Pumped storage is great, but it's simply not viable at a large scale. There are very few places where natural landscape allows it, and making more artificial ones would require flooding vast areas. Considering how difficult it often is to build solar plants on deserts (e.g. consider Ivanpah solar plant, which almost did not get build due to its impact on habitat of desert tortoises, which ended up getting relocated at a cost of $300k each), I don't expect the green interest groups to accept such wholesale destruction of environments.

Existing hydro lakes can act as storage (within the constraints of how much inflow there is and minimum outflow rates).

Decrease lake outflow when solar and wind are producing power. Increase lake outflow when they are not.

https://www.hydro.org/waterpower/why-hydro/available/

Your link says that at best we could double our current hydro generation capacity, which supports my point: it's simply too little for our storage needs, and if we electrify more of our economy (i.e. use it to replace heat and transport for which we use a lot of fossils now), it will be even less. It might still be worth doing, but is far from solving the storage problem: it just has significant limits on its potential scale.

> Your link says that at best we could double our current hydro generation capacity

No, it says "that without building a single new dam" [hydro could roughly double its existing capacity in the US].

I'll assume you just misread that, but in any case that's pretty different to building new dams, or utilising tech like mines, or at-sea pumped storage.

> No, it says "that without building a single new dam" [hydro could roughly double its existing capacity in the US].

No, that's not what it says. It says:

> The report estimates that without building a single new dam, these available hydropower resources, if fully developed, could provide an electrical generating capacity of more than 12 gigawatts (GW), equivalent to roughly 15 percent of current U.S. hydropower capacity.

Without constructing any new dams, you only increase it by 15%, not double it. Also, consider that 12 GW is 105 TWh per year. US consumes 4100 TWh of electricity per year. It would sure be nice to increase non-fossil electricity production by 2.5%, but that's clearly not very much. If the plan is to use hydro to cover the shortfall when the renewables are not producing enough, you need much more generating capacity than 12 GW, and more than 65 GW your link suggests could be potentially built. Finally, 2.5% is on the order of our annual growth in electricity consumption, which will in fact accelerate as we move off fossils. Thus, building out all possible hydro will only buy one year of growth in consumption.

Yes, sorry you are right!

My error was confusing the "7% total capacity" and "15% existing capacity" not being off the same baseline.

> I don't expect the green interest groups to accept such wholesale destruction of environments.

In the grand scheme of things, this is like refusing chemotherapy for cancer because it makes your hair fall out.

Climate change is a huge issue. You have to be willing to sacrifice what would normally be valid environmental concerns to address it. You either believe it is an emergency or not.

There are probably not one general solution that will work everywhere. But for example in Sweden where about half of the electricity already is from hydropower, it will work well to even out seasonal variations, from for example getting very little sun in the winter. But say for California, where there’s enough sun most days of the year, generating hydrogen might work better to even out the electricity generation between night and day.

And considering solar power, there’s no shortage of available space. There’s plenty of roofs to cover with panels. Or line the sides of, say, Interstate 5 with a wall of vertical panels that also helps keep wild animals from the road and reduce noise pollution.

There is no reasonable and economic way to store Terawatthours of electricity.

Even huge hydrostorage plants have only a few GWh.

Huh? Norway alone has 85 TWh of hydrologic storage.

New Zealand has about 4 TWh, but they are considering adding an additional 5-12 TWh with one single storage project:

https://www.odt.co.nz/regions/central-otago/scientific-thoug...