A team of researchers in China suggest that, in the context of promoting the use of clean fuel vehicles and increasing vehicle fuel efficiency, CO₂ emissions of China’s urban passenger transport sector could reach a peak of 225 MtCO₂ in 2030.

If the mode share of public transport could further increase, the CO₂ emissions from the urban passenger transport sector in China are possible to peak at around 2020 with the emissions ranging from 171 to 214 MtCO₂. A paper on their study appears in the journal Energy Policy.

This study sheds light on the urban passenger transport sector in China, which accounted for around 20% (188 MtCO₂) of the total carbon emissions of the transport sector in 2016, and aims to answer whether the CO₂ emissions from the urban passenger transport sector can reach its peak before 2030 and how to reach the peak. The energy consumption and carbon dioxide emissions from the urban passenger transport sector in China is supposed to continue to increase in the future, because of three main considerations: (1) the further expansion of the urbanization and the increase of residents’ income will not only boost the demand for travel, but also cause the rapid growth of private car ownership; (2) vehicle fuel is oil dependent with more than 73% of buses being traditional petroleum buses and 99% of private cars are traditional gasoline vehicles; and (3) the mode share of public transport is much lower than the international advanced level, e.g., 58.2% in Greater London, 65% in Hong Kong, and 61% in Tokyo in terms of share of public transport among auto mobility. The mode share of public transport in most cities in China are less than 40%, and the share for some big cities is even less than 10%. Therefore, it is more necessary to identify how to mitigate the potential growth of energy demand and emissions in the urban passenger transport sector in China.

… This study implements three main research contents. (1) We forecast the passenger travel demand by city scale and by travel mode. Considering that residents from different size cities always perform different travel patterns such as travel frequency, travel mode, and travel distance, hence, the Chinese cities are first classified according to the population size, and then the passenger traffic volume of each travel mode is predicted by city. (2) We build a technical database containing parameters related to different travel tools, such as initial cost, operation and maintenance cost, life cycle, fuel price, energy efficiency level, annual mileage, and passenger load rate for vehicles that distinguish between fuel types and energy efficiency levels for each travel mode and vehicle. At the same time, a policy database is established with the quantitative parameters of policies or plans that have been promulgated by the Chinese government (e.g., the promotion of clean energy, limits for vehicle fuel efficiency, technology replacement, and the promotion of public transportation). (3) Under the premise of satisfying passenger travel demand, we develop a bottom-up technology selection model NET-Transport to analyze the effects of different policies and measures on energy conservation and emission reduction, and explore when peaking for CO₂ emissions from the urban passenger transport sector could occur.

—Li and Yu

Some of their conclusions:

1. The CO₂ emissions from urban passenger transport sector in China is likely to peak at around 2020 with the joint effort of shifting to alternative clean fuel, improving vehicle fuel efficiency and promoting public transport. The corresponding CO₂ emissions would be ranging from 171 to 214 MtCO₂ depending on the degree of public transport promotion. It is further found that measures for promoting public transport would have the greatest potential for energy conservation and emission reduction, followed by improving vehicle fuel efficiency. Shifting to the alternative fuels also plays an important role.

2. The CO₂ emissions of cars account for more than 60% of the total carbon emissions of the urban passenger transport in China. And the peak of CO₂ emissions for urban passenger transport is highly dependent on the peak of CO₂ emissions from cars, which implies that cars are the main obstacle for the low carbon development of urban passenger transport.

3. Energy demand is able to peak at around 2020, with the peak amount ranging between 86 Mtce and 107 Mtce (million tonnes of coal equivalent), and energy consumption is likely to drop to 70–84 Mtce in 2050. Correspondingly, the energy structure would become much cleaner, with the share of gasoline declining from 62% in 2012 to 29% in 2050 and the share of electricity increasing to 56% in 2050.

Technical roadmap of bus,taxi, and car for peaking the CO2 emissions at 2030 or before. Li and Yu.

The researchers also offered a number of suggestions:

1. The energy consumption per unit passenger turnover of buses, taxis and cars need to decrease by 51%, 50% and 44%, respectively. They suggest that the average fuel consumption of gasoline cars should fall to below 5.2L/100 km (45 mpg US) in 2030 and below 3.4L/100 km (69 mpg US) in 2050. The average fuel consumption of pure electric cars should fall to below 13.2 kWh/100 km in 2030 and below 8 kWh/100 km in 2050.

2. New-energy private cars need to be vigorously promoted, with a target of achieving a 24% share among private cars in 2030 and 56% in 2050. At the same time, new-energy vehicles and clean-fuel vehicles need to be promoted among buses and taxis. By 2050, the proportions of pure electric buses among all buses are suggested to reach 89% and pure electric taxis proportions reach 37%. Natural gas taxis are expected to account for 54% in 2050.

3. The targets proposed in the “13^th Five-Year” development plan for urban public transport should be strictly followed and supervised. In 2020, the share of urban public transport for all cities with more than 5 million urban residents in China should increase to more than 40%; the share for all cities with urban resident populations of 1–5 million should increase to more than 30%; and the share for all cities with less than 1 million urban residents should increase to more than 20%. In addition, providing a friendly environment for walking and bicycle to increase the proportion of green travel would also contribute a lot to the low-carbon development.

4. The low-carbon development of urban passenger transport will increase the cost. Shifting to alternative clean fuels and improving vehicle fuel efficiency could peak CO₂ emissions in the urban passenger transport sector in China before 2030 with the lowest cost increase. Its cumulative cost is 4.6 trillion RMB higher than that of BAU scenario from 2012 to 2050. Further construction and promotion of public transport can enable the urban passenger transport sector to achieve the peak of carbon emissions earlier, but the cost would be 31%–67% higher than that of BAU scenario, mainly due to the cost increase of the rail transit.

Resources

• Xi Li, Biying Yu (2019) “Peaking CO₂ emissions for China’s urban passenger transport sector,” Energy Policy, Volume 133, 110913 doi: 10.1016/j.enpol.2019.110913.