[AceJohnny2]

> I love pumped storage, too bad it's not used more

Pumped storage is awesome and the most cost-efficient way to store energy. It's used as much as possible, but...

I attended a USGS [1] talk about dams (in California) a few years ago.

The key takeaway is: all places worth damming have been dammed. There are no more dammable places, hydrologically and geologically speaking.

When I drive through the central valley, I see a lot of roadside signs about "build more dams!" It's sad to see the miscommunication...

[1] https://www.usgs.gov/science-support/communications-and-publ...

(I cannot immediately find a link to the specific talk. USGS is fun: full of crusty geologists, who even in the heart of the Silicon Valley aren't particularly technologically sophisticated (a nice reminder of how niche we all are) )

[femto]

With pumped storage you don't need anywhere near the amount of water or storage needed for straight Hydro. In a 24 hour cycle, you can empty the top dam into the low dam, running the generators flat chat (unlike typical hydro which is limited by water supply), then pump it back up again for reuse. If you do the numbers (E=m.g.h) the amount of water required to store energy for a city of millions is quite tractable, assuming a decent head.

Australia is doing exactly this with "Snowy 2.0" (by connecting existing dams).

https://www.snowyhydro.com.au/snowy-20/about/

350,000 megawatt hours of energy storage, which is enough to power 3 million homes for a week, or (if there was enough generation/transmission capacity to get the energy in/out fast enough) the entire nation for 12 hours.

[RyanPringnitz]

Another recent example in 2021. Kauai is supposed to be up to 80% powered by renewables with their pumped storage install. Small scale, but great example.

https://www.powerengineeringint.com/renewables/kauai-island-...

[martyvis]

They are only adding 2GW of generation capacity, so I guess the 350GWh stored would take a week (175 hours) to be consumed by Snowy 2.0 that way.

[gregwebs]

I think you are describing pump-back hydro dams which are only a subset of pumped storage. Strictly speaking pumped storage only requires an elevation change and a water supply

[mjevans]

If not near a water supply or lack of intent to use some of the pumped water for irrigation anyway, as the parent post said, (nearly) everywhere it was worthwhile to do is already doing it.

The alternative is another form of gravity battery, often involving railway on a hillside and cars loaded with stone.