Agricultural productivity and yield have been increasing for many decades. This is because the food requirement for the ever-growing population of the world have been increasing. The good news for us is that elevated carbon dioxide (CO2) levels increase fruit and vegetable productivity by promoting photosynthesis. Therefore, positive effects of CO2 on agriculture give great concerns for many researchers and agricultural organization. The combustion of all carbon-based fuels, such as methane (natural gas), petroleum distillates and coal produces carbon dioxide. The high purity and concentration of CO2 for the agricultural application does not required, the use of CO2 in the exhaust gas is green technology for us. However, the low removal efficiency and the high cost for the toxic NOx elimination from the exhaust gas are recognized as a major problem. In this study, to overcome this problem, we developed a NO oxidation catalyst to diminish ozone consumption. 45–55% of NO in the exhaust gas can be converted to water soluble NO2 using zeolite as a catalyst (ZSM-type zeolite). When NOx concentration of inlet gas was 790 ppm (NO was 670 ppm) and total flow rate was 6 dm3·min‒1, NO oxidation ratio was 0.564. A high NO oxidation ratio was observed in 1.5 s of mean residence time. Under optimum condition, the complete removal of NOx from combustion exhaust gas was studied on Kikugawa biogas power plant and Bell Farm. Using an ozone generator, remaining NO was completely converted to NO2. NOx in exhausted gas decreased in 10ppm by flat glass-fiber filter NOx absorption equipment. Reducing the outlet NOx concentration to 10 ppm or less, and verified the durability of the oxidation reaction in the NO oxidation catalyst layer for about two years were achieved.