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Is It REALLY Clean Energy? – Exploring the Environmental Impacts of Geothermal Energy

Often hailed as a clean and sustainable source of power, geothermal energy has been gaining attention as the world seeks alternatives to fossil fuels. But what are the environmental impacts of geothermal energy?

Harnessing the Earth’s natural heat, geothermal energy has the potential to provide a reliable source of electricity while reducing greenhouse gas emissions.

However, like all energy sources, geothermal energy is not without its environmental consequences.

In this article, we will delve into the environmental impact of geothermal energy, examining both its advantages and drawbacks, and exploring its role in a sustainable energy future.

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Definitions and production of geothermal energy

Before delving into its environmental impact, let’s first understand what geothermal energy is and how it is produced. Geothermal energy is derived from the heat stored within the Earth’s crust.

This heat originates from the Earth’s core and is a renewable resource that can be harnessed for various purposes, including electricity generation and heating.

The production of geothermal energy typically involves drilling wells into the Earth’s crust to access hot water or steam reservoirs. This hot fluid is then used to drive turbines connected to generators, ultimately producing electricity. The process is efficient and continuous, making geothermal energy a reliable source of power.

The role of geothermal power plants

Geothermal power plants are the backbone of geothermal energy production. These facilities vary in size and design but share the common goal of converting geothermal heat into electricity.

There are three primary types of geothermal power plants: dry steam, flash steam, and binary cycle.

Each type employs a different approach to harness geothermal resources, but all contribute to the generation of clean energy.

Geothermal energy: A clean source of electricity?

One of the main selling points of geothermal energy is its cleanliness. Unlike fossil fuels, geothermal energy production does not involve the combustion of hydrocarbons, which release harmful pollutants and greenhouse gases into the atmosphere.

How clean is geothermal energy?

This means that geothermal power plants emit significantly fewer pollutants such as carbon dioxide (CO2), sulfur dioxide (SO2), and nitrogen oxides (NOx).

Furthermore, geothermal power plants operate with a small carbon footprint.

The emissions from geothermal energy are predominantly limited to non-toxic gases like carbon dioxide, and the overall emissions are considerably lower than those of fossil fuel power plants.

Geothermal power plant emissions compared to fossil fuels

To evaluate the environmental impact of geothermal energy, it’s crucial to understand the role of emissions in energy production. Emissions, particularly greenhouse gases like CO2, SO2, and NOx, contribute to climate change and air pollution.

Fossil fuel power plants are significant contributors to these emissions, while geothermal power plants aim to minimize them.

Comparative analysis of emission rates

When comparing the emission rates of geothermal power plants to fossil fuel power plants, the contrast is stark. Fossil fuel power plants release substantial amounts of CO2, SO2, and NOx into the atmosphere, contributing to global warming and air quality degradation.

In contrast, geothermal power plants produce negligible amounts of these harmful emissions.

While geothermal power plants are not entirely emission-free, their environmental impact is significantly lower than that of fossil fuel power plants.

The emissions from geothermal energy production are mainly confined to CO2 and trace amounts of other gases, making them a cleaner option for electricity generation.

Comparing geothermal energy to other renewable sources of energy

To assess the environmental impact of geothermal energy fully, it’s essential to compare it to other renewable energy sources, such as solar and wind power.

Geothermal energy stands out in several ways:


Geothermal energy is highly reliable, providing a consistent and stable source of power, unlike solar and wind energy, which are dependent on weather conditions. This reliability can be a significant advantage in maintaining a consistent power supply without the need for extensive energy storage solutions.

Land use

While solar and wind power often require large areas of land or extensive infrastructure, geothermal power plants have a smaller land footprint. They can be built on relatively small plots, making them suitable for locations with limited available land.

Water impact

Geothermal power plants consume water, primarily for cooling and reinjection into the reservoir. However, their water usage is significantly lower compared to traditional fossil fuel power plants. In regions where water conservation is crucial, geothermal energy can be a more sustainable choice.

Environmental impact

When considering the overall environmental impact, geothermal energy’s emissions are lower than those of fossil fuels but slightly higher than solar and wind power.

