How Does Geothermal Energy Work? Understanding Alternative Energy Options

power plant

featured image source: pixabay.com

Many people who are conscious about the environment would like to know more about alternative energy options. One of these would be geothermal energy. You might want to know now, how does geothermal energy work?

How Does Geothermal Energy Work?

People who have an interest in alternative energy sources will be likely to ask the question, "How does geothermal energy work?" Basically, it uses a natural source of power that you can find below the surface of the Earth.


There are pools of water underneath the surface of the Earth. They draw heat from magma or molten rocks, and they form the geothermal reservoirs of the Earth.

Geothermal energy harnesses the power within these reservoirs. It then converts it to a form that can power, heat, and cool devices and buildings above the Earth's surface. But exactly how does geothermal energy work?

geothermal icon

Three Types Of Geothermal Energy Plants


You might want to know about geothermal energy plants if you're interested in the answer to the question, "How does geothermal energy work?" There are three main types of these plants, and they all generate power in slightly different ways.

Dry Steam Power Plants

These are the most common type of geothermal power plants. In fact, about half of the currently installed geothermal power plants are dry steam power plants.


What these plants do is pipe hot steam from underground reservoirs directly into turbines. This hot steam powers the generators to create electricity. Once the steam has powered the turbines, it condenses into water and goes back into the ground by way of the injection well.

Flash Steam Power Plants

Flash steam plants are different from the dry steam plants because they pump hot water directly to the surface, rather than just pumping steam. The water is pumped at high pressure from underground into a flash tank, which is located aboveground.


The flash tank has a much cooler temperature. The sudden change in temperature from underground to the tank causes the liquid to turn into steam quickly. Just like in the dry steam plants, this steam powers the turbines; it's cooled, condensed, and then pumped back into the ground.

Binary Cycle Power Plants

In these plants, the liquid from underground never actually makes direct contact with the turbines. Water from the geothermal reservoirs is pumped through a heat exchanger. Here, it heats a second liquid that has a lower boiling point than water, such as isobutene.


It's the second liquid that ends up heated into steam, and this steam powers the turbines. The turbines drive a generator. The hot water from underground is recycled back into the Earth using the injection well, and the second liquid is recycled through the turbine and goes back into the heat exchanger; after this, it can go through another cycle of the same.

energy icon

Geothermal Heat Pumps


People who want to use geothermal energy in their own homes or workspaces generally use geothermal heat pumps. This allows them to harness temperatures from under the Earth's surface to either heat or cool a building. Temperatures aboveground fluctuate throughout the year, but the temperature below the Earth's surface typically remains between 50 and 60 degrees Fahrenheit throughout the year.


There are four types of geothermal heat pumps. Three of them involve closed-loop systems, and the other one involves an open-loop system.

Closed-loop Systems

With closed-loop systems, pipes below the surface of the Earth circulate a mixture of water and antifreeze. The environment underground will either heat or cool the liquid within the pipes. Then, the liquid will be transferred via an exchanger to either provide heat or cool air to a structure, such as a building.


This type of system makes it so that your heater or AC system doesn't have to work very hard. In the winter, the temperatures underground are warmer than the air aboveground, so it'll pump in warmer fluid and transfer heat through the ducts in your building this way. In the summer, the pipes will draw heat away from the building and absorb it into the water or Earth underground.


There are three different types of closed-loop systems. These include closed-loop horizontal systems, closed-loop vertical systems, and closed-loop systems that involve a pond or lake.


Closed-loop horizontal systems are typically the most cost-effective for residential areas, although closed-loop systems that involve a pond or lake are usually the cheapest ones. These two types typically don't extend very far underground.


The closed-loop vertical systems are more often used for larger commercial buildings. These systems sometimes have pipes that can go as far as 400 feet deep into the ground.

Open-loop Systems

In open-loop systems, water is taken directly from a source, such as a lake or a pond. Then, it goes into a heat pump aboveground and helps power a building.


Eventually, it's recycled and goes either back into its original source or into another water source with no pollution; the only change to the water during the process is a slight change in temperature.

What Is Geothermal Energy?

outdoor geothermal plant

image source: flickr.com

It's easy to wonder, how does geothermal energy work? However, it also helps to understand what geothermal energy is in the first place.

