Impacts of Future Energy Transition on the U.S. Air Quality: Projections of Emissions and Air Quality in 2050Kai Wang1, Yang Zhang1, Shen Wang2, Benjamin Hobbs2, Hugh Ellis2, Emily Fisher2, Ken Gillingham3, and Michelle Bell3
1Department of Civil and Environmental Engineering, Northeastern University, Boston, MA
2Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, MD
3School of Environment, Yale University, New Haven, CT
Understanding impacts of emission changes--especially those caused by the ongoing energy transition--on future air quality and human health is challenging due to the complex interactions among population and economic growth, energy demand, air pollution, and climate change. In this study, emission change factors (ECFs) of major air pollutants for energy-related sectors such as power plants, industrial, commercial, and residential, etc. are used in conjunction with the Sparse Matrix Operator Kernel Emissions model to project future emissions. The ECFs are generated through the downscaling approach based on the year 2050 projections from the National Energy Modeling System under a set of energy transition scenarios representing different drivers and shifts in the energy production/consumption in the future. The scenarios examined include a reference scenario without the clean power plan (refnocpp), a scenario with “abundant natural gas” (highNG), a scenario with “high electric vehicles penetration” (highEV), a scenario with “port electrification” (port), and a scenario with “high building energy efficiency” (highEE). Multiple 5-year (2008-2012) simulations using the Weather Research and Forecasting model with Chemistry (WRF/Chem) are carried out over the U.S. at a horizontal grid resolution of 36-km using current-year emissions based on the National Emission Inventory 2011 and projected future emissions in 2050. Our objectives are to 1) examine the emission changes for key air pollutants between future and past years under various energy transition scenarios, and 2) quantify the impacts of those emission changes on future air quality and human health. The preliminary results show large wide-spread reductions of CO, NOx, SO2, and primary PM2.5 emissions (~ 40-60% for gases and ~20% for aerosols) over the U.S. in 2050 for all scenarios, mainly due to coal power plants retirement and electric vehicles penetration, but much smaller reduction (~10%) for VOCs because the increases of their emissions from natural gas/oil production over source regions such as TX, PA, OH, and KY offset the decreases caused by power plant, industry, and transportation over the rest of domain. WRF/Chem predicts wide-spread domain-mean and maximum reductions of max 8hr O3 by < 2.0 ppb (~3.0%) and up to 8 ppb (~15%), respectively, and those for PM2.5 are by < 1.0 ug m-3 (~10%) and up to 6 ug m-3 (~50%), respectively, for all scenarios. The highEE scenario shows the largest reduction over the U.S. These reductions indicate the important impacts of energy transition on future air quality. The benefits of reduced air pollution on human health and economy under different scenarios will be further assessed in our future work.