But an oversize elevator, with motor-generators, lifting something like a kilometer cube of earth? Or gather up all the used lithium batteries from the cellphone industry and tie them in parallel?

Flywheels?
Supercapacitors?
i got it __ a giant wimshurst machine
... fill the lake with mercury

As opposed to conserving, and living conservatively. Which USians will refuse to do ... we are so so screwed.

WRT your ball bearing lakes idea:

Just thinking about the "power house" i.e. the point at which the bearings turn the "turbine":

This is just intuitive guess on my part, but I think it would actually be quite difficult to design a geometry that would both not have the balls jam the impeller, and also not have the balls clog in the intake chute, while at the same time transmitting a siginificant amount of back pressure from the resevoir.

I would expect that you would see a void develop upsteam of the powerhouse with a surface that looked like a cantinary curve rotated in the third dimension i.e. sort of an eliptical contic section extending from the powerhouse entry to the sides of the intake sluceway {Sure wish there was an easy way to stuff a napkin and a felt tip through this software :) }

There would of course be a huge embedded energy in producing the balls to fill the resevoir. If one of the main drawbacks that you see to using water is evaporative loss in arid regions I think it would be cheaper to cover the resevoir surface with loating rafts to reduce this... Why not install PV panels on the rafts while your at it?

If a hard landing then seems to me to be pretty impossible.

Taum Sauk is a water reserviour in mid Missouri owned and built by Union Electric. They use/d excess generated power to pump the water to the top of a hollowed out mountain(actually large hill) and then released the water to drive turbines as needed later.

Well last year it broke out of its holdings and did a darn heck of a flooding job on small towns located in its flood path. Roaring walls of water scared the shit out of many who were just out moseying around the town. Flattened a lot of real estate.

Never did hear about the the eventual outcome.

I wouldn't want to be in the path  of zillions of speeding ball bearings. Water I could handle.

Water seems like it would be easier to engineer something like this with. Steel seems a bit harder. Lots of water towers still in use. Methods of pumping the water still exist. Obtaing the power to do so after an infrastructure crash might be a problem.

How about a windmill that hoists and stores water then you drive the small electric turbine when you release the water. Such windmills are still being built and used out west, I believe.

In fact a few of my neighbors have put some up just to decorate their farms with. Low tech stuff. Available ,and you get free running water to boot. Nice to have indoor plumbing in your 'Thoreau' shack out in the hinterlands. Always a bitch toting water uphill from the local spring.

The steel would see much better use in tubular towers for wind turbines.

Let's say you wanted to store the energy from a GW source over a 24 hour period. That equals roughly 10^14 joules.

Second, assume you were to raise your ball bearings 1000 meters up. To store that much energy, you would need 10^10 kg of mass, or about 6.6 million cars. And about 10^12 ball bearings about a cm in size.

Of course, you would lose a lot of energy to rolling resistance, friction between the balls, etc. Plus, you generate heat moving them up. And then you have to melt down the cars first. Perhaps you could have TODers, who have nothing better to do, carry them uphill.

Better ways of using gravity employ water, pumping water uphill into a reservoir rather than having the sun lift it for you. Alternately, you can pressurize an underground reservoir with air. None of the mass transfer approaches are really that efficient, though. On-site hydrogen generation might be better.

It's the second law that gets you that will require more energy, to create the potential, than you will generate through whatever process.  It's the entropy and the entropic rate that present a problem in nearly all scenarios.  Using low entropic processes (biomass for example) to replace high entropic processes (burning of fossil fuels) will get you everytime.  

High-temp superconductors are quite interesting in conjunction with lightning - as they can retain charge linearly with length, and handle the currents involved at a relatively small point.

-----------------------

We've had hundred of years of perfecting water pumps + generators.

And it's led to a very similar solution - Pumped Storage.  1 dam (for cost effectiveness, usually mostly natural dam), 2 bodies of water, one on top and one on the bottom.  Pump the water up with electric motors in the daytime, act as a hydroelectric dam in the nighttime.  We get something like 70-80% of the energy back - which is fantastic in thermodynamic terms.  More importantly, it's capable of storing vast amounts of energy for long periods of time practically - batteries, flywheels, and other forms of energy storage that can store a major powerplant's output for hours should be more expensive than the powerplant.

Raccoon Mountain, run by the Tennessee Valley Authority, is the largest US pumped storage plant, and has 32 gigawatt-hours of capacity on 1600 megawatts of potential power.

You are right in that these(and conventional dams that just switch off frequently) are going to be a lot more important if our power is highly variable from solar/wind.  Right now our transient demand does shift from day to night, but not by that much.

Evaporation is apparently a minor problem in current pumped hydro dams - but I'd imagine it's one that we can fix rather easily without constructing a giant cover - just dump a few tons of white styrofoam onto the surface.  Or hell, if you keep the reservoirs above a certain level, grow algal biodiesel in it.

When you solve the evaporation problem, pumped hydro is also not too difficult to make environmentally sound in terms of watershed variability - simply install a floodgate at a river where it attaches to your closed bottom reservoir, and only open it to draw a small portion of the flow(or add a small portion in flood conditions) after the initial fillup.

--------------

On a related topic, the vast amounts of coal we're gonna be digging up are often scalped from mountaintops, which are then dumped into the valleys as fill - IMO a well-guided energy strategy should consider where pumped storage hydro can be used, and if we're gonna destroy the landscapes anyway, build reservoirs with the fill.

why not Slinkies ?

Have you considered using all the asphalt down there as the basis for a solar oven that would heat a liquid that would then be pressurized and fed into a turbine and then recycling the liquid for another round? I know about the salt tower experiment.

Not to belittle the amount of thinking and effort that went into your idea, wouldn't it be better to use what assets are available in your region to generate electricity while buliding underground housing?

I suppose a "dive" would be a good time to watch Das Boat. Those plasma TVs use up a lot of power but the LCD TVs use a lot less. That's why I like an LCD monitor and those compact fluorescent lights. At one time I coded up the "UPSer .FAQ" file, still found with Google. If you're a homeowner, you can use a generator, but apartment dwellers must settle for a UPS (or similar) or go without in the coming days of routine rolling blackouts. Got batteries? A_A_A_RE Y_O_U_U R_E_A_D_Y?????? (about the best I can put into text Jonathan Davis of Korn fame)

There is another at least theoretical alternative: enormous
homopolar generators which store energy in the angular momentum of a very heavy steel & concrete rotor.

I don't know if these are really feasible on a cost basis for utility level load leveling, but I think the efficiency could be high.  You can dump tremendous electrical energy into them and get enormous currents.

They've been used for power "shots" for nuclear fusion research reactors, where trying to take that power from the grid would black out a whole state.