CO2 and pollutant emissions from passenger cars in China

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Mar 2, 2011 - b School of Environment, Tsinghua University, Beijing 100084, PR China c Institute for Climate and ..... emissions from gasoline PCs are lower compared to current diesel cars, PM10 ..... China Automotive Industry Yearbook.

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CO2 and pollutant emissions from passenger cars in China Haikun Wang a,b,c, Lixin Fu b, Jun Bi a,c,n a b c

State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Nanjing 210046, PR China School of Environment, Tsinghua University, Beijing 100084, PR China Institute for Climate and Global Change Research, Nanjing University, Nanjing 210046, PR China

a r t i c l e i n f o

a b s t r a c t

Article history: Received 1 November 2010 Accepted 2 March 2011

In this paper, CO2 and pollutant emissions of PCs in China from 2000 to 2005 were calculated based on a literature review and measured data. The future trends of PC emissions were also projected under three scenarios to explore the reduction potential of possible policy measures. Estimated baseline emissions of CO, HC, NOx, PM10 and CO2 were respectively 3.16  106, 5.14  105, 3.56  105, 0.83  104 and 9.14  107 tons for China’s PCs in 2005 with an uneven distribution among provinces. Under a no improvement (NI) scenario, PC emissions of CO, HC, NOx, PM10 and CO2 in 2020 are respectively estimated to be 4.5, 2.5, 2.5, 7.9 and 8.0 times that of 2005. However, emissions other than CO2 from PCs are estimated to decrease nearly 70% by 2020 compared to NI scenario mainly due to technological improvement linked to the vehicle emissions standards under a recent policy (RP) scenario. Fuel economy (FE) enhancement and the penetration of advanced propulsion/fuel systems could be cobenefit measures to control CO2 and pollutant emissions for the mid and long terms. Significant variations were found in PC emission inventories between different studies primarily due to uncertainties in activity levels and/or emission factors (EF). & 2011 Elsevier Ltd. All rights reserved.

Keywords: Air pollution CO2 emissions Passenger car

1. Introduction Because of economic growth and accelerating urbanization in China, the vehicle population has increased rapidly and road vehicles are becoming one of the major sources of CO2 and pollutant emissions (Yan and Crookes, 2007). However, China’s per capita ownership of road vehicles, especially passenger cars, is still much lower than that of developed countries and the world average level so the potential for future growth is very high (Wang et al., 2006; Yan and Crookes, 2010). The population of passenger car (PC) in China increased by a factor of 2.8 between 2000 and 2005, compared with a per capita GDP increase of only 1.2 (Han and Hayashi, 2008; NBS, 2001–2010). Because PCs use a substantial amount of fossil fuel and produce significant CO2 and pollutant emissions, it will be a challenging task for China to provide enough fuel to satisfy this rapid vehicle growth and prevent a decline in air quality. According to Yan and Crookes (2009), energy demand for China’s road transport increased from 57 to 86 Mtoe (million tons of oil equivalent) and associated CO2 emissions grew from 169 to 255 Mt between 2000 and 2005. The private PCs are found to contribute to nearly half of the increases.

n Corresponding author at: School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing 210046, PR China. Tel./fax: þ 86 25 89680533. E-mail addresses: [email protected] (H. Wang), [email protected] (J. Bi).

With the rapid increase of vehicle population, vehicular emissions were found to be major sources of air pollutants such as CO, NOx, VOC and PM in many cities (Barletta et al., 2005; Bo et al., 2008; Liu et al., 2008; Xie et al., 2008; Yi et al., 2007). An increase of nitrogen dioxide in the troposphere over China has also been recently observed from space (Richter et al., 2005). The hourly average concentrations of O3 frequently exceeded the second class of the national ambient air quality standards in Beijing, Guangzhou and Shanghai during spring and summer between 2000 and 2005. As these pollutants are closely related to the vehicular emissions and due to the high potential for future growth of PCs, it is necessary to establish the emission inventory of PCs, analyze their distribution and project future emission trends. Since there are no statistical data available for CO2 or pollutant emissions from road vehicles in China, a number of studies have estimated China’s vehicle emissions in recent years (Cai and Xie, 2007; Han and Hayashi, 2008; He et al., 2005; Streets et al., 2003; Wang et al., 2007; Yan and Crookes, 2009; Zhang, 2005). However, these studies usually separated the estimation of vehicular CO2 and pollutant emissions, and either calculated vehicular emissions for a specific year or for a past period of time. A similar approach was applied in previous studies to derive the energy demand from three factors: vehicle population, fuel economy (FE) and vehicle kilometers traveled (VKT). CO2 emissions were calculated based on the assumption that all of the carbon in the fuels was converted into CO2.

