I run a consulting practice around flexibility. Been around the energy space for 15 years. Boy if I had a dollar for every time I've heard "grid scale [x] will soon be everywhere"
this post was submitted on 22 Dec 2025
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It came from a gas supplier....
Where do you think supplier got it from?
Also: WHERE ARE THE ROUNDTRIP EFFICIENCY NUMBERS???
This CO2 is acting as a reusable fluid in a closed loop. The initial capture of the CO2 costs energy, but the battery keeps using the same CO2 over and over again. So the question of efficiency should be more about land usage and maintenance of the rest of the parts and the labor needed for each megawatt stored vs what other grid scale energy storage costs in materials and labor.
The rough reality is that batteries aren't going to be up to the task of grid scale energy storage unless they have a couple huge breakthroughs. Something like this is a far less materially expensive way to store energy for later use.
Currently most grid scale energy storage is just pumping water up a hill and letting it back down through a generator. It is extremely limited in where it can be used and requires tremendous space to be effective.
Compressing gas generates heat, and a significant part of that heat will be lost. Heat dissipation is irreversible, and this lowers efficiency a lot.
BTW the same reason why in industry, pneumatic drives are universally replaced by electric motors: Their efficiency is too low.
There is a thermal energy storage included as s major part. This works because compressing CO2 to 55atm adiabatically heats it up to some 450-ish C, so that heat is pretty high grade, and only the final stage cools it down with heat exchanger open to air. In discharging direction, some heat is taken from outside air to evaporate part of CO2 and heat stored is used up
The number of decommissioned but still usable batteries are growing fast though, and plenty of storage sites use old battery packs, both from cars and home energy storage and stuff like it
Sure wish they mentioned the effeciency.
Could be very high, even the waste heat from the compression could be used to achieve more compression and turbines get to above 90%, that all depends on the scales they're building this at. 70% overall doesn't seem unrealistic as an educated guess.
On their website (energydome.com) they claim “75%+” round trip efficiency, so not a bad guess!
That’s a hell of a lot better than most other systems. If true, and if scalable, this is a huge innovation.
compressors, turbines (like steam turbines), piping, some of which heat-resistant (500C), container for liquid carbon dioxide, lots of plastic for the bubble, something for thermal storage, dry and clean carbon dioxide, these aren't unusual or restricted resources, don't depend on critical raw materials or anything like that
Compressed air without heat recovery is more like 30%, so this is huge
Carbon dioxide can be liquefied relatively easily which is what i guess makes this efficient
I was just about to bang out that they must lose a lot of heat from the compression. But apparently not! That’s amazing.
I’m struggling to think of systems that would significantly outperform “75%+”. Chilled superconducting coils? Those are expensive, and would fail rather catastrophically.
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Sure wish they mentioned the effeciency.
Without it you should dismiss the whole article as worthless garbage
We had these things called Gasometers in the UK for a long time. They expanded with the amount of gas stored in them, and they kept the pressure of the local gas supply up. A local gas reservoir, or "gas battery" if you like.
These bubbles are basically the same idea but at higher pressure.
It's still near atmospheric pressure. Liquid CO2 expanding is powering the gas turbines.
Ah the bubble is the expansion volume. Not the storage volume... got it. I had it backwards.
So yes, very similar then.
I imagine that the bubble portion is light weight enough, one could put it on the roof of a data center, apartment building, strip mall, etc. That appears to be the piece that takes up the most space.
Another thought. I wonder if the bubble portion could be oriented vertically, maybe inside a simple enclosure to protect it from wind.
I wonder how resilient they are to big winds.
Also from the article:
If the worst happens and the dome is punctured, 2,000 tonnes of CO2 will enter the atmosphere. That’s equivalent to the emissions of about 15 round-trip flights between New York and London on a Boeing 777. “It’s negligible compared to the emissions of a coal plant,” Spadacini says. People will also need to stay back 70 meters or more until the air clears, he says.
160km/hr as per TFA.
Guilty, I only skimmed it. Thanks.
And if there is a known high wind coming, the plant can forcefully go through the compression cycle to remove the bubble.
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The article also mentions that they can deflate it in around 10 hours
Sounds pretty good
Wonder how small you can scale these and retain efficiency, at twice the footprint (but I'm guessing a lot more volume) of a lithium grid battery, will we see these replacing home batteries down the line?
They are talking hectares in this and it looks like the power density is below that of batteries, but its also cheaper per MWh.
I home long term battery makes a lot of sense, I have thought for a while something that goes from water and the air into methane or even liquid fuel would be highly beneficial as it could run from a generators through the winter and act for long term storage without requiring a turbine.
The tanks might go underground mitigating (perhaps) the pressure explosion risk as opposed to lithium fire risk, but the honking great tent is an issue. Should have a longer life than Li Ion and be repairable vs somewhat recyclable. At scaled production it could certainly be cheaper, but some of the newer immobile battery chemistries might beat it. Synthesized fuel also makes a lot of sense. We shall see. What certainly makes sense is microgrids and power self-sufficiency.
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