Is Hydraulic Fracturing the Next Big Breakthrough in Battery Tech?

Abstract

Drill a well. Induce a fracture. Pump water. Start flowback. This sounds like the steps used to bring to life tens of thousands of tight-oil and gas wells over the past quarter century. But what it really describes is the emerging approach that a pair of Houston-based companies are using to turn rock formations into giant batteries. Differences aside, the respective processes developed by Quidnet Energy and Sage Geosystems involve hydraulically fracturing vertical wells, injecting water into fractures, and flowing that water back to surface under high pressure to drive a small industrial turbine. Founded in 2013, Quidnet was the first to try to commercialize this concept which represents a new twist on a very old technology known as pumped storage hydropower. Introduced in the 1890s, the technique works chiefly by sending water uphill—e.g., a mountain or a fjord—to create a gravity-assisted energy system. And despite its geographical limitations, this pumped storage represents more than 90% of the world’s energy storage today, an estimated 9,000 GWh. Of course, what both Quidnet and Sage want to do instead is to have subsurface rock formations do the heavy lifting and force the water uphole like it was shooting out of a geyser. To highlight this distinction, Quidnet refers to its version as “geomechanical” pumped storage while Sage so far prefers to call it “mechanical” pumped storage. Each firm claimed this year to have shown through respective field tests that all this is not merely theoretical. Most of this work has involved existing wells but both companies have plans for dedicated new-drill wells. Quidnet and Sage say the electric outputs they’ve achieved so far are promising enough to start considering pumped storage in rocks as a way to solve grid shortages and the intermittency issues that hamper wind farms and solar arrays. During periods of low grid demand, the proposal is to run water pumps on surplus electricity. Hours or days later when demand rises, that water is released to the surface and most of the electricity required to pump it down can now flow back into the grid. Sage shared figures at a geothermal conference in September boasting its nascent approach as already cost competitive with traditional pumped storage and commercial-scale lithium-ion batteries. That optimism is built upon the company’s first and only test well in Starr County, Texas, which bested expectations. “The output just blew us away,” Cindy Taff, CEO of Sage, said at the PIVOT conference last month. “We literally had to repipe the surface equipment three times because we were getting more force and pressure than what we had anticipated.” Taff, who previously spent 35 years working in the oil and gas business for Shell, said the well produced a flow stream that was converted into 200 kW for 18 hours. This adds up to 3,600 kWh, which is roughly four times the electricity consumed each month in the average US household.