0301-4215/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2011.03.013

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Compared to existing vehicular emissions inventories in China, our study has the following major characteristics: (1) CO2 and pollutant emissions were studied simultaneously for PCs in China; (2) the emission factors of air pollutants and CO2 were evaluated based on a literature review, portable emissions measurement system (PEMS) data and the COPERT IV model, which enhances the inventory relative to the on-road values and (3) the future reduction potentials of PC emissions were analyzed under various scenarios.

2. Methodology The emissions of CO2, CO, HC, PM10 and NOx for PCs were evaluated based on VKT and emission factors. The emissions at the provincial level were estimated and aggregated to represent the national inventories for PCs in the years 2000–2009, using Eqs. (1) and (2). Scenario analysis of PCs’ future emission trends were calculated at the national level. Qp,i ¼ EFp,i  VKTp  Sp  106 Qi ¼

X

ð1Þ

Qp,i

ð2Þ

where Qp,i represents the emissions of pollutant i for PCs in province p, tons; EFp,i is the emission factor of pollutant i in province p, g/km; Sp is the stock of PCs in province p; VKTp is the annual mileage of PCs in province p, km and Qi represents the total emissions of pollutant i for PCs in China, tons. The emissions from PCs in Hong Kong, Macao and Taiwan were not calculated in this study. EFs of PCs were calculated separately for Beijing and Shanghai (provincial-level cities) because of the different vehicle emission standards implemented in these two cities. Table 1 shows the

specific timetable for the application of vehicle emission standards in China and the European Union (EU). The other provinces used similar emission factors at national average level. Euro 5 emission standards for PCs in China were assumed to be implemented in 2013. 2.1. Population of passenger cars in China The data regarding the provincial or national population of PC from 2000 to 2005 were obtained from official statistical yearbooks (CAIA, 1997–2006; NBS, 2001–2010). Fig. 1 shows the proportion of PC in each province in China 2005. It shows that the distribution of PCs is unbalanced. Beijing, Shanghai, Jiangsu, Zhejiang, Shandong and Guangdong are the most developed areas in China, while accounting for only 6% of the country’s territory; however, they include nearly 25% and 45% of the total human and PC populations, respectively. On the other hand, the western and inland regions containing over 60% of the territory and human population represent only 20% of the PC population. Using Gompertz curve (Dargay and Gately, 1999) and based on the trends of human population and per capita GDP in China (NBS, 2001–2010), the future stock of highway vehicles (HWV, including passenger cars, buses and trucks) has been forecast as shown in Fig. 2. Fig. 2 illustrates that the PC population may reach 159 million in 2020, which is over 30 times the amount in 2000. The proportion of PC to the total HWV will continue to increase from 30% in 2000 to nearly 70% in 2020. Our projections are closed to the results (146 million) of business-as-usual scenario in Ng and

2020

Emission China standards Nationwide Beijing Shanghai

EU

Pre Euro 1 Euro 1 Euro 2 Euro 3 Euro 4 Euro 5

1973 17 1992 8 1996 8 2000 7 2005 5 2009 4

1990 2000 2004 2007 2010 2013

1990 1999 2004 2005 2008 2013

1990 1999 2004 2007 2009 2013

Difference between China and EU (years)

Year

2015 Table 1 Timetable of vehicle emission standards in China and European Union.

63

159

46

89

2010

33

41

2005 13 18

PCs Other HWVs

2000 5 11 0

40

80 120 160 Vehicle stock (million)

200

240

Fig. 2. Trend of PC population in China until 2020.

Percentage of PC stock

12% 10% 8% 6% 4% 2% 0%

Fig. 1. Distribution of PC’s population at the provincial level in China, 2005.

