Geothermal companies and scientists have looked for years at different ways to generate geothermal energy, but the research is now drifting in a new direction: fossil fuels.
State research officials in North Dakota are examining two new options — pairing geothermal with active oil and gas sites and using captured carbon dioxide as a feedstock for geothermal power production.
The North Dakota Industrial Commission in June greenlit a $250,000 feasibility study to look into whether those two new geothermal technologies could be used in the state.
Bipartisan support for geothermal power — along with federal tax incentives for geothermal and carbon capture and storage, or CCS, projects — created an environment where companies and researchers can start to explore different methods of production, said Matt Villante, an earth scientist with the Pacific Northwest National Laboratory.
“Learning from these first-of-a-kind demonstration projects is really critical to moving the sector forward,” Villante said at a recent webinar hosted by the U.S. Energy Association. “There is extensive support for both geothermal and CCS around the globe, but also in the United States.”
In an executive order, President Donald Trump has called for removing “all illegitimate impediments” to developing geothermal projects. And Energy Secretary Chris Wright has prioritized geothermal as a target for the Department of Energy’s research and development efforts.
Another big factor: The 45Q federal tax credit for capturing, storing or using carbon dioxide was preserved after concerns it would be gutted as part of Republicans’ megabill that Trump signed into law this month.
Exploring new methods of harvesting energy from geothermal sources has proved popular across the political spectrum, said Drew Nelson, vice president of programs, policy and strategy with Project InnerSpace, a nonprofit that advocates for the use of geothermal. Green energy advocates have lauded geothermal as a way to harness low-carbon resources, he said, and people who support fossil fuel development point to the industry’s technical overlap with oil and gas drilling.
North Dakota Gov. Kelly Armstrong (R) said at an Industrial Commission meeting in June that working to grow the industry in his state was an obvious choice.
“There was a lot of discussion about this at the Western Governors’ Association, and it was one of the rare places in energy where you have room bipartisan support,” Armstrong said. “It makes it real simple.”
While support for geothermal is widespread, projects exploring new ways to produce it are not. In 2023, only about 0.4 percent of the nation’s power came from geothermal sources, according to the U.S. Energy Information Administration. Nelson said investors are still waiting for the existing technology to become safer bets, which has left little room for exploring new technologies.
‘A few variables’
Geothermal energy is typically harnessed by drilling and pumping up brine from deep within the earth. That brine is usually at least 300 degrees Fahrenheit when it reaches the surface, and the heat is used to generate steam to turn massive turbines to generate power.
But instead of using brine to transfer the earth’s heat to the surface, some researchers are looking instead at using captured carbon dioxide.
“When you look at a few variables in combination, carbon dioxide tends to come out on top relative to water,” said Jeff Bielicki, a research lead for sustainable energy at Ohio State University’s Sustainability Institute.
There are a few ways it could be used, Bielicki said. One use could be injecting vast quantities of CO2 underground to push out the hot brine. Another approach could be pushing CO2 underground to the heat source, and pumping back up the heated CO2 to power the turbines, then injected the cooled carbon dioxide back underground in a closed-loop system.
A third method would essentially use hydraulic fracturing techniques to break apart “hot dry rock” with carbon dioxide, Bielicki said.
“The ability for the carbon dioxide to flow through the permeable rock in ways that are related to its density and viscosity is higher than that of water,” Bielicki said. “That’ll allow it to pick up more heat.”
Carbon dioxide can lose more heat than the brine when it reaches the surface, Bielicki said, but it remains a potential vehicle for geothermal heat.
Oil could also prove to work as a conduit for bringing geothermal heat to power plants, Bielicki said.
“Anytime you’re producing a fluid, whether it’s brine or oil or natural gas, and bringing it to the surface, it’s likely to be warm, and potentially even hot enough to pull off the heat and use it,” he said.
Geothermal companies and oil companies for years have discussed repurposing old and nonproducing oil and gas wells into wells used to harness geothermal energy, Nelson said. But pulling heat out of active oil operations is a newer concept, Bielicki said.
Geologically, most oil and gas basins differ from the ideal underground environments for harnessing geothermal power, Bielicki said. Some deeper wells reach crude deposits that are nearly 250 degrees Fahrenheit underground, according to the EIA.
That’s not quite hot enough to power most geothermal power plants, Bielicki said, but companies are looking at ways to harness geothermal energy at lower temperatures.
He said some active oil sites are already using geothermal power at their wellheads.
“There have been investigations that have looked at, well, can we pull the heat off of this oil and use it?” Bielicki said. “And sometimes they do use it mostly my understanding is mostly locally on the field on the site of the oil production.”
Seeking value
North Dakota officials are hoping to dig further into using carbon dioxide and oil production to generate more geothermal power.
Already the state has studied using decommissioned oil wells to produce geothermal power, said Tyler Hamman, assistant vice president of strategic partnerships for the University of North Dakota’s Energy & Environmental Research Center. Now, the Center has been awarded $250,000 to study whether geothermal wells can produce both power and more oil from older wells.
He said more oil is likely to also come to the surface in the process of drilling for geothermal brine.
“You separate the two on the surface,” Hamman said of the brine and oil. “But it’s basically oil and gas that wouldn’t be economical to recover without having some sort of value-added opportunity, like producing geothermal energy along with it.”
He said his research center will also study whether the value-added proposition of geothermal could work for carbon dioxide use and storage.
“Anytime you’re doing anything with the subsurface, there’s always opportunity to look at the possibility of CO2 storage,” Hamman said.
But getting pilot projects for new geothermal technologies takes time and money, especially when it’s a first-of-its-kind project, Nelson said. He said the industry is just now at a place where investing in geothermal projects of any kind seems less risky for investors.
“How do we turn this from a couple of wells into an industry where the financial community knows how to price and risk and fund it?” Nelson said. “That’s where the industry is right now.”
