technology, takes steam out of fractures in the ground and uses it to directly drive a turbine. Flash plants pull deep, high-pressure hot water into cooler, low-pressure water. The steam that results from this process is used to drive the turbine. In binary plants, the hot water is passed by a secondary fluid with a much lower boiling point than water. This causes the secondary fluid to turn to vapor, which then drives a turbine. Most geothermal power plants in the future will be binary plants.

Geothermal energy is generated in over 20 countries. The United States is the world’s largest producer, and the largest geothermal development in the world is The Geysers north of San Francisco in California. In Iceland, many of the buildings and even swimming pools are heated with geothermal hot water. Iceland has at least 25 active volcanoes and many hot springs and geysers.

Advantages and Disadvantages

There are many advantages of geothermal energy. It can be extracted without burning a fossil fuel such as coal, gas, or oil. Geothermal fields produce only about one-sixth of the carbon dioxide that a relatively clean natural-gas-fueled power plant produces. Binary plants release essentially no emissions. Unlike solar and wind energy, geothermal energy is always available, 365 days a year. It’s also relatively inexpensive; savings from direct use can be as much as 80 percent over fossil fuels.

But it has some environmental problems. The main concern is the release of hydrogen sulfide, a gas that smells like rotten egg at low concentrations. Another concern is the disposal of some geothermal fluids, which may contain low levels of toxic materials. Although geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down.

Related Topics

• GEOTHERMAL ENERGY
• EARTH SCIENCES

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Geothermal energy essay.

This Geothermal Energy Essay example is published for educational and informational purposes only. If you need a custom essay or research paper on this topic, please use our writing services. EssayEmpire.com offers reliable custom essay writing services that can help you to receive high grades and impress your professors with the quality of each essay or research paper you hand in.

Geothermal energy is derived from heat within the earth. Earth’s internal heat is due to the residual heat that was produced when Earth formed, in addition to heat generated by radioactive decay. Earth’s temperature increases with depth below the surface. The inner core has a temperature of about 4,000 degrees C. The increase in temperature with depth is referred to as the geothermal gradient. A normal geothermal gradient is 15 to 30 degrees Cl kilometer. The geothermal gradient is much higher, double or triple, in areas of recent volcanic activity. Generally, the higher the geothermal gradient, the higher the heat flow to the surface.

Generally, geothermal energy is tapped either by drilling wells into bedrock and allowing hot water and steam to flows up to turn a turbine on or near the surface. Usually the water and steam extracted is routed back into the subsurface to close the circuit and add pressure for extraction.

The world’s major geothermal energy fields are associated with areas of active or recent volcanism. The Pacific Rim of Fire has many developed geothermal fields associated with subduction zone volcanism associated with the convergence of tectonic plates. Some of the popular geothermal areas include New Zealand, Indonesia, the Philippines, Japan, northern California, Mexico, and several countries in Central America.

Iceland is located along the Mid-Atlantic Ridge, a divergent plate boundary. Icelanders use geothermal energy to the extent that, together with hydropower, they are able to supply electricity and heat to the entire island. Because of this, Iceland is independent of fossil fuels except as an automobile fuel.

The geothermal fields at Lardarello, Italy, are the oldest in the world. They were developed in the early 1900s utilizing dry steam. This geyser and hot spring area is associated with the recently active volcanism north of Rome. The geothermal fluids have a high content of boric acid, which is utilized along with the heat.

In areas of high geothermal gradient, the geothermal resources occur as hot or dry steam, or hot water that circulates through a permeable zone, such as Yellowstone National Park. The hot water or steam can be used as a direct source of heat or as a source of mechanical energy to turn turbines and generate electricity. Circulation is usually deep, but more recently the circulation of shallow groundwater in areas of high heat flow has been utilized.

Hot dry rocks occur in areas where magma or recently solidified magma is isolated from groundwater. Hot dry rocks require that water be pumped into the ground and recycled to extract the power. Temperatures can reach as high as 1,200 degrees C, depending on the type of magma.

Geopressurized systems are associated with areas of deep burial such as along the Gulf Coast of the United States, where the normal heat flow is trapped by insulating layers of sediment. Along the Gulf Coast, temperatures reach over 270 degrees C at depths of 4 to 7 kilometers.

Areas of normal geothermal gradient are extremely common but have a low level of energy. Geothermal heat pumps utilize lower geothermal gradient, and may therefore be useful in most areas, whether or not they are close to volcanic centers.

Geothermal energy is a relatively clean and environmentally friendly source of energy. Adverse effects occur mainly in the form of gas emissions, and thermal and chemical pollution from the wastewater. Geothermal energy is considered a renewable resource because there is no practical limit to the supply of this energy.

