《1 Introduction》

1 Introduction

Decarbonization is a core principle in the development of China’s national economy and in the formulation of national strategies. Consequently, the greatest challenge faced by the Chinese automobile industry is successfully reducing CO₂ emissions. According to a report by the Intergovernmental Panel on Climate Change (IPCC), to prevent a global rise in temperature beyond 2 °C, CO₂ emissions globally must be restricted to 3.15×10¹² t. As of today, 2×10¹² t of CO2 has already been emitted. To address this issue, 195 countries, including China, have signed the Paris Agreement. In this agreement, China committed to curb its CO₂ emissions and reduce its CO₂ emissions per unit of GDP by 60%–65% below 2005 level by 2030. Therefore, it is essential to consider the challenge of decarbonization in the formulation of a sustainable development strategy for China’s automobile industry. This strategy is expected to play an important role in helping the automobile industry transition toward a low energy consumption–low carbon paradigm [1]. Studies on the decarbonization development of China’s automobile industry are thus highly significant, given the present need to restrict CO₂ emissions [2]. The objective of this work is to systematically study the decarbonization of the automobile industry based on its life cycle. The various phases involved in the automobile industry include research and development, production, and manufacture, automobile sales, automobile usage, and automobile recycling. Each phase of this life cycle involves and affects various fields, including raw materials, mechanics, electronics, energy, finance, services, and infrastructure construction.

《2 Systems engineering study on the decarbonization of China’s automobile industry》

2 Systems engineering study on the decarbonization of China’s automobile industry

This systems engineering study encompasses six different aspects: a systems framework for reducing carbon emissions from automobiles, the current state of automobile CO₂ emissions, a predictive model for automobile CO₂ emissions, prediction of the total CO₂ emissions of automobiles, the proportion of CO₂emitted by automobiles to the total CO₂ emitted by China, and the evaluation of automobile CO₂ emissions.

The systems framework for decarbonization consists of seven different phases: mining of energy resources, processing of energy resources, transportation of energy resources, manufacture of automobile materials, manufacture of automobiles, usage of automobiles, and recycling of automobiles.

According to statistical data from the National Bureau of Statistics of China, the usage phase accounted for 75 % of all automobile CO₂ emissions in 2015; the manufacture of materials, the manufacture of automobiles, maintenance, and recycling phases accounted for the remaining 16%, 6%, 1%, and 2% of the emissions, respectively (Fig. 1). In developed countries, the usage phase usually accounts for approximately 60 % of the total CO₂ emitted by automobiles. Thus, the emission intensity of China is higher than that of developed countries in every phase involved in the automobile industry, from the oil wells to wheels.

《Fig. 1. 》

Fig. 1. Statistical analysis of automobile CO2 emissions in China.

The CO₂ emissions of China’s automobiles in the usage phase were 3.2×10⁸ t in 2000, 6.1×10⁸ t in 2008, and 8.6×10⁸ t in 2015. It is apparent that the carbon emissions due to the automobile industry have risen rapidly over time [3]. In contrast, the emissions due to automobiles in Japan were 2.37×10⁸ t in 2000 [4], 2.23×10⁸ t in 2008, and 2.01×10⁸ t in 2014, indicating that CO₂ emissions due to the Japanese automobile industry have decreased every year.

In Japan, low emissions, mostly due to technological advancements, in the usage phase have contributed to the stabilization and gradual decrease in the overall amount of CO₂ emitted. The amount of CO₂ emitted by automobiles in China, on the other hand, is increasing rapidly, in tandem with the rise in car ownership. A large quantity of CO₂ is released during the manufacturing phase; however, the rise in CO₂ emissions is, at present, gradually plateauing. In 2013, Japan produced half the number of automobiles as China, but only emitted 1/9 of the amount of CO₂ emitted by China [5]. The amount of CO₂ emitted during the production of a car by a foreign automobile company can be as low as approximately 0.7 t per car. In China, although the amount of CO₂ emitted during the car manufacturing phase is decreasing every year, there is still significant room for improvement as Chinese companies still emit approximately 2.9 t of CO₂ per car in this phase. China also emits more CO₂ than the United States in the production of materials for automobile manufacturing. The production of steel that is required for each car produces emissions of 3.27 t in China, whereas in the United States, only 2.49 t of CO₂ is emitted. Similarly, aluminum production produces 1.46 t of CO₂ per car in China, but only 0.28 t of CO₂ per car in the United States.

