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The role of transport electrificationin global climate change mitigationscenarios

Zhang, Runsen; Fujimori, Shinichiro

Zhang, Runsen ...[et al]. The role of transport electrification in globalclimate change mitigation scenarios.

2020-03

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Environmental Research Letters

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Environ. Res. Lett. 15 (2020) 034019 https://doi.org/10.1088/1748-9326/ab6658

LETTER

The role of transport electrification in global climate changemitigation scenarios

RunsenZhang1 and Shinichiro Fujimori2

1 Graduate School for International Development andCooperation,HiroshimaUniversity, 1-5-1Kagamiyama,Higashi-Hiroshima7398529, Japan

2 Department ofUrban and Environmental Engineering, KyotoUniversity, 361KyotoUniversity Katsura Campus,Nishikyo-ku, Kyoto6158540, Japan

E-mail: rzhang@hiroshima-u.ac.jp

Keywords: transport electrification, electric vehicles, cross-sectoral interaction, energy consumption,mitigation cost

Supplementarymaterial for this article is available online

AbstractElectrification is widely considered an attractive solution for reducing the oil dependency andenvironmental impact of road transportation.Many countries have been establishing increasinglystringent and ambitious targets in support of transport electrification.We conducted scenariosimulations to depict the role of transport electrification in climate changemitigation and how thetransport sector would interact with the energy-supply sector. The results showed that transportelectrificationwithout the replacement of fossil-fuel power plants leads to the unfortunate result ofincreasing emissions instead of achieving a low-carbon transition.While transport electrificationalonewould not contribute to climate changemitigation, it is interesting to note that switching toelectrified road transport under the sustainable shared socioeconomic pathways permitted anoptimistic outlook for a low-carbon transition, even in the absence of a decarbonized power sector.Another interesting findingwas that the stringent penetration of electric vehicles can reduce themitigation cost generated by the 2 °C climate stabilization target, implying a positive impact fortransport policies on the economic system.With technological innovations such as electrified roadtransport, climate changemitigation does not have to occur at the expense of economic growth.Because a transport electrification policy closely interacts with energy and economic systems,transport planners, economists, and energy policymakers need towork together to propose policyschemes that consider a cross-sectoral balance for a green sustainable future.

1. Introduction

The transport sector accounts for approximately aquarter of global greenhouse gas (GHG) emissions and isone of the major sectors where emissions are still rising[1–4]. Within the transport sector, road transport is byfar the biggest emitter, accounting for more than half ofall transport-related GHG emissions. Rapidly growingmobility needs and private vehicle ownership counteractthe global efforts to reduce global GHG emissions fromtransport [5]. Due to society’s persistent reliance on fossilfuels, the reduction of global GHG emissions fromtransport to limit the magnitude or rate of long-termclimate change will be more challenging than in othersectors [6, 7]. Low-carbon vehicles, powered by

electricity, offer an alternative to conventional fossil-fueltechnologies, and switching to electricity for road trans-port has been proposed as a significant way to reducedirect CO2 emissions and ease the imbalance betweenthe supply anddemandof oil [8].

Because electric vehicles (EVs) are often con-sidered a promising technology and an attractive solu-tion for low-carbon transport [9, 10], severalgovernments have set goals and timelines for thephase-out of diesel and then gasoline engines by 2050.The European Union aims to be a major force in theEVmarket, andmost European countries have assem-bled a series of measures that would help them revita-lize the automotive industry and provide more high-technology jobs. The United States does not have a

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federal policy to boost EV adoption, but several stateshave set goals to reduce national vehicle emissions tozero by 2050. Japan has set a goal of selling only EVs by2050. India is one of the few countries that has a con-crete strategy for transport electrification and also hascommitted to end the sale of fossil-fuel powered vehi-cles by 2030. China is working on a plan to ban theproduction and sale of vehicles powered solely by fos-sil fuels and achieve a zero-emissions fleet by 2050. Indeveloping countries there are a range of policies, withsome countries embracing the future of electric-pow-ered mobility, while others are skeptical about whe-ther EVs will penetrate the market and have resistedthe trend toward transport electrification. Althoughmany countries have proposed bans to prohibit vehi-cles powered by diesel or gasoline, only a few nationsor individual cities have actually legislated againstinternal combustion engine (ICE) vehicles. Thus,most vehicle bans will not be effective due to the lackof legal enforcement [11].

