In 2009, Shenzhen, China, a city of 12 million that links Hong Kong with mainland China, was selected as the first of 13 pilot cities for demonstration and promotion of new energy vehicles in China. This includes not only electric cars, but also electric buses. By the end of 2017, a total of 16,359 electric buses had been implemented, making the city’s entire bus fleet completely electric. This made Shenzhen the first city in not only China, but the entire globe, to realize the full electrification of its public transport.
In the following years, bus electrification brought some clear benefits to Shenzhen. Compared with the former diesel buses, Shenzhen’s e-buses have greatly reduced dependence on fossil fuels and lessened environmental pollution. Fuel consumption in the public transport industry has been reduced by more than 95%. Based on the operating mileage in Shenzhen in 2016, electric buses consume 72.9% less energy than diesel buses, with a daily average operating mileage of 174.4 km, and energy consumption 106.3 kWh/100 km. According to the Shenzhen Municipal Transportation Commission, the resulting energy savings amount to 366,000 tons of coal saved annually, substituted by 345,000 tons of alternative fuel.
There are also major reductions in CO2 emissions. On average per year, electric buses emit 67.02 kg of CO2 per 100 km, compared to diesel vehicles which emit 129.91 kg, corresponding to a reduction rate of about 48%. According to the statistics from the Shenzhen Municipal Transportation Commission, the 2017 data shows a total reduction of CO2 emissions of 1.353 million tons. Furthermore, the annual emission of pollutants such as nitrogen oxides, non-methane hydrocarbons and particulate matter was reduced by 431.6 tons.
The performance of these buses relative to diesel has been improving. In 2016, the average daily operating mileage of electric buses and hybrid buses in Shenzhen were 174.4 km and 163.0 km, respectively, representing 76.2% and 71.2% of the operating distance of a traditional diesel bus, which averages at 228.8 km. However, the average daily mileage of electric buses has increased year by year, with an increase of 40.6% in 2016 compared to 2012.
The World’s Largest Vehicle Market
The 2018 Annual Report of China’s Motor Vehicle Environmental Management, published by the Ministry of Ecology and Environment, shows China as the world’s largest motor vehicle market, in both production and sales, for nine consecutive years. Motor vehicle emissions are now a major source of pollution in China, contributing heavily to CO2 emissions. The increasing development of new energy vehicles offers a possible way forward.
New energy vehicles include pure electric vehicles, extended-range electric vehicles, hybrid vehicles, and fuel cell electric vehicles, among others. Companies are offering different types of electric buses to meet market demand, and the industry has developed rapidly, with the production and sales volume of new energy vehicles increasing 101 times in the last five years.
China Electric Bus Sales — 2011–2017
Government support for new energy buses has been strong. In 2015, the Ministry of Transport, Ministry of Finance, and Ministry of Industry and Information Technology jointly issued a stipulation that the proportion of new energy buses to be added and replaced in Chinese cities must be divided proportionally: 80% in Beijing, Shanghai, Tianjin, Hebei, Shanxi, Jiangsu Zhejiang, Shandong, Guangdong and Hainan; 65% in Anhui, Jiangxi, Henan, Hubei, Hunan and Fujian; 30% in other provinces (regions and cities). At the same time, national and local governments have introduced a series of subsidy incentives and tax reductions to encourage and promote the development of new energy vehicles.
The “Zero Emissions” Question
It’s clear that China sees rapid development of new energy vehicles as a way to continue its pace of rapid development while reducing emissions. However, this has been accompanied by questions about whether this approach is really as effective as promised. Terms such as “zero emissions” to describe new energy vehicles have been criticized as misleading. Many have pointed out that new energy vehicles transfer pollution from roads to power plants, rather than being fully “zero emissions”. Advocates counter that it would be the case with renewable energy, but there has not been comparable progress in decarbonizing the grid. In 2016 in China, coal-generated power accounted for 72% of all power sources.
In order to calculate the environmental impact of new energy vehicles, the conventional method is to calculate the standard carbon dioxide production by multiplying the power consumption per 100 kilometers by the carbon emission factor. However, there are many different types of new energy vehicles, each with a different method of measuring vehicle emissions, as well as different power consumption based on the location. Therefore, the results of the calculations would be quite varied.
According to the Study on Demonstration Promotion and Business Model of New Energy Buses issued by the China Electric Vehicle 100 People’s Congress, a 12-meter-long, Category 4 emissions bus with a fuel consumption of 38L/100km emits 1103 grams of CO2 per kilometer. Based on the average standard and composition of the national power grid, an electric bus that consumes 120 kWh of electricity per 100 km emits 943 grams of CO2 per km, and a plug-in hybrid bus emits 870 grams. After electrification, CO2 emissions decreased 15-20% compared to diesel vehicles- a marked difference in reducing carbon emissions.
