How Renewable Is Geothermal Energy? A Life-Cycle Analysis
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Experts predict the growth of renewable energy capacity will account for nearly 95% of the increase in global power capacity through the year 2026. Geothermal energy is one of our most utilized renewable technologies, so we had to ask: How renewable is geothermal energy?
Overall, geothermal energy is considered to be renewable energy. It is virtually inexhaustible and continuously replenished by the sun at a rate faster than we can deplete it. Renewable energy is naturally replenishing, virtually inexhaustible, and limited in the amount of energy available at one time.
Keep reading to learn how renewable geothermal energy is throughout its life cycle, what its carbon footprint is, what role it plays in combating climate change, and how safe or dangerous it is.
Here’s How Renewable Geothermal Energy Is
Geothermal energy is the conversion of heat from the Earth’s core into electrical energy.
“Geothermal: involving or produced by the heat that is inside the earth”
Cambridge Dictionary
Geothermal energy is one of our more underutilized renewable energy technologies that has a great energy generation potential. Renewable energy sources are flow-limited, naturally replenishing, virtually inexhaustible, and limited in the amount of energy available in a set amount of time.
“Renewable Energy: energy that is produced using the sun, wind, etc., or from crops, rather than using fuels such as oil or coal | types of energy that can be replaced naturally such as energy produced from wind or water”
Cambridge Dictionary
Given the worsening climate crisis, renewable energy has to come to represent a larger share of the overall energy market.
To understand how renewable geothermal energy is, we must assess its life cycle and each stage’s carbon footprint. This life-cycle assessment (LCA) is a method to evaluate the environmental impacts of products and materials. Over the years, companies have strategically used LCA to research and create more renewable products. So, let’s have a look at the LCA of geothermal energy!
| How renewable is geothermal energy overall | Overall, geothermal energy is renewable because it is virtually inexhaustible and is continuously replenished by the Earth at a rate faster than we can deplete it. Geothermal fluid can be re-injected and components of power plants can be recycled and repurposed at the end of their lifespan. |
| Building of geothermal energy | This initial stage of geothermal energy is not considered to be renewable because it involves constructing and not repurposing or re-using. |
| Operating and maintaining of geothermal energy | This stage is renewable because we harness only a fraction of the amount of heat the Earth gives off, and it naturally replenishes itself over time. |
| Building back of geothermal energy | Geothermal plants are built to last up to 50 years, and components can be recycled and repurposed at the end of their life cycle. |
How Renewable Is Geothermal Energy Overall
Overall, geothermal energy is renewable because it is virtually inexhaustible and is continuously replenished by the Earth at a rate faster than we can deplete it. Geothermal fluid can be re-injected and components of power plants can be recycled and repurposed at the end of their lifespan.
How Renewable Is the Building of Geothermal Energy
The building stage of geothermal energy involves drilling geothermal wells and constructing the power plant and delivery mechanisms.
Geothermal power plants require many components including wells, condensers, and cooling towers as well as transmission lines, transformers, and substations, all of which come with their own carbon footprint and resulting emissions.
This initial stage of geothermal energy is not considered to be renewable because it involves constructing and not repurposing or re-using.
How Renewable Is the Operating and Maintaining of Geothermal Energy
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 classified as a renewable energy source because the Earth has an almost unlimited supply of heat generated by its core, and the water extracted from the reservoirs can be recycled via re-injection into the ground. Reinjection helps to maintain reservoir pressure, recharge the reservoir for further extraction, and reduce subsidence.
Geothermal energy is also renewable because it is continuously replenished by the Earth at a rate faster than we can deplete it. Even if everyone on the planet went 100% to using geothermal energy, Earth would have enough thermal energy stored to outlive the sun. Experts also 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.
Given that we generated 14,877 megawatts (MW) of geothermal energy in 2022, we can continue to harvest geothermal energy for many years to come.
How Renewable Is the Building Back of Geothermal Energy
Building back geothermal energy involves decommissioning the wells, deconstructing the power plant infrastructure, disposing of hazardous waste, and restoring the land to its original condition.
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. Many components of geothermal power plants can also be recycled at the end of their life cycle, helping to make this stage more green.
What Is the Carbon Footprint of Geothermal Energy
The carbon footprint is one of the ways we measure the effects of human-induced global climate change. It primarily focuses on the greenhouse gas (GHG) emissions associated with consumption and includes other emissions such as methane (CH4), nitrous oxide, and chlorofluorocarbons (CFCs).
