<;P>;PROBLEM TO BE SOLVED: To surely reduce CO<;SB>;2<;/SB>;by collecting and isolating algae having absorbed CO<;SB>;2<;/SB>;. <;P>;SOLUTION: The algae 3 are stored in a reactor tank 2, CO<;SB>;2<;/SB>;from a thermal power plant 1 is supplied to the algae 3, which are irradiated with the sunlight to perform photosynthesis. The algae 3 having absorbed CO<;SB>;2<;/SB>;by the photosynthesis is isolated into an underground cavity 6 to isolate CO<;SB>;2<;/SB>;. <;P>;COPYRIGHT: (C)2011,JPO&INPIT