Geothermal energy is a renewable and sustainable energy source that is important in reducing global greenhouse gas (GHG) emissions and mitigating climate change. It has increased in capacity over the years, but it remains a virtually untapped resource. So, we had to ask, how safe is geothermal energy really?

Overall, geothermal energy is considered to be safe. Holistically and throughout its life cycle, geothermal is safe and beneficial for human and animal health, the environment, and the energy grid.

Keep reading to find out how safe geothermal energy is overall, holistically, and in terms of its life cycle. Then, we’ll describe geothermal energy’s pros and cons, look at how effective it is, and determine how it can help mitigate climate change.

The Big Picture of the Safety of Geothermal Energy

Geothermal energy is produced when radioactive materials in the rock and fluid of the earth’s core decay. Drilling down to hot water reservoirs up to a mile below the surface creates steam that rotates a turbine, which spins a generator to generate electricity. 

“Geothermal: involving or produced by the heat that is inside the earth”

Cambridge Dictionary

The three main types of geothermal power plant technologies are:

1. Dry Steam: Wells are drilled into underground reservoirs of steam. The steam is piped directly from the well to the power plant where it powers turbines and generators.

2. Flash Steam: Very hot (360 degrees Fahrenheit, 182 degrees Celsius) water flows up through wells towards the surface under its own pressure. As it reaches the surface, some of the water boils into steam.

3. Binary Cycle: Wells are drilled into underground reservoirs of hot water (225-360 degrees Fahrenheit, 107-182 degrees Celsius). The heat from the water is used to boil a working fluid, which is vaporized into steam and then used to power turbines and generators at the power plant.

All three systems take heat from the Earth’s core and convert it to electricity, just by slightly different mechanisms. Flash steam power plants are the main geothermal technology used today, although binary cycle plants and other new technologies are becoming more common.

Here’s How Safe Geothermal Energy Is Holistically and Across Its Life-Cycle

One way to combat the current global climate crisis threatening Earth’s environmental, economic, and social health is to transition away from traditional fossil fuels and toward renewable energy sources, such as geothermal energy. 

Just as with any energy source, it is important to understand how safe geothermal energy is before we implement it on a commercial scale. This involves analyzing all aspects of geothermal energy. 

For this reason, we have split our analysis into the following categories:

• Overall safety
• Holistic safety
• Life-cycle safety
• Comparative safety

How Safe Is Geothermal Energy Overall

Overall, geothermal energy is a safe form of energy regarding human and animal health, the environment, the energy grid, and throughout all stages of its life cycle. Geothermal energy has a low carbon footprint and can be a beneficial addition to our power grid that can promote decentralization and reduce air pollution.

How Safe Is Geothermal Energy at a Holistic Level

Experts predict geothermal energy installed capacity and electricity generation to increase in the coming years due to emerging technologies and country-specific climate goals. Therefore, it is important to understand how safe it is at a holistic level.

“Holistic: relating to the whole of something or to the total system instead of just to its parts”

Cambridge Dictionary

To understand how safe geothermal energy is holistically, we must take into account how it affects us, the environment, and our technology.

How Safe Is Geothermal Energy When It Comes to Human and Animal Health

Overall, geothermal energy is considered safe for human and animal health. 

The main risks to humans and animals involve air and groundwater contamination, and land use and habitat disruption.

Steam vented from power plants can contain hydrogen sulfide, ammonia, methane, and CO₂, and plants can discharge dissolved solids including sulfur, chlorides, silica compounds, vanadium, arsenic, mercury, and nickel into the air or underground water systems. If concentrated, these gasses and dissolved solids could adversely impact human and animal health.

Hydrogen sulfide in particular can significantly impact human health, causing mild respiratory irritation at low levels and nausea, convulsions, or even death at high levels. Gas detection, proper ventilation, and monitoring systems can reduce these risks.

Groundwater contamination is the other main concern associated with geothermal energy. Geothermal fluids containing heavy metals (e.g., arsenic, mercury, lead) can contaminate drinking water if leached into the surrounding environment. Chronic exposure to arsenic has been linked with skin disorders and cancer, whereas long-term mercury exposure can impact the brain and nervous system. 

As with any energy source, geothermal energy can also cause habitat fragmentation, which affects wildlife’s ability to migrate, reproduce, and find food. Surface construction involving drilling, pipelines, and power plants can disturb critical habitats, reduce continuous habitats, and alter soil, vegetation, and water resources. Implementing buffer zones and restoring the land post-construction can mitigate this risk to wildlife.

Ways to further increase the safety of geothermal facilities include performing environmental assessments before construction to determine the potential negative impacts of geothermal facilities and implementing regular monitoring and maintenance protocols. 

Overall, geothermal energy is safe for human and animal health and can be made safer with proper siting, monitoring, and maintenance of geothermal facilities. 

How Safe Is Geothermal Energy When It Comes to the Environment

Geothermal energy emits minimal greenhouse gas emissions and has a minimal effect on the environment, provided that proper siting of facilities and disposal of waste occurs.

