Impact assessment of new electric generating units on urban air quality in Central and South Texas

Negative health effects are expected from large quantifies of harmful pollutants that will be emitted by new electric generating units (EGUs) into the atmosphere. This research focused on evaluating the impact of seven new EGUs, located in Central and South Texas, on the urban air quality using air quality models. Dispersion modeling simulations showed that large new sources may contribute high hourly concentrations of NOx, SO2 and PM10 near the source during episodes that observed high pollutant concentrations. The natural gas fueled EGUs were observed to have least impact on the primary pollutants in Corpus Christi. Furthermore, the study showed insignificant contribution to the annual average concentrations of NO x, SO2 and PM10 compared with the observed annual averages in the CAMS sites. Also, the simulated annual deposition fluxes for NOx and SO2 were higher than the recommended threshold value of 0.001 g/m2/year, which may cause significant impact on the ecosystem.Contribution of NOx emissions from power plants to the formation of harmful ground level ozone is also a major concern. Studies showed ozone formation at far downwind of power plants and titration of ozone near them. This non-linear behavior of ozone formation engenders the need to determine the response of ozone formation to the new EGUs and control technologies. A photochemical model was used to study the potential impact of the new EGUs on urban ozone levels. A maximum increase of 2.75 ppb in the peak 8-hour ozone concentrations was simulated due to the addition of the new sources. Modeling demonstrated a nominal effect on ground level ozone concentrations due to the natural gas fueled EGUs in Corpus Christi. Ozone production efficiency per NOx was observed to be higher for power plants in Victoria than in Corpus Christi and San Antonio. The photochemical model was also employed for sensitivity analysis of ozone formation to different feasible NO x control technologies in the EGUs. The sensitivity analysis established selective catalytic reduction as the most effective NOx control technology for ozone reduction.