a UK company got $10M to build it, see here http://www.greentechmedia.com/articles/read/liquid-air-for-utility-scale-energy-storage/ . Can this be at least hypothetically feasible or is it more like pure quackery for stupid investors? ETA: to clarify, I don't doubt that it would "work" the same way as thermoelectric generator "works". The question is about the reasonableness of this kind of thermal machine as an efficient energy storage. Are air liquefaction machines sufficiently efficient nowadays that you can lose some energy on liquefaction, then lose some more energy on the limitations of the heat engine and still output big enough percentage of energy input to make it a meaningful grid storage technology?