U.S. startups are advancing new methods for storing renewable energy by utilizing hydraulic fracturing technology. These companies are drilling wells to store energy from solar and wind sources in pressurized water reservoirs deep underground.
As renewable energy’s share of electricity generation increases in Texas, the demand for effective energy storage solutions rises. This storage ensures that clean energy remains available when needed. The new pressurized storage technology could offer a cost-effective alternative to lithium-ion batteries if proven successful.
Grid-connected batteries in states like California and Texas are already playing a critical role in stabilizing the energy system. According to Ed Crooks, Vice-chair of Americas at Wood Mackenzie, these batteries are essential for balancing the grid. Now, several Houston-based startups are piloting projects to store water under pressure in underground reservoirs. This water can then be released to generate power when required.
Sage Geosystems, founded in 2020, is one such company making strides in this field. The company recently secured $17 million in Series A funding, led by Chesapeake Energy, for its EarthStore facility. This 3 MW project will use Sage Geosystems’ technology to extract energy from pressurized water stored underground. It will provide both short-term and long-term energy storage and can be paired with renewable sources like wind and solar to deliver consistent, dispatchable power.
Last year, Sage Geosystems successfully tested the EarthStore system in a commercial pilot in Texas. The pilot demonstrated the system’s capability by producing 200 kW for over 18 hours and 1 MW for 30 minutes. The system achieved a roundtrip efficiency of 70-75% with minimal water loss, according to Sage Geosystems.
The company has now announced a new project location in Christine, Texas, following a land use agreement with San Miguel Electric Cooperative Inc. (SMECI). Sage Geosystems plans to operate the EarthStore system as a merchant, buying and selling electricity to the ERCOT grid. Additionally, the technology will supply carbon-free power to Meta’s data centers.
Other startups in this sector include Fervo Energy and Quidnet Energy. Fervo Energy has developed FervoFlex, a proprietary geothermal technology for energy storage and generation. The company’s horizontal well design connects subsurface wells with hydraulically conductive fractures surrounded by impermeable rock, enabling multi-day energy storage. Fervo Energy received a $10 million strategic investment from Devon Energy last year.
Quidnet Energy is working on a modified pumped hydro energy storage system, known as Geomechanical Pumped Storage. This technology involves pumping water into confined underground rock to create high pressure, which can then be used for energy storage. Quidnet Energy claims this method is highly deployable and cost-effective.
The fracking processes used in these energy storage technologies are less intensive than traditional oil and gas production. Mike Eros, Sage’s Chief Geoscientist, described the company’s fracking process as being about one-tenth the scale and intensity of conventional methods. “We call it an Earth battery,” Eros said.