- Where Geothermal Reservoirs Are Found
- Uses of Geothermal Energy
- Development of Geothermal Energy
- How Does Geothermal Power Affect the Environment?
- What Is the Future of Geothermal Power?
- Cost of Geothermal Power
- Fossil Fuels Are Harmful to the Environment
- Low Emission Levels
- Greenhouse Gases
- Waste and Fumes
- Risk of Earthquakes
- Technologies and Resource
- Geothermal Energy for Heat and Electricity
The interior of the earth is tremendously hot. Some of the heat is due to energy released during the formation of the planet. The radioactivity of materials in the ground produces a massive amount of heat energy.
Heat transmission to the surface is limited by the low heat transfer capabilities of the components that make up the earth’s interior. As a result of the trapped heat, the temperature of earth materials has increased.
In some places, this hot material is close to the surface, and lava does reach the surface during volcanic eruptions. In some areas, water that has seeped into the depths is heated and restricted, whereas in others, it returns to the surface as hot water or steam. This “unrestricted” energy is available at your service for consumption.
Furthermore, hot dry rock lies beneath the entire surface of the earth and could be an important energy source in the future. Humans must change subterranean conditions and add water to transfer energy to the surface in order to obtain this energy.
Heat pumps can also be utilized to improve heating and cooling efficiency by utilizing the earth. The near-constant temperature found a few feet beneath the earth’s surface is preferable to ambient air for usage as a heat source or heat sink in heat pump applications.
The Earth’s core generates heat more than 4,000 miles (6,437 kilometers) below the surface. Temperatures in the deep mantle of the Earth can reach around 9,000°F (4,982°C). When the heat from the earth’s crust warms the rocks surrounding it, magma is created. The majority of magma stays beneath the Earth’s crust, but some make their way to the surface as lava and form volcanoes.
Groundwater seeps into the soil through cracks in the rock and is heated by hot rocks. Water collects in subsurface reservoirs in some regions, reaching temperatures of 700°F (371°C). Flaws and cracks in the earth’s crust allow hot water and steam to escape.
Structures such as buildings, pools, greenhouses, and even sidewalks can be heated with geothermal energy. Geothermal energy is produced by drilling wells into geothermal reservoirs. The energy is then converted into electricity or used in various ways.
According to the US Geological Survey, geothermal energy’s potential is 500 times greater than the world’s total oil and gas resources.
Where Geothermal Reservoirs Are Found
Most geothermal reservoirs are deep underground, with no visible indication above ground. Tectonic plates are massive plates that make up the Earth. Plate boundaries are the points where these massive plates meet, collide, and occasionally slip beneath one another. Hot lava rises through the crust near plate boundaries, forming volcanoes.
It is one of the most active geothermal areas on the planet. The Ring of Fire encompasses the South American Andes, Central America, Mexico, the western United States, Alaska, and western Canada. Parts of Russia, Japan, the Philippines, Indonesia, and New Zealand are bordered by the Pacific Ocean.
Geothermal reservoirs and volcanoes can also be found in places such as Iceland and Kenya’s Rift Valley. The Hawaiian Islands are a chain of volcanic islands that arose from a geothermal hot point. Other active geothermal sites can be found in hot places when the earth’s crust is thin enough for hot magma to rise.
Geothermal energy may be found all over the world, ranging in depth from 10 feet (3m) to a few hundred feet (m). Geothermal reservoirs with the greatest temperatures are typically located near plate borders or hot areas.
Geothermal energy is derived from a hot dry rock located 2 to 6 miles (4 to 10 kilometers) under the earth’s surface. Geothermal energy might become economically viable if scientists can create equipment to collect this heat.
Uses of Geothermal Energy
Turbines are powered by high-temperature water or steam from a geothermal reservoir to generate energy. After geothermal energy is converted to electricity, it is transported over long distances via power lines to heat homes and businesses.
The geothermal reservoir can still be used for direct heating if it isn’t hot enough to generate electricity. Because geothermal water has difficulty transferring heat over long distances, it is necessary to employ a radiator or another type of heat exchanger to extract as much heat as possible from the earth.
Iceland’s geothermal system heats almost all of the buildings in Reykjavik, Iceland. Direct-piped geothermal water can be used for bathing, washing, and other similar activities. The geothermal water is either thrown away or injected back into the hot rocks to warm.
