Sure, some people have proposed that, but if you calculate how much has to be lifted to get 20 MW stored (or so), it gets pretty ridiculous pretty quickly. Like "Lift the largest aircraft carrier 20 meters" silly. You have some pretty severe size/mass issues.

It makes more sense to use water + a dam, but then again, we like to use water for things besides energy storage, and we're talking about a _lot_ of water.

This gas bag is effectively the same as water+dam, except the pressure is from the tanks and the compressor creates it, vs pumping uphill to create pressure.

Very unlikely. All the technologies involved work best at scale; for example, the area-to-volume ratio of the liquid gas storage vessel is a critical parameter to keep energy losses low.

The turbines would have to spin at very high speeds at those sizes to be efficient.

Aren’t CATL already producing sodium-ion batteries for about 60% the cost of lithium-ion for equivalent capacity?

It could be made much less vulnerable by dividing the gas storage balloon structures into a set of multiple smaller structures, ideally with some further internal partitioning so a single punctured surface does not release all the gas in that structure. Everything else is as 'hard' or 'soft' as any other piece of industrial plant, and can be hardened further by putting it inside a reinforced building or set of buildings, internal redundancy etc.

No reason this couldn't be put underground, except cost.

Customers will evaluate the risks. Thermal power plants are an easy target too, and oil and gas pipelines. And the oil tankers, according to the news of the last weeks. By the way, nobody cares about oil spills anymore. I guess all those ships were sailing empty /s

> So the question is, how much does it cost? The article is completely silent on this, as expected.

Honestly considering the design overall, I feel like one could make a single use science project version of this on a desk (i.e. aside from the CO2 recharging part) for under 200 bucks. 12oz CO2 tank, some sort of generator and whatever you need to spin it that is sealed, tubing, and a reclamation bag for the used CO2.

And IMO using CO2 makes the rest of the design cheaper; Blow off valves are relatively cheap for this scenario, especially because CO2 gas system pressures are fairly low, and there's plenty of existing infrastructure around the safety margin. And I think even with blow off valves this could be a 'closed' system with minimal losses (although that would admittedly add to the cost...)

I guess I'm saying is the main unknown is how expensive this regeneration system is for the quoted efficiency gains.

they do say

> Energy Dome expects its LDES solution to be 30 percent cheaper than lithium-ion.

The tanks to hold liquid CO2 will likely be a lot cheaper than compressed air tanks because the required pressure is much lower. But they are going to loose a lot of energy to cooling the gas and reheating the liquid. I would be surprised if the round-trip efficiency is higher than 25%.