US startups use fracking technology to store clean energy

US startups are developing proprietary technologies based on hydraulic fracturing to drill wells to store renewable energy from solar and wind in pressurized underground water reservoirs.

As the share of renewable energy in electricity generation in the top US oil state of Texas grows – so does the need for energy storage, which ensures clean energy is available when needed.

The new pressurized storage technology could be an alternative to lithium-ion batteries if it proves commercially feasible and cost-effective in new pressurized energy storage systems.

Grid-connected batteries in California and Texas, for example, have begun to play a significant role in helping balance the system, Ed Crooks, vice president for the Americas at Wood Mackenzie, wrote earlier this year.

Now, at least three Houston-based startups are working on and piloting projects to store water under pressure in underground reservoirs and release it to turn a turbine when needed to generate power.

“Zero-carbon energy storage that leverages oil and gas technology is here because we can store solar and wind renewables underground,” Mike Eros, chief geoscientist at Sage Geosystems, said earlier this year when the company — founded in 2020 – announced its first nearly $17 million in Series A financing, led by Chesapeake Energy, for a commercial facility.

The 3MW facility, called EarthStore, will use Sage Geosystems technology that harvests energy from pressurized water stored deep underground. The facility will be able to store energy for short and long periods and can be paired with intermittent renewable energy sources, including wind and solar, to provide baseload, dispatchable energy and inertia to the power grid.

Last year, the company successfully demonstrated the EarthStore system in a large-scale commercial pilot project in Texas. The pilot produced 200 kW for more than 18 hours (long duration) and 1 MW for 30 minutes (after load), generating electricity with Pelton turbines to run equipment at the site. The system has a round-trip efficiency of 70-75 percent and water loss of less than 2 percent, Sage Geosystems said in February.

Earlier this month, the company announced the location of the project after entering into a land use agreement with San Miguel Electric Cooperative Inc. (SMECI) for the Geopressured Geothermal System energy storage facility. The EarthStore system will be in Christine, Texas, near SMECI’s lignite-fired power plant. Sage will operate as a trader, buying and selling electricity to the ERCOT grid.

“Geothermal energy storage is a viable solution for long-term storage and an alternative to short-term lithium-ion batteries,” said Sage Geosystems CEO Cindy Taff.

Sage will also use its patented Geopressure geothermal system to provide carbon-free power to Meta data centers, the company said this week.

Other companies opening pressure storage systems include Fervo Energy and Quidnet Energy.

Fervo Energy boasts that it has developed a proprietary geothermal technology called FervoFlex that can provide reservoir energy storage and dispatchable generation attributes. Fervo’s horizontal well design connects underground wells with a set of hydraulically conductive fractures surrounded by impermeable rock. The company says its technology “effectively enables Fervo to operate its assets to achieve multi-day energy storage attributes in addition to the traditional benefits of clean and firm geothermal energy.”

Fervo Energy is also backed by a US shale firm. Last year, it announced a $10 million strategic investment from Devon Energy.

Fervo said at the time that it was the first geothermal company to successfully drill and complete a pair of horizontal wells for commercial geothermal production, using technologies, skills and processes pioneered by Devon for oil and gas production.

For its part, Quidnet Energy aims to develop a modified pumped hydro energy storage system that stores energy through high-pressure water underground. To charge, the team will pump water into the rock trapped underground, creating high pressures.

Quidnet Energy calls the technology Geomechanical Pumped Storage and says it is widely deployable at very low cost.

“Rock layers below the surface are transformed into energy storage reservoirs for large-scale renewable integration and grid management,” the company says.

The fracking process in these technologies is less intensive than in oil and gas production.

Sage’s chief scientist, Mike Eros, told Inside Climate News that the company’s fracking process is about one-tenth the scale and intensity.

“We call it an Earth battery,” he added.

By Tsvetana Paraskova for Oilprice.com

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