As I have mentioned before several different companies are developing near isothermal gas compression systems which inject water vapor into the compression chamber in order to remove heat from the compressed gas. I have recently read about another company called Carnot Compression which has developed an isothermal gas compressor which injects gas into water. The compression fluid is a gas/water emulsion (i.e. a mixture of gas bubbles in water matrix). The emulsion is contained inside a spinning cylindrical chamber where the gas bubbles are compressed as they migrate to the outer surface of the cylinder. The water absorbs the heat generated in the gas by compression which the compression nearly isothermal. Exactly how the gas gets out of the rotating compressor chamber into the pressure vessel is not clear from the limited description given on Carnot's web site. Apparently only gas gets out and not water, since Carnot claims that the compressed gas is very dry and does not require further drying steps as do other varieties of gas compressor.
I am not really sure how this technology differs from that of a company called Oscomp which has also developed a multiphase (i.e. water + gas) rotary compressor. Oscomp claim that their compressor can achieve 60 compression ration in a single stage while Carnot claims that they can theoretically achieve a 200 to 1 compression ratio. I assume that the use of the word theoretical in this claim implies that the real world implementation of this technology will not actually reach this compression ratio.
In discussing possible applications of their compressor Carnot does mention energy storage, although this use is at the bottom of their list. Carnot's view is that they have developed an efficient, low energy use, low cost gas compressor which is suitable for a wide variety of existing applications, so they are chasing obvious markets and obvious money making opportunities. If a compressed air energy storage market comes into existence they will be positioned to support it, but they themselves are not pursuing this rather risky business opportunity.
As far as I can tell their compressor is not reversible, so that a compressed air energy storage system based on their technology might require a separate expander stage, which might be a disadvantage compared to the technology of energy storage companies like Lightsail Energy and SustainX. Nevertheless, Carnot's technology is new in the field of gas compression and could conceivably play a role in commercializing compressed air energy storage.
This article was originally posted on www.energystoragenews.com on Jan 30, 2015