Based on the automobile life cycle, a carbon emissions model was constructed for automobile usage, manufacture, materials, maintenance, and disposal/recycling phases. Notably, the CO₂ emissions of the automobile usage phase also include CO₂ emissions of the fuel production phase.

Total CO₂ emission, Mco₂_tot = Mco₂_road + Mco₂_manuf + Mco₂_maint + Mco₂_dis + Mco₂_mat

In this equation, Mco₂_tot, Mco₂_road, Mco₂_manuf, Mco₂_maint, Mco₂_dis, and Mco₂_mat are the total CO₂ emissions, CO₂ emissions of automobile usage, automobile manufacture, automobile maintenance, automobile disposal/recycling, and material manufacture phases, respectively.

The life cycle CO₂ emission of automobiles is the sum of CO₂ emissions of automobile usage, automobile manufacture, automobile maintenance, automobile disposal and recycling, and the production of automobile material phases.

The CO₂ emitted by automobiles during their usage on roads is given by:

Mco₂_road = ΣG_r × A_k / A_r × e_k × m_k × e_t × C_k × l_k

where G_r is fuel consumption over a reference year, i.e., the fuel consumption of a known year; A_k is the predicted number of cars in the future, i.e., the number of cars in the forecast year; Ar is the number of reference cars, i.e., the number of cars of a known year; mk is the correction factor for the average annual mileage; e_k is the correction factor for the automobile fuel consumption of a future year; et is the traffic efficiency factor; C_k is the CO₂ emission coefficient per unit mass of fuel; lk is the CO₂ emission coefficient over a life cycle.

In this model, corrections to the theoretical fuel consumption was made based on the total annual fuel consumption to avoid issues due to the inconsistencies between the actual and theoretical fuel consumptions and because it is impossible to calculate the actual fuel consumption. The CO₂ emission of the automobile manufacturing phase may be expressed as:

Mco₂_manuf=Mquantity × Cco₂_quantity

In this equation, Mquantity is the number of cars produced and Cco₂_quantity is the average CO₂ emitted to produce each car.

The following assumptions were made according to the proportion of an automobile’s life cycle CO₂ emissions accounted for by each phase in other countries.

The ratio of maintenance-related CO₂ emissions to usagerelated CO₂ emissions is 0.008∶0.769; the ratio of materialproduction-related CO₂ emissions to automobile-manufacturingrelated CO₂ emissions is 0.131∶0.068; the ratio of disposaland-recycling-related CO₂ emissions to usage-related CO₂ emissions is 0.022∶0.769.

The inputs of our model include forecasted nationwide automobile sales in 2020, 2025, and 2030 (30 million, 35 million, and 38 million, respectively) and the energy consumption reduction targets listed in the Technology Roadmap for Energy-saving and New Energy Vehicles, calling for 20 %, 35 %, and 50 % reductions in the energy consumed to produce each car compared with 2015 levels in 2020, 2025, and 2030, respectively. The CO₂ emissions of automobiles in China were thus forecasted using our model and the aforementioned inputs and assumptions. It was shown that a large reduction in CO₂ emissions will be achieved in the automobile usage phase and overall automobile life cycle by 2030 (Fig. 2), which indicates that target CO₂ emission levels will be achieved ahead of schedule. At present, the CO₂ emissions of the automobile manufacturing phase are already beginning to decrease; however, the greatest contribution to CO₂ emission reduction is expected to originate from the automobile usage phase. The decrease in CO₂ emissions in the automobile manufacturing phase will help the automobile industry save energy and reduce emissions. The reduction of CO₂ emissions in the automobile usage phase may be attributed to two causes: ① the fuel and power consumption of cars is continuously decreasing over time in accordance with regulatory requirements; ② annual car sales, car disposal, and car ownership will stabilize after 2025. However, if CO₂ emissions of the usage phase cannot be controlled, it will become very difficult to maintain a steady increase in the nationwide car sales up to 2030.

《Fig. 2. 》

Fig. 2. Forecasted total CO2 emissions by automobiles in China.

The proportion of CO₂ emissions due to road transportation to the total CO₂ emissions globally and that to China are shown in Figs. 3 and 4, respectively [6]. CO₂ emissions in road transportation account for 17 % of the world’s total CO₂ emissions, whereas China’s CO₂ emissions account for 4.6 %, 5.3 %, and 7.0 % of the world’s total CO₂ emissions in 2005, 2010, and 2015, respectively. Although CO₂ emissions in road transportation account for a relatively smaller proportion of China’s emissions (owing to the high CO₂ emissions of China), this proportion has increased significantly from 2005 to 2015 and is continuing to increase rapidly. A significant quantity of CO2 is therefore produced by automobiles in China.

