the co 2 4 a steam generator is employed to provide steam to a turbine which generates mechanical work to run the densification compressor or to run the compressor of a compression refrigeration cycle unit that provides cold refrigerant to liquefy or solidify the co 2 5 a small shape memory alloy engine or compressor utilizes the waste heat to change the shape of an alloy such as cusn inti tini and mncu and generates mechanical work that is used to increase the density of the captured co 2 the engine compressor works by having a hot side and a cool side of the alloy to generate the compression needed the following patents describe heat engines based on these types of unusual alloys u s pat no 3 913 326 u s pat no 4 055 955 u s pat no 5 442 914 u s pat no 7 444 812 and published application 2009 0315489 the disclosures of these patent documents are incorporated herein by reference 6 single or multiple heat recovery systems are installed on the exhaust gas and coolant systems 7 single or multiple heat recovery systems are installed to generate the required power and effectively reduce the temperature of the exhaust gases and thereby reduce the downstream energy required to compress liquefy and or solidify the co 2 in a further embodiment of the present invention a portion of the co 2 that is recovered after regeneration of the capture agent is returned via a suitable.