Bibliography:

• Wendell A. Duffield and John Sass, Geothermal Energy: Clean Power from the Earth’s Heat (U.S. Geological Survey, 2003);
• S. Department of Energy, Geothermal Division, Geothermal Energy, the Environmentally Responsible Energy Technology for the Nineties (U.S. Department of Energy, 1993).
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Best Earth Essay Examples

Geothermal energy.

350 words | 2 page(s)

Geothermal energy refers to heat energy stored in the Earth’s surface and crust, where energy is naturally produced by the Earth’s seismic activity. Hot springs are the most common observable source of this type of energy being produced naturally. Geothermal energy production is the process of capturing this energy, such as using hot springs to power generators, which in turn produces usable electricity (Boyle, 2004).

The main advantage of geothermal energy is that it is naturally produced, does not create much pollution, and theoretically limitless due to constant seismic activity. However, the main challenge with this form of energy is that it tends to be concentrated in areas where there is notable seismic activity, so only limited areas can be used for generator placement (Barbier, 2002). Also under current technologies, the cost of producing a sizable amount of energy from geothermal sources is substantial, so there is a current barrier in regard to geothermal investments. However, in areas where geothermal activity is present, such as in parts of Nevada, Idaho, Montana and other western states, there is considerable opportunity for the investment of geothermal energy sources that could be used to produce electricity (Dickson and Fanelli, 2013).

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Geothermal energy remains a potential source of sustainable energy that the United States could develop, and in doing so, creating more renewable energy sources that would reduce the reliance on the import of energy and fossil fuels from foreign sources. The barriers to this form of energy are a matter of cost, rather than capability; if these costs can be reduced, and technology can be developed that would be able to transport this available power to parts of the country where there is not as much seismic activity, then geothermal energy has significant potential over the long term. The more the United States is able to generate its own energy, the less reliance it has on foreign energy sources.

• Barbier, E. (2002). Geothermal energy technology and current status: an overview. Renewable and Sustainable Energy Reviews, 6(1), 3-65.
• Boyle, G. (Ed.). (2004). Renewable energy. Oxford: Oxford University Press.
• Dickson, M. H., & Fanelli, M. (2013). Geothermal energy: utilization and technology. Routledge.

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Geothermal Energy: Harnessing the Earth's Heat for Sustainable Power

Geothermal energy is a powerful and sustainable source of renewable energy derived from the Earth's internal heat. It harnesses the natural geothermal gradient, using the Earth's subsurface temperatures to produce electricity and provide heating and cooling for various applications. This essay delves into the utilization of geothermal energy, exploring the mechanisms of geothermal power generation, its benefits, and its potential role in the transition to a more sustainable energy future.

The Earth's core is a hot and molten region, with temperatures reaching several thousand degrees Celsius. This intense heat radiates outward, creating a geothermal gradient, which means that temperatures increase with depth below the Earth's surface. In certain regions, such as near tectonic plate boundaries or volcanic areas, this geothermal gradient is more pronounced, creating ideal conditions for harnessing geothermal energy.

Geothermal power generation typically involves tapping into geothermal reservoirs, which are underground reservoirs of hot water and steam. To access these reservoirs, wells are drilled deep into the Earth's crust. The heat from the geothermal reservoirs is used to produce steam, which drives turbines connected to generators to produce electricity.

There are several types of geothermal power plants, including dry steam, flash steam, and binary cycle plants. Dry steam power plants utilize steam directly from the geothermal reservoirs to power turbines. Flash steam power plants use high-pressure hot water from the reservoirs to produce steam that drives turbines. Binary cycle power plants use low-temperature geothermal resources to heat a working fluid, such as isobutane, which then vaporizes and drives turbines.

Geothermal energy offers numerous advantages as a renewable energy source. First and foremost, it is a continuous and reliable source of power, as the Earth's internal heat is essentially inexhaustible. Unlike solar and wind energy, which are intermittent and dependent on weather conditions, geothermal energy is available 24/7, providing a stable and constant power supply.

Moreover, geothermal power plants have a relatively small environmental footprint. Once the geothermal wells are drilled, they have a long lifespan, and the land used for geothermal power generation can often be shared with other activities, such as agriculture or recreation.

Geothermal energy also produces minimal greenhouse gas emissions compared to fossil fuels. The use of geothermal energy helps to reduce the reliance on carbon-intensive energy sources, contributing to global efforts to combat climate change and lower greenhouse gas emissions.

Additionally, geothermal energy has the potential for decentralized power generation. It can be harnessed locally, reducing the need for long-distance transmission of electricity and increasing energy security for remote or isolated communities.

Despite its many benefits, geothermal energy faces challenges and limitations. The availability of suitable geothermal resources is geographically limited, and the cost of drilling and developing geothermal wells can be high. However, advancements in drilling technology and exploration techniques are gradually expanding the reach and accessibility of geothermal energy.

