Evaluating Technologies and Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty Vehicles
This page last reviewed December 23, 2013
The recently introduced 2010 emission standards for heavy-duty engines have established a limit for oxides of nitrogen (NOx) emissions of 0.20 g/bhp-hr, a 90% reduction from the previous emission standards. However, it is projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with the 2010 emission standards, the upcoming National Ambient Air Quality Standards (NAAQS) requirements for ambient particulate matter and ozone will not be achieved in California without further significant reductions in NOx emissions from the heavy vehicle fleet. There is currently little incentive for manufacturers to pursue emission reductions beyond the current standards, and so the potential for further reductions is unclear. To address this lack of information, ARB is funding a research program for the next three years (2013-2016) to explore and investigate the feasibility of reducing NOx emissions to levels significantly lower than the levels required by existing standards.
The proposed study will investigate the feasibility of achieving NOx emissions lower than the current engine standard by evaluating enhanced aftertreatment technology choices, aftertreatment configurations, catalyst optimizations, urea dosing strategies, engine tuning, and engine management practices for two heavy-duty engines: one natural gas engine with three-way catalyst (TWC), and one diesel engine with selective catalytic reduction (SCR). The target NOx emission rate for this project is 0.02 g/bhp-hr, which is a 90 percent reduction from the current standard.