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Schipper study (2006) and much higher than the results (93 million) of high-growth scenario in Wang et al. study (2006). Therefore, the projected population of PC in this study is relatively optimistic. 2.2. Annual vehicle kilometers traveled of passenger cars In the previous studies, one average value for the annual VKT of PC was usually applied throughout the country to establish a national vehicle emission inventory. However, there are differences from one province or city to another for the diverse driving habits, urban size, PC ownership, economical development, etc. VKT of PCs for each province in China was acquired based on Wang et al. (2010, 2008c), Yao et al. (2007) and The First Census of Pollution Source in China. The national average VKT was calculated using a weighting average method based on the PC stock in each province and compared with other studies. Fig. 3 illustrates the annual average VKT of PC in China in various studies (Borken et al., 2008; Cai and Xie, 2007; He et al., 2005; Li et al., 2003; Wang et al., 2006), which shows that most annual average VKT estimates are within the range from 20,000 km to 35,000 km. The annual VKT (29,000 km) of China’s PC used in this study is much higher than that in developed countries, which lie mainly in a range of 10,000–18,000 km (Han and Hayashi, 2008). This may be explained by the difference in the composition of PC between China and developed countries. For example, PC ownership rate (vehicles/1000 people) is very low in China while government and company used vehicles represent a high proportion of the PC stock. These kinds of PCs are usually driven more frequently than private cars and hence are in higher VKT. Since there are no published data of annual VKT for China’s PCs in the future, we assume that the annual average VKT for PCs will decline with the rapid increase of private PCs and increasing fuel prices. The annual VKT of PC in 2010, 2015 and 2020 is estimated as 26,000, 23,000 and 20,000 km, respectively. 2.3. Scenarios analysis Three different scenarios are employed to simulate future CO2 and pollutant emissions for the PCs in China. They are, respectively, no improvement (NI) scenario, recent policy (RP) scenario and a comprehensive policy (CP) scenario. In the NI scenario, the EF of new PC will remain at the level in 2005. It means that Euro 1 and 2 were, respectively, implemented in 2000 and 2004 according to the timetable of vehicle emission standards in China (see Table 1), and no further policies or measures were implemented to control vehicle emissions after 2005.

Annual VKT (1000 km)

60 50 40 30 20 10 0

He et Wang et Borken et Cai and Li et al, 2005 al, 2006 al, 2008 Xie, 2007 al, 2003

This study

Fig. 3. Annual VKT of PC in China during the period from 2000 to 2005.

3

In the RP scenario, it is assumed that the Chinese government will fully implement the new emission standards according to the schedule in Table 1. Euro 3 and 4 will be implemented in China in 2007 and 2010, respectively. We assumed that Euro 5 will be introduced in 2013. In the CP scenario, we project the future emissions from PC using a combination of regulatory measures and policies. Along with the more stringent emission standards used in the RP scenario, FE improvement and the penetration of advanced propulsion/fuel systems of PC are also integrated. The FE improvement measures will be carried out in three phases: 2010, 2013 and 2018, which are similar to He et al. study (2005), and in each phase FE will be improved by 20%, 10% and 10% of new PC relative to the previous period. In 2009, the Chinese government initiated a program named ‘‘Ten cities and Thousand Vehicles’’, which plans to select over 10 cities and to introduce more than 1000 HEVs and EVs in each of the selected cities in three years with government subsidy. Thirteen cities were selected to participate in this program, and the number of cities is increasing. China is considered to be a very promising market for EVs (Huo et al., 2010). Therefore, an optimistic development of HEV was assumed in China. Based on EPRI (2007), we assumed the market share of hybrid electric vehicle (HEV) among the new PC will reach 15% and 20% in the year 2015 and 2020 in China, respectively. 2.4. Emission factors of PC PEMS has been used to test vehicular fuel consumption and emissions on the road by Tsinghua University in many Chinese cities during recent years (Wang et al., 2008a; Wang and Fu, 2010; Yao et al., 2007). In this study, the emissions factors of PCs from 2000 to 2009 were calculated based on the PEMS data, and the COPERT IV model, which has already been applied in our previous studies (Wang, 2010; Wang et al., 2010), was applied to project PC emissions in the future under various scenarios. Table 2 illustrates the emission factors of PC under three different policy scenarios in this paper.

