Spotlight on how natural gas heavy-duty vehicles can help California meet clean air goals
California has the most stringent air quality and climate protection policies in the nation. Nonetheless, the state is not on track to meet smog reduction requirements and will have to generate greenhouse gas (GHG) emission reductions earlier than currently projected to maximize the benefit of GHG reductions on global climate change. Although California is working to harmonize its air quality and climate protection planning, policymakers face significant challenges in their efforts to devise a “pathway” that can simultaneously help the state achieve NOx and GHG reduction targets. Compared to the 2010 “Business as Usual” scenario — which includes all adopted emission control measures for the South Coast — NOx levels must be reduced by 65 percent and by 75 percent to meet the 2023 and 2032 ozone standards, respectively. An 80 percent reduction of GHG emissions is targeted for 2050, relative to 1990 levels.
Heavy-duty diesel trucks are the largest contributors to the nitrogen oxide (NOx) inventories of the South Coast and San Joaquin Valley ozone non-attainment areas. They are also major producers of toxic air contaminants and GHGs. In order to meet federal deadlines for attainment of ozone and fine particulate matter (PM2.5) standards, these regions must expeditiously phase in heavy-duty vehicles (HDVs) that emit at, or below, the equivalent of “zero-emission” battery-electric vehicles when accounting for pollution from base load electricity generation. This constitutes a NOx reduction of approximately 90 percent below the current federal heavy-duty engine standard of 0.2 grams per brake horsepower-hour (g/bhp-hr).
Heavy-duty natural gas engines are well along the path to achieve a 90 percent NOx reduction from the existing heavy-duty engine NOx standard while also becoming increasingly fuel-efficient to reduce GHG emissions. Widespread deployment of these near-zero and power plant emission-equivalent heavy-duty natural gas vehicles (NGVs) are needed to meet tough air quality and climate protection goals. To realize these benefits, supportive public policies and public-private partnerships are needed that continue to encourage the development, demonstration, and deployment of critical natural gas-fueled heavy-duty vehicle technologies.
