What is Geothermal Energy?- Uses, and Effect

What is Geothermal Energy?

Geothermal energy is heat within the earth. The word geothermal comes from the Greek words geo (earth) and therme (heat). Geothermal energy is a renewable energy source because heat is continuously produced inside the earth. People use geothermal heat for bathing, heating buildings, and generating electricity.

Geothermal energy is the heat that comes from the sub-surface of the earth. It is contained in the rocks and fluids beneath the earth’s crust and can be found as far down as the earth’s hot molten rock, magma.

To produce power from geothermal energy, wells are dug a mile deep into underground reservoirs to access the steam and hot water there, which can then be used to drive turbines connected to electricity generators. There are three types of geothermal power plants; dry steam, flash, and binary.

Dry steam is the oldest form of geothermal technology and takes the steam out of the ground and uses it to directly drive a turbine. Flash plants use high-pressure hot water into cool, low-pressure water whilst binary plants pass hot water through a second liquid with a lower boiling point, which turns to vapor to drive the turbine.

Geothermal energy comes from deep inside the earth

The slow decay of radioactive particles in the earth’s core, a process that happens in all rocks, produces geothermal energy.

The earth has four major parts or layers:

  • An inner core of solid iron that is about 1,500 miles in diameter.
  • An outer core of hot molten rock called magma that is about 1,500 miles thick.
  • A mantle of magma and rock surrounding the outer core that is about 1,800 miles thick.
  • A crust of solid rock that forms the continents and ocean floors that is 15 to 35 miles thick under the continents and 3 to 5 miles thick under the oceans.
Geothermal energy is a type of renewable energy taken from the Earth’s core. It comes from heat generated during the original formation of the planet and the radioactive decay of materials. This thermal energy is stored in rocks and fluids in the centre of the earth.

Scientists have discovered that the temperature of the earth’s inner core is about 10,800 degrees Fahrenheit (°F), which is as hot as the surface of the sun. Temperatures in the mantle range from about 392°F at the upper boundary with the earth’s crust to approximately 7,230°F at the mantle-core boundary.

The earth’s crust is broken into pieces called tectonic plates. Magma comes close to the earth’s surface near the edges of these plates, which is where many volcanoes occur. The lava that erupts from volcanoes is partly magma. Rocks and water absorb heat from magma deep underground. The rocks and water found deeper underground have the highest temperatures.

Is geothermal energy renewable?

Yes, Because its source is the almost unlimited amount of heat generated by the Earth’s core. Even in geothermal areas dependent on a reservoir of hot water, the volume taken out can be reinjected, making it a sustainable energy source.

Geothermal Power Plant

Geothermal power plant (flash steam, combined cycle) in Iceland. Geothermal power plants are used in order to generate electricity by the use of geothermal energy (the Earth’s internal thermal energy). They essentially work the same as coal or nuclear power plant, the main difference being the heat source.

Geothermal power plants use hydrothermal resources that have both water (hydro) and heat (thermal). Geothermal power plants require high-temperature (300°F to 700°F) hydrothermal resources that come from either dry steam wells or from hot water wells.

People use these resources by drilling wells into the earth and then piping steam or hot water to the surface. The hot water or steam powers a turbine that generates electricity. Some geothermal wells are as much as two miles deep.

Types of geothermal power plants

There are three basic types of geothermal power plants:

  • Dry steam plants use steam directly from a geothermal reservoir to turn generator turbines. The first geothermal power plant was built in 1904 in Tuscany, Italy, where natural steam erupted from the earth.
  • Flash steam plants take high-pressure hot water from deep inside the earth and convert it to steam to drive generator turbines. When the steam cools, it condenses to water and is injected back into the ground to be used again. Most geothermal power plants are flash steam plants.
  • Binary cycle power plants transfer the heat from geothermal hot water to another liquid. The heat causes the second liquid to turn to steam, which is used to drive a generator turbine.
Geothermal power plants

Use of geothermal energy

Some applications of geothermal energy use the earth’s temperatures near the surface, while others require drilling miles into the earth. There are three main types of geothermal energy systems:

  • Direct use and district heating systems
  • Geothermal power plants
  • Geothermal heat pumps

1. Direct use and district heating systems

Direct use and district heating systems use hot water from springs or reservoirs located near the surface of the earth. Ancient Roman, Chinese, and Native American cultures used hot mineral springs for bathing, cooking, and heating.

Today, many hot springs are still used for bathing, and many people believe the hot, mineral-rich waters have health benefits.

