California Air Resources Board

Principal Investigator/Author(s): Christopher Sharp

Contractor: Southwest Research Institute

Contract Number: 18RD006

Project Status: Completed

Relevant CARB Programs: Air Pollution, Heavy-Duty Low NOx

Topic Areas: Reduced NOx Standards

Research Summary:

Given the ongoing air quality challenges in California, there has been significant interest extending the efforts of recent on-highway Low NOX technology demonstration efforts into the Off-road sector. Off-road engines account for 11 percent of statewide NOX emissions and 29 percent of statewide diesel PM emissions. This project, and subsequent demonstrations of Low NOX technology focusing on the Off-road sector, is intended to provide important technical support for the promulgation of more stringent standards to reduce NOX and PM emissions from these engines with relatively little impact on CO2 emissions, or potentially to leverage additional engine technology to pursue both NOX and CO2 reduction, albeit at higher system cost and complexity levels. The program efforts detailed in this report include gathering off-road market information, detailed baseline testing of Tier 4 engines, and modeling efforts to examine potential approaches to reaching NOX levels up to 90 percent below the current Tier 4 standards, and PM levels 75 percent below the current Tier 4 standards. These efforts include examination of engines under lower load conditions than are currently regulated under the Tier 4 standards. It is anticipated that at least one of the engines used in this program could be carried forward into a future planned Off-road Low NOX technology demonstration.

Keywords: low NOx, off-road diesel, particulate matter, PM, low emission, heavy duty vehicle, tier 4 standards