Geothermal energy is one of the most sustainable energy sources, which produces 0.03% of the emissions. It is by far the least carbon footprint compared to other energy sources.

Although this renewable source of energy is getting the recognition it deserves in recent years, it has been in use for more than 2,000 years. The actual geothermal fact might surprise you.

But, what exactly is geothermal energy?

Geothermal energy is a prominent source of renewable energy that generates heat from the sub-surface of the earth. Geothermal energy mainly transfers heating or cooling in homes or produces clean electricity.

However, to generate electricity through this technology, high or medium-temperature resources are a must. These temperature resources are usually located in regions that are close to tectonically active.

For these reasons, geothermal energy supplies a significant share of power in more than 24 countries, including New Zealand, the Philippines, Iceland, El Salvador, and Kenya. It also provides more than 90% of heating supplies in Iceland.

Having said that, this energy source does not only have its advantages. It has a fair share of disadvantages too!

So, let’s dig into it and learn about the pros and cons of geothermal energy.

How is Geothermal Energy Generated?

In simple words, Geothermal energy is the thermal power generated from the earth’s internal heat. If you dig a hole under the earth’s surface, you’ll notice that the temperature rises as you go deeper. Why? Because the subsoil of the earth stores heat, converting the heat to the power supply is Geothermal energy.

There are mainly two ways to generate geothermal energy:

1. Geothermal Power Plants

The primary purpose of the geothermal power plant is to generate electricity.

This method requires a person to drill wells of about 2 miles deep underground and pump hot water or steam to the surface. The ideal places to install these power plants are places that have plenty of hot streams, volcanic mountains, or geysers. As per the areas, the selective types of geothermal power plants are hence built.

How do geothermal power plants work?

  • First, the pumping of hot water from the underground reservoirs under high pressure through a well begins.
  • As the water reaches the surface, the applied pressure is dropped, which turns the water into steam.
  • This steam then spins a turbine that connects to the electricity generator.
  • Further, the steam cools down in a cooling tower and liquifies back to the water.
  • The cooled water is forced back into the surface of the earth to begin the process.

2. Geothermal Heating Pumps

The major use of the Geothermal heating pump is for heating or cooling homes and buildings. Heat pumps transfer heat by pumping water or a refrigerant through looping pipes below the surface of the earth, where the temperature is 50 to 60 degrees Fahrenheit.

How do geothermal heating pumps work?

  • At first, the water or a refrigerant transfers through the looping pipes system.
  • During cold weather, the water or the refrigerant heats up while traveling through the loop that is buried underground.
  • When it reaches the ground, the warm water transfers the heat into homes or buildings.
  • Then, the water or the refrigerant cools down. The cooled water is pumped back again, where it heats once again, starting the entire process.
  • During a hot day, the entire system can run in reverse. Instead of heating the building, the water or refrigerant cools the place down.

What is Geothermal Energy Used For?

In some countries, people have mostly been using geothermal energy for cooking and heating for thousands of years. The underground reservoirs of geothermal power plants contain hot water and steam. The hot water and steam of these reservoirs help generate electricity and to heat homes or other buildings.

A geothermal pump system extracts heat from underground and transfers them to buildings and homes through a looping pipe system.

Additionally, to produce electricity from geothermal energy, wells are drilled into the reservoirs that tap hot water and steam to drive turbines, which link directly to the power generators.

Advantages and Disadvantages of Geothermal Energy

Geothermal energy is an excellent alternative to non-renewable energy. Although significantly promising, this energy source does not get the attention it deserves.

Geothermal energy is sustainable and effective, making it a highly-rated alternative energy source across the globe. However, with plenty of advantages, geothermal energy also has a few surprising downsides.

Advantages of Geothermal Energy

1. Environment-Friendly

The best benefit of geothermal energy is that it is harmless to the atmosphere. This environmental aspect is the only reason why several applications use this renewable energy.

Geothermal energy is an exception. Unlike non-renewable energy, this energy creates less toxic emissions. It also helps to reduce dependence on burning fossil fuels for energy.

2. Geothermal System is Highly Efficient

Geothermal energy is highly-rated when it comes to efficiency. The heat pumps of geothermal energy consume up to 25% to 50% less electricity than conventional systems.

Additionally, the flexible designs of the pumps occupy smaller spaces and are adjustable to different circumstances.