《Fig. 3. 》

Fig. 3. Proportion of CO2 emissions produced by road transportation to the total CO2 emissions of the world.

《Fig. 4. 》

Fig. 4. Proportion of CO2 emissions produced by road transportation among the total CO2 emissions of China.

We constructed a system for evaluating the decarbonization of the automobile industry from a systems engineering perspective on automobile decarbonization, which contains seven first-level indicators and 32 second-level indicators. The first-level indicators include industry decarbonization, product decarbonization, energy decarbonization, infrastructure decarbonization, travel decarbonization, decarbonization of the policy environment, and the development of a low-carbon culture, as shown in Fig. 5.

《Fig. 5. 》

Fig. 5. System of evaluative indicators for the decarbonization of a nation’s automobile industry.

The evaluation was conducted by assigning weights to each indicator and having experts score the indicators. In terms of the overall level of automobile decarbonization in each country, Japan and Germany have attained the highest scores, and there is a sizeable gap between China and other developed countries. Based on these scores, Japan and Germany occupy the first tier of development (in terms of decarbonization) as they have both attained scores above 8.5. China is in the third tier of development as it has attained a score lower than 7. Other than the decarbonization of its policy environment, China has attained lower scores for all the other indicators as compared to other developed countries. The Paris Agreement mandates that each country must measure, predict, and control its carbon emissions as they see fit. Some countries have proposed to stop selling.fossil-fuel-powered cars by 2030 to satisfy the demands of ecologically sustainable development. Our research shows that China will achieve peak automobile CO₂ emissions by 2028, with China’s total CO₂ emissions being restricted to 1.5×10⁹ t. Automobile CO₂ emissions will account for 12 % of China’s total CO₂ emissions at this point.

《3 Technology roadmap for the decarbonization of passenger cars in China》

3 Technology roadmap for the decarbonization of passenger cars in China

China has passed highly stringent regulations for automobile fuel consumption (Fig. 6) to restrict automobile CO₂ emissions [7]. These mandatory regulations on CO₂ emissions from passenger vehicles must be implemented immediately by car manufacturers in China. Moreover, these mandatory regulations will soon also be applied to commercial vehicles. In the past, Electricity and heating 43% Manufacture and construction 19% Road transportation 17% Non-road transportation 6% 28% 25% 16% United States European Union Japan Other industries 10% Other energy industries 5% Fig. 3. Proportion of CO₂ emissions produced by road transportation to the total CO₂ emissions of the world. Fig. 4. Proportion of CO₂ emissions produced by road transportation among the total CO₂ emissions of China. Electricity and heating 49% Manufacture and construction 31% Road transportation Non-road transportation 2% Other industries 7% Other energy industries 4% 7.0% 5.3% 4.6% 2015 2010 2005 Automobile decarbonization Industry decarbonization Product decarbonization Energy decarbonization Infrastructure decarbonization Travel decarbonization Decarbonization of policy environment Development of a low-carbon culture Decarbonization of designs Decarbonization of manufacturing processes Decarbonization of product usage Decarbonization of services Decarbonization of disposal processes Proportion of car ownership Proportion of car sales Degree of vehicle aging Conventional fuels Electricity Energy Internet Road infrastructure Charging infrastructure Intelligent network connected infrastructure Rate of transportation sharing Current number of buses Car utilization Average traveled distance per annum Passenger and freight volume Fuel consumption regulations NEV points Recycling policy Decarbonization energy policies Consumer awareness of decarbonization consumption Consumer awareness of decarbonization mobility Awareness of decarbonization developments in the car industry Penetration of decarbonization culture Average number of passengers per trip Driving habits Policy for transportation infrastructure construction Road rights management policies Public transportation policies First-level indicators Second-level indicators Fig. 5. System of evaluative indicators for the decarbonization of a nation’s automobile industry. although pollutant emissions were restricted by laws and regulations, fuel consumption was dictated purely by market forces. CO₂ emissions are now a major priority for China, as reflected by the passage of stringent fuel consumption regulations to control CO₂ emissions from passenger cars. These fuel consumption laws have three sets of requirements. The first is “admittance,” which requires a manufacturer to fulfil certain conditions to gain permission to sell cars in China. The second is the restriction of the manufacturer’s fleet emissions below a certain level. The third pertains to fuel consumption targets: if the cars sold by a manufacturer cannot achieve the mandated fuel consumption targets, the manufacturer must purchase carbon allowances. Chinese fuel consumption regulations (CO₂ regulations) affect all industries, and they are the strictest set of rules applying to the country’s automobile industry. These regulations will ultimately determine the survival of Chinese industries. The stringency of these regulations is an indication of the importance the Chinese government places on reducing CO₂ emissions from the automobile industry. Fig. 6 shows that a 27 % reduction in fuel consumption is required between Phase III and Phase IV; a further decrease, greater than 20%, is required by Phase V.