In conclusion, geothermal energy offers a sustainable and reliable source of renewable power, tapping into the Earth's heat to generate electricity and provide heating and cooling for various applications. Its continuous availability, minimal environmental impact, and potential for decentralized power generation make it an attractive option in the transition to a more sustainable energy future. As global efforts to combat climate change intensify, geothermal energy holds promise as a vital component of the diverse and interconnected energy mix needed to meet our energy needs while preserving the planet for future generations.

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THE BIG PICTURE: Geothermal Power Landscape (Infographic)

According to the Global Geothermal Power Tracker (GGPT), a comprehensive dataset of geothermal power facilities, about 14 GW of geothermal power is operational worldwide.

The U.S. has the largest installed capacity at 3,900 MW, followed by Indonesia (2,418 MW), the Philippines (1,952 MW), Türkiye (1,691 MW), New Zealand (1,042 MW), and Kenya (985 MW). Most of the world’s operating geothermal fleet consists of flash power plants, which operate at higher temperatures and directly convert geothermal fluids into steam that drives a turbine.

About 1.6 GW reportedly uses binary cycle technology, which operates at a lower temperature than flash plants, using organic Rankine cycle (ORC) turbine technology, where subsurface fluids heat a secondary fluid to drive a turbine. Interest is also growing in enhanced geothermal systems (EGS) , which employ a subsurface circuit of multiple wells and fractures containing a fluid heated by a geothermal resource through direct contact with the resource. Source: Global Geothermal Power Tracker, Global Energy Monitor, May 2024 release

A Burgeoning Technology Landscape for Geothermal Power

According to the International Renewable Energy Agency’s 2023 Global Geothermal Market and Technology Assessment , geothermal energy in electricity generation has grown at a modest rate of around 3.5% annually. Today, it is evolving beyond a focus on the power market, absorbing a broader range of applications within the energy sector, including heating and cooling.

Conventional Technologies

Most of the world’s operating geothermal power plants utilize three primary plant technologies.

Flash Steam Plants.  The most prevalent type of geothermal power plant, flash steam plants operate with high-temperature geothermal fluids (typically above 180C). These fluids are brought to the surface under high pressure. When the pressure drops, the fluid “flashes” into steam, which is separated from the liquid and used to drive a turbine. Some plants use a double or triple flash process to maximize energy extraction, flashing the remaining liquid multiple times to generate additional steam.

Dry Steam Plants. Dry steam plants utilize geothermal steam directly from reservoirs to drive turbines and generate electricity. This technology is applicable where geothermal fluids are primarily in the form of steam at high pressures and temperatures, typically above 150C. The steam is extracted from the well and routed to a turbine connected to a generator, producing electricity. The steam is then condensed and re-injected into the reservoir or released (depending on environmental regulations).

Binary Cycle Plants. Binary cycle plants are ideal for lower-temperature geothermal resources (70C to 150C). These plants use geothermal fluid to heat a secondary working fluid, which has a lower boiling point than water. The secondary fluid vaporizes and drives a turbine to generate electricity. Because the geothermal fluid does not come into contact with the turbine, binary plants can operate with a closed-loop system, adding to their efficiency.

Wellhead Generators.  Modular wellhead generators, typically under 10 MWe, are installed directly at the wellhead. These small-scale units allow for early power generation while larger plants are being developed, enabling quicker returns on investment. They are particularly beneficial in remote locations or for testing new fields, as they can be deployed rapidly and scaled according to field development needs. POWER profiled an example here: A Modular Power Plant Is Steaming Up Kenya’s Geothermal Efficiency.

Emerging Geothermal Technologies

New technologies are emerging that could allow for the production of geothermal energy from deep-seated resources beyond the ones mentioned above. For a more in-depth look at key players, see POWER ’s 2023 explainer here .

Enhanced Geothermal Systems (EGS). EGS technology enhances the permeability of geothermal reservoirs where natural permeability is insufficient. This is achieved by injecting fluids at high pressures to fracture the rock, creating artificial reservoirs that allow for the economic extraction of heat. EGS expands the potential of geothermal energy by making it feasible to extract heat from areas that were previously unsuitable for conventional geothermal development.

Advanced Geothermal Systems (AGS). AGS involves the creation of deep, artificial closed-loop circuits where a working fluid circulates and is heated by surrounding rocks through conductive heat transfer. Unlike conventional systems, AGS does not rely on naturally occurring water-bearing formations with good permeability, making them potentially applicable in a wider range of locations. However, this method requires longer well bores and more sophisticated drilling techniques, which could increase costs.

Supercritical Geothermal Systems.   Supercritical geothermal systems target fluids at extremely high temperatures and pressures found deep within volcanic hydrothermal environments. Fluids, which exist in a supercritical state, offer much higher energy content than conventional geothermal fluids. While this technology promises significantly higher power outputs, it faces challenges such as handling corrosive fluids and maintaining equipment integrity under extreme conditions.

— Sonal Patel is a POWER senior editor ( @sonalcpatel ,  @POWERmagazine ).

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