“Carbon footprint: the amount of greenhouse gasses and specifically carbon dioxide emitted by something (such as a person’s activities or a product’s manufacture and transport) during a given period”
Merriam Webster
Although geothermal energy emits zero to no GHG emissions upon operation, there are emissions associated with other stages of its life cycle including manufacturing, transportation, installation, maintenance, decommissioning, and dismantlement of materials.
On a life-cycle basis, geothermal energy emits 38 grams of carbon dioxide (CO2) equivalent per kWh of electricity produced, the 6th lowest out of all fuel types.
Have a look at the illustration below to see the average life-cycle CO2 equivalent emissions of different energy sources and how they compare to geothermal energy.
What Role Does Geothermal Energy Play in Combating Climate Change
Climate change is arguably the most severe, long-term, global impact of fossil fuel combustion. Every year, approximately 37 billion tons of CO2 are emitted from burning fossil fuels. The carbon found in fossil fuels reacts with oxygen in the air to produce CO2. This warms the earth by acting as a heating blanket, and a warmer earth comes with a host of negative side effects.
Using geothermal energy instead of fossil fuel energy helps mitigate the following negative effects of climate change:
- Increasing temperatures: Earth’s atmosphere has warmed 1.5℃ since 1880. This may not seem like a lot, but these degrees create regional and seasonal temperature extremes, reduce sea ice, intensify rainfall and drought severity, and change habitat ranges for plants and animals.
- Rising sea levels: Global sea levels have increased approximately 8-9 inches since 1880, displacing people living along coastlines and destroying coastal habitats. Roads, bridges, subways, water supplies, oil and gas wells, power plants, sewage treatment plants, and landfills remain at risk if sea level rise goes unchecked.
- Melting of sea ice: Since 1979, arctic sea ice has declined by 30%. Sea ice plays a major role in regulating the earth’s climate by reflecting sunlight into space and providing habitat for animal species. If all of the glaciers on Earth melted, sea levels would rise by approximately 70 feet, effectively flooding out every coastal city on the planet.
- Changing precipitation patterns: Extreme weather events (e.g., hurricanes, floods, droughts) are becoming more common and more intense. Storm-affected areas will experience increased precipitation and flooding whereas areas located further from storm tracks will experience decreased precipitation and droughts.
- Ocean acidification: The ocean absorbs 30% of the CO2 released into the atmosphere, which decreases the pH (increases the acidity) of the ocean. In the past 200 years, the pH of oceans has decreased by 0.1 pH units, which translates to a 30% increase in acidity. Aquatic life unable to adjust to this rapid acidification will die off. A prime example of this is coral bleaching, where coral expels the algae (zooxanthellae) living in their tissues as a result of changes in temperature, light, or nutrients.
The more we reduce CO2 emissions, the more we slow the rate of 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.
To help keep global temperature rise below 1.5C, as outlined in the Paris Agreement, we must shift at least 80% of our electricity generation to low-carbon sources. Over 120 countries have already stated their net-zero carbon emissions ambitions for 2050 or 2060. But only 12 countries have thus far proposed or enacted any legislation, indicating that there is more work to be done.
How Clean Is Geothermal Energy
Overall, geothermal energy is considered to be clean energy.
“Clean energy: energy, as electricity or nuclear power, that does not pollute the atmosphere when used, as opposed to coal and oil”
Collins Dictionary
Geothermal energy produces virtually no greenhouse gasses or any other kind of environmental pollution upon its operation.
| How clean is the building of geothermal energy | Emissions at this stage vary based on the type and size of the geothermal facility, with larger geothermal facilities requiring more materials and resulting in more emissions from construction. Essentially, the smaller the geothermal facility, the cleaner the building stage is considered. |
| How clean is the operating and maintaining of geothermal energy | There are very few CO2 emissions or waste products associated with operating and maintaining geothermal energy, making this stage very clean. |
| How clean is the building back of geothermal energy | Emissions at this stage vary based on the type and size of the geothermal facility, with larger geothermal facilities requiring more effort to decommission. Essentially, the smaller the geothermal facility, the cleaner the building back stage is considered. |
How Green Is Geothermal Energy
Overall, geothermal energy is considered to be green energy.
“Green Energy: energy that can be produced in a way that protects the natural environment, for example by using wind, water, or the sun”
Cambridge Dictionary
Geothermal energy has a low to zero-emissions profile and carbon footprint reductions that provide the highest environmental benefits.
| How green is the building of geothermal energy | The building stage of geothermal energy has a low carbon footprint when compared to fossil fuels, and geothermal can have a minimal impact on the land if proper siting measures are followed. |
| How green is the operating and maintaining of geothermal energy | Geothermal energy emits minimal greenhouse gasses and has a minimal effect on the environment, provided that proper siting of geothermal facilities occurs. |
| How green is the building back of geothermal energy | Recycling components of end-of-life geothermal facilities can help reduce their environmental impact. |
How Sustainable Is Geothermal Energy
Overall, geothermal energy is considered to be sustainable energy.
