Texas is hot. Above and below ground. Heat seated six miles and further below the surface is untapped energy, which in the very near future could cool your home.
“We’re going after a resource deep in the earth just like oil and gas,” said former Shell company executive Cindy Taff. “Instead of hydrocarbons, we’re going for heat.”
Today, Taff is the chief executive officer for startup Sage Geosystems, a Texas-based company on the deep search for geothermal energy.
“This can be a game changer,” said Taff from inside a design and testing lab inside Southwest Research Institute in San Antonio.
The Earth’s core is 10,832°F (6,000°C), slightly hotter than the temperature of the sun’s surface. At six miles or 10 kilometers beneath our feet or shallower, almost every place on Earth has sufficient heat for power generation.
This buried heat resource is viable to mine for electricity production in many parts of the Lone Star State. Geothermal is green energy.
A recent study released by the University of Texas at Austin Energy Institute states that drilling 1.4 million wells worldwide by 2050 could power 77% of the world’s projected electricity demand.
“This is 100% clean, renewable energy," Taff said.
In 2021, Sage Geosystems partnered with the Bureau of Economic Geology at the Jackson School of Geosciences at UT Austin to begin testing new technology in an existing 19,000-foot dry oil well in Starr County, near the U.S.-Mexico border. The project is funded by the U.S. Air Force under an initial feasibility study grant.
Sage reentered the dry well. At 11,500 feet Taff said they found the right temperatures to test the heat as a source to create electricity.
“The bottom hole casing at the bottom of the well casing is at 300°F, which is right on the edge for being geothermal and allows us to do our testing.”
The oil and gas industry is key for geothermal exploration.
“To do geothermal, you need the same services: drilling, casing, cementing, drilling fluids. So, what we can do with our solutions is leverage the oil and gas industry,” said Taff.
Texas leads the nation in the oil and gas industry. “The geothermal industry can be hugely impacted by the oil and gas industry," Taff said.
At the lab in San Antonio, engineers partnered with Taff’s team to design a prototype turbine, critical to produce electricity from geothermal heat. Researchers recently completed the 3-megawatt machine.
Lead engineer John Klaerner said the prototype is much small than other geothermal turbines currently used to generate electricity.
“For this setup alone here, that can be put on roughly the size of an 18-wheeler [and] can power up to 2,000 homes," Klaerner said.
Sage plans to test the turbine at the lab in August. At the site of the Starr County well, researchers would like to generate electricity in 2024 to continue their research.