This study investigates methane emissions from natural gas vehicles (NGVs) in China, revealing that their growth may negatively impact climate change. Real-world emission measurements show high methane emissions from heavy-duty NGVs, exceeding current emission limits by 90%. This oversight in previous emission estimates has led to biased results. Life-cycle analyses indicate a net increase in greenhouse gas emissions since 2000 due to the shift to NGVs. Scenario analyses highlight the critical role of the upcoming China VI standard for reversing this trend. Implementing and enforcing this standard is challenging, and the study's methodology provides valuable information on fleet-level methane emissions.

Da Pan, Lei Tao, Kang Sun, Levi M. Golston, David J. Miller, Tong Zhu, Yue Qin, Yan Zhang, Denise L. Mauzerall, Mark A. Zondlo