China's transportation decarbonization in the context of carbon neutrality: A segment-mode analysis using integrated modelling

China aims to peak carbon dioxide (CO2) emissions before 2030 and achieve carbon neutrality before 2060. Currently, 9% of China's CO2 emissions come from the transportation sector. Transportation decarbonization is important for China to achieve carbon neutrality. By representing the transportation sector with nine segments and 20 modes in Global Change Analysis Model, this study explores China's transportation decarbonization and potential role of electricity and hydrogen at the segment-mode level under three illustrative scenarios - policy scenario (PS), 2060 carbon-neutrality scenario (CN60), and 2050 carbon-neutrality scenario (CN50). The PS reflects the continuation of current low-carbon policies and trends, while the CN60 and the CN50 represent China's pursuit of net-zero emissions before 2060 and 2050, respectively. Results in the PS show a gradual saturation of service demand and an increasingly efficient modal structure for China's future transportation. Compared to the PS, the two carbon neutrality scenarios specifically emphasize the importance of decarbonizing transportation fuel structure after 2030. In the CN60, China's transportation emissions peak in 2035 and fall to 0.36 GtCO2 in 2050; electricity and hydrogen provide 43% and 12% of transportation energy in 2050, respectively. The CN50 features further penetration of low-carbon fuels to reduce transportation carbon intensity, with transportation emissions peaking in 2030 and declining to only 0.21 GtCO2 in 2050. In 2050 of the CN50, the share of electricity and hydrogen in China's transportation energy increases to 53% and 16%, respectively, with near-zero emissions being achieved in urban, rural and business passenger segments, as well as in car and bus; hydrogen provides 17% and 26% of China's airplane and ship energy consumption, respectively.