Impact of Changes in Electric Generation on Air Quality in Northern New Jersey Modeling of short-term NO_2 and PM_(2.5) emissions

摘要

In recent years the mix of fossil-fuel electric generating facilities in New Jersey has changed substantially. Driven by cheap shale gas, as well as regulatory initiatives, coal-fired plants and aged peaking combustion turbines have retired, as state-of-the-art gas-burning single and combined cycle generators have come online. Here we demonstrate, using dispersion modeling of short-term facility emissions, that this has had a significant short-term benefit on ambient NO_2 and PM_(2.5) concentrations. Worst case emissions for 17 facilities in and near a 5-county region of northern New Jersey, were evaluated using available emission data from 2005 and 2015, with estimates drawn from known trends for 2025. Both 1-hour NO_2 and 24-hour PM_(2.5) maximum predicted concentrations, (the 98th percentile values are the equivalent to the National Ambient Air Quality Standards NAAQS), were assessed for the region in each of the three years, using the USEPA's latest AERMOD dispersion model. Concentrations of both NO_2 and PM_(2.5) decreased dramatically through the study period, even as new electric generating units (EGUs) were added to replace those which were retired. Emissions were also impacted by the changes in fuel mix through the period which saw the elimination of coal as fuel for electrical generation in the study region. While oil continues as a secondary fuel for some units, its current usage is essentially zero. For estimated emissions in 2025, projected but not yet built units were given the characteristics of the most recently constructed state-of-the-art combined cycle EGUs in New Jersey. Modeling results showed potential exceedances of currently existing standards for both NO_2 and PM_(2.5) in 2005, in subsequent years modeled concentration were generally well under the (NAAQS).