If you start digging into the Earth, you'll notice that the temperature gets higher as you go deeper. This is because there's a lot of heat on the inside of the Earth. Technically, this heat is geothermal energy.


Generally, it's much easier to draw geothermal energy from water sources beneath the surface of the Earth. This heat can provide the power that can help people above the Earth's surface.


Geothermal energy is a renewable energy source. It doesn't require the burning of fossil fuels at all. The hot water or steam that's used will be returned to the ground and can be used again, making this a way to obtain energy that doesn't hurt the planet.

If you're interested in learning more about geothermal energy, there are plenty of books available on the subject.

geothermal icon

Where It's Available


Technically, you can find geothermal energy almost anywhere. However, you can access it more easily in some places than in others.


Regions that are full of hot springs and other natural hot water reservoirs beneath the earth's surface, for example, are better sources. This is because, in these regions, the heat of the earth is closer to the surface. Because of this, it's easier to access and use geothermal energy.


In the United States, most geothermal power plants are in the Western regions. These are the areas in regions with active volcanoes, generally close to tectonic plate boundaries where the crust is thin enough to allow the heat to pass through.


The Pacific Rim has a variety of hot spots, in Alaska, Oregon, and particularly California. There are more than 40 geothermal plants in California, and these plants gave the state almost 6 percent of its electricity in 2017. People all over the world use geothermal energy; Iceland gets more than half of its energy this way, with geothermal energy heating most of the buildings in the nation.

money icon

Cost Concerns


Geothermal energy is a type of clean energy. Instead of harming the Earth and taking away from its resources, you're just harnessing a renewable and natural resource. Of course, a lot of people wonder how much it costs.


The price can actually vary quite a bit if you're looking at a heating and cooling system that's based on geothermal energy. If you're looking at one of these systems for a home or small-scale commercial operation, it can range from anywhere between $10,000 and $25,000.


The reason that there is such a wide range is that the cost depends on the specific conditions in that area. Soil conditions, site accessibility, plot size, system configuration, and the amount of digging and drilling that the professionals will need to do are all factors. That should make sense, now that you better understand the answer to the question, "How does geothermal energy work?"


However, there are many federal, state, and local incentives that can help offset these initial costs. This means that a lot of people don't have to pay these full prices in order to go geothermal.


In fact, you'll actually most likely save money by switching to geothermal energy. People generally save between 30 and 70 percent on heating and between 20 and 50 percent on cooling costs by using geothermal heat pumps.

For most people, this means that they would save between $400 and $1,500 each year. This means that the geothermal energy system would end up paying for itself within a matter of years.

system icon

How Long Do These Systems Last?


You might have been thinking about the components beneath the surface of the Earth when you first asked the question, "How does geothermal energy work?" However, the elements that are aboveground are fairly important as well.


In fact, the components aboveground are what make these systems last for such a long time. Indoor components of geothermal systems typically last about 25 years, and the ground loop usually will last for more than half a century.


Compare this with a furnace or conventional AC unit, which will typically last 15 years at most.


These systems are protected from outdoor elements. They also have fewer moving parts. Because of this, they don't require a lot of maintenance and will typically last for a very long time.

Other Alternative Energy Options

two giant windmills in a wind farm

image source: pixabay.com

You might have an interest in different alternative energy options if you wanted to know the answer to the question, how does geothermal energy work? Here are other alternative energy sources that might interest you:

  • Tidal energy
  • Hydrogen gas
  • Natural gas
  • Biomass energy
  • Biofuels
  • Wind energy
  • Wave energy
  • Hydroelectric energy
  • Nuclear power
  • Solar power

If you want to learn more about alternative energy sources, there are books on the subject that can enlighten you.

Save Your Energy

As you have seen, there are many different ways to harness geothermal energy from the inside of the Earth. The one that is best for any particular situation depends on a variety of factors, the location being one of the most important.


The use of geothermal energy is really good for the planet. It's sustainable, and it also ends up saving people a lot of money in the long run. Just like any other clean energy source, it's definitely worth considering.


What do you think of our answer to the question, "How does geothermal energy work?" Let us know by leaving a comment!


Icons via Flaticon

LEAVE A REPLY

Please enter your comment!
Please enter your name here