A method for pest control in a confined space using flue gas from a biomass power plant. The method includes: treating flue gas from a biomass power plant to yield treated flue gas having a volume concentration of carbon dioxide exceeding 85 volume %, and conducting pest control in a confined space according to the following steps: continuously aerating the confined space with the treated flue gas during a fallow period to allow a gas pressure in the confined space to reach between 0.110 and 0.140 megapascal of absolute pressure and the volume concentration of carbon dioxide in the confined space to reach between 50 and 90 volume %.