Is Geothermal Energy Pollution-Free?

We’ve all heard about all the good things that geothermal energy can do for the environment. Some even claim that it is one of the best energy sources that we can harness because it’s renewable and sustainable. But is it really as pollution-free as we think?

Geothermal energy with a closed-loop system is pollution-free, and it doesn’t harm the environment. Geothermal energy with an open-loop system is, on the other hand, not pollution-free. Still, as we will see below, it’s a much cleaner energy source than others we currently use.

Several factors affect the pollution that geothermal energy produces, and we’ll discuss all of them in great detail. Stick around because this article will be quite an eye-opener for you, and it might even change your perception when it comes to geothermal energy.

What Is Geothermal Energy?

The Earth produces heat through the continuous decay of radioactive isotopes. It can reach a temperature of 5,000°C (9,032°F), going up to the surface to warm any geological material in its path. It’ll continuously heat any underground rock formation that it touches. Once it reaches anywhere from 700°C to 1,300°C (1,300°F to 2,400°F), these rock formations will become magma.

Magma is responsible for heating other rocks and underground aquifers that create various geothermal energy sources, such as hot springs, steam vents, hydrothermal vents, and more.

As you can imagine, the Earth’s crust produces a lot of geothermal energy that we can convert into electricity. It’s a renewable and sustainable energy source that can replace much of the electricity we get from fossil fuels and other unsustainable energy sources. 

The biggest reason why more and more people are using it is that it harnesses something we took for granted for centuries—the Earth’s naturally-occurring energy. Whether we use geothermal energy or not, the Earth will produce it, and it has the potential to supply a large portion of the electricity that the world needs.

Aside from being renewable and sustainable, geothermal energy is far more reliable than any source that we currently use. Throughout the year, the underground temperature is constant, and the deeper you go, the hotter it gets. We call it geothermal gradient, and it’s highly predictable at a rate of 25°C per kilometer (1°F per 77 feet).

Unlike fossil fuel, solar power, wind energy, and natural gas, there is almost nothing that can disrupt geothermal energy. It’ll generate the heat that we need, regardless of the temperature on the surface.

Pollution Caused by Geothermal Energy

As we have said, geothermal energy is pollution-free, as long as it is in a closed-loop. Having said that, while we consider geothermal energy pollution-free, it is true that there are items related to it that are not pollution-free.

Which are these items? Well, we need equipment and infrastructure to harness the energy and those elements, unfortunately, do produce carbon emissions. So, while geothermal energy itself can be pollution-free, the creation of the equipment and infrastructure to generate that energy is not pollution-free.

And not all geothermal energy is pollution-free. As we said, that is only the case with closed-loop systems. But even if it is not completely pollution-free, geothermal energy is much more sustainable than other energy sources.

As an average, according to the U.S. Energy Information Administration, geothermal power plants produce 99% less carbon dioxide than burning coal or gas. These power plants also produce 97% fewer sulfur compounds, which contributes to acid rain formation.

What does this mean in absolute numbers? For example, open-loop systems release at least 0.1 lb of carbon dioxide into the atmosphere per kilowatt-hour. Some geothermal systems that require drilling and pumping of hot water can generate around 0.2 lb of carbon dioxide per kilowatt-hour.

On the other hand, as we said, closed-loop systems don’t release gases into the atmosphere.

So, to sum up, geothermal energy can be pollution-free, but it doesn’t mean that it has zero carbon emissions. Most of the equipment that we use today had some level of emissions, making it almost impossible, at least for now, to make also all the equipment and infrastructure around geothermal energy pollution-free.

It may sound bad, but it’s only a by-product of our reliance on fossil fuel. Despite the advancements in our fight against global warming, we’re still far from using products and equipment that don’t have carbon emissions. However, if you compare it with burning coal and fossil fuel for electricity, we can say that geothermal energy is still one of the cleanest energy sources.

Other Advantages of Geothermal Energy

Geothermal energy is pollution-free, but harnessing its power has some levels of emissions. It may still take quite some time before we can be more efficient in harnessing it. You don’t have to wait for it, though, because there are already a lot of other benefits that you can get, including the following:

  • Stable and reliable supply: Unlike all energy sources that we can use—coal, gas, solar, wind, and more—geothermal energy is stable and reliable. Several factors can affect the output of other energy sources, making it hard to predict the capacity that we may need to keep all of our systems running. On the other hand, geothermal power plants have a very high capacity factor.
  • Renewable and sustainable: We’ve already talked about its sustainability. Whether we harness it or not, the Earth will continuously produce geothermal energy. It holds so much power that it can take out a significant portion of all our electric consumption from other unsustainable energy sources.
  • Massive potential for further developments: The world uses about 17.7 terawatts of power, and in 2017, geothermal power plants only produced 12.7 gigawatts. However, based on various estimates, geothermal energy advancements may allow our power plants to produce as much as 2 terawatts of power just from the heat that the Earth generates.

Why Not Everyone Is Using Geothermal Energy

If geothermal energy is as clean as what research shows, why do most houses still rely on non-renewable energy sources? Well, there are two reasons for it: cost and availability.

Further advancements will make sourcing geothermal energy more cost-efficient. We’ve already seen improvements in harnessing this energy, but we still have a long way to go to completely harness the massive energy that’s right under our feet.

Availability is an even bigger challenge for geothermal energy because it’s only available in certain parts of the world. It’s also one of the biggest driving factors for its cost. Even if we can’t get it everywhere, replacing 2 terawatts of power with a renewable source is still a huge reason for us to support its further developments.


Geothermal energy is pollution-free. It doesn’t have carbon emissions and shows great potential in our fight against global warming. Unfortunately, our reliance on fossil fuels makes it almost impossible, for now, to harness geothermal energy without carbon emissions because the equipment and infrastructure required to harness the energy will produce some carbon emissions during its creation.

If you liked this post, be sure to check “Is Geothermal Heating Bad for the Environment?” & “Is Geothermal Heating Cheaper Than Natural Gas?


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