a cryogenic air separation unit is used to separate carbon dioxide from a flue gas stream . the temperature and pressure of the carbon dioxide are controlled so that the separated carbon dioxide coming from the cryogenic air separation unit is in a liquid phase . the liquid phase carbon dioxide is converted to carbon monoxide by safely reacting the carbon dioxide with carbon at high temperature in a plasma arc reactor . the carbon monoxide produced by this reaction has sufficient energy potential to be used as a fuel .