Why geothermal power generation will be a key part of reducing GHG emissions for generations to come
Recent advances in drilling technology are making geothermal power more affordable than ever. Some countries like Canada have deep expertise in deep well drilling and that same capability can be used to build geothermal wells rather than drill for oil or natural gas.
In the quest to generate electrical power with low-emission output, geothermal energy has been traditionally excluded from consideration. While the world focuses on other alternatives such as wind and solar – each with their challenges in terms of reliable, stable electricity generation, comparatively very little has been done to harness the power capability of geothermal energy.
There is an increasing body of evidence to indicate that geothermal energy should receive more attention due to its numerous advantages. However, government intervention is crucial because it is a capital-intensive endeavour. The private sector cannot be exclusively relied on for the explorative phases of geo-thermal development. Understanding the risks associated with mining for geo-thermal energy is required for governments to act in assisting the private sector to offset those risks. Without doing so, we risk losing out on what promises to be a game-changing low-emission energy generation opportunity to help reduce our impact on climate change.
Iceland – Paving the way in Geothermal
Many of us are familiar with the success that the small island nation of Iceland has had with the utilization of geo-thermal energy for direct applications such as heating homes, swimming pools and baths. Such uses go back as far as the Viking age however in recent years, Iceland has also harnessed geothermal energy for electricity generation. As of 2020, Iceland had an installed capacity of about 800MW which provides about 25% of the total power capacity. Hydroelectric, wind and fossil fuel based power generation contributes the rest. Iceland is in a unique position due to the active nature of their geology, which provides hot water and steam relatively close to the earth’s surface which they can utilize to run turbines to produce electricity. There is much to learn from Iceland’s example but accessing geothermal energy in many other parts of the world requires specialized drilling techniques to drill down far enough into the earth’s crust to replicate what Iceland has done.
The importance of low-emission electricity generation
Low-emission sources of electricity generation are arguably the most critical change we can make to reduce greenhouse gas emissions to help fight climate change. Power generation accounts for roughly 36% of global emissions [1] and reducing these will also benefit transportation emissions. Despite the increase in renewables, power generation was responsible for the greatest increase in GHG emissions in 2022 and also hit its highest level in 2022 [2]. As demonstrated in a previous article by Lark Scientific, the adoption of Battery Electric Vehicles (BEVs) will have a minimal impact on emissions unless we use clean power for charging. We need to rapidly expand clean power generation to not only reduce emissions from power generation but also be able to capitalize fully on the transition to BEV’s which we cannot do today.
If the grid used to charge passenger BEVs were to be free of GHG emissions globally, that alone would decrease global emissions by a significant amount.
The key question we must ask is: what source or combination of sources of electricity is the right choice? What are the decision factors that guide this thinking? Decisions around power generation made today will have far-reaching consequences, impacting the world for many decades. There are enormous costs associated with grid infrastructure development, much of which is burdened onto the public through taxation or through higher electricity prices. The same money could be used for improving medical care or education or other infrastructure so making sure this public money is being used effectively is very important. Making the correct choice is a significant step toward sustainably powering the world and providing affordable energy to people of all income levels, particularly in developing countries. Other ramifications of an incorrect choice could be minimal GHG emissions reductions, higher electricity prices, and increased reliance on cheaper fossil fuels for global energy. Our collective goal must be affordable, safe, and environmentally friendly power generation if we are genuinely committed to addressing GHG emissions.
The infinite power source beneath our feet - if we choose to harness it
The Earth's core essentially represents an infinite (in practical terms) power source for humanity. It is estimated that there exists in excess of 200 million years of stored energy (in the form of heat) within 3 km of the surface of the earth. Extracting the heat from beneath the Earth's crust to generate power is known as geothermal power generation.
Geothermal electricity generation uses the heat underground to heat water to generate steam. The steam is then used to turn a turbine and generate electricity. The heat underground comes from the earth’s core and is created by the decay of radioactive elements and also the heat remaining from the formation of the earth.
Historically geothermal power generation was done in areas where a heat source underground is relatively close to the surface, such as in natural hot springs, or in areas where there is ground water close to hot rocks near the surface. The first commercial Geothermal power plant was built in Larderello Italy in 1913 [3]. The site was chosen since the presence of hot springs in the area made it possible to easily access the heat. The power plant at that site is still in operation today and provides roughly 2% of Italy’s electricity. In areas that are far away from these surface heat sources with ground water, wells need to be drilled several kilometers deep, often increasing costs dramatically.
Figure 1. Traditional Geothermal Power Generation. Heat in the Earth’s core heats ground water that is naturally occurring. The hot water is pumped to a powerplant that uses the heat to create steam to turn power generating turbines. This combination of natural features close to the surface occurs in limited areas around the globe.
What's Changed?
