A Carbon Footprint of High-Speed Railways in China: A Case Study of the Beijing-Shanghai Line

A carbon footprint (CF) assessment of Chinese high-speed railways (HSRs) can help guide further development of the world's longest HSR network. In this research, a hybrid economic input-output and life cycle assessment (EIO-LCA) method was applied to estimate the CF of the Beijing-Shanghai HSR line. Specific CFs were analyzed of different subsystems of the line, different stages of production, and three calculation scopes. Results showed that the annual CF of the Beijing-Shanghai HSR is increasing, whereas the per-passenger CF constantly declined between 2011 and 2014. Scope 1 emissions account for an average of 4% of the total annual CF, Scope 2 contribute 71%, and Scope 3 comprise 25%. Among the different stages, operation contributes the largest (71%), followed by construction (20%) and maintenance (9%). In the construction stage, the bridges have the largest CF, followed by trains, and then rails. A trade-off exists between the increase in carbon emissions due to construction of bridges and the reduction in operation emissions affected by leveling changes in terrain. The Beijing-Shanghai HSR line has a relatively higher per-passenger CF than eight other HSR lines, which is largely due to China's coal-based carbon-intensive energy mix of electricity generation, high proportion of bridges, higher operating speed, and heavier train body. In the future, cleaner electricity supply options, more efficient raw material production, and improvement of trains are keys to reducing the CF of Chinese HSRs.