Assuming 1GW pumps, that means you can pump a GW-worth of power during the day, and tap ~800MW of power at night (assuming 80% efficiency due to evaporation and other conversion losses).

It seems like the Shasta Dam is currently ~700MW and plans to be ~2GW soon. To give you the scale of power demands.

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Its estimated that California's current Solar capacity is ~30GW btw. Soooo... you'll need like 8 to 15 dams the size of Shasta to absorb that power.

Well, you wouldn't need to absorb all of it. You'd need to absorb just enough to run California at night. But still, you can see the amount of electrical usage California already has, and how much storage it needs. Especially if solar continues to grow.

Solar + Wind is nifty, because Wind generates most power at night, while Solar generates most of its power during the day. But even with a team of different plants working together, the energy storage problem is serious.

That's just the day-night cycle. Weather cycles (ex: hot, but cloudy days) are probably harder to plan for.

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EDIT: Anyway, pumped-hydro HAS to be part of the plan. Its one of the few Giga-scale storage methodologies we have. But even then, Gigascale isn't enough.

Realistically, California (or really, the world in general) just needs to builds its economy around the concept of "negative cost energy". Sometimes, there will be energy out there that needs to be absorbed by someone.

IIRC: Germany has aluminum plants which spin up to absorb the cost. People can plan to charge their electric cars during negative-cost energy times, or run their AC-units on overdrive to store some extra cold air. That's the sort of thing that will be sustainable in the long term.

Pumped Hydro (and other energy storage tech) will capture what we can to use later. But building out a "smart grid" which can take advantage of negative-cost energy would be the most obvious way to take advantage of solar.

Peak Solar only lasts for an hour or two. But for those two hours, negative cost energy costs will become a thing.

>Based on German hourly feed-in and consumption data for electric power, this paper studies the storage and buffering needs resulting from the volatility of wind and solar energy. It shows that joint buffers for wind and solar energy require less storage capacity than would be necessary to buffer wind or solar energy alone. The storage requirement of over 6,000 pumped storage plants, which is 183 times Germany’s current capacity, would nevertheless be huge.

The power plants i work on are 5-10 years for permitting.

Bc hydro has been studying the site C dam for 35 years and finally started construction but the project was nearly cancelled 2 years in due to changing political winds they were ready to abandon the project with 2 billion dollars already spent.

The engineering and construction is the easy part.