Since conventional internal combustion engine vehicles (hereinafter referred to as ICEs), currently the mainstream vehicles, constitute one of the main factors contributing to climate change and urban air pollution. In the development of sustainable transportation, battery electric vehicles (hereinafter referred to as EVs) are highly expected. The replacement of ICEs by EVs is considered as one of the key pathways for the transport system to achieve a low carbon transition. However, in recent years, the debates on whether EVs are truly environmentally friendly and low carbon has been going on. Relevant studies considering important influencing factors such as different incentive policies, industrial manufacturing technologies, power system mix, battery life and battery recycling technology, have brought light to discussion. Most of these studies use Life Cycle Assessment (LCA) to compare the advantages and disadvantages of EVs, ICEs and vehicles using other technologies in terms of carbon emissions, public health impacts and ecological impacts. Based on a review of recent studies, this paper considers China’s fast-developing EV market in recent years and proposes relevant policy recommendations related to sustainable transportation development in China.

Are EVs really green? A process of continuous knowledge gaining

Studies on whether EVs meet sustainable development goals are mainly focused on the following influencing factors: impacts on climate change, impacts on human health, and impacts on environmental ecosystems. To compare the advantages and disadvantages of EVs and ICEs based on LCA, studies not only need to calculate the emissions of pollutants and greenhouse gases in the collection process (such as mining) of automotive raw materials and battery raw materials, and those in the automotive production process, but also the various impacts generated in automotive recycling and battery recycling and disposal, as well as the carbon emissions and pollutant emissions of the power system in the whole process. Such studies will include new factors as people’s knowledge increases. Therefore, it is a dynamic process to assess whether EVs are truly green, one that varies with different policy, technological, environmental, social and economic factors. However, existing studies show that replacing ICEs with EVs is in line with sustainable transportation development in general.

A report published by Norwegian researchers in 2013¹ compared the environmental impacts of EVs and ICEs based on LCA (production, use and scrapping of automobiles). For the production phase, the research team built a unified non-powertrain system framework to compare the environmental impacts of the main components of EVs and ICEs. The EVs which are chosen in the research project are those with LNCM battery (214 kg) and LiFePO4 battery (273 kg); for the use phase, the team adopt the industrial performance test specifications required under the EU driving cycle rules, taking into account factors such as vehicle size, performance, tires and transportation losses; for the scrapping phase, the team use the transport model built by the Argonne National Laboratory of the United States to assess the environmental impacts of automotive recycling and disposal. Battery scrapping of EVs include the environmental impacts of battery dismantling and cryogenic grinding.

The environmental impacts analyzed in this study included ten aspects: climate change potential, land acidification potential, particulate matter emission/forming potential, photochemical oxidation potential, human toxicity potential, freshwater ecotoxicity potential, land ecotoxicity potential, freshwater eutrophication potential, mineral resources depletion potential, and fossil fuels depletion potential. The main findings of the study indicate that the environmental impacts of EVs are primarily determined by the carbon intensity of the electricity consumed during their production and use. The study points out that extending the life of vehicles and batteries and making the power system cleaner and more low carbon is an important way to reduce the environmental impacts of EVs.²

It requires deeper studies from comparing environmental impacts to understanding health impacts based on LCA. To some extent, assessing public health impacts is more complicated, which not only needs to classify the specific health impacts (from various physical health problems to and mental health ones), but also figure out how to quantify health impacts so as to compare which type of vehicles causes greater health burden or risks. Thanks to plenty of quality studies in assessing the health impacts of air pollution, debating the air pollution impacts of EVs and ICEs based on LCA are more relevant and targeted. The research findings can provide direct support for policy options. A study published by the National Academy of Sciences in 2014³ is just a response to such needs.