Geothermal energy is also used to directly heat individual buildings and to heat multiple buildings with district heating systems. Hot water near the earth’s surface is piped into buildings for heat. A district heating system provides heat for most of the buildings in Reykjavik, Iceland.

Industrial applications of geothermal energy include food dehydration (drying), gold mining, and milk pasteurizing.

2. Geothermal electricity generation

Geothermal electricity generation requires water or steam at high temperatures (300° to 700°F). Geothermal power plants are generally built where geothermal reservoirs are located, within a mile or two of the earth’s surface.

3. Geothermal heat pumps

Geothermal heat pumps use the constant temperatures near the surface of the earth to heat and cool buildings. Geothermal heat pumps transfer heat from the ground (or water) into buildings during the winter and reverse the process in the summer.

Advantages of geothermal energy

There are many advantages of geothermal energy but also some challenges that need to be overcome in order to fully exploit this natural resource.

1. Environmentally Friendly

Geothermal energy is more environmentally friendly than conventional fuels like coal and other fossil fuels. In addition, the CO2 footprint of a geothermal power plant is small. Geothermal energy is associated with a certain amount of pollution, but it is relatively low compared to fossil fuels.

2. Renewable

Geothermal energy is a renewable energy source that will last until the earth is destroyed by the sun in around 5 billion years. The hot reservoirs on earth are replenished naturally, making them both renewable and sustainable.

3. Huge Potential

Worldwide energy consumption is currently around 15 terawatts, a far cry from the total potential energy available from geothermal sources.

While we are currently unable to use most of the reservoirs, there is hope that the number of usable geothermal resources will increase with the ongoing research and development in the industry.

It is currently estimated that geothermal power plants could deliver between 0.0035 and 2 terawatts of power.

4. Sustainable/Stable

Geothermal energy is a reliable source of energy compared to other renewable resources such as wind and solar power. This is because, unlike wind or solar energy, the resource is always available to be tapped.

5. Heating and Cooling

For the effective use of geothermal energy to generate electricity, water temperatures of over 150 ° C are required to drive turbines. Alternatively, the temperature difference between the surface and a soil source can be used.

Since the ground is more resistant to seasonal heat changes than the air, it can act as a heat sink/source with a geothermal heat pump just two meters below the surface.

6. Reliable

The energy generated from this resource is easy to calculate as it does not fluctuate like other energy sources such as the sun and wind. This means that we can predict the performance of a geothermal system with a high degree of accuracy.

7. No Fuel Required

Because geothermal energy is a naturally occurring resource, no fuel is required, such as fossil fuels, which are a finite resources that must be mined or otherwise extracted from the earth.

8. Rapid Evolution

A lot of geothermal research is currently underway, which means that new technologies are being created to improve the energy process. There are more and more projects to improve and expand this industrial sector. With this rapid development, many of the current disadvantages of geothermal energy are being alleviated.

Disadvantages of Geothermal Energy

1. Location Restricted

The single biggest disadvantage of geothermal energy is that it is site-specific. Geothermal plants need to be built in places where the energy is accessible, which means that some areas cannot use this resource.

Of course, this is not a problem if you live in a place where geothermal energy is easily accessible, for example in Iceland.

2. Environmental Side Effects

Although geothermal energy does not normally emit greenhouse gases, many of these gases are stored underground and released into the atmosphere when digging. While these gases are also naturally released into the atmosphere, the rate increases near geothermal facilities. However, these gas emissions are still far lower than those associated with fossil fuels.

3. Earthquakes

Geothermal energy also runs the risk of causing earthquakes. This is due to changes in the structure of the earth as a result of the trench. This problem is more common with improved geothermal power plants that push water into the earth’s crust to open cracks for greater exploitation of the resource.

However, since most geothermal systems are not located in population centers, the impact of these earthquakes is relatively minor.

4. High Costs

Geothermal energy is an expensive resource. The prices for a system with a capacity of 1 megawatt are between 2 and 7 million US dollars. However, if the upfront costs are high, the expense can be amortized as a long-term investment.

5. Sustainability

In order to maintain the sustainability of geothermal energy, the liquid must be pumped back into the underground reservoirs faster than it is depleted. This means that geothermal energy must be properly managed in order to maintain its sustainability.


Is geothermal energy renewable?

Yes, Because its source is the almost unlimited amount of heat generated by the Earth’s core. Even in geothermal areas dependent on a reservoir of hot water, the volume taken out can be reinjected, making it a sustainable energy source.

How does a geothermal energy works?