“Sustainable: The ability to be maintained at a certain rate or level | Avoidance of the depletion of natural resources in order to maintain an ecological balance”
Oxford Dictionary
Geothermal energy meets the needs of our current generation without compromising the ability of future generations to meet their own needs.
| How sustainable is the building of geothermal energy | Geothermal energy has become more sustainable in recent years with advancements in efficiency and technology. |
| How sustainable is the operating and maintaining of geothermal energy | This stage is sustainable because we harness only a fraction of the amount of energy the Earth gives off, meaning we can continue to use geothermal energy for many years to come. |
| How sustainable is the building back of geothermal energy | Geothermal plants are built to last up to 50 years, and components can be recycled and repurposed at the end of their life cycle, which increases their sustainability. |
How Environmentally Friendly Is Geothermal Energy
Overall, geothermal energy is considered to be environmentally friendly.
“Environmentally friendly: (of products) not harming the environment.”
Cambridge Dictionary
Geothermal energy does just as the word implies, it has a minimal, negative environmental impact.
| Building of geothermal energy | The building of geothermal energy can be environmentally friendly so long as construction activities do not disturb natural habitats, degrade the land, or lead to air or water pollution. |
| Operating and maintaining of geothermal energy | Geothermal energy emits minimal greenhouse gas emissions and has a minimal effect on the environment, provided that proper siting of geothermal power plants occurs. |
| Building back of geothermal energy | Recycling components of end-of-life geothermal facilities can help reduce their environmental impact. |
How Safe or Dangerous Is Geothermal Energy
Overall, geothermal energy is considered to be minimally dangerous. Holistically and throughout its life cycle, geothermal is safe and beneficial for human and animal health, the environment, and the energy grid.
Here’s How Safe Geothermal Energy Is
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.
| How Safe Is Geothermal Energy at a Holistic Level | Human and Animal Health: Geothermal energy is considered safe for human and animal health, with main risks involving air quality and groundwater contamination, and habitat disruption able to be mitigated with proper siting, monitoring, and maintenance of geothermal facilities. 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. Energy Grid and Infrastructure: Geothermal energy is a safe and beneficial addition to our power grid. It promotes the decentralization of our energy supply, which increases power grid efficiency by reducing peak time usage and decreasing the likelihood of power outages. |
| How Safe Is Geothermal Energy Across Its Life-Cycle | Building: Safe work practices and proper training of geothermal professionals can mitigate any risks associated with drilling wells and constructing geothermal facilities. Operating and Maintaining: Geothermal energy is considered safe to operate and maintain because it does not harm human health or the environment when producing energy. Building Back: 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. |
Here’s How Dangerous Geothermal Energy Is
Overall, geothermal energy is considered minimally dangerous in terms of human and animal health, the environment, the energy grid, and through all stages of its life cycle.
| How Dangerous Is Geothermal Energy at a Holistic Level | Human and Animal Health: Geothermal energy is considered minimally dangerous for human and animal health, with the main risks involving air quality and groundwater contamination, and habitat disruption. Environment: Geothermal energy is minimally dangerous to the environment, with land degradation and seismic activity being the two main concerns. Energy Grid and Infrastructure: Geothermal energy is not considered to be dangerous to our energy grid or supporting infrastructure. |
| How Dangerous Is Geothermal Energy Across Its Life-Cycle | Building: Building geothermal facilities can expose workers to a variety of hazards involving electricity, lack of fall protection, exposure to silica, trenching, and welding. Operating and Maintaining: Geothermal energy has minimal dangers associated with this stage, with exposure to high-temperature fluids from geothermal wells being the most common. Building Back: The most common workplace hazards of this stage include those resulting from lifting, trips and falls, electricity, and ladders. |
Final Thoughts
Overall, geothermal energy is renewable because it is virtually inexhaustible and is continuously replenished by the Earth at a rate faster than we can deplete it. Geothermal fluid can be re-injected and components of geothermal plants can also be recycled and repurposed at the end of their lifespan, making it more renewable.
Renewable energy is poised to see continued growth in the future as we look to reduce greenhouse gas emissions and mitigate global warming. As we look towards a future powered by renewables, geothermal energy is predicted to continue increasing in capacity because it benefits both our atmosphere and Earth’s biota.
Stay impactful,
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