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Comment by hardwaresofton | Hacker News Reader

depending on how you build the storage, you could also use the excess water for power, no? Some sort of gravity battery setup.

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Yep, it’s called pumped hydro: https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

I think it’s very promising/exciting as a method of smoothing out the demand curves of the electric grid. Plus, it’s fairly straightforward to modify existing dams/hydro infrastructure to have this capacity.

Since some dams are already used as water reservoirs for drinking/agriculture, this could be quite viable if the desalination can be done cheaply and efficiently at scale (not sure if this is even possible on the scales required for this idea to make sense, though).

Pumped hydro has been extremely effective in Australia since the mid 1960's. There's currently a project to extend the capacity of the Snowy Hydro scheme to soak up this extra transient renewable capacity.

https://www.snowyhydro.com.au/generation/the-snowy-scheme/

That's cool -- I didn't know that! Imo, the more effective and cheaply we can store energy and smooth out supply/demand curves, the more attractive solar and wind becomes.

Perhaps one way of encouraging a "greener" grid is to first encourage the development of cheap energy storage solutions, and then letting the market figure out the best way to utilize such storage (rather than the other way around). Might lead to more efficient/creative green energy solutions.

got get it up there ... places like Cali dont have a lot of rain that places itself up there and runoff is running out.

That's the point you can pump the water higher using excess renewable energy (in the event we get past 100% peak renewable power) to be used later when there's a deficiency. It's a fairly efficient method of time-shifting renewables without having to mine huge piles of lithium.

Pumped hydro if geography permits is very good storage method. Efficiency is not horrible, it is simple to ramp up and down. Technology is extremely mature. It scales pretty well. And as final bonus in some cases it can contribute to grid stability.

Yeah the biggest downside is the ecological impact of the flooding involved in creating a new hydro source. They could maybe look at retrofitting it onto an existing hydroelectric dam so it's not flooding a new area.

A hydro power reservoir doesn't need a watershed, so can have overwhelmingly less ecological impact.

It still needs volume to flood to hold the water though and unless we're building up artificially the cheap way to do that is to build fairly wide. All that area is habitat and covering it has an impact. In the end it's probably well worth it so long as we're not destroying rare habitats to do it but it is still destruction that has to be considered and weighed.

Pumping desalinated water up to Sierra Nevada reservoirs would take a hell of a lot of pipe. We use canals and rely on gravity to move water, today.

I'm going to assume you mean "up there" as in northern cali -- if we could get some clean hydrogen/electric transport trucking it shouldn't be impossible to move it around either!

I wonder whether the most efficient way to get water to the Sierra Nevada reservoirs would be to pump ocean water onto the desert, and let evaporation take it from there. Siphoning from the ocean into Death Valley, you wouldn't even need to pump it.

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