Nevertheless, geothermal power plants produce fewer emissions compared to other non-renewable sources and have a more predictable output.

Evaluating the environmental impact of geothermal energy

When we’re looking at environmental impact, we need to double-click on land subsidence and water.  

Land use in geothermal energy production

Geothermal power plants require land for their operations, but their land use is relatively minimal compared to some other energy sources.

The land occupied by a geothermal power plant is primarily used for the power plant infrastructure and access roads.

This land can often be used for dual purposes, such as agriculture or forestry, minimizing the environmental impact.

Land subsidence and sinkholes

One of the environmental impacts of geothermal energy extraction is land subsidence, which refers to a gradual sinking or sudden dropping of the Earth’s surface.

Subsidence can occur when there is an excessive removal of fluids from underground reservoirs, which can cause the ground to sink. This could potentially lead to sinkholes, which are not only hazardous but can cause significant damage to infrastructure and the environment.

However, this environmental impact is comparatively less severe than those associated with other forms of energy production. For instance, mining and oil drilling can significantly alter the landscape and cause widespread environmental damage.

Impacts on water quality

Geothermal energy production involves the extraction of hot water or steam from underground reservoirs. While this process has minimal impact on water quantity, it can have localized effects on water quality.

The hot water extracted can contain trace minerals and substances that may affect the local ecosystem if not properly managed.

Geothermal power plants reduce the environmental impact by re-injecting the water back into the reservoir, thus maintaining the system’s pressure and prolonging the life of the field.

But, they still use significant amounts of water for cooling, which could potentially strain water resources in areas where water is scarce.

The downsides: Negative environmental consequences of geothermal energy

While geothermal energy is generally considered environmentally friendly, it is not entirely devoid of environmental concerns. Some of the potential environmental issues associated with geothermal energy include:

Land disruption

The construction of geothermal power plants and the drilling of wells can disrupt local ecosystems and habitats. This disruption can impact wildlife and plant species in the area. It’s the main environmental concern that preservationists and conservationists alike take issue with.

Geothermal drilling involves the extraction of heat from the ground, which requires significant alteration of the landscape. This poses risks to local biodiversity as the physical presence of the plants, roads, and related infrastructure can fragment habitats and disturb wildlife. 

Ground vibrations and noise produced during drilling operations can distress animals or force them to vacate the area.

Further, drilling operations may have to clear large swaths of land to establish the necessary infrastructure for the operation. This can result in the destruction of habitats and natural vegetation, displacement of wildlife, and potential disturbances to migratory pathways.

There have also been reported cases of contamination of surface waters during the drilling process, impacting aquatic life, and potentially the people who rely on the water for their livelihood or survival.

Geothermal plants also need to routinely drill new wells to maintain production. This continuous drilling can lead to long-term, cumulative impacts on ecosystems, especially in sensitive environments. Not to mention that the disturbance from drilling has the potential to destabilize the ground and trigger landslides or erosion.

Also, the transmission lines used to transport the geothermal energy can have additional impacts on wildlife, particularly bird species that are vulnerable to collisions with power lines.

In conclusion, while geothermal energy is a cleaner source of power in contrast to fossil fuels, it is not without significant environmental challenges. These challenges require careful management to ensure that the benefits of geothermal power can be reaped without causing undue harm to the world’s ecosystems and biodiversity.

Areas chosen for geothermal development should be carefully assessed; and when possible, efforts should be made to choose locations with lower ecological values or greater resilience. This will help to balance our need for clean, renewable energy sources with the protection of our remaining natural spaces. 

Induced seismicity

In some cases, geothermal energy production has been linked to induced seismicity or human-induced earthquakes. This can occur when fluid injection or extraction alters subsurface pressure, potentially triggering seismic events.

Induced seismicity from geothermal energy extraction is generally small and less impactful than natural earthquakes. Nonetheless, it can cause minor property damage and sometimes temporary suspending of operations.

Two ways in which geothermal exploration can induce seismicity include hydraulic fracturing and fluid injection.

Hydraulic fracturing, or fracking, involves injecting high-pressure fluid into the ground to create fractures that make it easier to extract heat. These fluid-induced fractures can potentially trigger small earthquakes if they interact with an existing fault.

