Liquidmetal Technologies Inc (LQMT)

[vyper4]

When the compressed air expanded it would become cold, icing would become an issue is cooler climates. While on the surface this technology sounds good I think it lacks a practical application. Also you have the efficiency of the engry conversion to consider. Electrolysis for fuel cells can in theory be as high as 90%. I don't think you will get anywhere close with a mechanical air compressor.