Existing studies have identified the potential mar-ket for EVs and the key factors affecting EV utilizationand benefits, such as vehicle usage behavior, cost, bat-tery weight, charging patterns, battery range limita-tions, and the lack of public awareness about theavailability and practicality of these vehicles, the asso-ciated infrastructure, and safety regulations [9, 12, 13].Different types of EV (battery EVs, hybrid EVs, andplug-in hybrid EVs) have been compared to determinethe vehicle technology that is likely to dominate in thecoming decades [10]. Because integrated assessmentmodels (IAMs) have been extensively used to exploredecarbonizing pathways in the transport sector [2, 3,14–20], representations of technological advance-ment, consumer preferences, and increased marketshares of EVs have been input to global IAMs [5,21–23]. Current research clearly indicates the over-whelming importance of the role of transport elec-trification in a low-carbon transition. However,despite EVs reducing transport-related emissions andthese benefits not being substantially affected by chan-ges in travel distances, battery ranges, or charging fre-quencies [24], it is still very difficult to detect the cross-sectoral effects of transport electrification (e.g. theimpact of the deployment of EVs on the CO2 emittedby the power sector and the impact of EV penetrationon mitigation costs). It remains uncertain if EVs willdeliver the transition toward a green future.

Unlike ICEs, EVs do not emit carbon dioxide, butthe power in their batteries must be sourced fromsomewhere. A transport electrification policy couldproduce an additional demand for electricity, whichcould result in an increase in emissions if the electricityis generated from fossil fuels. It would be problematicto overlook the interaction between the transport sec-tor and other sectors (e.g. the power sector) when thedeployment of EVs is implemented. The electrifica-tion of the transport sector requires the integration ofvehicles into a reliable and efficient clean energy

network. The associated infrastructure, i.e. suitablerecharging points, is another determining conditionfor a fully electrified transport system [25–27].Although EVs will probablymake up a significant por-tion of our future transport needs due to technologicaldevelopment and decreasing battery costs, it is neces-sary to investigate whether EVs are as green as they areclaimed to be and what overall results transport elec-trification policiesmay have.

To investigate how transport electrification wouldimpact emission trajectories and climate change, as wellas what policies and strategies are needed for emissionreduction and climate change mitigation, this studyemployed a global transport model to project the globaltransport demand of passengers and freight in terms ofthe choice of transportmode and its technological detailsto predict world transport energy use and emissions. Thetransport model was coupled with a global economicmodel and a simplified climatemodel to reveal the inter-active mechanisms between transport electrification,economics, energy, and climate change. Such modelcoupling will enable electrified transport to be repre-sented in an IAM by providing technological or beha-vioral factors [28]. To explore the combined effects oftransport electrification and climate change mitigationefforts, we developed a set of six scenarios according tosocioeconomicpathways, transport electrification strate-gies, and energy policies, such as carbon pricing and ahigh reliance on renewable energy.

2.Methods

2.1. TransportmodelA global transport model was employed to providespatially flexible and temporally dynamic simulations oftransport demand, energy use, and emissions withconsideration given to various technological factors suchas device cost, speed, travel time, load factor, andpreferences. The transport model was developed as aone-year interval, recursive-type transport choicemodel,which is described in detail in Zhang et al (2018) [29]. Asummary of the model structure and its equations isprovided in the supplementary information, availableonline at stacks.iop.org/ERL/15/034019/mmedia. Themodel considered different distances, modes, sizes, andtechnologies for the global projection of passenger andfreight transport demand in 17 regions around theworld(see supplementary figure S1 and table S1). Globalpassenger and freight transport demand was distin-guished between short- and long-distance travel, anddifferent modes, vehicle sizes, and technologies (seesupplementary table S2). Energy use and CO2 emissionsfrom transport can be estimated according to technol-ogy-wise transport demand.

The passenger and freight transport demand wascalculated by GDP, industrial value added, popula-tion, and generalized transport cost. Then, discretechoice models were used to compute the shares of

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different distances, modes, sizes, and technologiesbased on the generalized transport cost, whichincludes the fuel cost, device cost, infrastructure cost,time cost, and carbon price. Fuel cost was calculatedby fuel price and vehicle energy efficiency. Device costwas the annualized purchase cost for the vehicledevice. The cost of travel time was estimated by thewage rate and vehicle speed. Infrastructure cost wasthe expense related to the infrastructure upgradesrequired at filling stations and EV charging stations.Technological improvements in EVs were incorpo-rated into the process of technology selection.Technology selection parameters for EVs (cars, buses,two-wheelers, and small trucks) in future years alignedwith different scenarios would increase gradually,accompanied by the implementation of transport elec-trification policies. The transport and energy datafrom 17 regions that were used for parameter estima-tion and calibrationwere collected from the Asia-Paci-fic Integrated Model database. The detailed datasources used in the transport model are listed in sup-plementary table S3.

