Today, an old technology that's getting a second look.

From American public media, this is Marketplace Tech.

I'm Lily Jamale. Back in the 1970s, the Tennessee Valley Authority built what remains today one of the largest energy storage

devices in the world. It's what's known as a pumped storage hydropower plant. A pump takes water from the Tennessee River, shoots it up a giant shaft,

and holds it there until power needs peak during the day. At that point, the water is allowed

to drain back down, spinning turbines that can generate enough

power for a million homes.

It's almost like a gravity-powered battery, as big as a cathedral and buried deep inside a mountain.

That's according to Robert Kunsig, a freelance journalist who recently wrote about this

in depth for the publication Science.

He says Pump Storage Hydro is getting a lot of interest thanks to generous tax

credits from the 2022 Inflation Reduction Act. To solve the climate crisis we're

going to need to decarbonize the electric grid and to do that we're going to need to decarbonize the electric grid.

And to do that, we're going to need to build a whole lot of renewable energy, solar and wind.

And the trouble with those energy sources, they don't emit carbon, but they're very variable.

So you need some way of storing the electricity they produce

when they're producing more than you need

so that you have it available when they're producing less than you need at night or when the wind is calm.

And pump storage hydropower is a proven technology for storing a lot of energy that you could use to tide you over a whole day or even longer

when the renewable energy is not producing what you need to meet the needs of the grid.

It would just be a very reassuring energy bank to have if you're a grid operator.

Yeah, and you describe in your article how this allows utilities to bank that power on a

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