Geothermal energy is heat from the core of the earth. The term geothermal is derived from the Greek words geo (earth) and thermal (heat). Because heat is constantly produced inside the earth, geothermal energy is a renewable energy source.

The core of our planet is located around 2,900 kilometers (1,800 miles) under the Earth’s crust, or surface.

A little fraction of the core’s heat is caused by the friction and gravitational pull that existed when Earth was formed almost 4 billion years ago. The greatest bulk of Earth’s heat, on the other hand, is continually produced by the decay of radioactive isotopes like potassium-40 and thorium-232.

At the core, radioactive decay is a continuous process. Temperatures can reach higher than 5,000° Celsius (about 9,000° Fahrenheit). Heat is continually flowing outward from the core, warming rocks, water, gas, and other geological components.

From the surface to the core, the temperature of the Earth rises with depth. The geothermal gradient is the progressive decrease in temperature. The geothermal gradient is around 25° C per 1 kilometer of depth (1° F every 77 feet of depth) in most places of the world.

Underground rock formations can become magma if heated to 700-1,300° C (1,300-2,400° F). Magma is a molten (partially melted) rock that is pervaded by gas and gas bubbles.

Magma may be found in the mantle and lower crust and occasionally bubbles to the surface as lava.

Magma heats the surrounding rocks and subsurface aquifers. Geysers, hot springs, steam vents, undersea hydrothermal vents, and mud pots can all emit hot water.

All of them are geothermal energy sources.

How Does Geothermal Energy Get Made?

Wells up to a mile deep or more are sunk into subsurface reservoirs to exploit geothermal resources. These resources can be derived from naturally occurring heat, rock, and water permeability, or via improved geothermal systems, which augment or produce geothermal resources through a process known as hydraulic stimulation. These geothermal resources, whether natural or improved, power turbines that are linked to electrical generators.

In 1904 at Larderello, Italy, geothermal heat was used to generate electricity for the first time. However, geothermal heat has been utilized for bathing since the Palaeolithic period. In Japan, monkeys have been observed using heated water from hot springs to keep warm during the winter months in hilly places.

Type Geothermal Power Plant

Geothermal power plant technologies are classified into three types: dry steam, flash steam, and binary cycle.

Dry Steam Power Plant

Dry steam plants make use of hydrothermal fluids that are primarily steam, which is a very uncommon natural occurrence. The steam is fed straight to a turbine, which operates an electric generator. Steam is regularly rejected into the reservoir after it condenses.

The Larderello geothermal power station in Tuscany is the world’s oldest dry steam power plant.

Dry steam power plant systems are the oldest form of geothermal power plant, having been utilized for the first time in 1904 at Lardarello, Italy. Steam technology is still important today and is now in use in northern California at The Geysers, the world’s biggest single source of geothermal power.

Power Plant Using Flash Steam

The most frequent form of geothermal power plant in use today is flash steam plants. Pumped from deep down, fluids with temperatures more than 182°C/360°F flow under high pressures to a low-pressure tank near the earth’s surface. Because of the pressure difference, part of the fluid rapidly transforms, or “flashes,” into vapor. The vapor then powers a turbine, which in turn powers a generator. If there is any liquid left in the low-pressure tank, it can be “flashed” again in a second tank to extract even more energy.

Power Plant with a Binary-Cycle Cycle

Since binary-cycle geothermal power plants may employ lower temperature geothermal resources, they are an essential technique for expanding geothermal energy output. The geothermal reservoir fluids never come into contact with the power plant’s turbine components in binary-cycle geothermal power plants, as opposed to dry steam and flash steam systems. Low-temperature geothermal fluids (below 182°C/360°F) run via a heat exchanger with a secondary, or “binary,” fluid. This binary fluid has a significantly lower boiling point than water, and the geothermal fluid’s mild heat allows it to flash to vapor, which powers the turbines, spins the generators, and generates electricity.

Top Ten of Geothermal Plant

The Geysers Geothermal Complex in the United States (900mw)

This enormous complex, located approximately 100 kilometres north of San Francisco, California, consists of 18 power units with a current production capacity of 900MW.

It covers 45 square miles and provides enough energy to power over 1 million households.

The Larderello Geothermal Complex in Italy (769 Mw)

The huge Larderello Complex, which consists of 34 units, is the world’s second biggest plant.

This geothermal facility has a net capacity of 769 Megawatts.

The first facility was built in 1913, making it the oldest of its kind.

This complex accounts for 10% of all geothermal energy produced worldwide and supplies over 27% of the region’s electricity needs.

Cerro Prieto Geothermal Power Station, Mexico (720 Mw)

The Cerro Prieto Geothermal Power Plant, located in northern Mexico, is the world’s third biggest, with a capacity of 720 MW.

This plant, like all other in Mexico, is owned by the Comisión Federal de Electricidad.

The facility is built on a geological feature that is relatively unique, a spreading fault line in a landlocked location. Normally, the phenomena are only encountered on the ocean floor.

