By Emily Foxhall, The Texas Tribune

This is the second of a three-part series on emerging energy sources and Texas’ role in developing them. Part one, on hydrogen fuel, published on Monday; part three, on small nuclear reactors, will publish on Wednesday.

STARR COUNTY — In 2009, on a plot of shrub-covered cattle land about 45 miles northwest of McAllen, Shell buried and abandoned a well it drilled to look for gas. The well turned out to be a dry hole. Vegetation grew back over the site.

In 2021, a Houston-based energy company run by former Shell employees came looking for it.

This company wasn’t drilling for oil or gas, though. Its engineers were looking for a place to experiment with their technology for producing geothermal energy, created by Earth’s underground heat.

A startup called Sage Geosystems leased the site. The company installed a wellhead and brought in a diesel-powered pump. They used fluid to create cracks in the rock deep below the surface, a technique similar to fracking for oil and gas.

One day last March, the crew pumped 20,000 barrels of water into the 2-mile-deep well. Hours later, an operator opened the well from a control room. Pipes above ground shook as the pressurized water gushed back up. The water spun small turbines, generating electricity.

Sage and other companies believe geothermal power is key to replacing polluting coal- and gas-fired power plants. Even though solar and wind are proven clean energy sources, they only produce electricity when the sun shines or the wind blows. Geothermal power could provide continuous, emissions-free energy.

“Geothermal heat doesn’t have those variable conditions,” University of Texas at Austin clean energy expert Michael Webber said. “If you hit a hot spot below ground — might be thousands of feet down — the heat won’t matter based on whether it’s cloudy or whether it’s summer.”

Texas has become an early hot spot for geothermal energy exploration. At least three companies are based in Houston, and scores of former oil industry workers and executives are taking their knowledge of geology, drilling and extraction to a new energy source.

“We’ve punched over a million holes in the ground in Texas since Spindletop,” said former Texas oil and gas regulator Barry Smitherman, who has become a geothermal advocate. “So we have a lot of knowledge, and we have a lot of history and skill set.”

Heat constantly radiates out from the center of Earth as radioactive elements break down. That energy warms water that bubbles up to or escapes as steam at the surface. Humans have taken advantage of that phenomenon — an early form of geothermal power — for heating, bathing and cooking since ancient times.

For more than 100 years, engineers have used that underground hot water or steam to generate electricity. Geothermal power in 2015 fueled 27% of the electricity in Iceland, which sits on one of the world’s most active volcanic zones. In 2022, it generated about 5% of the electricity in California. The United States is the top geothermal electricity producer in the world.

Still, the total amount of geothermal electricity produced in America is tiny compared with other sources. It accounted for about 4 gigawatts last year, according to a federal analysis, or enough to power about 800,000 Texas homes.

Businesses such as Sage and government researchers say there’s a lot more geothermal power to be had by pumping fluid through hot rock where there is no natural water. With technological advances, a government analysis predicts geothermal power in the U.S. could grow to 90 gigawatts by 2050. That would have been enough to power the entire Texas grid during last summer’s highest-demand day.

Companies are racing to develop their technology and techniques to harness this energy source. They vary in how deep they want to drill (from around 7,000 feet, which oil and gas equipment can handle, to 66,000 feet, which it cannot), how they heat the water (in the well or in the rock) and how they bring the heated water back up (in the same well that sent it down or with a second one).

Like oil wildcatters, the geothermal industry must figure out the best places to drill. They’ll face the same concerns about triggering earthquakes that have dogged oil and gas fracking operations and previous geothermal efforts. In 2006, a pilot geothermal plant in Switzerland caused a magnitude 3.4 earthquake that damaged buildings and led to the plant’s closure. In 2017, a magnitude 5.5 earthquake linked to a pilot geothermal project in South Korea injured dozens.

Companies should follow existing best practices informed by research to monitor seismicity and adjust or pause operations as needed, said William Ellsworth, an emeritus professor at Stanford University. States could also mandate these protocols. “You have to pay attention to what you’re doing,” Ellsworth said.

And perhaps most importantly, the geothermal businesses will have to show they can compete with the cost of other power sources, with help from the federal government in the form of Inflation Reduction Act tax credits.

The more the technology is deployed, the more the costs might come down, Rice University Associate Professor Daniel Cohan said. Getting the price where the federal government hopes for it to be cost-competitive is “feasible,” Cohan said, “but there’s no guarantee that the industry will get there.”

The federal Department of Energy said this month that $20 billion to $25 billion needed to be invested by 2030 to move toward widespread use.

“We’re all doing something a little bit different,” Sage CEO Cindy Taff said. “One of us is going to have a breakthrough that really commercializes this stuff.”

The daughter of a geophysicist who worked for Mobil, Taff studied mechanical engineering and built a 36-year career at Shell. She worked her way up from production engineer to vice president, managing a team with an annual budget of around $1 billion.

With freckles and curly hair that falls past her shoulders, Taff said she knew the world wanted to pivot to new energy sources. Her daughter, concerned about climate change, urged her mother to get away from the “dark side” of oil and gas.

When former colleagues from Shell told Taff they were co-founding Sage and invited her to join them, she got excited.

Taff saw that Sage was a nimble company with people she considered some of the smartest in the industry. The geothermal business had a lot of growing to do, like the early days of wind or solar. Her work could have a large impact.

“It was exciting to be working with people that I knew had a sense of urgency and made a difference,” Taff said. “And then, it was exciting to be working for yourself in a way that you can push the agenda.”

So, in 2020, Taff took the leap. Her daughter joined the company too.

Building interest in geothermal 

In 1989, the Exxon Valdez oil tanker spilled 11 million gallons of oil off the coast of Alaska, killing some 250,000 seabirds, 2,800 sea otters and 300 harbor seals. In Augusta, Georgia, 10-year-old Jamie Beard was riveted by the news coverage.

“I understood things enough to know that that was not something we wanted,” Beard said.

That experience pushed Beard into environmental activism, starting the next day, when she took a Kleenex box decorated like the ocean to raise money for coral reefs. She painted murals about environmental rights. In college, at Appalachian State University, she organized an Earth Day festival and tied herself to trees on a West Virginia mountaintop to protest workers scraping them away to mine for coal.

Beard went on to study environmental law at Boston University. She represented corporations, telling herself she could make change best from the inside. That