A solution to two energy problems may be emerging from a single source: abandoned oil and gas wells. Millions of these sites exist across the United States, and they can be repurposed to generate geothermal energy, a clean and renewable power source. This approach avoids the high costs and risks associated with drilling new wells for geothermal power, potentially accelerating the transition to cleaner energy.
This innovative strategy involves using the natural heat from within the Earth, which is brought to the surface through these existing wells. The process can be applied to both inactive and active oil and gas wells, offering a way to generate electricity and provide heating and cooling with minimal greenhouse gas emissions. This could provide a significant new revenue stream from aging fossil fuel infrastructure while contributing to a more sustainable energy future.
Repurposing Old Infrastructure for a New Purpose
The core concept of this technology is to circulate water through the deep, hot underground reservoirs accessed by former oil and gas wells. In a process known as a well retrofit, water is pumped down a well, heated by the Earth’s natural geothermal gradient, and then brought back to the surface. The captured heat is then used to power a thermoelectric generator, producing electricity. This method is particularly promising because it leverages the existing infrastructure of millions of wells, many of which are no longer productive for oil and gas extraction.
Another approach, called co-production, is used with still-active oil and gas wells. This technique captures the heat from the extremely hot water that is often a byproduct of oil and gas extraction. This hot water can be used to generate electricity, effectively allowing a single well to produce both fossil fuels and geothermal energy. The water is then reinjected into the reservoir in a continuous, recycling loop.
Government and Private Sector Initiatives
The U.S. Department of Energy’s Geothermal Technologies Office (GTO) is actively promoting this technology through its Wells of Opportunity (WOO) initiative. This program funds projects that aim to demonstrate the commercial viability of geothermal energy production from hydrocarbon wells. The initiative supports both well retrofitting and co-production projects across the country.
Projects Across the United States
Several companies are making significant strides in this field.
- Gradient Geothermal, a U.S. start-up, is repurposing abandoned wells to power the town of Pierce, Colorado. These wells, which were producing 98% hot water and only 2% oil, are now being used for zero-emission electricity. The company is also working on projects in North Dakota.
- In Texas, Geothermix, LLC is working to harvest waste heat from existing oil and gas wells to generate commercial-scale geothermal electricity.
- ICE Thermal Harvesting is utilizing 11 existing oil and gas wells in California’s San Joaquin Valley to produce electricity with an innovative power generation technology.
- The University of Oklahoma is using heat from a local oilfield to provide heating for two public schools in Tuttle, Oklahoma, saving the schools considerable energy costs.
Economic and Environmental Advantages
The most significant advantage of this approach is the cost savings from avoiding the need to drill new wells. Drilling is a major expense in traditional geothermal projects, so using existing wells dramatically reduces the upfront investment. Additionally, the geological and thermal data from previous oil and gas exploration provides valuable information, reducing the risk and uncertainty typically associated with geothermal exploration.
From an environmental perspective, generating geothermal energy from old wells produces almost no greenhouse gases. It offers a consistent, 24/7 power source, unlike intermittent renewables like solar and wind. Experts estimate there are 2 to 3 million disused oil wells in the U.S., with over 500,000 of them potentially suitable for geothermal energy production. Tapping into this resource could generate up to 13 gigawatts of clean energy and prevent 16.5 million tonnes of CO2 emissions.
Challenges and Technical Considerations
Despite the promise, there are technical and economic hurdles to overcome. One of the main challenges is the relatively low geothermal gradient in some abandoned wells, which means the water may not get hot enough for efficient electricity generation. Other issues include the cost of the thermal facilities on the surface and the need for proper well insulation to prevent heat loss.
The physical condition of the abandoned wells is also a factor. The diameter and length of the well can impact the efficiency of heat extraction, and there is a risk of oil and gas fluids entering the well, which could complicate the process. However, researchers are exploring various solutions to these problems, including the use of downhole heat exchangers and other advanced technologies to improve efficiency.
The Future of Geothermal Repurposing
The conversion of oil and gas wells for geothermal energy represents a significant opportunity to expand the nation’s clean energy portfolio while finding a productive use for aging fossil fuel infrastructure. The work of companies like Gradient Geothermal and the support of government initiatives like the Wells of Opportunity program are paving the way for wider adoption of this technology. As the technology matures and becomes more cost-effective, it could play a crucial role in the transition to a low-carbon energy future. The successful demonstration of these pilot projects will be critical in encouraging more widespread investment and development in this promising field.