The study was conducted in the context of automotive technology, automotive production and use in the transport and energy systems of the United States. It mainly discusses the differences of different types of vehicles in the emissions of inhalable fine particulate matters and ozone (the two types of pollutants are the most important factors causing health issues), and focused on emissions from the use of vehicles. It also analyze the generation of the two types of pollutants in the production of the “fuels” (such as electricity, fossil fuel and biomass fuel) used by automobiles. Because automotive scrapping (recycling and disposal) generates pollutants much less than those from manufacturing and use on road, it was not analyzed in the study. The study conclude that EVs solely using coal power cause the largest and most serious air pollution, followed by ICEs (including gasoline and diesel vehicles) and EVs solely using natural gas power and hybrid EVs (with both conventional internal combustion engine and rechargeable batteries), respectively. EVs solely using renewable energy power cause the smallest air pollution. The study points out that when the power system still relies mainly on coal power, the development of EVs actually makes more contributions to air pollution.⁴

The future of EVs: In a context of broader social, economic and technological conditions 

When comparing the environmental, health and social impacts of EVs and ICEs based on LCA, one cannot ignore two points: first, as mentioned in the first piece on sustainable transportation decision-making framework in this review report, the development of the transport system is closely tied with all aspects of society and economy. For example, as people pay more attention to climate change and air pollution control, EVs will be more popular. Or, with more people-oriented urban planning and design, people will have shorter travel distances and better mobility services, and accordingly, will be more inclined to choose electric public buses; second, technological innovation and application will also influence the role of EVs in the development of sustainable transportation. When technologies for the design, performance, recycling and disposal of EV batteries become more cost-effective and environmentally friendly, in addition to existing advantages over ICEs in terms of carbon emission reduction and urban air quality improvement, EVs will also fill the gap in public health and environmental health impacts. A new study discusses this issue and demonstrates how to make EVs more competitive in the transition to a sustainable transport system in the context of a circular economy.⁵ The report specifically mentions that EV development needs to focus on the following aspects: vehicle design, use, battery reuse, recycling and the power system mix. In addition, there are studies and experiments exploring the second life-energy storage application of decommissioned EV batteries, because these batteries still have considerable energy capacity, which, according to relevant data, can reach 60% or higher of the capacity of a new battery.⁶If significant technological progress is made in extending the battery life, this will significantly reduce the carbon emissions of EVs in their life cycle. A study reviews the existing new developments in EVs battery technologies and estimates the emission reduction potential of new technologies, as shown in Table 1.

Table 1: Potential for Carbon Emission Changes from Technological Progress in the Production and Use of EV Batteries

Note: A negative number denotes the potential for emission reduction, and a positive number denotes the potential for increasing emissions.

Source: Effects of Battery Manufacturing on Electric Vehicle Life-cycle Greenhouse Gas Emissions, Dale Hall and Nic Lutsey. The International Council on Clean Transportation, 2018. p 10. Link: https://theicct.org/sites/default/files/publications/EV-life-cycle-GHG_ICCT-Briefing_09022018_vF.pdf

Therefore, we need to constantly pay attention to studies on the various life cycle impacts of EVs. However, according to most of the existing research findings,⁷ EVs have definite advantages in reducing carbon emissions and air pollution in sustainable transportation development. Of course, the key conditions of the grid power structure mentioned above are indispensable.

From the perspective of effective pollution control, EVs have certain advantages over conventional ICEs. Most of the pollutant emissions of conventional vehicles occur during the use of the vehicles, which is a typical mobile source pollution and relatively hard to control. The pollutant emissions of EVs mainly occur during the production and recycling of the vehicles and their batteries, as well as during the energy resource exploitation and power generation for the electricity used. EVs do not emit pollutants during driving. The pollution of EVs mainly come from manufacturing and recycling, which are point sources pollution and are relatively easy to control. Therefore, as long as the power system is transformed into a renewable energy-dominated power system, the environmental and public health benefits of EVs will be very significant. However, no matter how much oil refining technology and fuel efficiency are improved, large-scale mobile source pollution is unavoidable from the operation of ICEs. Once pollutants are discharged into the air, they will undergo complex photochemical reactions and generate photochemical smog (secondary pollutant), including ozone and secondary particulate matter (PM_2.5), which obviously increases the difficulty of control.

Developing EVs: the challenge for China is to achieve low carbon development of power system as soon as possible

As mentioned earlier, the largest share of the life cycle carbon emissions of EVs comes from electricity consumption, so, the carbon intensity of the power system is the biggest factor influencing the carbon emission level of EVs. A study shows that with other conditions unchanged, and putting EVs used in the power systems of different countries in the life cycle, which means the proportions of renewable energy power and fossil energy power in the power systems of these countries are different, the carbon emission levels of EVs are also quite varied in these countries, as shown in Figure 1. Seen from the average carbon intensity of the power grids in the EU, EVs life cycle carbon emissions are significantly lower than those of the most energy-efficient conventional vehicles. However, if EVs were used in individual countries, their carbon emission levels are quite different. Since France is dominated by nuclear power and Norway by hydropower, the use of EVs in these two countries can bring the biggest carbon emission reduction compared to ICEs. In Germany, the use of EVs had the same climate change impact as the most energy-efficient ICEs. In other words, given the power mix of Germany in 2015, the replacement of the most energy-efficient ICEs by EVs had no carbon emission reduction effect.

