I can't really agree with 'promising'. A tower that can lift 100 tons 50 meters is not exactly cheap, and only stores 13.6 kilowatt hours.

Here’s a company pursuing that very idea.

https://qz.com/1355672/stacking-concrete-blocks-is-a-surpris...

Ah, if you actually build the structure out of the items you're lifting, then that certainly changes the math. Compared to just lifting with a crane you get a thousand times the capacity at the same infrastructure price.

Exactly. It’s really the same principle as pumping water uphill except using concrete blocks and a crane. Potential energy is potential energy.

I’d just love to see it in action.

consider off shore gravity batteries that can drop mass down 2 to 4km. Major fixed cost is Hvdc out 100miles, but it’s extremely scalable after that.

Lead-acid batteries are pretty damned heavy and would make a great kinetic battery as well as a chemical one.

I wonder how much more energy this setup would store if they added cranes. Also it could be possible to make a circular vacuum maglev train out of these and add energy to it by accelerating.

There was an episode of Nova about energy storage that included a company that made kinetic energy storage devices. IIRC they had 5000 pound flywheels that spin in a vacuum and can be installed in your home. Expensive to purchase and install but essentially unlimited lifespan and totally renewable.

I've heard about either a working system, or a calculation of something like that but with regular trains. Long story short, it can't actually store that much energy.

More efficient (and less mechanically complicated) would be pumping water up a hill into a lake.