Fluid injection, on the other hand, involves injecting fluid into a well for enhanced geothermal systems (EGS) to increase the permeability of the rock and extract more heat.

Just like fracking, these pressurized fluids can induce micro-earthquakes if they intersect with or create new faults.

However, the risk of induced seismicity can be mitigated through careful site examination before operations, constant monitoring, better reservoir management, and timely response to seismic events.

Moreover, most instances of induced seismicity in geothermal operations are not felt at the surface and falls under the microseismic category. This type of seismic activity is usually detectable only with specialized equipment.

Despite these challenges, geothermal energy remains an important source of renewable energy that can help offset carbon emissions and mitigate climate change. Therefore, the focus should be on developing safe, efficient, and sustainable methods for geothermal energy extraction, which includes managing and mitigating risks associated with induced seismicity. 

Chemical contamination and pollution

Another environmental concern is contamination. The hot fluids extracted from geothermal reservoirs can contain trace elements and minerals that, if not managed properly, may contaminate surface water and soil. 

The process of geothermal energy extraction can also release greenhouse gases stored deep within the earth. However, the total emissions are lower than those of conventional fossil fuels.

Furthermore, the process of withdrawing geothermal fluid can sometimes bring up dangerous heavy metals and gases. Careful management and disposal of these materials are required to minimize the environmental impact.

 During the exploration and development of geothermal energy, drilling operations can cause seismic disturbances and release fluids that may compromise local water systems.

The spent geothermal fluids that are typically re-injected back into the reservoir may contribute to increased seismic activity, commonly known as induced seismicity, which we just discussed above.

Radioactive materials and gasses that may be hazardous to human health and the environment can also be brought to the surface during the extraction of geothermal energy.

These include radon and other naturally occurring radioactive materials (NORMs), which can potentially pose health risks and require proper handling and disposal.

Moving to the operation stage of geothermal power plants, the cooling towers used in the process can create visual and noise pollution. This can be minimized by using technologies such as binary cycle plants, which do not require cooling towers.

Finally, geothermal power plants can greatly change land use patterns and aesthetics, as they require large areas for their operation. They may also disrupt wildlife habitats and ecosystems. Hence, comprehensive environmental impact assessments should be done at each stage of geothermal energy development to ensure the least possible harm to the ecosystem.

Risk and downside management

It’s important to note that many of these environmental issues associated with geothermal energy can be mitigated through proper planning, monitoring, and regulation. Good communication with local communities also matters and supports risk reduction.

For instance, conducting thorough environmental impact assessments before geothermal projects begin can help identify potential risks and develop strategies to minimize them.

Additionally, advanced drilling and reservoir management techniques can help reduce the risk of induced seismicity, and appropriate water treatment and reinjection can prevent chemical contamination of surface water and soil.

Regulatory oversight also plays a crucial role in ensuring that geothermal energy projects adhere to environmental standards.

Geothermal energy is a clean source overall—but what does the future hold?

The future of geothermal energy holds promise for further reducing its environmental impact. Ongoing research and development efforts aim to enhance the efficiency of geothermal power plants, making them even cleaner and more sustainable.

Innovations in geothermal technology include the development of enhanced geothermal systems (EGS), which could expand geothermal energy production to regions that were previously unsuitable.

EGS involves creating artificial reservoirs by injecting water into hot, dry rock formations, increasing the availability of geothermal resources.

The role of geothermal energy in a sustainable future

As the world grapples with the challenges of climate change and the need to transition to sustainable energy sources, geothermal energy can play a vital role. Its reliability, low emissions, and relatively small land footprint make it an attractive option for meeting future energy demands.

Geothermal energy can also complement other renewable sources, providing a stable source of electricity to balance the intermittent nature of solar and wind power. This integration can help create a more resilient and sustainable energy grid.

As we look to the future, geothermal energy holds significant promise as a clean and sustainable energy source. Ongoing research and innovation will likely lead to even more environmentally friendly geothermal power plants, further solidifying its role in a greener and more sustainable energy landscape.