2.2.Model couplingwith a global economicmodelThe transport model was coupled with a globaleconomic model and climate model to capture theinteractions and tradeoffs between the transportsector, energy, emissions,macroeconomy, and climatechange (figure 1). The frameworks of the computablegeneral equilibrium (CGE) model and the Model forthe Assessment of Greenhouse-gas Induced ClimateChange were employed for global economic andclimate modeling. The CGE model was developed for17 regions, which was consistent with the transportmodel. The CGE model is classified as a multi-regional, multi-sectoral model that covers all eco-nomic goods, while considering production factorinteractions [30]. An iterative procedure was used toobtain the convergence of the coupled model. Theeconomic model passed the macroeconomic variables

to the transport model to project the transportdemand, with consideration given to the modalstructure and technology shares. Then, the transportdemand, energy consumption from transport, andtransport device cost from the transport model werefed back to the economic model to re-estimate theparameters. This loop continued until the energyconsumption from transport calculated in the eco-nomic model and the transport model were equal.Next, global GHGs and other air pollutant emissionswere passed to the climate model to generate climateoutcomes, such as radiative forcing and global meantemperature changes. The mitigation costs, such ascarbon price and economic losses were estimated bythe CGE model according to the emission constraintsgiven by a Dynamic Integrated Climate—Economy—type intertemporalmodel.

2.3. Scenario settingsScenario simulationswere developed not only to provethe positive effects of the deployment of EVs ontransport decarbonization and emission reduction butalso to detect how transport electrification policesinteract with the power sector. A set of scenarios wascreated to investigate the long-term (to year 2100)impacts under various EV technology assumptionsand energy policy schemes. These scenarios weredefined according to two dimensions covering themodel assumptions of transport electrification andenergy policies, respectively. Transport electrificationis designed based on the technological preferences forEVs, including cars, buses, two-wheelers, and smalltrucks, which reflect the key behavioral factors influ-encing consumers’ willingness to purchase or selectEVs. It was assumed that 100% EV market share willbe achieved around the world by 2050 due to the EVpolicy incentives in the HiEV scenarios, while nostringent EV policy would be considered in the LoEVscenarios. In theHiEV scenarios, the parameters of thetechnological preferences for ICE vehicles were

Figure 1.Model structure.

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exogenously set to zero by 2050, while higher pre-ference parameters were given in relation to consu-mer’s purchasing decisions regarding EVs to achievethe target of 100%market share.

Scenarios for energy policies included carbon pri-cing and a preference for renewable energy. The car-bon pricing scenarios considered corresponded to a2 °C climate stabilization target versus no climateaction. The ‘BaU’ scenario assumed no climatemitiga-tion efforts, whereas the ‘2D’ scenario imposed a priceon carbon, which was consistent with the 2 °C target,with the global mean temperature increase peaking at1.82 °C in 2090 and settling at 1.8 °C in 2100. Theradiative forcing level associated with the 2 °C targetwas around 2.8 W m−2 in 2100. The radiative forcingfor the BaU and 2D targets is provided in supplemen-tary figure S2. The renewable energy preference sce-narios examined the sensitivity of high preferences onrenewable energies. In the CGE model, a factor forrepresenting renewable energy preference determinedthe share parameter as a logit function, which acceler-ated the usage of renewable energies, such as wind andsolar, when a high valuewas used.

Such scenario settings, considering the differentmodel assumptions of the transport and power sec-tors, were structured to analyze cross-sectoral rela-tions and tradeoffs, while also assessing mitigationpathways associated with the deployment of EVs(table 1). The default values of the underlying socio-economic conditions, other than road transport-rela-ted parameters (e.g. GDP and population), were basedon Shared Socioeconomic Pathway 2 (SSP2) [31].