Why Enhanced Geothermal Systems are a game changer
Recent advances have allowed the development of what is referred to as “Enhanced Geothermal Systems” (EGS). This is a technology that allows rocks that would normally be unsuitable for heat extraction to be opened up and made porous to allow injected water or fluids to pass through them and extract the heat for power generation. Essentially these are human made underground water reservoirs that are used to extract the heat from the rocks. This technology greatly expands the geographical areas where Geothermal power generation can be viable, making it a much more cost-effective choice for generating power. Ultimately, we can convert heat from the Earth's core into clean electricity with minimal GHG emissions and a compact power plant footprint.
Figure 2. Enhanced Geothermal Systems. New drilling technologies are expanding the potential sites for Geothermal power as well as bringing down the costs. Geothermal power generation is no longer limited to very specific locations.
Why Geothermal over other Renewables?
Solar and Wind Energy Sprawl
One of the key benefits of Geothermal over Wind and solar power is its very small footprint. Similar to a Nuclear power plant, Geothermal power generation requires minimal land area compared to the vast areas needed for solar installations or wind farms. The land use and GHG emissions per kWh of power produced have been estimated and the results show that when looking at these criteria alone, nuclear ranks best and Geothermal ranks second [14]. Land area is expected to become a serious constraint on the expansion of solar and wind power. The increasing energy demand in the United States alone is estimated to require an area of approximately 800,000 km, which is larger than the size of Texas, by 2040 [15]. What is being termed “Energy Sprawl” represents the source of the greatest land use change in coming years [15]. These immense swaths of land must come at the expense of other forms of land use and will impact ecosystems, biodiversity and agriculture. Taking up large land areas means that ecosystems are impacted. The larger the area the greater the impact. Minimizing land use needs to be a key criteria when considering renewable energy installations going forward.
Figure 3. Enhanced Geothermal Systems. human made fractures in normal dry rock allows the injection of fluid to extract the heat from below the earth’s crust. This heat is pumped to a power plant where the heat is converted to steam to turn turbines and generate electricity in a small footprint power plant.
Continuous Power
Geothermal power generation offers advantages over most other low-emission power generation methods. Geothermal power plants don't consume traditional fuels and can provide continuous power regardless of weather conditions – a huge advantage. In contrast, solar and wind energy sources are intermittent, requiring fast backup power often in the form of natural gas generation to maintain a balanced grid. It is an unfortunate reality that much of the time this intermittent nature of wind is the reason why you see windmills at a stand still even under windy conditions. When this happens it usually means that the grid is already at capacity and there is no way to store the additional energy being generated by the wind turbines, therefore they have to remain turned off.
Waste Management
Another consideration in the move to renewables will be recycling and waste management. For example, according to the International Renewable Energy Agency, solar panels reaching end of life globally are expected to reach a cumulative amount of between 60 million tons and 78 million tons by 2050 [17] Although some recycling of the materials and heavy metals present in solar panels is beginning to take place, the potential for large numbers of panels ending up in land fills or being disposed of in the environment is a serious risk. Much like the plastics we see ending up in the environment, managing the waste created by solar panels in the future will be a challenge.
What are the Risks?
Although the technology for EGS has its origins in the oil and gas industry where the drilling techniques are known as “Fracking”, the goals of EGS are to provide clean power without emissions. EGS is not extracting fossil fuels nor is it drilling new wells continuously for new power. If managed correctly, an EGS plant can extract power from a site for hundreds of years [18]. Much like oil drilling, other aspects need to be managed as well such as the possible triggering of seismic events and any impact on ground water. These potential issues need to be managed in EGS drilling and regulated as they are in the oil and gas industries. Ground water is typically found at shallower depths of a few hundred meters compared to the depths of EGS installations of thousands of meters. A recent study conducted by the US National Renewable Energy Laboratory (NREL) found that no cases of ground water contamination have occurred at any sites in the US [16]. This finding was most likely attributable to the requirements in place for geothermal wells in the United States. These risks need to be understood and managed to ensure that we are not replacing one environmental issue with another.
But how much will the power cost?
One of the factors that has been a hurdle for geothermal power generation historically has been the cost of drilling to reach the depths required. To understand the lifetime costs of an electricity generation plant a value known as the Levelized cost of Electricity (LCOE) is used. LCOE is the cost of generating electricity over the entire lifetime of a power plant or energy generation system. It represents the price per unit of electricity required to cover all the costs associated with planning, financing, building, operating, maintaining, and decommissioning an energy project.
