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

Abstract

Abstract. The California Regional Multisector Air Quality Emissions (CA-REMARQUE) model is developed to predict changes to criteria pollutant emissions inventories in California in response to sophisticated emissions control programs implemented to achieve deep greenhouse gas (GHG) emissions reductions. Two scenarios 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 model to optimize costs across the entire California economy and so they include changes in activity, fuels, and technology across economic sectors. Separate algorithms are developed to estimate emissions of criteria pollutants (or their precursors) that are consistent with the future GHG scenarios for the following economic sectors: (i) on-road, (ii) rail and off-road, (iii) marine and aviation, (iv) residential and commercial, (v) electricity generation, and (vi) biorefineries. Properly accounting for new technologies involving electrification, biofuels, and hydrogen plays a central role in these calculations. Critically, criteria pollutant emissions do not decrease uniformly across all sectors of the economy. Emissions of certain criteria pollutants (or their precursors) increase in some sectors as part of the overall optimization within each of the scenarios. This produces nonuniform changes to criteria pollutant emissions in close proximity to heavily populated regions when viewed at 4 km spatial resolution with implications for exposure to air pollution for those populations. As a further complication, changing fuels and technology also modify the composition of reactive organic gas emissions and the size and composition of particulate matter emissions. This is most notably apparent through a comparison of emissions reductions for different size fractions of primary particulate matter. Primary PM2.5 emissions decrease by 4 % in the GHG-Step scenario vs. the BAU scenario while corresponding primary PM0.1 emissions decrease by 36 %. Ultrafine particles (PM0.1) are an emerging pollutant of concern expected to impact public health in future scenarios. The complexity of this situation illustrates the need for realistic treatment of criteria pollutant emissions inventories linked to GHG emissions policies designed for fully developed countries and states with strict existing environmental regulations.

Effects of Low‐Carbon Energy Adoption on Airborne Particulate Matter Concentrations With Feedbacks to Future Climate Over California

“…The altered marine emissions increase surface PM 2.5 EC by as much as +0.62 μg m −3 (Figure 2d), surface PM 2.5 sulfate by +0.29 (Figure 2j), surface PM 2.5 OC by +0.13 μg m −3 (Figure 2f), and surface PM 2.5 nitrate by +0.04 μg m −3 (Figure 2h) over the shipping lanes. Increased use of biofuels over land is an economically optimal way to use the limited quantity of biofuels for maximum GHG emissions reductions in the GHG‐Step scenario (Zapata et al, 2018a, 2018b).…”

“…The majority of the surface PM 2.5 mass reduction at the Port of LA was associated with EC (Figure 2d), primary OC (Figure 2f), and sulfate (SO 4 2− ) (Figure 2j), which reflects reductions in PM emissions from direct combustion. Switching to the GHG‐Step scenario increased surface PM 2.5 mass concentrations over the ocean by as much as +0.95 μg m −3 (Figure 2b) due to increased demand for biofuels over land leading to the consumption of more traditional marine diesel fuels over the ocean (Zapata et al, 2018a). The altered marine emissions increase surface PM 2.5 EC by as much as +0.62 μg m −3 (Figure 2d), surface PM 2.5 sulfate by +0.29 (Figure 2j), surface PM 2.5 OC by +0.13 μg m −3 (Figure 2f), and surface PM 2.5 nitrate by +0.04 μg m −3 (Figure 2h) over the shipping lanes.…”

“…PM 2.5 emissions decrease by ~30%, and NOx emissions decrease by ~15% in the BAU scenario in comparison to the 2010 basecase. Emissions under the GHG‐Step scenario are further decreased due to the policies and technologies needed to achieve deep GHG reductions (Zapata et al, 2018a). Table 1 lists California‐wide emissions of CO, NO x , SO x , VOC, NH 3 , and PM under the 2050 BAU and GHG‐Step scenarios.…”

“…in order to optimize the overall GHG emissions across the state. Zapata et al (2018a) provide further comparisons between the BAU and GHG‐Step scenarios.…”

“…The purpose of this paper is to quantify the potential change in regional climate forcing over California associated with regional reductions in SLCP concentrations. Airborne particulate matter (PM) concentrations in 2050 are predicted under two California emissions scenarios: a Business‐as‐Usual (BAU) scenario based on existing rules and regulations and a climate‐friendly GHG reduction scenario (GHG‐Step) designed to meet California's goals of an 80% reduction in GHG emissions relative to 1990 levels (Zapata et al, 2018a). The GHG‐Step scenario directly targets LLCP emissions, but the fuels and technologies adopted also significantly reduce SLCP emissions.…”