Climate Change, Energy, PWH Graduate Essay Prize Geothermal Energy: A Missing Piece in the Equitable Energy Transition

Max Pisciotta is a PhD candidate concentrating in chemical engineering, and the winner of our inaugural Graduate Essay Prize. Pisciotta's research focuses on carbon capture and carbon removal technologies and industrial decarbonization. Prior to starting their PhD at Penn, they graduated with a BS and MS in mechanical engineering from the Colorado School of Mines, and briefly worked as a technology analyst at Accenture. When Pisciotta is not in the lab, they can be found doing LGBTQ+ advocacy on Penn's campus, running, or working to communicate scientific findings to the public. They are also part of the 2022-2023 cohort of Graduate Associates at Perry World House, a program designed to help Penn graduate students build networks and develop skills to engage policymaking.

According to the sixth assessment IPCC report, there is unequivocal proof that human influence has warmed the atmosphere, ocean, and land, contributing to climate change. This human influence is from the emission of greenhouse gases into the atmosphere, most prominently, carbon dioxide (CO2). These emissions are generated from all sectors of the economy, from agriculture and aviation to cement production and steelmaking, via the use of fossil fuels, namely coal, oil, and natural gas. To have a 66% chance of achieving average global warming less than 1.5 ºC by 2100, an important goal laid out in the Paris Agreement, emissions need to be drastically reduced and legacy emissions in the atmosphere must be removed (IPCC 2021).

While some culprit industries are much easier to decarbonize than others, due to recent advancements in technology, a common slogan among the climate conscious is “electrify everything.” The idea is that one path to achieving global climate goals is to use electricity to power all applications and industries because carbon-free electricity can be generated via renewable energy quite “easily.” The intermittency of these resources is often addressed using some version of “there is already existing technology that can be used to store this electricity easily,” i.e., batteries. However, few of these conversations are discussing just how large battery infrastructure needs to be to meet seasonal demand and how the raw materials for solar panels, wind turbines, and batteries are sourced, let alone disposed of at end-of-life. Within these same conversations, the only renewable energy resource that has the capacity to generate electricity 24/7, or baseload power, is rarely mentioned: geothermal energy (U.S. DOE 2019).

Geothermal energy is the energy that comes from the heat deep in the Earth’s surface. There are traditionally three types of geothermal power plants, which are designed to maximize the energy production from a given resource based on the formation, fluid temperature, and salinity of the geothermal fluid (Shulman 1995). Hot geothermal fluid is accessed by drilling wells (3-7 km deep) into the earth (U.S. DOE 2019), attaching a pump to draw the hot geothermal fluid up to the surface. It is then used to power via a thermo-power cycle, often a turbine, which generates electricity (Shulman 1995). Geothermal energy is responsible for producing less than 1% of US electricity today, but with conventional methods, has the potential to produce more than 8% by 2050 (Geothermal Technologies Office 2021). Other countries that rely on geothermal energy include Iceland (799 MW), Kenya (~790 MW), and Indonesia (2.28 GW). Enhanced geothermal systems (EGS) are being developed to expand access to geothermal energy in regions where deeper wells are needed to access this resource, to bolster the potential for low-carbon electricity generation.

Although geothermal energy has many attractive qualities, namely, the ability to produce baseload, low-carbon electricity, and its wide expanse of access, it is still deeply rooted in the essence of extraction. This positionality makes for a contentious place in the portfolio of solutions to avoid the detrimental impacts of climate change.

Provided that the fossil fuel industry is underpinned by extraction, deep parallels between the two industries can be drawn. However, there are still critical distinctions that set geothermal energy apart and make it a valuable addition to a comprehensive strategy for mitigating climate change. These deep parallels have the potential to serve a much wider purpose that should not be ignored; they allow for expertise, skills, and assets to be transferred from the fossil fuel industry to the emergent and more climate conscious geothermal energy industry (Smith 2023).

