Life cycle greenhouse gas emissions of multi-pathways natural gas vehicles in china considering methane leakage

Abstract

Natural gas has been promoted rapidly recent years to substitute traditional vehicle fuels. However, methane leakages in the natural gas supply chains make it difficult to ascertain whether it can reduce greenhouse gas emissions when used as a transport fuel. This paper characterizes the natural gas supply chains and their segments involved, estimates the venting and fugitive leakages from natural gas supply chains, decides the distribution among segments and further integrates it with life cycle analysis on natural gas fueled vehicles. Domestic natural gas supply chain turns out to be the dominant methane emitter, accounting for 67% of total methane leakages from natural gas supply chains. Transportation segments contribute 42–86% of the total methane leakages in each supply chain, which is the greatest contribution among all the segments. Life cycle analysis on private passenger vehicles, transit buses and heavy-duty trucks show that compressed natural gas and liquefied natural gas bring approximately 11–17% and 9–15% greenhouse gas emission reduction compared to traditional fossil fuels, even considering methane leaks in the natural gas supply chains. Methane leakages from natural gas supply chains account for approximately 2% of the total life cycle greenhouse gas emissions of natural gas vehicles. The results ascertain the low-carbon attribute of natural gas, and greater efforts should be exerted to promote natural gas vehicles to help reduce greenhouse gas emissions from on-road transportation.