The return tide is a plate of carbon emissions from high-speed rail and airplanes

Halfway through the Spring Festival, the "return tide" has begun. According to the forecast data previously released by the Ministry of Transport, during the Spring Festival this year, the cross-regional flow of people across the country is expected to reach 9 billion, a record high, and is expected to become the "hottest" Spring Festival.

In the face of the "great migration" of the Spring Festival, high-speed rail and airplanes are undoubtedly important means of travel. According to the information released by the WeChat official account of "China Railway", on February 18, the national railway sent 15.608 million passengers, exceeding 15 million passengers for four consecutive days. At the same time, airlines are also competing for Spring Festival passenger flow in a variety of ways.

Then, on the way home, traveling, or returning, you may take a high-speed train, a local train, or a plane. Today, let's take a look at the carbon emissions of high-speed rail and airplanes.

Civil Aviation & High-speed Rail, Whose Carbon Emissions Are High?

The competition between high-speed rail and civil aviation can always become a topic of conversation. For example, during the Mid-Autumn Festival and National Day Golden Week in 2023, the phenomenon of civil aviation fares plunging is impressive. Many passengers reported that they found that the price of air tickets had dropped sharply before departure, so they hurriedly refunded their tickets and repurchased them to reduce their losses. The decline in volume and price has deducted points for the overall performance of civil aviation in this round of competition. Some industry insiders pointed out that this is related to the excess capacity of airlines.

After surviving the Golden Week, the Spring Festival has become another wave of competition. The discussion about high-speed rail and civil aviation is heating up again. But in addition to fares, travel time, riding experience, etc., in the context of "dual carbon", will you pay attention to their carbon emissions?

Mao Baohua, executive director of the China Comprehensive Transportation Research Center at Beijing Jiaotong University, who has long been concerned about this issue, conducted an interesting study and told reporters: "The carbon emission factor of civil aviation is about 3.6-3.9 times that of high-speed rail. ”

How is this calculated?

Mao Baohua introduced that when assessing the carbon emission level of high-speed rail and civil aviation, the carbon emissions generated by construction are not considered, and only three parts are considered: energy production emissions, infrastructure maintenance and maintenance emissions, and vehicle operation emissions. Emissions from energy production include emissions from the use of electricity, fuel oil, etc. It is easy to understand that in this regard, civil aviation does not have an advantage. Because the main energy source of high-speed rail is electricity, civil aviation transportation relies on aviation kerosene, which has a high carbon content.

In terms of infrastructure, high-speed rail involves the energy consumption and maintenance of station sections, while civil aviation involves airport energy consumption. The vehicle stage mainly refers to the process of passenger travel.

According to the research of Mao Baohua's team, from 2017 to 2019, the carbon emission factor of China's high-speed rail traction stage was 24.70gCO₂/person-kilometer — 26.27 gCO₂/ person-km. Considering the energy consumption of stations and the emissions of railway maintenance and maintenance, in 2019, the carbon emission factor of the whole process of China's high-speed rail was about 30.48 gCO₂/ person-km.

So, what about the carbon emissions of civil aviation?

In 2019, the carbon emission factor of passenger transport during civil aviation flight in China was 95.3gCO₂per personkm, down 13.0% from 2016. Talking about the reasons for the decline, Mao Baohua said: "First, the technological progress of China's civil aviation aircraft has reduced the carbon emissions per unit mileage; second, the civil aviation occupancy rate has increased year by year, and the average passenger load factor of civil aviation has increased from 80.87% to 86.39% from 2010 to 2019; third, the average distance of civil aviation has increased, and the average distance of civil aviation has increased from 1,509 kilometers to 1,774 kilometers from 2010 to 2019." ”

From the perspective of the whole process, the carbon emissions of civil aviation passenger transportation are about 108.3gCO₂/person-kilometer — 112.9 gCO₂/ person-km. Among them, the flight phase accounts for the largest proportion, about 88.0%-94.4%.

Mao Baohua said: "According to our calculations, the carbon emission factor of civil aviation is about 3.6-3.9 times that of high-speed rail. Therefore, in the future, the civil aviation power system revolution will have a great impact on carbon emissions."

In which year did China's railway and civil aviation passenger turnover surpass that of highways?

The answer is: railway in 2014, civil aviation in 2018.

