Future energy use and CO2 emissions of urban passenger transport in China: A travel behavior and urban form based approach

Work on comparing cities in terms of their transport energy consumption and CO2 emissions in the urban passenger transport sector has rarely been done using detailed travel activity data that takes into account city level differences in terms of economic development, population, and urban form. A personal activity based approach is necessary to better reflect travel behavior change results from different social, economic, urban form, technical, and transportation policy situations in the future. The present study extends the existing activity, modal share, energy intensity, fuel/carbon intensity (ASIF) modeling framework by disaggregating travel activity into key structural components and city-specific factors for 288 prefectural level cities in China. Testable econometric modeling systems were built to link mode split and mode specific travel distances with local economic and urban form characteristics in four different population sizes and two urban form types, based on 187 travel surveys in 108 Chinese cities in the past two decades. Scenarios of energy use and carbon emissions between 2010 (baseline) and 2050 were developed. Results showed that in 2010 urban passenger road transport in China generated 396 Mt CO2 emissions and per capita urban passenger transport energy use increased as city size expanded. By 2030, under business as usual scenario assumptions, energy use in the urban passenger transport sector comprised 23.2 Mt of gasoline, 1.72 Mt of diesel, 3.36 billion M3 of natural gas, and 0.62 billion kWh of electricity. While national policies targeting travel behavior change have been shown to mitigate emissions to some extent, urban transport policies targeted at specific spatial and temporal drivers of energy demand and emissions may be more effective in meeting policy goals. Short-term policies that promote car-pooling and ride sharing and medium-term policies that increase the cost of driving and promote public transport (such as transit oriented development, walkable neighborhood design, and parking pricing/restraint in city centers) help stabilize carbon emissions over the long term. However, the decision of building polycentric cities might have less significant impact on mitigating urban passenger transport in big cities. Moreover, large-scale promotion of electric vehicles should be designed from a long-term perspective rather than from a short-term one to achieve balanced carbon emissions in regard to the decarbonization process of electricity generation in China.