3. Results and discussion 3.1. Emissions inventory of PC in 2005 Vehicular emissions of CO, HC, NOx, PM10 and CO2 were respectively calculated to be 3.16  106, 5.14  105, 3.56  105, 0.83  104 and 9.14  107 tons for China’s PC in 2005, which are lower than Cai and Xie calculations (2007) due to differences in annual VKT. As shown in Fig. 3, the VKT used in Cai et al.’s study is significantly higher than in other studies, and is nearly twice as high as that used here. The spatial distribution of pollutant emissions is illustrated in Fig. 4, which provides a map of estimated 2005 CO2 emission intensities from PC at the provincial level. The distribution of other emissions is similar to CO2. The map illustrates that the distributions of PC’s emissions are quite uneven in China, with emission intensity decreasing considerably from the eastern and coastal regions to the western and inland areas. This is consistent with the expected imbalance in economic development and PC population (as shown in Fig. 1) among regions. The Beijing– Tianjin–Hebei region, Yangtze River Delta (including Shanghai, Jiangsu and Zhejiang province), and Pearl River Delta (Guangdong province) are the three most developed regions in China and are also the regions most affected by vehicular pollution (Wang et al., 2010). They cover only 2.3%, 2.2% and 1.9%, respectively, of

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Chinese territory, while generating about 16.8%, 17.1% and 11.3%, respectively, of the PC emissions in 2005. Fuel consumption of PC was also calculated in this study based on the PEMS data (Wang, 2010). It shows that PC consumed 2.9  107 tons of fuel in China for the year 2005. According to the projection by He et al. (2005), the total fuel consumption of China’s on-road vehicles, which included the motorcycles, was nearly 9.0  107 tons in 2005. Therefore, PC should account for nearly 30% of the fuel consumption of total on-road vehicles. 3.2. Emissions of PC in the future 3.2.1. Projection of pollutant emissions Fig. 5 illustrates that each pollutant emissions of PC in China will show different trends under the three scenarios. The total VKT of PC will increase by 2020 to over 20 times the 2000 level at an annual rate of 16.5%. Under the NI scenario, the emissions of CO, HC and NOx are estimated to increase from 2.71  106, 4.68  105 and 2.16  105 tons in 2000 to 1.43  107, 1.27  106 and 8.79  105 tons in 2020 at an annual average rate of 8.7%, 5.1% and 7.3%, respectively, which are smaller than the growth rate of

Table 2 Average EFs of PC in China under three different policy scenarios, g/km. Scenarios