《Fig. 6. 》

Fig. 6. Fuel consumption regulations for passenger cars in China. CFCR: combined fuel consumption rating

The reduction of CO₂ emissions and energy consumption from the automobile industry is the collective responsibility of society as a whole, including the government, industry, and consumers. As a decrease in fuel consumption will lead to an increase in product costs, the willingness of customers to pay for more expensive cars that satisfy fuel consumption regulations will be crucial for the survival of the automobile industry. According to willingness to pay (WTP) surveys based on product life cycle returns, passenger car customers are only willing to pay for increased purchase costs if these can be ameliorated by savings in fuel consumption within three years. The cost required to reduce fuel consumption by 0.1 L was obtained as shown in Fig. 7; an A0-class car requires additional 230 CNY to achieve this target, whereas a C-class car requires additional 474 CNY for the same. These cost increases must be borne by the industry if emissions reduction targets are to be achieved. Therefore, the Chinese automobile industry must confront the cost pressures imposed by technological innovations as it strives to achieve Phase IV fuel consumption ratings by propagating fuel-saving technologies. Cost pressures are therefore a major constraint in the electrification of the automobile industry.

《Fig. 7. 》

Fig. 7. Estimated cost of reducing the fuel consumption of passenger cars in China. CFCR: combined fuel consumption rating.

Here some of the technologies that could be used to achieve the CO₂ emissions targets are discussed for each phase of theChina fuel consumption regulation (CFCR) while maintaining economic viability. The technologies that could be used to achieve Phase IV targets before 2020 (a gasoline engine thermal efficiency of 38 % and 5 L/100 km) include Miller cycle engines, start-stop systems, variable valve lift, integrated exhaust manifolds, high-efficiency superchargers, and low-friction and lightweighting technologies. Phase V fuel consumption targets for 2025 require a fuel consumption of 4 L/100 km and gasoline engines with a thermal efficiency of 42 %. The technologies that could be used to achieve these goals include variable valve actuation (VVA), thermal management, 48 V hybrid electric or plugin hybrid electric vehicles (HEV or PHEV, respectively), electric superchargers, exhaust gas recycling, cylinder deactivation, variable compression ratios (VCRs), waste heat recovery (WHR), water injection system, and lean-burn engines. Phase VI fuel consumption reduction for 2030 requires a thermal efficiency of 45 % and fuel consumption of 3.2 L/100 km; this will require costlier technologies, such as low-temperature combustion, high stroke-to-bore ratios, WHR, adiabatic engines, motor electrification, and HEV/PHEV technologies.

By combining these technologies with existing new energy electrification, China FAW developed the concept of engine electrification, which simultaneously accounts for the costs and fuel-saving potential of engine electrification. The first generation of FAW hybrid engines utilizes a belt-driven starter generator (BSG), whereas the second generation innovates upon the first by electrifying other engine accessory components (Fig. 8).

《Fig. 8. 》

Fig. 8. Engine electrification.

Further technological innovations may be pursued through electrification of the transmission, which allows for full and plug-in hybridization. The core purpose of such innovations is the integration of the electric motor and transmission. Phase IV fuel consumption targets may be achieved in B-class vehicles using 48 V mild-hybrid systems, which are more cost-effective than high-pressure hybrid systems. Phase IV targets for B/C-class hybrid electric vehicles may be achieved using hybridization technologies based on electrified transmission. For B/C-class vehicles to attain Phase V fuel consumption targets, PHEV technology will be required.

Electric vehicles are expected to contribute very significantly toward the achievement of fuel consumption targets during each regulatory phase. A single A0-class electric vehicle can offset the fuel consumption of 7.9 units of conventional B-class cars during Phase IV or 2.3 units of B-class cars in Phase V. Alternatively, an A0-class electric vehicle offsets the fuel consumption of 6.1 units of conventional C-class cars in Phase IV or 2 units of C-class cars in Phase V. The potential for entirely-electric cars to balance current corporate average fuel consumption (CAFC) regulations is, given the policy for passenger cars, expected to increase several fold in the near future.

