Pumped hydro has been a concept for a while now for grid storage of power; one of the limitations of it is just the rather unique geography required. Most places with adjacent reservoirs and enough vertical separation between them also have cottages, roads, and other infra that make it hard to be constantly draining and filling.

It is not just a concept, it represent the vast majority of grid energy storage today, we are talking about gigawatts.

Hydro is the best, so good in fact that most of the good spots are already taken, because as you said, it requires a very specific geography.

It’s less that (IMO) - cottages and roads are usually not as dense on steep hillsides and the like, though of course they can’t be ignored entirely. The pipes involved are usually not the big issue, and the pumping ops are usually not the big issue either.

The business model for pumped hydro requires relatively low cost to be economic and if it requires building a giant concrete water retention systems on top of large flat topped hills/mesas, near large drops in elevation, with water retention at the bottom of the large drop that is also really really expensive to build and requires specific geology to be economic.

And if something gets messed up, it’s a huge liability [https://en.m.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Powe...], as it can cause very damaging flooding and be expensive to repair/replace.

Worth doing when there is cheap power that can be stored and sold at higher rates later, but construction costs are really a huge part of it.

Or you can use multiple ordinary hydro power dams (i.e. ordinary lakes where one or more outlets are blocked).

I'm fairly certain we have these multi level semi natural systems here in Norway, but I am not sure if we use them for pumped hydro.

(Og course, if one doesn't care about ecology, one of those levels can be the sea.)

Of course, and they are. They are even more limited in quantity, geologically.

Yep, but just needs enourmous amounts if construction, not insane amounts.

> My crazy idea would be to use the heat and the pressure of these to pump water uphill.

This is a great idea, not crazy.

It ignores the steampunk future that awaits us all!