In France, agriculture and fish farming enterprises use direct-piped hot water. It’s also possible to use geothermal energy to melt ice on highways, heat fish farms, and spas, and dry fish, fruits, and vegetables. Geothermal energy is also utilized in a number of industrial settings.
Buildings that are not near geothermal reservoirs utilize geothermal heat pumps to cool and heat them. The ground underneath the surface of the earth maintains a constant temperature of 40°F to 50°F (4.4°C to 10°C) throughout the year.
Through subterranean pipes, the geothermal heat pump circulates air or a liquid-like antifreeze. The pump reverses its operation in the summer, moving heat from the home’s air to the colder ground.
A heat pump consumes energy, but significantly less than traditional furnaces and air conditioners. In areas with extreme temperatures, geothermal heat pumps are one of the most energy-efficient heating and cooling options.
Development of Geothermal Energy
Geothermal energy has been used for millennia. The ancient Romans used geothermal water to heat their buildings in Pompeii. Native Americans believed that hot mineral springs had healing properties. The Maori people of New Zealand used it for cooking.
In 1892, the city of Boise, Idaho, developed the world’s first advanced district heating system. Residents used piped water from nearby hot springs to heat the town’s constructions. In the city, geothermal energy is being used in approximately 200 homes and 40 enterprises.
Boise, Idaho, features the world’s largest district heating system. Furthermore, district heating systems heat 5 million square feet (464,515 square meters) of residential, commercial, and government space. It’s similar to other systems used throughout the world to heat homes and businesses with hot water extracted from the ground.
Due to heat loss during long-distance transport, geothermal energy could only be used locally until the twentieth century. In 1904, workers in Larderello, Italy, attempted to generate electricity using geothermal steam. They excavated a hole in the ground and ran a conduit through it to a large geothermal reservoir.
How Does Geothermal Power Affect the Environment?
One of the most environmentally friendly energy sources is geothermal energy. It produces fewer emissions and pollution than fossil fuels. Geothermal energy uses less land than solar panels and wind farms and, unlike nuclear power facilities, produces no harmful toxic waste.
Geothermal energy, despite its environmental benefits, has some drawbacks. There is still a risk that bringing underground water to the surface will pollute local water supplies and the ground with naturally occurring but possibly harmful minerals and chemicals as a result of tiny emissions.
Geothermal energy has been linked to earthquakes. Calpine Corporation reports between 3,000 and 5,000 earthquakes per year in California. Earthquakes, according to a geothermal energy company, are small, measuring between 0.5 to 3.0 on the Richter scale.
What Is the Future of Geothermal Power?
The world will face various energy supply problems in the future. Many individuals believe that geothermal energy can assist the world in making the shift to a cleaner, more sustainable energy source.
With new technologies in development to dig deeper and capture geothermal energy from hot dry rock, the future of geothermal energy appears bright. “The internal fireball of the Earth is a resource.”
Cost of Geothermal Power
Geothermal resource development is a time-consuming and expensive process. Only one out of every five exploratory wells drilled, according to the National Geothermal Collaborative, indicates the presence of a viable and usable geothermal resource. The location, temperature, and depth of drilling determine the cost of drilling a well.
A geothermal well might cost anything from $1 million to $5 million. The least expensive wells are those that produce high temperatures at shallow depths. Even in relatively shallow wells, drilling costs can account for one-third to one-half of the total project cost.
Furthermore, because several geothermal resources are located in remote areas, towns must incur additional costs to build power-generating lines to deliver electricity to clients.
Geothermal energy accounts for less than 1% of total fossil-fuel-fired power plant capacity. The development of geothermal energy has lagged behind that of fossil fuels and other alternative energy sources. According to the Energy Information Administration, fossil fuel-fired power plants generated roughly 76 percent of the country’s electricity.
For a home, a geothermal forced-air heating and cooling system might cost anywhere from $15,000 to $40,000. Direct-use geothermal energy applications also require large upfront costs.
Fossil Fuels Are Harmful to the Environment
Although fossil fuels have been a reliable source of energy, concerns about the environmental damage they do are growing. The extraction of fossil fuels destroys nearby land and ecosystems, resulting in soil erosion and flooding.
