[LegitShady]

>Use the excess summer power to fill up a near empty dam with desalinated water?

Pumped storage hydroelectricity is the biggest form of power storage at the moment, and has efficiencies around 70-80%. The losses for desalinization (pumping through media) are ruinous compared to just pumping uphill, and storing desalinized water means you can't use it without spending potential power. There might be good reasons not to mix desalinization and energy storage.

[PopeDotNinja]

As I understand it, the main challenge with pumped storage is that you can't do it everywhere. You need fairly specific geography for it, and it's a big civil engineering project. Here's a good video on by Practical Engineering:

https://youtu.be/66YRCjkxIcg

[LegitShady]

> You need fairly specific geography for it, and it's a big civil engineering project.

You need elevation difference and fairly stable soil. Everything else is technologically solveable. It's a big civil engineering project but its a profitable one and not particularly challenging.

[MaxBarraclough]

Good video, thanks. It briefly mentions the idea of pumped seawater storage. Is that really any different from using freshwater, other than location?

[LegitShady]

seawater is saline, you have to be careful what you do with it because you dont want to literally salt the earth where you are (soil remediation friggin sucks).

seawater is also not valuable. You don't care about the water quality in the reservoir, you just let it fall back into the sea. If it evaporates you're losing energy but you aren't losing potable water that you sell, and it doesn't require a connection to a water distribution main.

[PopeDotNinja]

I imagine the main difference would be salt content, but I can't speak to how that would affect things.

[twic]

I think the idea here was simply to use the excess energy to stock up on potable water, which people could drink later, rather than to also use it for pumped storage.

[LegitShady]

> I think the idea here was simply to use the excess energy to stock up on potable water, which people could drink later, rather than to also use it for pumped storage.

If it was a reasonable and profitable use of energy we would already be doing it, but we're not because its ruinously expensive. You also run into storage issues (how much of your excess power is being evaporated from the surface of your storage reservoir? The longer you hold your potable water the more you throw away). You also need to consider what you're going to do with the highly saline byproduct of any such process.

There's nothing wrong with purifying water but its very energy intensive and already something we do. Adding more expensive potable water from excess energy generation doesn't make much sense.