A comparative study of the three existing types of hydrogen fuel cell vehicles, i.e., the energy supplementing, hybrid, and fully fuel-cell-powered types, concluded that the third is the most suitable in terms of contributions towards decarbonization. A fully fuel-cell-powered vehicle does not require external charging as it uses a rapidly hydrogenated fuel cell stack that performs at a level comparable to conventional internal combustion cars. These vehicles, therefore, represent a mainstream technological trend in the development of low-carbon vehicles.

《4 Technology roadmap for decarbonizing commercial vehicles in China》

4 Technology roadmap for decarbonizing commercial vehicles in China

Commercial vehicles are facing a major challenge from fuel consumption targets in China as the country intends to implement Phase III and Phase IV regulations by 2020 and 2025, respectively. This will impose a mandatory 15 % reduction in fuel consumption on vehicles. In comparison, the United States intends only to implement Phase II regulations by 2021, whereas the European Union is still collecting CO2 emissions data and is only expected to announce emissions limits for commercial vehicles in 2022.

Commercial vehicles currently account for 53% of the CO₂ emissions from all automobiles, whereas passenger cars only account for 47 % of the same. Chinese reliance on imports for 65 % of its petroleum needs, and the majority of this is used for commercial vehicles. Enhancing the fuel economy of commercial vehicles will involve two steps, with the first being the development of a commercial vehicle engine with a 47 % thermal efficiency. Commercial vehicles are still largely reliant on diesel engines, as electric vehicle batteries do not currently have sufficient capacity to serve as a viable alternative for highway transport vehicles. The required thermal efficiency may be achieved if the combustion processes of diesel engines is improved. The key to this goal lies in the improvement of three crucial aspects: the combustion chamber, common rail, and supercharger. One of the most important milestones for this goal is the creation of a common rail injection system with variable injection rates. To this end, China FAW has developed a dual rail injection system with separate high- and low-pressure rails. Three different fuel injection rates can be obtained by combining these rails using a control system, and a national patent has been granted for this system. The reduction of NOx emissions and fuel consumption are the most important priorities in the optimization of combustion processes. A supercharger must be highly efficient at both low and high speeds, and the best technological solution, in this regard, is the dual-channel asymmetric supercharger developed by China FAW.

The second step is to utilize clean fuels, which is an important step towards reducing carbon emissions from commercial vehicles. For example, China-adapted World Transient Vehicle Cycle (C-WTVC) test cycles show that natural-gas engines could reduce CO₂ emissions significantly by approximately 7 %. Commercial vehicle engines developed in the future should be based on natural gas engines and diesel engines should be considered alternate variants. This type of development would represent a major innovation in the automobile industry.

Phase IV mandates a thermal efficiency of 50 % in diesel engines. One of the most important technological pathways toward this goal is WHR; it has the potential to increase thermal efficiency by 2%–4 %.

The use of hybrid power systems is another important low-carbon technological pathway for commercial vehicle development, as hybrid systems could reduce CO₂ emissions by 7 %–10 %. The “smartization” of commercial vehicles also has tremendous potential to reduce fuel consumption: road conditions could be predicted via intelligent prediction technologies, and smart formations could reduce wind resistance. The latter has the potential to reduce fuel consumption by approximately 20 %.

《5 Suggestions》

5 Suggestions

In this work, systems engineering study of the decarbonization of automobiles in China was conducted. Based on results and other issues discovered while performing this study, following suggestions are listed to decarbonize automobiles in China and accelerate the country’s progress in this regard.

(1) A decarbonization automobile industry system, including the establishment of a decarbonization database, decarbonization industrial chains, and a management system for decarbonization development, should be established.

(2) The energy and automobile industries should be developed in a coordinated manner. For example, the development of power installations, hydrogen energy, and alternative fuels should be coordinated with those of electric cars, hydrogen fuel cell vehicles, and commercial vehicle technologies, respectively

(3) A decarbonization strategy should be formulated for commercial vehicles. CO₂ emissions reductions may be achieved via improved thermal efficiency and the use of low-carbon fuels, and energy transformations and decarbonization may be achieved simultaneously through the use of hydrogen fuel cell technology.

(4) Green manufacturing should be implemented to reduce CO₂ emissions and promote green production processes in the automobile industry. A recycling system that matches the scale of the automobile industry should also be established, and the use of recyclable raw materials promoted on a wide scale.

(5) The development of intelligent networked vehicles should be promoted to accelerate the development of smart cars, accelerate infrastructure development, and further expand industrial cooperation.

(6) Big data, the Internet, and artificial intelligence should be used to reduce CO₂ emissions during automobile usage.