Summarizing the pros and cons

Geothermal energy offers numerous environmental advantages, including low greenhouse gas emissions, minimal land use, and relatively low water consumption compared to fossil fuels. It provides a steady and reliable source of power, contributing to energy stability.

However, it is essential to acknowledge the potential environmental challenges associated with geothermal energy, such as land disruption, induced seismicity, and water quality concerns. These issues can be effectively managed through responsible project planning and regulatory oversight.

Final thoughts on the environmental impacts of geothermal energy

Geothermal energy is a valuable asset in the transition to a cleaner and more sustainable energy future. While it is not entirely devoid of environmental impacts, its benefits far outweigh its drawbacks, making it a crucial component of our efforts to combat climate change and reduce our reliance on fossil fuels.

With responsible management and continued advancements in technology, geothermal energy can play a pivotal role in shaping a cleaner and greener world for generations to come.

Environmental impacts of geothermal energy FAQs

What is the role of the National Renewable Energy Laboratory in the use of geothermal energy?

The National Renewable Energy Laboratory (NREL) conducts research and development to improve our understanding of geothermal resources and develop efficient ways of extracting this type of energy.

Part of their work involves assessing the environmental impacts and efficiency of open-loop and closed-loop systems, how best to generate electricity and the amount of carbon dioxide equivalent emitted per kilowatt-hour.

How do closed-loop geothermal systems work?

Closed-loop systems, also called heat pump systems, use a circulating fluid that absorbs heat from the earth and transports it to the building for heating or cooling. The warmth absorbed from the ground is then lost as steam, which can be reused in the system, making it more environmentally friendly.

Why do some people oppose the use of open-loop geothermal systems?

While open-loop geothermal systems are effective in energy generation, they have certain environmental drawbacks. The operation of geothermal facilities often results in the release of hydrogen sulfide, a harmful gas, into the atmosphere, and these systems can also produce a significant amount of carbon dioxide equivalent when compared to other renewable electricity options.

How do geothermal power facilities use hot rock?

In geothermal power facilities, water and steam are pumped under high pressures into hot rock located deep beneath the Earth’s surface. When the water comes into contact with the hot rock, it produces steam which is used to generate electricity. The water used in this process is then often re-injected back into geothermal reservoirs, reducing the environmental impact.

What environmental impacts are associated with the use of geothermal energy?

The use of geothermal energy can result in both direct and indirect environmental impacts. Direct impacts include land disturbance at geothermal sites and pollution caused by the release of gases like hydrogen sulfide. Indirect impacts can include the release of carbon dioxide equivalent in the atmosphere from drilling and the operation of geothermal facilities.

How is geothermal power compared to coal plants in terms of carbon emission?

According to a report by the Intergovernmental Panel on Climate Change (IPCC), geothermal power plants emit around 1% of the carbon dioxide equivalent per kilowatt-hour that is emitted by coal plants, making geothermal a far cleaner source of energy.

What is the importance of water in geothermal energy systems?

Water plays a key role in both open-loop and closed-loop systems. In open-loop systems, water is pumped directly from geothermal reservoirs, while in closed-loop systems, a constant supply of water is necessary to create the steam needed to generate electricity. Advanced geothermal plants re-inject water back into geothermal reservoirs to minimize water loss and environmental impact.

What is the power capacity of the average geothermal facility?

This can vary a great deal but, according to the Geothermal Energy Association, the average power capacity of a geothermal power plant in the United States is about 25 megawatts, enough to power approximately 20,000 homes.

Do geothermal power plants cause any harm to human health?

While geothermal power plants can cause environmental disturbances, studies have shown that the direct risks to human health from exposure to geothermal fluids and gases are minimal, especially when compared with traditional energy sources such as coal. The gases released, including hydrogen sulfide, are at concentrations that pose little danger to human health.

Is geothermal energy expected to play a greater role in energy generation in future?

Yes, according to the Intergovernmental Panel on Climate Change, the use of geothermal energy is expected to grow significantly due to its numerous environmental benefits, high efficiency, and the vast, largely untapped potential of geothermal resources worldwide.

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Lauren is the founder and editor of Climate Energy Homes. A long-time advocate of green living, she's constantly learning about ways to minimize environmental impact with sustainable choices while saving money.

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