Characterisation of ammonia emissions from gasoline and gasoline hybrid passenger cars

Abstract

Recent evidence suggests NH 3 emissions from road vehicles play an important role in the formation of fine particulate matter, especially in urban areas. However, there is little data available for NH 3 emitted from road vehicles under real driving conditions, in part due to its lack of regulation in vehicle emission legislation. In this study, we use 210,000 vehicle emission remote sensing measurements to evaluate the complex mix of factors affecting NH 3 emissions from gasoline and gasoline hybrid passenger cars. The influence of vehicle model year and manufacturer on NH 3 emissions is considered, as well as the effect of vehicle deterioration. It is found that the amount of NH 3 emitted increases as vehicle mileage increases. A comparison of cold start and hot exhaust NH 3 emissions reveals that on average, cold start emissions are a factor of 1.7 times higher. New NH 3 emission factors are developed, in addition to speed-emission curves that are potentially useful for national inventories. A new application of remote sensing data is reported, whereby the proportion of failed CO 2 measurements for hybrid vehicles provides unique insight into the real world battery use of both conventional hybrid electric and plug-in hybrid electric vehicles, which is used to refine the NH 3 emission factors for these vehicles. • Vehicle emission measurements using remote sensing. • New NH 3 emission factors for gasoline and gasoline hybrid cars. • Quantification of NH 3 cold start penalty. • NH 3 increases with increasing vehicle mileage. • Fraction of failed CO 2 measurements gives unique insight into hybrid battery use.