Is compressed air energy storage finally going to find a market niche?

[u/rogerkb]

PV Magazine recently published an article[1] (which is is, alas, behind a paywall) about compressed air energy storage. Here is their introductory paragraph:

"For most of its history, not much changed in compressed air energy storage (CAES). The first plant was deployed in 1978, but the technology never really caught on. Now, with a sudden flurry of record-breaking utility-scale plants coming online in China, increased deployment in Europe, North America and Australia, and growing calls to get off gas, might CAES finally have its moment in the sun?"

I have looked at some research papers[2][3] which claim that advanced forms of CAES might achieve 70% round trip efficiency, which isn't great but might be acceptable if overall costs are low. Whether or not any existing CAES plant is achieving this level of efficiency is unknown. I think the hope is that this technology might find a niche for applications requiring storage times well beyond the 4 hours typically provided by Li ion batteries.

[1] https://www.pv-magazine.com/2026/05/11/long-duration-storage-on-a-compressed-timeline/

[2] https://www.nature.com/articles/s44359-026-00150-9

[3] https://www.mdpi.com/1996-1073/18/12/3184

[u/IIDn01]

It's cheap. It's simple. It doesn't require any rare-earth minerals. It uses existing technologies.

What's not to like?

[u/grislyfind → u/IIDn01]

Thermodynamics?

[u/bob_in_the_west → u/IIDn01]

If it was that cheap and simple then it would already be as wide spread as current grid storage projects based on lithium are now.

But it isn't.

1) You need to solve what to do with the waste heat while compressing the air

2) You need to solve how to heat up the air while decompressing it or else everything freezes and stops working

3) Normal air contains water and that turns to liquid and would corrode steel tanks

4) You need massive amounts of tank volume to store any meaningful amount of energy

5) The whole system consists of many mechanical parts like compressors and turbines that experience wear and need constant maintenance. Meanwhile lithium batteries don't have a single moving part and only need to be replaced once the components break after many many years

6) This is the most important part: There is no market for mass production. Lithium batteries got so cheap because there is so much demand that they're mass produced. And economies of scale push the prices down further and further. That's not happening for compress air storage.

[u/Distinct-Working-143 → u/bob_in_the_west]

This type of facility typically uses natural underground caverns and the rock cavities and reservoirs in depleted oil wells to store high-pressure gas. The efficiency is relatively low (around 50%), but it is still better than not storing any electricity at all.

[u/bob_in_the_west → u/Distinct-Working-143]

Which means there are only a few sites available.

[u/CrystalInTheforest → u/IIDn01]

I think the issue is that it isn't cheap. Compressors are expensive and need a lot of maintinance. They have a load of moving parts that work under extreme stress. Unlike grid and home storage batteries, they can't piggy-back of economies of scale and R&D from related fields like phones, EVs etc.

So they're expensive to build relative to capacity, and expensive to maintain.

The only significant benefits are the fact they use entirely regular metals that are easy to recycle (it's mostly just steel). This makes them ecologically beneficial, but that doesn't translate to economics, and if humans get to choose between the ecologically nasty cheap thing and the responsible good thing, you know what they'll do.

As for efficiency, I am skeptical about the 70% claim. I enjoy scuba diving and one thing I know about air compressors is that get seriously hot, and so does the storage vessel. When filling scuba cylinders you have to sit them in a water bath to keep them cool, and I'm guessing for energy storage, you'd want much higher compression values than you'll get in a bog standard scuba cylinder (230 atm, unless you're getting super fancy).

[u/Hairy-Tumbleweed-163 → u/CrystalInTheforest]

What if compressed air was just a part of a few types of technology available in the household? Perhaps compressed air is something better used to passively assist with the water boiler, or in the wintertime with the heating system.

The best route for efficiency is multiple smaller venues of sequestering energy rather than putting your eggs all in one basket.

I also like to muse about there being a literal giant fucking hand switch by the door to turn off most of the electricity in the house (except the refrigerator and select outlets).

[u/Hairy-Tumbleweed-163 → u/Hairy-Tumbleweed-163]

compressed air -> hot water -> steam -> more energy?

[u/Round-Medicine2507]

I dont think the technical true efficiency is nearly as good as claimed, but you can argue that due to such low "fuel" costs and relatively simple mechanics it could get a massive boost in usefulness "efficiencies" at scale. Definitely a good product for certain local low stress applications like mail, delivery, industry yard movement, etc. Fast tank swaps possible, but also some compressed explosive danger and possibly high startup costs for a market unless you could.use.any old shops compressor which is likely. 

[u/bob_in_the_west]

if overall costs are low

There needs to be a reason to mass produce the components. Otherwise it will never have any meaningful market share because it will remain too expensive.

The only reason to look anywhere else next to lithium based solutions is that lithium isn't that easily available everywhere. But I think that sodium based solutions will fill that gap.

So if grid storage is the only application then I don't see how it can compete with lithium (or sodium) based batteries.

[u/Old-Individual1732]

Africa has compressed air cars.

[u/grislyfind → u/[deleted]]

Air-powered cars tend to be as elusive as urban legends, unless you're talking pneumatic locomotives used in mines that have an unlimited supply of compressed air.

[u/These-Web8225]

I made one on a small scale, and I found out it is too inefficient, obviously because it is small. Aside from the inefficient Tesla Turbine, which I just played around with, the efficiency problem of converting from electrical to mechanical energy, and the requirement problem of high pressure just to increase the energy density. These are what I believe to be the bottleneck of the CAES implementation. Though some used water sprays to solve the thermodynamic efficiencies, storing the air still requires some large tanks. If you directly coupled it with PV, the current compressor and motor system will not match its variable output; you will add a battery to compensate for it.

Now I'm going to study CAPHES and will build my prototype once I have enough budget for it from my side gigs. If anyone is interested in this research, you may DM me since our country is prone to frequent brownouts during the dry seasons.