Geothermal power plants use steam to produce electricity. The steam comes from reservoirs of hot water found a few miles or more below the earth’s surface. The steam rotates a turbine that activates a generator, which produces electricity.

What are the Disadvantages of Geothermal Energy?

  • Location Restricted. The largest single disadvantage of geothermal energy is that it is location specific.
  • Environmental Side Effects.
  • Earthquakes.
  • High Costs
  • Sustainability.

Why is it bad to use geothermal energy?

Cons of geothermal energy: generates waste, reservoirs require proper management, it’s location-specific, has a high initial cost, and can cause earthquakes in extreme cases. Geothermal has the potential to become a major global energy source but is held back by its high upfront costs.

Is geothermal energy a good idea?

Experts say geothermal energy is cleaner, more efficient, and more cost-effective than burning fossil fuels, and it can reduce our dependence on foreign oil. … Geothermal plants are also considered to be more reliable than coal or nuclear plants because they can run consistently, 24 hours a day, 365 days a year.

What are 3 main uses of geothermal energy?

Geothermal energy can heat, cool, and generate electricity: Geothermal energy can be used in different ways depending on the resource and technology are chosen—heating and cooling buildings through geothermal heat pumps, generating electricity through geothermal power plants, and heating structures through direct use.

What are the 3 ways to get geothermal energy?

There are three main types of geothermal energy systems:

  • Direct use and district heating systems.
  • Geothermal power plants.
  • Geothermal heat pumps.

How long does geothermal last?

How long do geothermal heat pumps last? Geothermal heat pumps last significantly longer than conventional equipment. They typically last 20-25 years. In contrast, conventional furnaces generally last anywhere between 15 and 20 years, and central air conditioners last 10 to 15 years.

Why is geothermal energy a renewable resource?

Because its source is the almost unlimited amount of heat generated by the Earth’s core. Even in geothermal areas dependent on a reservoir of hot water, the volume taken out can be reinjected, making it a sustainable energy source.

Is geothermal energy cheap?

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. Although geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down.

Will geothermal energy cool the earth?

The simple answer is no-geothermal does result in cooling, but the impact is insignificant. Some 42 million megawatts of energy reach the surface continually and are radiated into space as the earth cools from its initial molten state more than 4 billion years ago.

Is geothermal better at cooling or heating?

Efficiency. When it comes to efficiency, geothermal AC beats conventional central AC by far. Your geothermal heat pump isn’t wasting electricity trying to pump indoor hot air into the already-hot outdoors; instead, it’s easily releasing heat into the cool underground.

Is geothermal better than solar?

Climate will also dictate whether geothermal is a better option as the farther North you move, the more heat is needed during the winters. Because geothermal energy provides up to 500% efficiency compared to gas or oil heating, it’s highly recommended over solar power in colder areas.

Why is my geothermal bill so high?

Heating costs and the savings associated with a geothermal system are relative to energy prices. As the prices of natural gas, propane, and heating oil increase with respect to the price of electricity, the savings associated with getting geothermal increase too.

Is geothermal expensive?

On average, a homeowner can expect total expenses to reach between $18,000 to $30,000 on geothermal heating and cooling cost. This cost would cover a complete geothermal installation. The price can range from $30,000 to $45,000 with high-end ground-source heat pump systems for large homes.

Why geothermal energy is important?

Geothermal energy, one of the most promising among renewable energy sources, has proven to be reliable, clean and safe, and therefore, its use for power production, and heating and cooling is increasing. It is a power source that produces electricity with minimal environmental impact.

What are 5 uses of geothermal energy?

Its current uses include heating buildings (either individually or whole towns), raising plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes, such as pasteurizing milk.

What is the main source of geothermal energy?

Geothermal energy comes from deep inside the earth. The slow decay of radioactive particles in the earth’s core, a process that happens in all rocks, produces geothermal energy.

What are the major sources of geothermal energy?

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.

How much energy can geothermal produce?

Geothermal power plants produce about 0.4% of the United States’ overall electricity output, amounting to 16.7 kWh in 2018.

How deep do you have to dig to get geothermal energy?

How deep does a geothermal horizontal field need to be? For a horizontal loop, you only need to dig between 6 – 8 feet deep. For a vertical loop, you need to drill between 250 and 300 feet deep.

How long does it take to build a geothermal power plant?

Retrofits can be expected to take 6 to 8 weeks from start to finish. Installations in new construction typically take longer due to the coordination and scheduling with other contractors. Each stage of a geothermal installation can be expected to take the following lengths of time: Permitting and Design – 2 to 3 Weeks.

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