“As the name suggests, geothermal energy typically relies on such heat, which can be used for industrial purposes or to create electricity.

But the project Sage is developing with San Miguel takes a different approach — one that is in many ways far more necessary for Texas’s increasingly renewables-powered grid.

Rather than seeking to tap underground heat, the project uses ‘earth storage’ and a turbine built from off-the-shelf parts to trap cheap power from wind and solar and sell it back to the grid when it’s needed.

The technology is somewhat akin to an upside-down version of ‘pumped storage,’ in which water is pumped uphill into a hydro dam reservoir when power is cheap and allowed to run back downhill when it is expensive — although in this case when the water gets tapped, it flows back up through the well. 

‘You give the earth the energy, and it gives it back like a balloon,’ said Cindy Taff, CEO and co-founder of Sage.”

From The Hill.