Membrane preconcentration of carbon dioxide from exhaust gas sources

A process of preconcentrating CO2 in an exhaust gas stream, comprising:

• flowing all the exhaust gas stream from an exhaust gas source to a CO2 preconcentration system;
• and
• within the CO2 preconcentration system, feeding at least a portion of the exhaust gas stream to a membrane separation module comprising a polymeric membrane that has a perm-selectivity for CO2 over N2 and O2, to produce a CO2 rich exhaust gas at a permeate side of the membrane separation module and a CO2 lean gas at a retentate side of the membrane separation module;
• driving separation at the membrane separation module using a vacuum pump of the CO2 preconcentration system on the permeate side, wherein the CO2 rich exhaust gas from the permeate side is sent directly to the vacuum pump to produce a preconcentrated exhaust gas;
• and
• wherein the exhaust gas stream has a CO2 concentration as low as 400 ppm CO2, the CO2 rich exhaust gas has a CO2 concentration of up to 20 vol. % CO2, and wherein the preconcentrated exhaust gas has a CO2 concentration corresponding to an exhaust gas CO2 concentration at which another CO2 treatment system connected to the CO2 preconcentration system is optimal or otherwise particularly suited.