Pollutants

2000

2005

2010

2015

2020

NI

CO HC NOx PM10 CO2

18.50 3.19 1.47 0.023 246

8.25 1.34 0.93 0.022 238

5.36 0.71 0.49 0.021 230

4.78 0.47 0.32 0.021 230

4.54 0.40 0.28 0.021 230

RP

CO HC NOx PM10 CO2

18.50 3.19 1.47 0.023 246

8.25 1.34 0.93 0.022 238

4.13 0.50 0.44 0.021 217

1.77 0.20 0.20 0.02 224

1.12 0.12 0.09 0.018 214

CP

CO HC NOx PM10 CO2

18.5 3.19 1.47 0.023 246

8.25 1.34 0.93 0.022 238

4.13 0.49 0.44 0.021 217

1.68 0.18 0.18 0.018 179

0.93 0.09 0.08 0.015 140

VKT. This is mainly due to the implementation of Euro 1 and 2 emission standards for the new PC in China that decreases the emission factors significantly. But the effect of Euro 1 and 2 emission standards will soon be counteracted by the rapid growth in PC population if there are no more stringent emission standards implemented after 2005. Pollutant emissions will increase substantially after 2010. Under the RP scenario, due to the introduction of Euro 3, 4 and 5 emission standards (as shown in Table 1), CO, HC and NOx emissions for PC in 2020 will be 3.54  106, 3.79  105 and 2.84  105 tons, achieving the reduction rates of 75.3%, 70.1% and 67.6% compared to the NI scenario, and comparable and even lower compared to the estimations of the 2000 baseline. The pollutant emissions of PC in 2020 will be further reduced by 10– 20% under the CP scenario compared to the RP scenario. As more PCs are equipped with advanced propulsion or fuel systems in the future, the reduction potential of the CP scenario will become more apparent. As 98% of PCs in China use gasoline as fuel and PM10 mass emissions from gasoline PCs are lower compared to current diesel cars, PM10 emissions from gasoline PCs are usually ignored. However, PM10 is the most important pollutant from a health or cost perspective, thus it was calculated in this study. As illustrated in Fig. 5, PM10 shows different trend characteristics compared to the other three pollutants. PM10 emissions from PCs are estimated to increase continuously under various scenarios with a growth rate of  16% from 2000 to 2020, which is similar to the growth rate of VKT. This illustrates that the stringent vehicle emission standards have little impact on PM10 emission factors of gasoline PCs. It should be noted that we are not optimistic about the prospect of diesel car when we project the future population of PC in China. There are several key factors to hinder the development of diesel cars in China. First, China’s diesel qualities are far behind the quality requirement of the clean diesel cars. As we know, clean diesel engines have to use clean diesel to reach the stringent emission standards. But the sulfur content of diesel sold in China is 350–500 ppm, which is much higher than the level in Europe (10 ppm). And China’s diesel quality requirements for the Euro 4 emission standard have not yet been published. Second, over the last decade, China’s diesel–gasoline ratio has shown a rising trend, but the market still cannot meet the increasing

Fig. 4. Spatial distributions of CO2 emission intensity (ton/km2) for China’s passenger cars in the year 2005.

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1500

800

RP scenario CP scenario

900 600 300 0 2000

2005

2010

2015

2020

CO2 emission (106 ton)

CO emission (104 ton)

NI scenario

1200

5

640

NI scenario RP scenario CP scenario

480 320 160

Year

0

NOX emission (104 ton)

100

2010 Year

2015

2020

Fig. 6. Annual emissions of CO2 for China’s passenger cars, 2000–2020.

40

4.0

3.2.2. Projection of CO2 emissions Fig. 6 shows that annual CO2 emissions by PCs will continue to increase dramatically even under CP scenario, because improvements in the FE of new vehicles will not offset the rapid increase in the PC population. However, vehicle FE improvements and penetration of new technology vehicles in China could make a significant contribution to saving oil and consequently in reducing CO2 emissions. Under the NI scenario, CO2 emissions from China’s PCs will increase at an average annual growth rate of 16.2% and reach 728 million tons in 2020, which is 20 times that of the year 2000. Under the CP scenarios, PC’s CO2 emissions will be 442 million tons in the year 2020, resulting in a 39.1% reduction compared to the NI scenario. It should be noted that, for the different objectives of air pollution and energy conservation controls, the policies and measures to reduce air pollutant emissions may not result in reduction in CO2 emissions, and vice versa. As shown in Figs. 5 and 6, the stringent emission standards aim to reduce pollutant emission levels from PCs in China, basically have no effects on the reduction of CO2 emissions. The CP scenario shows that FE improvement could reduce CO2 emissions significantly, but has little effect on reducing pollutant emissions before 2020. As vehicular pollutants and CO2 emissions are both becoming big challenges for the cities in China, synergetic control policies or measures of air pollutants and CO2 emissions should be paid more attention to realize the co-benefit.

2.0

3.3. Uncertainty analysis

20

2005

2010

2015

2020

2015

2020

Year 150

HC emission (104 ton)

2005

60

0 2000

120 90 60 30 0 2000

2005

2010

Year 8.0

PM10 emission (104 ton)

2000

80

6.0

0.0 2000

2005

2010

2015

2020

Year Fig. 5. Annual emissions of CO, HC, NOx and PM10 for China’s passenger cars, 2000–2020.

demand for diesel, often leading to a shortage of diesel supply phenomenon. For example, a serious diesel shortage swept China at the end of 2010. To a certain extent, this also limits the development of diesel cars. Last but not least, with the growing concerns in energy safety and environmental issues, various alternative and clean sources of energy, such as hybrid electric vehicle (HEV) and electric vehicle (EV), have already been developed by the automobile industry in China. And they have also been paid more attention to in China’s 12th Five Year Plan. As diesel cars still use the traditional fossil fuel, it is very hard for them to attract the supporting policies from government.