There is explicit expertise that is transferrable between the two industries. Geothermal energy is based on the extraction of geothermal brine and reinjection into an underground reservoir where the brine is reheated. Reservoir and drilling engineers in the oil and gas industries have expertise within the areas of reservoir dynamics and management, and deep well drilling and management, respectively. As the demand for carbon-intensive oil and gas declines and companies begin to constrict, the geothermal energy industry may become home to some of the previous oil and gas labor force due to the reduced need for retraining.

In addition to expertise and labor force, the often-proprietary geologic data collected by oil and gas companies stands to benefit the geothermal energy industry as well. Prior to drilling an operational well for oil or gas extraction, companies must have the subsurface characterized either via contract services or in-house. Throughout this process, samples are taken, analyzed, and geomechanical models are developed; leading to a lot of data acquisition (Santos, Dahi Taleghani, and Elsworth 2022). The results from these tests and models are then analyzed to determine if the subsurface has the potential for productivity (i.e., oil and gas extraction) and the economics that would surround this project. Whether or not the project is pursued, the company has acquired data via the drilling exploration process. The data collected from this process is not uniquely useful for the oil and gas industry.

Before geothermal energy wells can be drilled, drilling exploration must also be done to determine the existence of a geothermal reservoir, formation temperature, and geothermal brine conditions and composition (Santos, Dahi Taleghani, and Elsworth 2022). Furthermore, there are projects that have begun to evaluate the potential to repurpose abandoned or retired oil and gas wells for the use in geothermal energy production. In 2021, the first abandoned oil well was converted into a closed-loop geothermal system in Hungary and went on to produce 0.5 MW of thermal energy (Santos, Dahi Taleghani, and Elsworth 2022). Further demonstration projects are underway in the U.S. and Slovenia (Santos, Dahi Taleghani, and Elsworth 2022). To illustrate the vast opportunity for geothermal energy production using existing abandoned or retired oil and gas wells, in the U.S. alone, there are 3.7 million abandoned oil and gas wells as of 2020 and only 41% of those have been decommissioned or plugged, according to the U.S. EPA (Smith 2023). With the U.S. positioned to repurpose these wells and institute low-carbon baseload power generation, we have the potential to lessen the reliance on other renewable energy sources, like solar and wind, protecting grid stability and bolstering energy independence.

The deep parallels between oil and gas and geothermal energy have the potential to raise similar concerns in both industries, specifically the impact of drilling on local communities, which are not to be negated. Drilling into the Earth either for extraction or reinjection has the potential for increased seismicity and groundwater contamination concerns (Smith 2023; Santos, Dahi Taleghani, and Elsworth 2022). With the use of reservoir characterization and appropriate well planning, the risk of increased seismicity can be minimized (Smith 2023). Furthermore, abandoned oil and gas wells have the potential for their cement casings to leak, which can result in buildup of dissolved methane in drinking water, or in the most extreme cases, separation of the methane into the gas phase, leading to possible asphyxiation or explosion (Santos, Dahi Taleghani, and Elsworth 2022). This leakage also makes it difficult to use these wells for geothermal energy, rather, incentives developed for the repurposing of these wells should include the evaluation of the casing integrity and the improvement of well casing when needed. This would not only protect the geothermal system from contamination, but also the public drinking water.

In any electricity generating project, airborne emissions are also a concern. In open-loop geothermal systems, the CO2 and hydrogen sulfide (H2S) emissions are expected to be the highest, still much less than that of the fossil-fuel alternative, but non-negligible compared to solar and wind sources. To reduce these onsite emissions, closed-loop geothermal systems can be adopted, which result in no emissions because all of the extracted brine is reinjected into the reservoir (U.S. DOE 2019; Shulman 1995). Accessing geothermal energy resources runs the risk of lessening any surface expression of geothermal systems, such as hot springs or geysers. This poses a significant problem when these surface expressions have substantial cultural or economic value to a region. By using geologic data and geomechanical modeling, these impacts can be readily assessed before a project breaks ground. Lastly, to gain and retain public support for a geothermal project, specifically one that will be using an abandoned or retired well, seeking to establish a community benefits agreement may be advised. These agreements are legally binding arrangements that are forged between a developer and the local community that ensure the deployment of a project has explicit benefit to the local community impacted by its presence. These agreements can range from benefits including local hiring practices, providing money for local trust funds, funding job training and educational services, and financing new community development projects.

