The EpiQair engine delivers power from a cryogenic air cycle energised by renewable wind and solar energy with storage and regeneration in a system capable of replacing all terrestrial power technologies depending on fossil carbon combustion. The key to its secret lies in the expansion during phase change when air boils and passes from liquid to gas state. This produces pressure analogous to steam engines which powered trains and ships for 100 years. It introduces a new era of zero carbon engines with scalability to meet all requirements for industrial, domestic power and heat and all terrestrial and marine transport applications. The energy is stored in 2 forms, cold as liquid air and heat from compression during liquefaction. The engine converts supercritical air from warmed liquid air to shaft power in an isothermal expansion process which makes best use of the stored heat. The result is compact rotary engines with power density greater than internal combustion engines.