2020 Volume 19 Issue 4 Pages 317-326
After a big earthquake and subsequent accidents at Fukushima Dai-ichi Nuclear Power Plant (NPP) in March 2011, the NPPs in Japan have been shutdown, and the power shortage has been compensated by Thermal Power Plants (TPPs). Such changes in the power generation mix would have affected air quality in the Osaka area. In this study, we estimated the change in the emission amount of pollutants from TPPs and evaluated the influence on photochemical ozone under typical midsummer conditions using a numerical model. By the shutdown of NPPs, NOx emitted from general electricity utilities became about two times larger in Kansai, Hokuriku and Shikoku areas. By the TPPs substitution photochemical ozone decreased in the middle of the Osaka plain and increased in the surrounding areas. This tendency is consistent with the photochemical regime we previously estimated. Observation showed similar result; however, the changes in ozone concentration were much larger than our model results possibly due to VOC reduction from other sources. The increase of TPP emission does not influence strongly on the photochemical ozone in the objective area. It is much more important to discuss it from the viewpoint of global warming.