Waste is the source of pollution in rivers, streams, and seas. Ecosystems and coastal wetlands are destroyed by accidents and spills. The only way to avoid more fossil-fuel disasters is to rapidly transition away from dangerous energy sources like oil and coal to green energy.
Furthermore, generating power with fossil fuels releases pollutants into the atmosphere. Air pollutants such as carbon monoxide, nitrogen oxides, sulfur oxides, and hydrocarbons can harm plants, animals, and people.
Fossil fuel emissions have been linked to smog, acid rain, and lung illness. Carbon dioxide is a greenhouse gas that increases atmospheric pressure and has been linked to global warming.
Low Emission Levels
Geothermal power stations provide electricity without burning fuel. They produce less than 1% of the carbon dioxide produced by a fossil fuel plant. Furthermore, geothermal plants emit 97 percent fewer sulfur compounds, which contribute to acid rain, than fossil-fuel plants.
Furthermore, geothermal binary cycle power plants produce no emissions since they use a closed-loop process to generate electricity.
Gases such as hydrogen sulfide and carbon dioxide, which are naturally found in geothermal reservoirs, are emitted by geothermal power plants. These gases would eventually disperse into the atmosphere without geothermal development but over a much longer period of time. To reduce emissions, many geothermal facilities use scrubbers to remove gases before they reach the environment.
According to scientists, global warming poses a major threat to the environment and human health. Carbon dioxide is created when fossil fuels are burned, and it is a greenhouse gas that traps heat in the earth’s atmosphere. In the United States, carbon dioxide is responsible for 83 percent of greenhouse gas emissions.
According to scientists, the use of fossil fuels has resulted in a 25% increase in the amount of carbon dioxide in the atmosphere over the last 150 years. More effort is needed to reduce emissions, according to the Energy Information Administration.
Unlike fossil-fuel power plants, geothermal power plants emit comparatively little carbon dioxide. Furthermore, before releasing gases into the atmosphere, geothermal fluids are pumped into subsurface reservoirs to reduce emissions. Carbon dioxide emissions at Nevada’s Dixie Valley geothermal power plant decreased by 39% when it began reinjection.
The construction of a heat pump at the township’s water treatment facility in Langley, England, reduced greenhouse gas emissions in 2009. Thermal energy was recovered from the plant’s previously treated drinking water using this cutting-edge technology. Within a short amount of time, officials noticed a decrease in carbon emissions.
Waste and Fumes
However, some argue that geothermal energy does not produce any emissions or waste. A geothermal reservoir’s hot water or steam transfers naturally occurring metals, minerals, and gases to the surface.
The discharge of potentially dangerous minerals and chemicals into the environment can occur during geothermal testing. These minerals are also present in the water used in geothermal testing, which might be hazardous to one’s health.
Geothermal energy generates more metals, minerals, and gases than natural processes. The method of getting geothermal energy enables it to be released considerably faster and in higher amounts than would occur normally.
Byproducts of geothermal power plants include hydrogen sulfide and mercury. Heavy metals exist in geothermal fluids, which are highly brackish. They smell like rotten eggs because of the H2 S [hydrogen sulfide] in the hydrogels.
Furthermore, geothermal systems produce sludge from dissolved solids while condensing geothermal steam. Silica, chlorides, arsenic, mercury, nickel, and other toxic metals may be present in this sludge. To manage these pollutants, some industries dry the sludge and transport it to hazardous waste disposal sites.
Other facilities dump redissolved solids or liquid wastes into the geothermal well. Both methods of disposal can be costly. Closed-loop plant designs, on the other hand, return steam or water to the ground before releasing it into the atmosphere.
In geothermal systems, satellite wells around the steam well are used to replenish the geothermal resource. By replenishing steam fields with local wastewater, geothermal operations reduce water pollution in nearby towns. Geothermal energy has the ability to reduce pollution in the area where it is deployed.
Risk of Earthquakes
Developers are putting technology to the test in order to drill deeper and obtain hotter geothermal resources. They are also experimenting with techniques to fracture hot dry rock regions and pump cool water down for heating. If this technique is effective, it will greatly enhance global access to geothermal energy in the future.
Some people are concerned that digging deeper into the ground would result in a huge earthquake. Tremors can be caused by drilling for underground geothermal deposits, however, they are usually mild and go unnoticed. Water drilling has the potential to generate earthquakes. Deeper drilling raises the likelihood of a greater earthquake.
