Recommendations for the next generation of China’s heavy-duty vehicle emission standard based on testing of China VI vehicles
To better understand the real-world emissions of current truck engines and emission control technologies in China, this paper analyzes on-road and laboratory tests conducted on two N3 trucks certified to the China VI-b emission standard. The tests were performed by the Xiamen Vehicle Emission Testing Center and, based on the results, the authors make policy recommendations for the next generation of heavy-duty vehicle (HDV) standards, China VII.
Although both vehicles complied with the China VI emission standard for emissions of regulated pollutants, the tractor-trailer (Vehicle 2) tended to have higher air pollutant and greenhouse gas (GHG) emissions than the straight truck (Vehicle 1) in all the parallel portable emissions measurement system test cycles and on the same chassis dynamometer test cycle. Additionally, both are far from meeting the limits that have been proposed for the upcoming Euro VII standard. In particular, tests showed that control of emissions of nitrogen oxides (NOx) did not perform well in certain circumstances, including cold-start, long-idling, and low-load conditions. Given this, China’s next regulations should include clear regulatory provisions that target these. Many technologies exist that can simultaneously reduce NOx and CO2 emissions, and many more can reduce NOx without increasing CO2.
Further, as illustrated below, nitrous oxide (N2O) emissions were a non-negligible component of total GHG emissions; they were an average of 5% of total tailpipe GHG emissions from Vehicle 1 and 9% for Vehicle 2. As such, the authors recommend that China regulate both N2O and CO2 emissions to reduce total GHG emissions from HDVs.