Geothermal energy produces a fraction of the pollution and toxic chemicals that fossil fuels produce, helping to protect air quality. Geothermal power plants emit 99% less CO₂ than fossil fuel plants of comparable size. Dry and flash steam plants emit mostly water vapor whereas binary steam plants emit virtually no gasses at all because they operate under a closed-loop system. All three systems also produce very low amounts of sulfur dioxide and no nitrogen oxides and scrubbers can remove 99.9% of sulfur emissions when utilized. 

The two main environmental concerns are land degradation and the potential to cause earthquakes.

Geothermal power plants can cause subsidence, or the gradual sinking of land. This occurs as underground hydraulic fractures collapse in on themselves due to the depletion of reservoirs. If severe enough, it could damage pipes, roads, buildings, and natural drainage systems. To mitigate this, operators can reinject spent geothermal fluid into the reservoir, which helps to maintain underground pressure.

High-pressure, geothermal fluid injections close to neighboring fault lines also have the potential to trigger earthquakes. Although most are too small to be felt or registered on the Richter Scale, a larger quake could be more threatening or cause the geothermal project to be shut down.

Seismologists have a few theories as to why geothermal energy can induce earthquakes:

• Withdrawing steam and heat causes contractional stresses on the surrounding rocks
• Re-injecting cold water into hot rocks causes a stark thermal contrast
• Injection fluid can find its way into faults and lead to further fracturing

Geothermal operators can reduce this risk by conducting geological surveys to identify and avoid drilling close to fault lines. Seismicity can also be limited by carefully controlling geothermal fluid injection rates.

How Safe Is Geothermal Energy When It Comes to the Energy Grid and Infrastructure

Geothermal energy is not only safe, but it is also a beneficial addition to our energy grid and supporting infrastructure. Geothermal energy promotes the decentralization of our energy supply, which increases power grid efficiency by reducing peak time usage and decreasing the likelihood of power outages. 

Renewable energy, including geothermal energy, draws energy from various geographic locations, so the grid can distribute power from multiple plants.

Although the addition of large amounts of renewable energy to the grid at one time may seem like it would have a destabilizing effect, renewable energy becomes more predictable as it is added to the grid. This is thanks to the law of large numbers. 

“Law of large numbers: as the number of identically distributed, randomly generated variables increases, their sample mean (average) approaches their theoretical mean.”

Britannica

In terms of renewable energy, the output of every geothermal power plant that is connected to the power grid Is less volatile and more stable than the output of one individual generator. This decentralization in turn reduces peak time usage and decreases the likelihood of power outages. It also increases the efficiency of power production and power distribution.

How Safe Is Geothermal Energy Across Its Life-Cycle

To understand how safe geothermal energy is, we must look at its life cycle and how safe each stage is. This includes assessing the safety of geothermal energy’s building, operating and maintaining, and building back stages.

How Safe Is Geothermal Energy in the Building Stage

The building stage of geothermal energy involves drilling geothermal wells and constructing the power plant and delivery mechanisms.

This includes building the many components found in geothermal facilities including wells, condensers, generators, and turbines as well as the transmission lines, transformers, and substations required for delivering electricity to consumers. Some of the most common hazards associated with this stage involve electricity, lack of fall protection, exposure to silica, trenching, and welding. 

Safe work practices and proper training of geothermal professionals can mitigate any risks associated with constructing geothermal facilities. 

How Safe Is Geothermal Energy in the Operating and Maintaining Stage

The operating and maintaining stage of geothermal energy includes the process by which geothermal facilities convert the earth’s heat into electricity. 

Geothermal energy is considered safe to operate and maintain because it does not harm human health or the environment when producing energy. 

Geothermal power plants do release minute amounts of CO₂, nitrogen oxides, and particulate matter, but not during combustion. These gasses are naturally occurring in geothermal reservoirs and would eventually vent to the surface and into the atmosphere, albeit at much slower rates. 

There are very few CO₂ emissions or waste products associated with operating geothermal energy, making the carbon footprint of this phase very low. CO₂ emissions at this stage are associated with the operation of the mechanical equipment (e.g., turbines and generators) at the power plant. 

One of the biggest concerns associated with the operation of power plants involves ​​exposure to high-temperature fluids from geothermal wells, which can cause serious burns. Proper personal protective equipment (PPE) can limit this risk.

How Safe Is Geothermal Energy in the Building Back Stage

Building back geothermal energy involves decommissioning the wells and deconstructing the power plant infrastructure.

Geothermal heat pumps can last more than 20 years, and the underground infrastructure has a historical life expectancy of up to 50 years. This makes them a long-term, reliable source of energy. 

This final stage is considered to be safe overall, with the most common workplace hazards (lifting, trips and falls, electricity, and ladders) being mitigated by safe work practices. 

What Are the 6 Pros and 3 Cons of Geothermal Energy

Geothermal energy is a renewable and sustainable energy source, has a low carbon footprint, protects air quality, has a minimal land use impact, generates few waste products, and promotes energy independence and security. 

However, geothermal energy has location restrictions, can trigger seismic activity, and comes with high upfront costs.

These Are the 6 Pros of Geothermal Energy

Geothermal energy has various pros that make it effective at reducing carbon emissions.

