With a $1 million investment from the Governor’s Office of Resiliency, researchers at the Arizona Geological Survey, or AZGS, housed in the University of Arizona College of Science, have launched a landmark two-year effort to update and map Arizona’s untapped geothermal potential.

“Arizona is at a crucial crossroads in its energy story, and we have the key resources needed to be a leader in geothermal energy production,” Gov. Katie Hobbs said in a recent news release. “I am taking the steps to make that happen by investing in the Arizona Geological Survey, proposing funding for new geothermal research in my Executive Budget, and convening a geothermal working group."

Unlike traditional renewables that rely on sun or wind, geothermal power taps heat stored deep within the Earth, often using steam or hot fluids to drive turbines. New drilling and modeling technologies are expanding development beyond the volcanic regions and hot springs that have traditionally guided exploration. 

That could benefit Arizona, where an arid landscape offers few surface clues to geothermal resources. In neighboring states, detailed subsurface data already guide construction and financing. AZGS researchers are working to build a similar foundation, reducing uncertainty and helping utilities, policymakers and private developers assess Arizona’s geothermal resources for clean, reliable power.

“First-of-its-kind modeling from the Clean Air Task Force suggests that Arizona has significant superhot rock resources and tapping into just 1% of those resources would provide the equivalent of 58 times Arizona’s 2023 electricity consumption,” said Tomás Díaz de la Rubia, senior vice president for research and partnerships. “Governor Hobbs’ investment, coupled with the University of Arizona’s long history of geothermal research expertise, brings us one step closer to the day when localized geothermal becomes a realistic source of clean, dense energy for Arizonans.”  

Steady power, new potential

Geothermal energy has generated electricity in the United States for decades, especially in the West, where natural features like geysers and shallow, high-temperature rock and fluids make underground heat accessible. The country leads the world with nearly 4 gigawatts of installed geothermal capacity, according to the National Laboratory of the Rockies. This is enough to power about 3 million U.S. homes for one year. Plants in states like California and Nevada provide steady baseload power that helps reduce the need for costly backup generation and keeps consumers’ rates predictable.

Arizona has yet to develop geothermal energy on a large scale, said Philip Pearthree, AZGS director and state geologist. But new methods are making it possible to access heat in dry rock where natural water or steam is limited. Enhanced geothermal systems, or EGS, create engineered underground reservoirs by injecting fluid into hot rock to increase circulation, allowing electricity generation in places that were previously unsuitable. 

“EGS doesn't require hot water near the surface – just hot rock at depth,” Pearthree said. “That could be huge for Arizona, because we have plenty.”

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Utah has become a prominent testing ground with its FORGE research site. With support from the U.S. Department of Energy, or DOE, scientists at the site are developing, testing and improving EGS techniques, and a large next-generation project in southwestern Utah is expected to begin supplying continuous power to the grid sometime this year. Utah’s funding of geothermal research helped support these developments, said Brian Gootee, a senior research geologist and chief of the Energy Geology Group at the AZGS, who is leading Arizona’s project.

Gootee has already worked directly with the teams behind Utah’s geothermal projects and has been consulting with experts from other nearby states to understand their development process. The new geothermal working group within the Arizona Energy Promise Taskforce drew on guidance and input from these advisers to shape the framework and priorities for the project. 

Once the research is complete, the group will use the data to inform policy, planning and investment decisions. Members will explore ways to attract funding while actively addressing the state’s growing energy demand and concerns like water usage. They will investigate methods such as reusing water in EGS systems and using highly saline groundwater.

Opening Arizona for business

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Gootee and co-primary investigators Lisa Thompson and Tawnya Wilson began building a geothermal data catalog for Arizona in January. While this is the state’s first comprehensive geothermal research project, the AZGS has amassed decades of subsurface data, including well logs, temperature measurements and geologic maps. That information exists across multiple formats and locations and has not yet been systematically organized or analyzed to specifically guide geothermal energy development in Arizona.

Over the two-year project, the team will integrate legacy material with newly collected and newly applied information. For example, they will analyze near-infrared data gathered by a NASA imaging instrument flown on research aircraft. The technique, traditionally used for mining exploration, has not previously been applied to geothermal research in Arizona. It measures light beyond the visible spectrum to identify surface minerals that can signal underground heat. The detailed images will help the researchers examine known areas of hydrothermal activity and identify potential new sites, Thompson said.

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“We can really target some remote, rugged areas without putting boots on the ground,” she said. “Not having to send anyone out for field work saves a lot of time and money.”

Thompson, Gootee and Wilson will also use high‑resolution LiDAR, a laser‑based technology that maps topography, to identify surface features such as faults and fractures that may indicate pathways for underground heat. They will combine these data with legacy seismic measurements from the U of A, which track how vibrations travel through rock layers to model subsurface structures.

The project also builds on the National Geothermal Data System, an effort AZGS led to compile and publish geothermal data from all 50 states for researchers and industry. AZGS spearheaded that project with funding from the DOE. The effort ended in 2014, but the system datasets remain active. Gootee said the Arizona team aims to make national datasets more usable by combining them with new, state‑specific information and presenting it in a way that supports practical decision‑making for Arizona.

In addition to the catalog, deliverables over the next two years include creating educational materials to build public understanding and provide potential geothermal partners with a clear roadmap of the Arizona locations best suited for further geothermal exploration.

As Gootee and his team begin their research, he is encouraged by the state’s support, interest from utilities and industry players, and insights shared by other states, he said. Sustaining these assets will be key to carrying Arizona through its geothermal exploration phase within four to five years and positioning the state to begin development of a new power source.

“This is the beginning of a long-term process and long-term relationships,” Gootee said. “These connections send a message that we're open for business. That’s going to give the industry comfort with navigating the geothermal playbook.”