Figure 1: Comparison of Life Cycle (over 150,000 km of mileage) Carbon Emissions of EVs and Conventional Vehicles in Europe in 2015

Source: Effects of Battery Manufacturing on Electric Vehicle Life-cycle Greenhouse Gas Emissions., Dale Hall and Nic Lutsey. The International Council on Clean Transportation, 2018. Figure 1. p 5. Link: https://theicct.org/sites/default/files/publications/EV-life-cycle-GHG_ICCT-Briefing_09022018_vF.pdf

The power mix directly influences the carbon emission reduction effect of the replacement of ICEs by EVs. Compared with Germany, China homes a power mix heavily dependent on coal. According to the BP Energy Statistics Yearbook (2018), there was a significant gap between the power generation structures of Germany and China in 2017 (shown in Table 2). Low carbon power sources, including nuclear, hydro, and renewable energy, were as high as 45% in Germany, while in China, the proportion was 29%. The power source with the highest carbon intensity is coal. Due to the high dependence on coal in its history, 37% of the electricity generated in Germany was still based on coal by 2017. The proportion in China was as high as 67%. From this point of view, at present, there is no carbon emission reduction effect from replacing ICEs with EVs in China. Of course, China’s rapidly developing EV market in recent years may stimulate the economy, increase employment, enhance technological innovation and reduce the growth rate of urban air pollutant emissions from the road transport sector.

Table 2: Comparison of Power Generation Structures in Germany and China (2017)

   book

Conclusions

As climate change becomes increasingly urgent, we see more and more countries and policy makers setting the rapid development of EVs as a way to deal with climate change in the transport sector. Seen from the intrinsic requirement of the energy system to go low carbon (that is, quitting fossil energy and using renewable energy), such a strategy is reasonable. Particularly, in the long term, a lot of LCAs on the impacts of EVs on climate change, ecological environment and public health show that the development of EVs is the best available way to achieve sustainable transportation in the future. However, in order to effectively realize the carbon emission reduction effect from replacing ICVs with EVs, those countries whose power systems are heavily dependent on coal should decarbonize the power systems in priority or in the first place. On top of that, it may make sense to realize the role of ECs in sustainable transportation development.

References

1. Troy R. Hawkins, et al., 2013. Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles, Journal of Industrial Ecology, 17(1), pp. 53-64.

2.Wang Yiyi, 2015. Debate over Environmental Impacts of Electric Vehicles: Energy Efficiency and Clean Power Remain Decisive Factors. Website of Rock Environment and Energy Institute. Link: http://www.reei.org.cn/blog/552

3.C. W. Tessuma, et al., 2014. Life Cycle Air Quality Impacts of Conventional and Alternative Light-duty transportation in the United States. Link: https://www.pnas.org/content/111/52/18490

4.Wang Yiyi, 2015. Public Health Impacts: Corn Ethanol Vehicles and 100% Coal Power Battery Electric Vehicles are Worse than Gasoline Vehicles. Website of Rock Environment and Energy Institute. Link: http://www.reei.org.cn/blog/547

5.European Environment Agency, 2018. Electric Vehicles from Life Cycle and Circular Economy Perspectives. EEA Report No 13/2018.

6.Effects of Battery Manufacturing on Electric Vehicle Life-cycle Greenhouse Gas Emissions, Dale Hall and Nic Lutsey. The International Council on Clean Transportation, 2018. p 10. Link: https://theicct.org/sites/default/files/publications/EV-life-cycle-GHG_ICCT-Briefing_09022018_vF.pdf

7.Transport & Environment, 2017. Electric Vehicle Life Cycle Analysis and Raw Material Availability. A Briefing by Transport & Environment. Link: https://www.transportenvironment.org/sites/te/files/publications/2017_10_EV_LCA_briefing_final.pdf