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Comment by Uhrheber | Hacker News Reader

When compressing air, a lot of heat is generated, and in most cases wasted. When the air is released, it cools down, and has to take heat from the surroundings. Which doesn't work very fast without additional heat exchangers, and especially not in cold environments. Compressed air storage is only efficient with additional heat storage, which is something that promoters of compressed air storage often "forget" to tell you.

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They didn't forget - it's addressed in detail. They are advocating "small scale"

The low efficiency is mainly since air heats up during compression. This waste heat, which holds a large share of the energy input, is dumped into the atmosphere. A related problem is that air cools down when it is decompressed, lowering electricity production and possibly freezing the water vapour in the air. To avoid this, large-scale CAES plants heat the air prior to expansion using natural gas fuel, which further deteriorates the system efficiency and makes renewable energy storage dependent on fossil fuels.

Going "small scale" does not solve the heat problem unfortunately. If it does then the authors did not mention it. All they mentioned is how large scale plants deal with the problem.

Come on dude...

Small-scale compressed air energy storage systems with high air pressures turn the inefficiency of compression and expansion into an advantage. While large-scale AA-CAES aims to recover the heat of compression with the aim of maximizing electricity production, these small-scale systems take advantage of the temperature differences to allow trigeneration of electrical, heating and cooling power.

And then also goes in to detail about small scale iso-thermal setups that have negligible thermal losses. Apparently "author did not mention" actually means "I did not read the article".

Did you read the article? All of that is in like the first paragraph.

What the parent said was still useful I think to people who might not know this particular trope throughout the industry.

I wonder how well it would work to have a compressed air storage system where the tank is in a loop with a solar water heating system. The heat from the loop could be used to provide heated water, or maybe drive something like a Stirling engine. You could use the output of the Stirling engine to compress a bit more air using the waste heat.

They talk about this in the middle bit. Some high pressure small scale systems report 70% efficiency when used for heating + refrigeration + electricity, even though the electricity part is only ~11% efficient.

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