Due to the risk of earthquakes, some geothermal projects have been cancelled. In 2006, the authorities in Basel, Switzerland, abandoned a geothermal project after a series of earthquakes terrified residents and destroyed houses.
After a government evaluation revealed that the earthquakes caused by the project were predicted to cause millions of dollars in damage every year, the project was permanently shut down in December 2009.
Technologies and Resource
Direct geothermal energy consumption has higher efficiency, ranging between 50 and 70 percent. Hot, dry rocks have a lot more energy stored in them than hydrothermal sources. To use this energy resource, you must develop the required permeability and pump water (or another fluid) through them.
Drilling wells into hot rock is an initial stage in developing a geothermal system. High-pressure water is injected, perhaps with chemicals to aid in fracturing. The goal is to construct a network of tiny tunnels that keep close touch between the water and the rock.
Geothermal heat pumps can be used for low-temperature geothermal resources (usually below 20°C). They may harvest heat from the earth and deliver it to houses or buildings in cold weather. They may also offer air cooling by extracting heat from dwellings and storing it in the soil.
Their functioning needs grid electricity, but they ultimately deliver considerably more energy than was spent. The most basic method of producing energy from hydrothermal sources is to employ dry steam or flash steam devices.
When the heat reservoir is mostly a liquid at sufficiently high temperatures (above roughly 160°C), flash steam systems are utilized. They may generate 20–30% more power than a single flash system. Flash steam technique often used when the temperature of hydrothermal fluid exceeds 350°F (177°C).
The use of a twin flash cycle improves the economics of most hydrothermal flash facilities. Systems in the 10–55MWe range have been developed. 20MWe units can be utilized in a modular fashion, as is now being done in Mexico and the Philippines.
Another technique that allows for the generation of power from geothermal energy is binary cycle plants. The heat from hot geothermally heated water is transferred to a second fluid with a lower boiling point in a heat exchanger. Electricity may be produced at a competitive cost with a primary liquid flow rate of many tens of liters per second.
A geothermal cycle is initially employed in steam-dominated resources, in which steam is routed via a steam turbine and subsequently condensed in a heat exchanger. With the use of supercritical fluids, a breakthrough in the field of geothermal power production may occur. Some reservoirs exist where the temperature exceeds 374°C and the pressure exceeds 220bars.
In Iceland, feasibility tests are being conducted to determine if it is viable to extract fluids at temperatures ranging from 400 to 600°C at depths of 5000 meters. If the water is raised to the surface under the same conditions, roughly ten times more energy may be recovered than with traditional reservoirs.
Geothermal Energy for Heat and Electricity
It is possible to locate energy sources near where the energy will be needed due to the abundance of potential improved geothermal energy sites. Long-distance power transmission or fuel transportation costs and energy losses would be reduced as a result.
Hot water forced through insulated pipes might offer heat to homes, businesses, and factories near geothermal sources. In places where hydrothermal sources are close to energy users, this approach is already in use. The proximity of energy sources and energy users increases the possibility of using hot water for space heating in buildings.
By supplying steam to turbine generators, geothermal energy can be exploited to generate electricity. Three different types of geothermal power plants are being developed. Where dry steam is available, power plants would use steam delivered directly to a turbine. In locations where hot water or steam water combinations are available, a flash steam system may be used.
Water or a steam-water mixture is fed into a lower pressure zone, where evaporation produces steam, which is subsequently supplied to a turbine in a flash steam system. In binary cycle power plants, heat is transferred to a second fluid with a lower boiling point than water, and the resulting vapor drives a turbine.
Geothermal power plants must have some type of cooling to condense the vapor that exits the turbine. The most efficient cooling method is to transfer heat to water in a lake, river, or ocean. The availability of water for the power plant is a key factor in determining whether or not a geothermal power plant is feasible.
If geothermal energy becomes more widely used, it has the potential to make a substantial contribution to America’s energy future. The technological and economic hurdles should not be underestimated. Geothermal energy should be aggressively pursued.
Many countries have yet to implement this. The global use of geothermal energy is increasing at a rate of 4% per year, although it is rising much faster in particular nations. Geothermal energy, which is now the world’s third most used renewable energy source, is anticipated to become an even more vital contribution to our energy demands in the future.