Diesel Fuel-Fired Heater Emissions from a Battery Electric Transit Bus in Real-World Conditions 2024-01-5011

Battery electric transit buses sold in Canada generally include a fuel-fired diesel auxiliary heater for cabin heating in cold weather. This report details a test project, performed in collaboration with OC Transpo, to capture and quantify the emissions from such a fuel-fired heater (FFH) installed on a New Flyer XE40 battery electric transit bus from OC Transpo’s fleet in Ottawa, Canada. The FFH was tested while the bus was both stationary and being driven on-road in cold conditions. The results include the emissions rates of carbon dioxide, carbon monoxide, nitrogen oxides, hydrocarbons and methane, and soot. Additionally, total particulate matter results were obtained during stationary testing. The results of stationary testing were compared to the California Air Resources Board and European Union standards for FFH emissions, even though these standards do not apply directly to buses operated outside of these jurisdictions. During stationary testing, average emissions of carbon monoxide and non-methane organic gases (hydrocarbons) were 0.069 g/mi and 0.035 g/mi, respectively, which are both within their respective regulated limits for FFH emissions in California. However, the California nitrogen oxide limit was exceeded during stationary testing with an average value of 0.337 g/mi. In addition, momentary exceedances of the concentration limits for carbon monoxide and hydrocarbons set in European Union Regulation 122 were detected during stationary testing, but these were very short-lived.