Good, old-fashioned rock-based energy storage via Iain Watt

Resource / Good, old-fashioned rock-based energy storage via Iain Watt

By Futures Centre / 18 May 2016

Forget Elon’s Batteries—Fix the Grid With a Rock-Filled Train on a Hill


THE ARES IS pretty simple, as cutting-edge energy storage technology goes. A lot of rocks. A few railcars that, if they weren’t traveling up and down the same 5.5-mile track on a Nevada hillside, would probably be hauling ore around a mining operation. Throw in an electric generator, and you’ve got the future of the American energy grid.

Well, one possible future. Energy storage is a hot topic, because federal and state guidelines are fast pushing utility companies to ramp up their use of renewable energy sources. (California’s supply, for example, has to be 50 percent renewable by 2030.)

The problem is, today’s coal and natural gas guzzling grid doesn’t hold onto the electricity it generates. Utilities immediately deliver whatever they produce, and produce exactly what’s needed, from moment to moment.

Renewables, though, don’t work that way. The wind doesn’t always blow, the sun doesn’t always shine. So utilities are in search of ways to store surplus energy when they’ve got it, so they can distribute it later, when it’s needed.

It’s a wonderfully simple idea, a 19th century solution for a 21st century problem, with some help from the abundant natural resource that is gravity. When the local utility’s got surplus electricity, it powers up the electric motors that drag 9,600 tons of rock- and concrete-filled railcars up a 2,000-foot hill. When it’s got a deficit, 9,600 tons of railcar rumble down, and those motors generate electricity via regenerative braking—the same way your Prius does. Effectively, all the energy used to move the train up the hill is stored, and recouped when it comes back down.

What might the implications of this be? What related resources have you seen?

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