WDWHTY: Giant "Battery" Based on Elevation + Gravity

WDWHTY - Why Don't We Have These Yet?

I'm just saying, I'm kind of surprised that we don't have giant "batteries" yet. Or do we and I am just completely in over my head?

Not being an electrical or mechanical engineer, or whatever kind of professional deals with these kind of things, there's probably a good reason -- maybe because of the "giant" part. Let me clarify what I'm thinking of.

Giant Sort of Battery
More traditional batteries that I know of (e.g. lithium-ion, lead-acid) store energy using relatively complex processes, chemicals, etc. Hydro-electric power uses water flowing from higher elevations to lower elevations to produce energy using turbines. Why not use the same idea to store energy at a smaller scale?

I'm thinking of a storage tank like a water tower with a basin at the bottom. Attached are a pump to move water from the basin to the tower to recharge, and a turbine to produce energy when water falls down. Pump lifts water when there's excess energy and water falls when power is needed. Good for storing that renewable energy (e.g. wind, solar) and turning it into a more consistent, reliable source of electricity? Didn't sawmills use rivers way back when to power things?


Bored and Wondering: Potential Energy Battery?

Likely reasons why I haven't seen any yet?
How much water do you need to produce enough power to power a home? How big does the turbine have to be? How big does the water tank have to be? How high up does it need to be? Could it be scaled down enough to fit in something like a backyard? Could it be made more compact by using something denser than water? How bad are the conversion losses? What kind of maintenance are we talking about? Would it be safe to have these everywhere? Conversion and evaporation losses? Water + electricity?

No clue.

There are probably some formulas available to figure all of this out, but that would take work and expertise. Anyway, putting something like this together might need something really big and tall unless one buries part of it -- stack turbine and lower reservoir directly under tower to resemble a silo? The size would more than likely be much bigger than an array of batteries with a similar storage capacity. Would it be more expensive and last longer though? They probably don't exist on a larger scale due to the whole make your own lake and dig your own giant pit problem.

Regardless, something like this probably wouldn't be that attractive. Neither are windmills or solar panels? Just an idea...