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Texas startup delivers landmark results with ‘earthen’ battery technology: ‘The opportunities … are significant’

“We have cracked the code.”

"We have cracked the code."

Photo Credit: Sage Geosystems

A trial run of Houston-based Sage Geosystems’ underground battery has delivered “groundbreaking” results, the company reported. 

The tech, sometimes called an “earthen” battery, is meant to store electricity generated from renewable sources. It’s also geared to be an alternative to lithium-ion battery storage systems, which require expensive and hard-to-gather materials to make. 

Field tests from 2022 to 2023 demonstrated that Sage’s system, marketed as EarthStore, can provide more than 18 hours of energy storage, with the ability to give 24/7 power “when paired with solar or wind generation,” a news release on the results stated. What’s more, the unique tech can help provide renewable energy during peak demand times, which is a sometimes elusive prospect for intermittent solar and wind systems. 

“We have cracked the code to provide the perfect complement to renewable energy, yielding reliable alternative baseload in a manner that is cost competitive with lithium-ion batteries and natural gas peaker plants,” Sage CEO Cindy Taff said in the release. 

The tech is promoted as having a small ground-level footprint. Most of the mechanism is buried. Sage drills several thousand feet into the earth, opening fissures with fracture technology. The fractures serve as reservoirs to store water deep underground. The fractures also store energy like a spring, using subsurface pressure to propel the water upward when a valve is opened on the surface, powering a turbine, all per a video clip from Sage. 

The water is pumped underground by energy bought from the grid (the video clip shows wind turbines supplying the juice) when there’s a glut of electricity. The water is stored below until it is needed. Sage has a couple of variations of the tech. One version with deeper wells uses heat to help push the water to the surface and is more efficient. EarthStore is what the company calls its “mechanical” version of the concept, which boasts a still impressive efficiency rate of 70%, all according to the clip. 

The recent news from Sage touts an energy production cost lower than or competitive with other innovations, including lithium-ion power packs. The release noted a “round-trip efficiency” of up to 75% for EarthStore. 

Using water to store electricity, while a seemingly odd combination, is being studied around the world. Energy leaders in Scotland are investing hundreds of millions of dollars in a water battery that leverages reservoirs and gravity to store power. The innovations are part of the way we can better generate and use electricity, reducing the amount of planet-warming dirty energy sources we burn.

“The opportunities for our energy storage to provide power are significant — from remote mining operations to data centers to solving energy poverty in remote locations,” Taff stated in the release.

There was no indication of earthquakes created from drilling and fracturing the ground during the pilot project. Sage reported that EarthStore can operate in new wells or existing oil and gas holes. 

The tech is now “ready to scale” without geographic limits, per the company.

“We can interconnect with power grids or develop island/microgrids with a cleaner energy solution that is proven and ready to scale,” Taff stated in the release. 

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