CO2 Emissions per Kilometer (g)
Regarding the emission of gaseous pollutants that cause smog, such as CO, VOC, NOx, and PM, the Study on Demonstration Promotion and Business Model of New Energy Buses stated that during their life cycle, the annual emissions of diesel vehicles average 1146 kg. In comparison, electric vehicles emit only 279 kg annually, amounting to a 75% reduction in emissions, while plug-in hybrid vehicles emit 895 kg annually, amounting to a 22% reduction.
Long Term, it’s About Power
Although China is still mainly based on coal-generated electricity, the continuous development of wind energy, nuclear energy, and other energy sources, as well as the control of emissions from coal-fired power plants, would help mitigate the problem of “pollution transfer”. Coal-generated power accounted for 80% of all power sources in 2010, dropping to 78% in 2013 and 72% in 2016. According to data from the China Power Federation, 1.0-1.2 grams of pollutant emissions (particulate matter, sulfide, nitrogen oxides, etc.) and 810 grams of carbon were produced per kilowatt hour of electricity in 2015-2016. Wang Hewu, deputy director of the US-China Clean Vehicles Consortium, believes that they are 70% to 80% lower than the 2010 pollutant emissions. In addition, according to BP’s Energy Outlook 2035 report, by 2035, thermal power generation will continue to decline both in China and globally, and the proportion of clean energy will gradually increase.
Primary Energy Used for Power Generation
At present, there are a large number of peak-to-valley differences in China’s daily electricity demand. Analysis shows that electricity demand may fluctuate by up to 1 billion degrees each day. As electric buses run during the day and charge at night, they can help provide a solution towards stabilizing these fluctuations, and 40 million electric vehicles can be charged using these differences in electricity demand. Therefore, the development of new energy vehicles will also help to improve the overall utilization efficiency of electricity, avoid the construction of pumped storage power stations, and save social costs.
According to statistics from the Ministry of Communications, the total number of public buses in China has increased from 509,600 in 2013 to 651,200 in 2017. The biggest change has been the proportion of traditional fuel buses, which has decreased from 62.7% of all buses in 2013, to just 29.7% in 2017. In accordance, the number of new energy buses has increased from less than 0.33% of the total in 2013, to 39.5% in 2017.
The proportion of new energy buses was extremely low in 2013, which provides a good opportunity to compare the impact of growth of China’s new energy bus fleet in the following years on the environment. Using CO2 vehicle emissions in 2013 as a baseline, by 2017, about 8.56 million tons of CO2 were reduced due to the increase in new energy buses.
Given the current trend of decreasing numbers of diesel and gasoline vehicles, if supposed that by 2021, all diesel and gasoline vehicles are replaced by new energy vehicles, CO2 emissions will be reduced by 33.08 million tons.
Progress is Impressive, yet Challenges Remain
Despite the encouraging progress of new energy vehicles, there are still serious issues to be addressed. China’s current subsidy policy has increasingly supported batteries with high energy densities, raising the minimum density threshold for non-fast-charging electric buses from 85 kWh/kg to 115 kWh/kg. However, the energy density of lithium iron phosphate batteries is limited, with a theoretical upper limit of 170 mAh/g, but an actual density of only 110 mAh/g currently. Ternary lithium batteries have a much higher density capacity; however, they carry certain safety hazards, so they are seldom used in public transportation. It is clear that electric buses must adopt new technical means to increase battery energy density.
In addition, some enterprises have taken advantage of loopholes in the subsidy policy to defraud subsidized funds by means of false production and products that do not conform to requirements, leading to the “false” development of electric vehicles and the massive loss of state subsidized funds. Therefore, in order to promote the healthy and stable development of China’s new energy automobile industry, the relevant state departments will improve subsidy standards and mechanisms, subsidy allocation, and establish a supervision system with local governments taking the main responsibility. Determining how to develop effective policies and reduce loopholes will require further careful consideration.
It’s clear that new energy vehicles are not a perfect product. Their development, and the technology for electric buses, is ongoing. However, it is clear that there are real benefits to be had in CO2 reduction, especially when compared to private cars, but even as compared to gas or diesel powered buses. China’s commitment to improvement and electrification of its bus fleet is commendable, and should serve as a model for other nations with high transport emissions. As Miao Wei of the Ministry of Industry and Information Technology said during the National People’s Congress in 2018, “As technology continues to progress and charging facilities continue to improve, new energy vehicles will show rapid growth in the future.”