Although there are no published data of CO2 or pollutant emissions specific for the PCs in China, several other studies have calculated total vehicular emissions (Cai and Xie, 2007; He et al., 2005; Wang et al., 2007) or included vehicular emissions as part of an inventory covering other economic sectors as well (Streets et al., 2003; Zhang, 2005). Fig. 7 shows the differences of other studies relative to our emission inventory in the base year 2000. It shows that apparent variations exist between our study and other published results, except for CO2 emissions. CO2 emissions estimated in various studies are mainly centralized in the range from 25 to 40 million tons, except for the research by Cai and Xie (2007). Cai and Xie calculated more than twice as much CO2 emissions as other studies. Their higher CO2 emissions reflect the high travel activity (as shown in Fig. 2), which was assumed by taking mileages recorded in Beijing as the national average. It seems that this resulted in a significantly higher estimation. For the other inventories, differences in the assumed VKT and FE balance each other and total CO2 emissions are within 730% of

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Fig. 7. Emission estimates for China’s passenger cars in the year 2000 relative to this study.

our estimate. For example, the FE (16.2 L/100 km) used in Han and Hayashi study (2008) is over 100% higher, however, their VKT (14,000 km) is 50% lower than the values used here. Total emissions of CO, HC and NOx for PC show significant variations among different inventories. This may be explained by the different activity levels, and by different emission factors applied in each study. The US EPA’s MOBILE model was usually applied to calculate vehicular emission factors in China. This may result in a higher estimation of pollutant emissions for PC because substantial differences exist in vehicle fleet composition and emission characteristics between China and USA. For example, the passenger cars used in USA usually have lager engine displacement, which will consequently result in higher emission factors, especially for CO2 and NOx (Wang et al., 2008b). This is why our calculations of PCs pollutant emissions are lower than that in Han and Hayashi (2008), Zhang (2005) and Street et al. (2003) studies. Furthermore, the detailed vehicle activity data are different in each study. The higher emission estimations are mainly caused by the higher VKT used in the Cai and Xie study (2007) because they also calculated vehicular emission factors by using the COPERT model.

4. Conclusions PC pollutants and CO2 emissions have grown rapidly from 2000 to 2005, and are distributed unevenly in China. The emissions are mainly concentrated in eastern China, which coincides with China’s unbalanced state of economic development. The Beijing–Tianjin–Hebei region, Yangtze River Delta, and Pearl River Delta are the three most developed regions in China, which cover only 6.4% of the Chinese territory, but generate nearly 50% of the PC emissions. The total VKT of PC will undoubtedly increase in China in the near future. However, the implementation of Euro 3 and 4 achieved 10–30% reduction of CO, HC and NOx emissions from PC in 2010 compared to the NI scenario. If Euro 5 can be further implemented in 2013, CO, HC and NOx emissions from PC in 2020 will be comparable and even lower to the emissions levels in 2000. But these policies seem to have little effect on CO2 emission, which illustrates that the policies and measures to reduce air pollutant emissions may not result in reduction in CO2 emissions. Therefore, FE improvement and the penetration of advanced propulsion/fuel systems of the PC should be considered to reduce CO2 and pollutant emissions simultaneously for mid and long terms. Total emissions for China’s PC show significant variations between different studies, which are mainly caused by the

different activity levels and/or emission factors. However, exceptionally high or low emission factors or VKT in some inventories would require further justification. The differences between inventories may not be adjusted by a simple scaling, e.g. to a common fuel consumption value; they could also result from different assumptions about the underlying technology as reflected by the widely different emission factors. Some defects in this study should be noted and improved in the future. For example, PC emissions in the future are projected based on the assumption that fuel quality in China is adequate to support implementation of more stringent emission standards. Actually, this will be a big challenge to the fuel suppliers in China. The application of COPERT model to estimate the future emission factors will also introduce some uncertainties. The activities of household, company and government used PCs should have various characteristics, which need further research on.

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Please cite this article as: Wang, H., et al., CO2 and pollutant emissions from passenger cars in China. Energy Policy (2011), doi:10.1016/j.enpol.2011.03.013