3. Highly Sustainable

Since geothermal energy uses the heat from underground, it is easy to find sources of this energy. The reservoirs of geothermal energy replenish naturally, unlike fossil fuels. According to scientists, geothermal energy will possibly last for billions of years.

While non-renewable energy is limited and takes billions of years to replenish, geothermal is a very sustainable source of energy and is consistent throughout the year.

4. Reliable Source of Energy

Geothermal energy is one of the most reliable sources of energy on the planet. Even renewable energy sources like solar energy or wind energy are highly dependent on the weather. Since solar power requires stable sunlight and wind energy requires the presence of adequate wind, they may, at times, fail to generate a constant power supply.

Meanwhile, geothermal energy does not rely on external factors. So, it ranks as the top power source in terms of reliability and consistency. This energy is relatively more predictable and manages to generate the necessary power supply all the time.

5. Low Maintenance Cost

The total lifespan of the geothermal heat pump system is much higher than other energy sources because it only uses a few movable parts that shelter inside a building.

Additionally, a heat pump can usually last for at least a couple of decades, and the warranty services of the heat pump pipe can last up to 50 years.

Disadvantages of Geothermal Energy

1. Surface Instability

Probably the biggest concern of Geothermal energy is the risk of potential natural disasters due to unstable surfaces. The construction of the power plants can harm the stability of the land surface.

The drilling process can cause deterioration of the landscapes, slowly but surely. Although it may go unnoticed in single-family houses, it makes a significant impact on large geothermal installations.

2. Concerns About Greenhouse Emissions

Although geothermal energy is an eco-friendly energy source, many critics argue that its impact on the environment is second to none. The process of extracting geothermal energy from the earth can lead to the discharge of greenhouse gases like methane, carbon dioxide, and sulfide.

Although the amount of gas released in the geothermal process is significantly low, it still harms the environment.

3. Possible Depletion of Geothermal Sources

Although geothermal energy is a very sustainable energy source, there’s a high possibility of depletion of the sources. In the long run, the ground energy of a few sites may cool down, making it impossible to harvest further energy from the location.

Sourcing the energy directly from magma is the only non-depletable option for geothermal energy. However, the technology for this innovation is yet to be efficient and is still in the developing process. This extraction is worth the investment for the long run, mainly because the magma will be around for billions of years.

4. Requires a Large Amount of Land

Geothermal plants need vast land to generate a sufficient amount of energy from the source. It is essential to identify a suitable property with ideal geological characteristics to exploit proper power with this technology.

It is not viable to install the power plants mainly in the large cities as the subsoil of the city areas is mostly used for other services like electricity and sewage pipeline. Additionally, it is not feasible to build geothermal reservoirs on rocky terrains as it is quite challenging to build wells in this kind of land structure.

5. High Investment Cost

The initial cost of installing the power plant is very high. A single geothermal energy project requires a proper study regarding the land structure and its potential to generate power. The research alone requires specific machinery that is quite expensive for an individual household.

Additionally, drilling and installing this complex system makes the cost even higher. However, the project has quite a profitable return on investment with the promise of earning the investment back in as long as 2 to 10 years.

It is a known fact that this renewable energy source lowers the carbon footprint, but how much does geothermal energy cost? Navigate here to study the cost of geothermal energy.

Future of Geothermal Energy

Sourcing power supply from geothermal energy has both advantages as well as disadvantages. However, this energy source has relatively more benefits to the modern world. Geothermal energy has the potential to minimize the use of fossil fuels like coal, oil, petroleum, and natural gas.

Although geothermal energy affects the environment in a minimal amount, proper research and innovation can overcome its disadvantages shortly. With the sea level rising and glaciers melting day after day, the reality of climate change has never been so obvious. But, with alternative energy sources becoming more affordable and easy, we can save and restore our environment.

Also, read about the advantages and disadvantages of renewable energy in our next article.

Nina Howell is a Rewenable Energy researcher and consultant based out of Houston, Texas Area. She earned her Master's Degree in Energy and Earth Resources from Austin Jackson School of Geosciences in 2010, and a Bachelor's Degree in Environmental Science from State University of New York College of Environmental Science and Forestry in 2008. Nina has been working in the energy sector since 2011. She worked as an Energy Supply Analyst from 2011 to 2017 in Bounce Energy and then as a Research and Energy Consultant at GE Renewable Energy from March 2017 to February 2020 . Nina is a mom of 2 beautiful children who are joy to her life. She strongly believes in eco-friendly living and is vocal about renewable energy, environmental issues, water crisis, and sustainable living.