Although the deep parallels may make pursuing geothermal energy exploration and generation a contentious endeavor to mitigate climate change, public policy has the potential to promote it to enhance grid stability, baseload power delivery, and offer opportunities for the labor force in oil and gas to be part of an equitable energy transition. As more intermittent renewable energy infrastructure comes online, it will be critical to keep baseload-delivering, dispatchable power plants online to ensure the stability of the electrical grid. This ultimately makes a case for keeping fossil fuel power plants online, however, public policy has the potential to promote the displacement of fossil fuel baseload-providing power plants by replacing them with baseload-providing geothermal power plants. A similar initiative is ongoing in California, where 1,000 MW of renewable baseload power is being deployed in response to a nuclear power plant being decommissioned.

Public policy can also be developed to support job retraining for members of the labor force who leave the oil and gas industries and want to contribute to the geothermal industry. Based on the plethora of transferrable expertise and skills between these two sectors, it can be inferred that the extent of retraining would be a lower lift than matching former oil and gas labor force members with solar panel or wind turbine technician roles. These job training programs could be designed specifically for matching the retired role with a similar one within geothermal or may be implemented similar to the apprenticeship programs detailed in the Inflation Reduction Act.

Lastly, public policy, specifically public regulation, should be developed to allow for abandoned and retired oil and gas wells to be repurposed into geothermal energy wells, where appropriate, as a method of land remediation. This would not only prevent the need to plug the existing wells, but it would also prevent the need to drill new wells when existing ones would have sufficed. Furthermore, repurposing as a remediation strategy would also position existing oil and gas companies to enter contracts that would require them to turn over the geologic data relevant to the wells, bypassing the often expensive and potentially time-prohibitive step of reservoir characterization. Many of the wells that could be repurposed for geothermal electricity generation are in regions where the individual state has the authority to determine remediation strategy for those located outside of federal lands (Smith 2023; US EPA 2022).

Although it is incredibly precarious to involve oil and gas companies in climate change mitigation solutions, especially provided their previous contributions to the problem and mis-/disinformation regarding the science, it is also evident that baseload electricity will need to be decarbonized to result in a decarbonized grid. Geothermal energy is one solution that can contribute to this decarbonized baseload electricity goal, but it does require drilling into the Earth. Public policy can not only promote the development of geothermal energy but also support the use of transferrable expertise, labor force, and assets from oil and gas to the geothermal industry. Furthermore, these policies can dictate the involvement that oil and gas entities have with this emerging industry and protect against profiteering efforts as has been done previously.

Overall, to address climate change more readily and holistically, grid decarbonization needs to start including baseload power and systems that can reliably generate baseload power. For the energy transition to be equitable, policies must also consider and support the labor force whose current industries are projected to constrict. Promoting the utilization of abandoned and retired oil and gas wells for geothermal energy access is one way to begin to address these wicked problems.

References

Geothermal Technologies Office. 2021. “2020 United States Country Report.” IEA Geothermal.

IPCC. 2021. “AR6 WGIII: Summary for Policy Makers.” https://www.ipcc.ch/report/ar6/wg1/chapter/summary-for-policymakers/.

Santos, L., A. Dahi Taleghani, and D. Elsworth. 2022. “Repurposing Abandoned Wells for Geothermal Energy: Current Status and Future Prospects.” Renewable Energy 194 (July): 1288–1302. https://doi.org/10.1016/j.renene.2022.05.138.

Shulman, Gary. 1995. “LOW TEMPERATURE FLASHED STEAM POWER GENERATION.”

Smith, Morgan. 2023. “Oil and Gas Technology and Geothermal Energy Development.” Congressional Research Service.

U.S. DOE. 2019. “GeoVision: Harnessing the Heat Beneath Our Feet.”

US EPA, OW. 2022. “Primary Enforcement Authority for the Underground Injection Control Program.” Overviews and Factsheets. June 9, 2022. https://www.epa.gov/uic/primary-enforcement-authority-underground-injection-control-program-0.