Makban Geothermal Complex, Philippines (458 Mw)

The Makban Geothermal Power Complex is the fourth biggest geothermal plant in the world, with a capacity of 458 MW.

This complex consists of 6 factories located in both Laguna and Batangas provinces.

The Philippines has an outstanding geothermal infrastructure, but to achieve 100% sustainability, geothermal production would need to be increased by a few hundred thousand.

Hellisheidi Geothermal Power Plant, Iceland (400mw)

Iceland is dotted with hot springs, and many residences outside of Reykjavik have private, secondary geothermal generators.

The fifth biggest geothermal plant in Iceland is located on Hengill volcano and has a capacity of 400MW thermal energy and 303MW electric energy.

It is Iceland’s largest power plant and is largely located above the plate boundary between the North American and European tectonic plates.

Calenergy Generation’s Salton Sea Geothermal Plants, USA (340mw)

This big plant in southern California is made up of 10 geothermal units packed together.

This network of plants is the sixth biggest geothermal energy generator in the planet, with a total output of 340MW.

According to experts, this location has more geothermal potential than any other in the United States, and the plant is really assisting in the prevention of soil erosion and the spread of hazardous amounts of salt throughout the region.

Tiwi Geothermal Complex, Philippines (289 Mw)

Geothermal plants provide more than a quarter of the power in the Philippines.

Albay, a Filipino province, is home to the world’s seventh largest geothermal plant.

It consists of three power plants, each with two units, and has a net capacity of 289 MW.

This plant has been in operation since 1979 and is one of the world’s oldest functioning geothermal plants.

Darajat Power Station, Indonesia (259mw)

The world’s eighth biggest geothermal plant is located in the Pasirwangi District of Garut, Indonesia.

It is made up of three plants that were developed independently between 1994 and 2007.

This plant has a capacity of 259MW and generates approximately 50% more electricity than the Sir Adam Beck pump producing hydroelectric station near Niagara Falls.

Indonesia has a very active volcanic geology, and geothermal energy is becoming increasingly popular throughout the country.

Malitbog Geothermal Power Station, Philippines (232.5mw)

With a capacity of 232.5MW, this power station in the Philippines is the world’s ninth biggest.

The Energy Development Corporation Company owns this plant, which provides energy to the island of Luzon.

It has been in operation since 199 and is anticipated to last at least another 30 years.

It is the world’s biggest single-roof geothermal power plant, and it is located in what many would call paradise.

Wayang Windu Geothermal Power Plant, Indonesia (227 Mw)

The world’s tenth -largest plant is likewise in Indonesia, in the region of West Java.

It is operated by a Star Energy subsidiary and was conceived and built by Aecom, Sumitomo Company, and Fuji Electric.

It has a capacity of 227 MW but covers a bigger geographical region than the Darajat station.

The geothermal field at Wyang Windu is 40 square kilometres in size.

Advantages of Geothermal energy

Eco Friendly

Geothermal energy is less harmful to the environment than traditional fuel sources such as coal and other fossil fuels.

Renewable energy

Geothermal energy is a renewable energy source that will persist till the sun destroys the Earth in roughly 5 billion years. The Earth’s heated reservoirs are naturally refilled, making it both renewable and sustainable.

Great Potential

The present global energy consumption is roughly 15 terawatts, which is significantly short of the entire potential energy accessible from geothermal sources.

Sustainability

In comparison to other renewable energy sources such as wind and solar power, geothermal delivers a consistent stream of energy. This is because, unlike wind or solar energy, the resource is constantly accessible to be used.

Dependable

Energy provided by this resource is simple to calculate since it does not fluctuate as much as other energy sources such as solar and wind. This means that we can accurately anticipate the electricity production of a geothermal plant.

Rapid Evolution

There is a lot of research going on right now in geothermal energy, which means that new technologies are being developed to enhance the energy process.

Disadvantages of Geothermal Energy

Limited location

The most significant drawback of geothermal energy is its location is specific. Geothermal facilities must be constructed in areas where energy is available.

Negative Environmental Impacts

Although geothermal energy normally does not emit greenhouse gases, many of these gases are stored under the Earth’s surface and are released into the atmosphere during digging.

Seismic activity

Geothermal energy also has the potential to cause earthquakes. This is due to changes in the Earth’s structure caused by digging. This issue is particularly widespread in enhanced geothermal power plants, which drive water into the Earth’s crust to open fissures for better resource extraction. However, because most geothermal facilities are located far from population centers, the effects of these earthquakes are negligible.

Expensive

Geothermal energy is a costly resource to access, with prices ranging between 2 and 7 million dollars for a 1 megawatt facility. Nonetheless, where the upfront expenses are substantial, the investment can be recouped over time.

Conclusion

Geothermal energy is derived from heat created in the Earth’s core by radioactive decay of minerals during the planet’s formation. This thermal energy, which is retained by rocks and fluids at the Earth’s core, may be exploited as a sustainable energy source.

This clean and sustainable energy supply is less expensive than many alternatives, and geothermal energy, unlike solar and wind energy, is constantly accessible.

References

https://www.energy.gov/