3. Results

3.1. Energy use and emissions from transportThe energy use in the transport sector indicated that thetransport sector would consume more electricity if thetargets for the implementationof electric road transportwere achieved through scenarios HiEV_BaU,HiEV_2D, and HiEV_Renew, regardless of whetherenergy policies were established (figure 2(a)). However,the global consumption of oil and biomass was lowerwith the deployment of EVs, implying that transportelectrification could reduce oil dependency and themoderate demand for biofuels. Figure 2(b) shows theCO2 emissions by transport mode. Without ambitioustransport electrification goals, cars and trucks were

major contributors to CO2 emissions, whereas with thepolicy goal of 100% EVs, emissions from road trans-port, including cars, buses, two-wheelers, and smalltrucks, decreased to zero. In all the transport electrifica-tion scenarios, transport modes such as large trucks,aviation, and navigation,which are currently difficult toelectrify without breakthrough efforts and technologi-cal changes, are expected to emit most emissions in thefuture. Moreover, the deployment of EVs (HiEV_BaU)was more effective at reducing emissions than carbonpricing without the introduction of EVs (LoEV_2D),because road transport cannot achieve zero emissionsby the implementation of carbon pricing alone. A highpreference for renewable energies did not have directpositive effects on emission reduction in the transportsector. Time series results of energy use andmode-wiseemission trajectories are provided in supplementaryfigures S3 and S4, respectively.

Despite the powerful and effective impact of trans-port electrification on reducing direct CO2 emissionsfrom the transport sector, it is unwise to reach anoverly optimistic conclusion by ignoring the indirectCO2 emissions from the electricity generation thatenergizes EVs. As displayed in figure 3, the deploy-ment of EVs increases emissions from electricity pro-duction. A comparison ofHiEV_BaUwith LoEV_BaUshows an increase in indirect emissions, althoughdirect emissions decrease with the stringent penetra-tion of EVs during 2005–2100. Thus, without dec-arbonization of the future power supply by means ofenergy policies, instead of a low-carbon transition,electrified transport would lead to an increase in totalemissions. A high preference for renewable energywould reduce the indirect emissions to some extent,whereas a significant emission reduction could beachieved by carbon pricing.

3.2. Emissions from the power sectorFigure 4(a) presents a more detailed analysis of CO2

emissions from the energy-supply sector. Without theambitious climate change mitigation efforts in thepower sector, the deployment of EVs resulted inincreased emissions from energy production. Suchincreases in energy-supply-related emissions can beinterpreted as a globally growing demand for theelectricity required as a result of deploying more EVs.The emission trajectories of LoEV_2D and HiEV_2Dshowed that carbon pricing could significantly reduce

Table 1. Scenario settings.

Scenario Description

LoEV_BaU NoEVpolicy, with no climate efforts

LoEV_2D NoEVpolicy, with carbon pricing for the 2 °C target

LoEV_Renew NoEVpolicy, with a high preference for renewable energy

HiEV_BaU 100%EVmarket share by 2050, with no climate efforts

HiEV_2D 100%EVmarket share by 2050, with carbon pricing for the 2 °C target

HiEV_Renew 100%EVmarket share by 2050, with a high preference for renewable energy

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Figure 2.Effects of transport electrification on energy use andCO2 emissions. Energy use from transport (a) and emissions fromtransport (b).

Figure 3.Direct CO2 emissions from transport and indirect CO2 emissions from electricity generation that energize electric vehicles(EVs).

Figure 4.CO2 emissions from the energy sector (a), and globalmean temperature increase above pre-industrial levels (b).

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the emissions in the energy-supply sector, because ofthe switch to renewable and less carbon intensive fuels(figure 5; see power generation composition andprimary energy in supplementary figures S5 and S6).As shown in figure 4(b), deploying EVs alone couldnot effectively mitigate temperature increases, imply-ing that an EV policy will not reduce CO2 emissionsfrom all sectors if the transport is not powered bydecarbonized electricity generation (see emissions bysector in supplementary figure S7).

3.3. BiofuelIn the near future, biofuels such as ethanol and biogasare expected to be at the leading edge of transportdecarbonization [32]. The widespread adoption ofambitious biofuel policies would apparently deliver a

rapid transition in the supply base of transport fuels.However, as shown in figure 2(a), it has already beenconfirmed that transport electrification exerts a nega-tive impact on biomass consumption in the transportsector. More interestingly, similar results were appar-ent when all sectors were considered, as shown infigure 6. The deployment of EVs produced a lowerconsumption of biomass. Because biomass produc-tion may compete with other land uses or land covers,there is a major debate concerning whether thebiomass feedstock production required by ambitiousbiofuel targets will threaten food security, exacerbatedeforestation, destroy ecosystems, and aggravate ruralpoverty [33–35]. Our simulations of transport electri-fication proved that an EV policy could be a promisingsolution for easing the increasing demand on biomass,

Figure 5.Global energy supply for electricity generation.

