Sage Geosystems Aims to Address Data Center Energy Dilemma Through Deep Underground Pressurized Water Storage

In the early months of 2022, as Cindy Taff surveyed the vast landscape of Starr County, Texas, she experienced an extraordinary sensation. “The ground beneath us was actually trembling,” she shared with TechCrunch, marking a defining moment of realization.

At that time, Taff’s venture, Sage Geosystems, was in the midst of trialing apparatus designed to extract thermal energy from deep within the earth. This process involved the injection and subsequent release of water from a well, which led to the eruption of heated, purified water. This phenomenon highlighted the potential of utilizing geothermal power on a global scale as a sustainable alternative to natural gas.

The concept of harnessing the earth’s subterranean heat is far from new, and Sage Geosystems seeks to innovate within this domain. The company is exploring the use of deep wells as a form of energy storage, pressurizing water to later draw upon for electricity production. This method has been under scrutiny in Starr County for more than a year, and as of Tuesday, they revealed plans for a commercial-scale operation near San Antonio.

This forthcoming facility is planned near a coal power station run by the San Miguel Electric Cooperative Inc. (SMECI), covering a significant portion of a 10-acre site. The aim is to create energy storage wells tied to a solar array, thereby providing continuous power to an onsite data center, with Taff likening the project to a pilot for larger data centers.

The anticipated geopressured geothermal system should yield 3 megawatts of electrical power, sufficient for over 600 households, at an estimated cost of 10 cents per kilowatt-hour.

With plans to commence drilling by mid-September, operations are expected to launch in December, Taff informed.

Taff, now CEO of Sage, joined the green energy sector after a long tenure at Shell and other industry giants, bringing with her extensive expertise in onshore drilling operations. She, along with others at Sage, found renewable energy an apt sector due to its focus on geology and energy storage – skills honed from decades in oil and gas.

Sage Geosystems initially aimed to lower electricity costs, having identified the injection of water into the ground as a significant expense for geothermal energy developers. Unlike the natural seepage process, Sage opts for a high-pressure water injection method, requiring significant energy input but offering the potential to recover some of this energy by using the pressurized water to turn a turbine.

“This method essentially expands the fractures, storing water under pressure,” explained Taff. “When power is needed, we simply open a valve, initiating the pressurized water’s release.” This approach presents a stark contrast to the conventional techniques used in oil and gas fracking, where water and grid are used to keep rock fissures open for fossil fuel extraction, often resulting in substantial water loss and brine production.

Instead, Sage aims for minimal water loss, primarily through evaporation. The company observed a decrease in water loss from around 2% to 1% per injection and recovery cycle within just over a month of operation at their test well.

After proving the viability of its first well, Sage intends to expand its operations to potentially ten additional wells, achieving up to 50 MW of capacity on the SMECI property. SMECI has plans to decommission its coal plant by 2026, considering a combination of solar panels and energy storage to replicate the consistent power supply of coal, with Sage expecting to recuperate at least 70% of the energy used in water injection.

Taff mentioned that SMECI is keenly observing their progress as it showcases a significant portion of Sage’s technology capabilities. Moreover, Sage is in discussions with major technology firms to deploy its geothermal and energy storage solutions in their data centers, presenting a cost-effective alternative to large-scale batteries, especially for overnight solar power utilization.

“We’re not positioning ourselves against lithium-ion batteries for short-term needs as they are more cost-efficient in that regard. However, for longer durations, our method proves to be more economical,” Taff elaborated.