The (LCOE) has been estimated in the literature for various conventional and renewable power generation methods. These estimates vary widely due to numerous cost-influencing factors. Estimating LCOE is complicated because technology costs change over time, and there are many differences for each project such as amount of sunlight, wind, difficulty of installation among other factors. The cost of decommissioning, recycling, or scrapping materials at the end of installation life also affects LCOE, making it challenging to estimate. For instance a Harvard Business Review article [6] estimates that including end-of-life costs may make solar panels' true LCOE four times higher than recent estimates, adding to the complexity of calculations. LCOE estimates for various power sources have been calculated and published [7]. The interested reader can review the figures in the reference provided. The range of LCOE values for renewables such as wind, solar and others cover wide ranges and the estimated geothermal LCOE overlaps with other renewables like solar and wind and is lower than nuclear.
Geothermal, unlike wind and solar, has seen limited development and investment resulting in few successful projects, making the estimates of Geothermal LCOE more difficult. In 2021, geothermal energy represented only 1% of global power generation [8] In Canada, the first geothermal power generation plant, Swan Hills Geothermal Power Project in Alberta, opened in 2023 [9]. Other Canadian projects are also in development by companies such as DEEP Earth Energy Production Corp [10].
The Time for Investment in Geothermal is Now
Perhaps the most important recent news in the Geothermal area are the recent advances in drilling techniques, such as those by US-based Fervo Energy in 2023 [11] where they have demonstrated that geothermal power can become even more cost-effective than ever before. Fervo's work indicates that, similar to solar and wind, costs will decrease over time as we gain more experience and knowledge. Similarly, the US Department of Energy’s “Earth Shot” project1 [12] aims to reduce the cost of EGS power by 90% by 2035. A recent report from the US National Renewable Energy Laboratory (NREL) in 2023 predicts that geothermal could represent 12% of the U.S.’s electricity generation in 2050 [13]. We feel that this likely underestimates the potential of geothermal given the long list of benefits. While solar and wind have already benefitted from decades of research and the future improvements may be slower, Enhanced Geothermal is relatively new and is only beginning to be developed.
Final Thoughts:
Geothermal energy stands out as one of the top solutions for global power generation. It is safe, clean, nearly limitless and reliable. Despite these advantages, geothermal energy accounts for only about 1% of global electricity production. The primary hindrance to greater adoption has been the high upfront costs and associated risks, deterring investors from taking on projects. Recent drilling technology advancements have shown that investments and R&D can lower geothermal costs below already competitive levels. Well managed EGS plants can extract power for hundreds of years, unlike other renewables such as solar and wind that typically have lifetimes of up to 30 years. Governments worldwide must step in with greater incentives and funding for geothermal projects and R&D, just as they have for solar and wind. With substantial investment in geothermal technology, we can meet our power requirements, achieve emissions targets, and provide affordable energy for all. There may be no better solution to the world's energy needs. At the very least global renewable power generation plans need to include geothermal in their proposed mix of power sources. Not doing so would be a missed opportunity that we will live with for generations to come.
REFERENCES:
https://www.power-technology.com/features/oldest-geothermal-plant- larderello/
https://www.energy.gov/eere/geothermal/enhanced-geothermal-shot
Fridleifsson, Ingvar B.; Bertani, Ruggero; Huenges, Ernst; Lund, John W.; Ragnarsson, Arni; Rybach, Ladislaus (11 February 2008). O. Hohmeyer and T. Trittin (ed.). The possible role and contribution of geothermal energy to the mitigation of climate change (PDF). IPCC Scoping Meeting on Renewable Energy Sources. Luebeck, Germany. pp. 59–80
https://www.lazard.com/research-insights/2023-levelized-cost-of-energyplus
https://www.lazard.com/research-insights/2023-levelized-cost-of-energyplus
https://www.energy.gov/eere/geothermal/enhanced-geothermal-shot
Lovering J, Swain M, Blomqvist L, Hernandez RR (2022) Land-use intensity of electricity production and tomorrow’s energy landscape. PLoS ONE 17(7): e0270155. https://doi.org/10.1371/journal.pone.0270155
Trainor AM, McDonald RI, Fargione J (2016) Energy Sprawl Is the Largest Driver of Land Use Change in United States. PLoS ONE 11(9): e0162269. https://doi.org/10.1371/journal.pone.0162269
Robins, Jody C., National Renewable Energy Laboratory (2021) The Impacts of Geothermal Operations on Groundwater, GRC Transactions, Vol. 45
https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2016/IRENA_IEAPVPS_End-of%20Life_Solar_PV_Panels_2016.pdf
Hackstein, F.V., Madlener, R. Sustainable operation of geothermal power plants: why economic matters. Geotherm Energy 9, 10 (2021). https://doi.org/10.1186/s40517-021-00183-2
Contributors
Researchers
Mauro Aiello, Ph.D.
Authors
Mauro Aiello
Axel Doerwald
Lark Scientific Financial Support
Axel Doerwald
Graphics
Adri Poggetti