CO2 separation system for installation in vehicle using internal combustion engine as power source

A CO2 separation method using a system for installation in a vehicle using an internal combustion engine as a power source, the system comprising the internal combustion engine, a first CO2 separation device comprising a CO2 permeable membrane separating a CO2 supply side and a CO2 permeation side, a first CO2 supply side introduction flow path for introducing exhaust gas generated by the internal combustion engine to the CO2 supply side of the first CO2 separation device, a first CO2 permeation side introduction flow path for introducing air from outside the vehicle to the CO2 permeation side of the first CO2 separation device, and a first decompression pump for decompressing the CO2 permeation side of the first CO2 separation device, the method comprising performing:

• (A) when the internal combustion engine is operating and the vehicle is travelling, a first mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO2 supply side of the first CO2 separation device via the first CO2 supply side introduction flow path, and air from outside the vehicle is introduced to the CO2 permeation side of the first CO2 separation device via the first CO2 permeation side introduction flow path using travelling wind, whereby CO2 in the exhaust gas selectively permeates from the CO2 supply side to the CO2 permeation side of the first CO2 separation device through the CO2 permeable membrane of the first CO2 separation device, using a first difference in CO2 partial pressure between the CO2 supply side and the CO2 permeation side of the first CO2 separation device as a first driving force, and
• (B) when the internal combustion engine is operating and the vehicle is stopped, a second mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO2 supply side of the first CO2 separation device via the first CO2 supply side introduction flow path and the CO2 permeation side of the first CO2 separation device is decompressed by the first decompression pump, whereby CO2 in the exhaust gas selectively permeates from the CO2 supply side to the CO2 permeation side of the first CO2 separation device through the CO2 permeable membrane of the first CO2 separation device, using a second difference in CO2 partial pressure between the CO2 supply side and the CO2 permeation side of the first CO2 separation device as a second driving force.