Mao Baohua said: "After 2012, the proportion of China's railway passenger turnover (that is, the product of the number of passengers transported and the distance transported in a certain period of time) in the main mode of transportation began to rise rapidly. This is related to the fact that after the high-speed rail reaches 10,000 kilometers (network), the competitiveness of passenger services has been significantly enhanced. Since 2012, China's high-speed rail network has developed rapidly, which has greatly made up for the lack of railway passenger supply. In 2014, the passenger turnover completed by railways surpassed that of roads, becoming the largest mode of inter-city travel in China. In 2018, the passenger turnover completed by civil aviation also surpassed that of highways, occupying the 'second place' in China's inter-city passenger transport industry. ”

He introduced that according to the research results of his team, from 2010 to 2022, under the background of infrastructure construction and economic growth such as high-speed railways and civil aviation airports, the proportion of China's civil aviation and railway passenger turnover continued to increase. According to the previous statistical caliber, after years of development, China's inter-city passenger transport structure has gradually changed from mainly by highways and supplemented by railways to a pattern of railways as the mainstay, supplemented by aviation and highways.

Of course, the roads here are mainly aimed at commercial passenger traffic, such as the familiar long-distance buses. If you add self-driving, the result is very different. The main reason why the "flow of people" in the 2024 Spring Festival has surged to 9 billion people, far exceeding the data of the 2022 and 2023 Spring Festival transportation, is that the statistical caliber of the Ministry of Transport has changed. Before the Spring Festival in 2023, only the commercial passenger traffic of railways, highways, waterways, and civil aviation will be counted. In 2023, the concept of "passenger flow" will be introduced for the first time during the Spring Festival transportation, and on the basis of commercial passenger traffic, the number of passenger car trips on highways across the country will be included in the statistical scope. In 2024, the Spring Festival transportation will further expand the statistical caliber and increase the travel volume of ordinary national and provincial highway passenger cars. Therefore, self-driving people have an absolute advantage in this "9 billion" travel army.

Statistics on the sharing rate of passenger travel modes between cities in China Courtesy of Mao Baohua

Note: (1) The data are from the China Statistical Yearbook and the Ministry of Transport of the People's Republic of China; (2) The statistical caliber of civil aviation passenger turnover is domestic routes, excluding international routes.

Residents of our countryyearNearly 5,000 kilometers of motorized travel per capita?

No more, no less, depending on who you compare with

According to the estimation of Mao Baohua's team, from 1998 to 2019, the annual per capita motorized travel mileage of Chinese residents increased from 1,276 kilometers to 4,969 kilometers, nearly quadrupled, basically keeping pace with economic development. Mao Baohua believes that on the one hand, this shows that with the improvement of China's economic development level, the living standards of residents are also improving; on the other hand, although the population growth rate will slow down in the future, the frequency of residents' activities will be further increased after the improvement of residents' living standards, and the demand for passenger transport will continue to grow.

According to statistics, the average annual motorized travel mileage per capita of British residents is 10,100 kilometers, and the United States has reached 19,201 kilometers. He believes that although the living and living patterns of Chinese residents are different from those of these countries, it can be seen from the gap that China still has a lot of room for improvement.

Therefore, Mao Baohua judged: "China's high-speed rail and civil aviation already have good infrastructure conditions and huge market space. From a low-carbon perspective, we should give better play to the advantages of China's high-speed rail network, which is also in line with the requirements of sustainable development of the transportation system. ”

He believes that due to the higher carbon emission factor of civil aviation and higher rail, if the future travel volume of highways and civil aviation can be partially transferred to high-speed rail, China's passenger transportation is more likely to achieve carbon peak before 2035.

What measures should be taken? He stressed the need for targeted guidance measures. Appropriately guiding the supply and travel behavior selection of high-speed rail and civil aviation markets according to the transportation distance is indeed one of the effective means for playing the big game of "low-carbon transportation".

Mao Baohua said: "From a national perspective, high-speed rail and civil aviation have their own advantages, and the main competition distance range is 400-1500 kilometers. As the distance increases, the carbon emission factor of civil aviation will decrease accordingly. Therefore, civil aviation should give better play to its advantages in long-distance transportation. ”

In addition, Mao Baohua believes that efforts should be made to improve the utilization rate of civil aviation passenger seats and increase the number of flights at regional (feeder) airports that are not covered by the high-speed rail network. While the carbon emission factor increases with the increase in aircraft stops, the carbon emissions from stopovers can be offset by increased load factor. Stopover flights should be fare lower than direct flights in order to attract more passengers and improve the economics of airline operations.

Mao Baohua also put forward some humane suggestions, such as the implementation of differentiated pricing of routes in different regions according to the differences in regional economic development levels, the implementation of more differentiated fares for trains of different speed classes and trains in different time intervals, the increase in the frequency of stops of trains on high-speed rail lines in underdeveloped areas at stations along the way, and the introduction of more preferential price strategies for different travel groups (such as the elderly, the disabled, students, etc.).

The good news is that we have seen that the relevant authorities have already tried to implement differentiated fares for trains with different speeds and different time intervals. We believe that in the future, there will be more effective ways to make travel more efficient and greener.