These Are the 3 Cons of Geothermal Energy

Understanding the drawbacks of geothermal energy is important in order to effectively mitigate climate change. 

How Effective and Efficient Is Geothermal Energy

In terms of effectiveness, geothermal energy effectively converts the Earth’s heat into electricity, has a low carbon footprint, protects air quality, and promotes energy independence and security. However, it also comes with high upfront costs and location restrictions and can trigger seismic activity. 

In terms of efficiency, geothermal energy efficiently converts the Earth’s heat into electricity, is a renewable and sustainable energy source, has a minimal land use footprint, increases the efficiency of our power grid, and generates few waste products.

Geothermal energy is effective because:

• Experts estimate that we could supply humanity’s total energy needs for the next 2 million years with only 0.1% of the heat content of the Earth.
• On a life-cycle basis, geothermal energy emits 38 grams of CO₂ equivalent per kWh of electricity produced, the 6th lowest out of all fuel types. 
• Geothermal energy produces a fraction of the pollution and toxic chemicals that fossil fuels produce, helping to protect air quality.
• Geothermal energy can help us transition away from fossil fuels and toward an energy-independent future.

However, geothermal energy can lack effectiveness because:

• Geothermal energy comes with high initial costs, with a 1 MW capacity geothermal power plant costing an average of $2.5 million.
• Geothermal energy has location restrictions and can only be harnessed in areas with volcanic activity or geothermal reservoirs.
• High-pressure, geothermal fluid injections close to neighboring fault lines have the potential to trigger seismic activity, specifically earthquakes. 

Geothermal energy is efficient because:

• Geothermal energy has a 12% average conversion efficiency and a 90% (or higher) capacity factor, meaning it is able to operate at maximum capacity almost all of the time.
• Geothermal energy is a renewable and sustainable resource that can reduce emissions for generations to come.
• Geothermal energy produces more power on less land than many other energy sources. 
• Geothermal energy promotes the decentralization of our energy supply which increases power grid efficiency by reducing peak time usage and decreasing the likelihood of power outages. 
• Geothermal energy produces substantially less waste than other forms of energy.

How Can Geothermal Energy Help Mitigate Climate Change

Climate change is a severe, long-term consequence of fossil fuel combustion. If left untreated, atmospheric CO₂ can remain there for tens of thousands of years and exacerbate the negative effects of climate change. Geothermal energy emits less CO₂ upon operation than fossil fuels and can therefore reduce our total emissions. 

How Is Climate Change Defined

Climate change is arguably the most severe, long-term global impact of CO₂. Every year, we emit approximately 37 billion tons of CO₂. The carbon found in fossil fuels reacts with oxygen in the air to produce CO₂. 

“Climate change: changes in the earth’s weather, including changes in temperature, wind patterns, and rainfall, especially the increase in the temperature of the earth’s atmosphere that is caused by the increase of particular gasses, especially carbon dioxide.”

Oxford Dictionary

When carbon enters the atmosphere, it absorbs sunlight and solar radiation, trapping the heat and acting as an insulator for the planet.

Since the Industrial Revolution, Earth’s temperature has risen a little more than 1 degree Celsius (°C), or 2 degrees Fahrenheit (°F). Between 1880-1980 the global temperature rose by 0.07°C every 10 years. This rate has more than doubled since 1981, with a current global annual temperature rise of 0.2°C, or 0.36°F, for every decade.

How Does Geothermal Energy Specifically Help Mitigate Climate Change

The global average concentration of CO₂ in the atmosphere today registers at 419 parts per million (ppm), the highest ever recorded. Geothermal energy can help lower this concentration because it can replace some of the burning of fossil fuels (e.g., coal, oil, natural gas) with a cleaner form of renewable energy.

Throughout its life cycle, geothermal energy produces 1/6^th the CO₂ of a natural gas power plant. In the US alone, annual geothermal energy resources effectively offset the emission of 4.1 million metric tons of CO₂, 200 thousand tons of SO₂, 80 thousand tons of nitrogen oxides, and 110 thousand tons of particulate matter, when compared to conventional coal-fired plants.

Increasing geothermal energy usage can reduce CO₂ emissions, and the more we reduce CO₂ emissions, the more we combat the negative effects associated with climate change including temperature rise, sea-level rise, ice melting, and ocean acidification. When these rates are slowed, the earth’s biodiversity does not have to struggle to adapt to temperature and pH changes. People will not be displaced due to the flooding of coastal areas. And icebergs will continue to provide climate regulation. 

Final Thoughts

At a holistic level, geothermal energy is considered to be a safe form of energy in terms of human and animal health, the environment, and the energy grid and supporting infrastructure. It has a low carbon footprint and can be a beneficial addition to our power grid that can promote decentralization and reduce air pollution.

Geothermal is also considered to be safe during its entire life cycle (building, operating and maintaining, and building back stages). Common hazards, including those associated with construction, electricity, and geothermal fluids can be mitigated by proper training and safe work practices. 

Forging a sustainable planet for future generations will require us to increase renewable energy usage, and geothermal energy is a great place to start. 

Stay impactful,

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