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Comment by toomim | Hacker News Reader

I agree this should be looked into, but one issue is that moving water uses energy, since water naturally flows downhill, and pushing it to where it doesn't naturally flow goes against entropy.

In California, we already spend 4.2% of the state's power on pumping water. This percent will increase if the water has to run uphill and/or cross mountain ranges. http://ww2.kqed.org/climatewatch/2012/06/10/19-percent-calif...

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When you pump water over a hill you need energy to pump it up and can retrieve some of that energy when it flows down hill. That's why CA uses some of its reservoirs as hydroelectric storage batteries, pumping water up when electricity is cheap and letting it flow down when electricity is expensive.

https://www.sdcwa.org/projects/san-vicente-pumping-facilitie...

Reservoirs and pump using renewable power would offset that somewhat.

Particularly you site the pumps near the renewable and they wouldn't necessarily need to be "on grid".

The energy required to pump water UP to the elevations of much of the southwest is astronomical. Huge parts of it are at 5000-7000', so even if you manage to avoid actual mountains, you still have a huge lift from either the coast or the Missouri/Missippii rivers. I have no doubt that there would be ways to move some water in such a manner, but not much.

If you bring water in from the rest of the US and supply the regions which depend on the water flowing down from the mountains you allow the high altitude regions to retain more of their water.

Sure, that means you generate less hydropower in the downriver dams, but overall I think it's a wash(pun intended).

Pumping seems like something that could run intermittently with renewable energy. Have to overbuild capacity I suppose.

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