When Cindy Taff was a vice president at Shell in Houston, she often worked from home, and her middle school-aged daughter, Brianna, would sometimes glance over her shoulder and ask, “Why are you still in oil and gas? Is there really a future in it? Why not move into something cleaner?”
Those questions weighed heavily on Taff. As a parent, she wondered if she was setting the right example. At Shell, she was responsible for drilling and producing oil and gas, mainly from unconventional sources like shale—where extracting the resources isn’t as simple as the gushing wells we see in movies. And in an industry dominated by gas-guzzling trucks, her coworkers teased her for driving a hybrid Prius. “You’re not helping oil and gas prices,” they’d joke.
Despite her commitment to Shell, Taff had long been intrigued by geothermal energy, which taps into the Earth’s natural heat. She even pushed for Shell to explore geothermal projects, but they never gained traction. The company felt it would take too long to see returns on the investment.
When Brianna went off to college, she shared her mother’s interest in energy—but her passion was in renewables. After her sophomore year in 2020, Brianna landed an internship at Sage Geosystems, a geothermal startup in Houston founded by some of Taff’s former Shell colleagues.
This time, it was Taff asking her daughter questions as she worked from home during the pandemic. It wasn’t long before Sage executives started asking Brianna if she could persuade her mom to come work for them. “We could use your mom here,” they joked.
Ultimately, that’s exactly what happened. After a 36-year career at Shell, Taff made the jump to Sage Geosystems, taking on the role of chief operating officer. She explained, “I didn’t understand why Shell wasn’t pursuing geothermal. Then this opportunity came along to pivot from oil and gas, and work with people I truly respect. Plus, I wanted to make my daughter proud.”
Today, Brianna, now 24, works as an operations engineer and spokesperson at Sage. She’s thrilled to have her mom on the team and believes that Sage wouldn’t be where it is today without her. “Of course, I’m biased because she’s my mom,” Brianna said, “but I really think she’s been instrumental to our success.”
Geothermal energy is still a relatively small player in the U.S. energy market. Despite the country being a world leader in geothermal electricity, it accounts for less than 0.5% of the nation’s total large-scale energy production, primarily concentrated in states like California, Nevada, and Utah. However, the U.S. Department of Energy estimates that next-generation geothermal projects—like the ones Sage is working on—could supply 90 gigawatts of power by 2050, enough to power 65 million homes.
Sage has been making progress with two key technologies. The first involves generating electricity from heat by drilling wells and fracturing hot, dry rock. Water is pumped into these fractures, where it heats up and is then brought to the surface to spin a turbine and generate electricity.
During testing in late 2021 in Starr County, Texas, the team stumbled upon another use for their technology: energy storage. Given the current challenges of storing energy from renewable sources like wind and solar—where lithium-ion batteries typically only provide about four hours of power—Sage’s technology offers a new solution. They envision using surplus energy from wind and solar farms to pump water into underground fractures, where it can remain stored for hours, days, or even weeks until it’s needed to generate electricity.
This innovation could be a game changer, according to Silviu Livescu, a geothermal expert who’s been following Sage’s work. “It’s the right moment for companies like Sage to show how geothermal can help us address climate change,” he said.
Taff has become a vocal advocate for geothermal energy, meeting with policymakers and attending global climate summits to spread the word. Sage has raised $30 million so far and is growing quickly. This year, the company is building a small geothermal energy storage system at a cooperative near San Antonio, Texas. They’re also collaborating with U.S. military bases in Texas and expanding internationally, with projects in Romania and partnerships with companies like Meta to power their data centers.
Looking ahead, Sage is finalizing a proprietary turbine to more efficiently convert heat into electricity. But Taff knows that widespread adoption of geothermal energy will depend on cost. “It’s going to be clean, and it’s going to be cheap,” she said, summing up Sage’s approach. She’s confident that geothermal is on the brink of becoming a key player in cleaning up and stabilizing the grid.
Reflecting on her journey, Taff said, “I’ve never looked back. I love what I’m doing, and I believe it’s going to be transformative.”
