A method and system are described for on-board treatment of an exhaust stream containing CO2 emitted by a hydrocarbon-fueled internal combustion engine (ICE) used to power a vehicle in order to reduce the amount of CO2 discharged into the atmosphere which include: a. a first waste heat recovery zone on board the vehicle for receiving the high temperature exhaust gas stream, at least one heat exchanger having an inlet for receiving the hot exhaust gas stream from the ICE for passage in heat exchange relation and a discharge outlet for discharging the exhaust stream at a lower temperature, the heat recovery zone further including at least one heat recovery device for converting the waste heat from the exhaust gas to electrical and/or mechanical energy; b. a membrane separation zone in fluid communication with the exhaust gas stream discharge outlet from the waste heat recovery zone, the membrane separation zone including a membrane module having a permeate side to which CO2 permeates and a retentate side that i
