Estimating criteria pollutant emissions using the California Regional Multisector Air Quality Emissions (CA-REMARQUE) model v1.0

摘要

The California Regional Multisector Air Quality Emissions (CA-REMARQUE) modelis developed to predict changes to criteria pollutant emissions inventoriesin California in response to sophisticated emissions control programsimplemented to achieve deep greenhouse gas (GHG) emissions reductions. Twoscenarios for the year 2050 act as the starting point for calculations:a business-as-usual (BAU) scenario and an 80 % GHG reduction (GHG-Step)scenario. Each of these scenarios was developed with an energy economic modelto optimize costs across the entire California economy and so they includechanges in activity, fuels, and technology across economic sectors. Separatealgorithms are developed to estimate emissions of criteria pollutants (ortheir precursors) that are consistent with the future GHG scenarios for thefollowing economic sectors: (i) on-road, (ii) rail and off-road, (iii) marineand aviation, (iv) residential and commercial, (v) electricity generation,and (vi) biorefineries. Properly accounting for new technologies involvingelectrification, biofuels, and hydrogen plays a central role in thesecalculations. Critically, criteria pollutant emissions do not decreaseuniformly across all sectors of the economy. Emissions of certain criteriapollutants (or their precursors) increase in some sectors as part of theoverall optimization within each of the scenarios. This produces nonuniformchanges to criteria pollutant emissions in close proximity to heavilypopulated regions when viewed at 4 km spatial resolution withimplications for exposure to air pollution for those populations. Asa further complication, changing fuels and technology also modify thecomposition of reactive organic gas emissions and the size and composition ofparticulate matter emissions. This is most notably apparent througha comparison of emissions reductions for different size fractions of primaryparticulate matter. Primary PM2.5 emissions decrease by 4 % inthe GHG-Step scenario vs. the BAU scenario while corresponding primaryPM0.1 emissions decrease by 36 %. Ultrafineparticles (PM0.1) are an emerging pollutant of concern expected toimpact public health in future scenarios. The complexity of this situationillustrates the need for realistic treatment of criteria pollutant emissionsinventories linked to GHG emissions policies designed for fully developedcountries and states with strict existing environmental regulations.