an improved process for the separation of carbon dioxide from the flue gas of an oxy - combustion power plant is provided . the flue gas is compressed , cleaned , cooled and dried . this clean , compressed dry flue gas is then further cooled , partially condensed and separated into liquid and vapor streams . the liquid streams , which contain a high concentration of carbon dioxide , are vaporized , compressed and exported to an end user . the vapor streams are heated and expanded , in order to extract useable energy . at least two expanders are used to extract this energy , with an intermediate warming step .