Figure 6. Impacts of transport electrification on the consumption of biomass.

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which would help mitigate the risk of increasing foodinsecurity due to ambitious biofuel goals.

3.4. Economic resultsThe economic costs and benefits of transport electrifi-cation over the long termwere evaluated using a globaltransport model coupled with an economic model,with the coupling model describing the interactionsbetween the transport sector and macroeconomy.Figure 7 shows the total annualized cost of roadtransport during 2005–2100. Cars and small truckswere the dominant modes, accounting for a majorproportion of the cost, while device costs generatedthe highest capital cost compared with energy con-sumption and infrastructure. Stringent transport elec-trification goals require higher capital costs for thevehicle,mainly due to themore expensive componentsof EVs. Although the device cost of EVs is assumed tocontinue to decline over the coming decades, it is stilllikely to be higher than that of ICE vehicles.

Another measure of the economic effects of trans-port electrification is to detect how the cost of climatechange mitigation would be modified with the strin-gent penetration of EVs, which can be indicated bycarbon price, GDP loss rate, and welfare loss raterequired to achieve an emission reduction consistentwith the stabilization objective of the 2 °C scenario.Figure 8 shows that the carbon price for achieving thetarget of a 2 °C global temperature rise decreased from1072 to 511 USD in 2100 due to the undertaking of anambitious transport electrification policy. The GDPand welfare loss rate associated with pricing carboncan be thereby mitigated significantly because the goalof emission reduction can be achieved more easily byelectrification of the road transport sector throughEVs rather than by putting a heavy price oncarbon emissions. Carbon-neutral road transport caninstantly contribute to the reduction of transport-related emissions by accelerating the market diffusionof EVs, which helps to relieve the negative impactsof climate change mitigation efforts on the

Figure 7.Effects of transport electrification on the total annualized costs of road transport.

Figure 8.Mitigation costmetrics for the 2 °C target.

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macroeconomy. Therefore, economic developmentdoes not necessarily have to run counter to climatechange policy goals when low-carbon transport tech-nologies are taken into consideration.

3.5. Sensitivity analysisDriven by transport electrification policies, themarketshare of EVs has been projected to increase signifi-cantly in the coming decades. However, there is stilluncertainty related to the future prospects of completeEV penetration by 2050, because only a few govern-ments have legislated to ban ICE vehicle sales. Thus, tounderstand more fully the relationships betweenpolicy settings andmodel outputs, it is necessary to testwhether the model and its results are robust in thepresence of uncertainty. One way to perform anuncertainty and sensitivity analysis is to simulate arange of transport electrification scenarios rather thanby focusing on a 100% market share of EVs. Figure 9displays the CO2 emission trajectories, with considera-tion given to different EV market shares between theLoEV and HiEV scenarios. The trajectories of thedirect emissions when assuming 30%, 50%, and 70%market shares of EV penetration were higher thanthose for HiEV and lower than those for LoEV,regardless of whether renewables penetrate further theenergy mix or not. The indirect emissions exhibitedcontrasting features, but the greater the market share,the higher the indirect emissions. However, totalemissions displayed the different dynamics betweenBaU and Renew. Without high preference for renew-able energies, total emissions showed increasing trendsin alignment with high market diffusion of EVs,

whereas opposite profiles can be found especially forthe total emissions during 2030–2080 because thereduction in indirect emissions offsets the increases indirect emissions. The robustness of model couplingand stringent EV penetration was verified by asensitivity analysis of themultiplemarket shares.

In addition, there were also uncertainties regard-ing the different socioeconomic assumptions ofpopulation and economic growth. Here, multiplesocioeconomic pathways were assumed that werealigned with SSP1-3 to explore how socioeconomicfactors influenced the emission profiles when con-sidering stringent transport electrification. It waspossible to determine whether there were futureswhere transport electrification wasmore or less bene-ficial, even in the absence of complete power sectordecarbonization. Figure 10 shows the emission pro-files for the three SSP scenarios. Transport electrifica-tion reduced direct emissions from the transportsector, but indirect emissions increased significantlyin all three SSP scenarios. However, whenconsidering the tradeoff between direct and indirectemissions, the total emissions displayed differencesamong the three SSPs. Interestingly, the stringentpenetration of EVs reduced the total CO2 emissionsin SSP1, whereas in SSP2 and SSP3 there were increa-ses in total emissions when the 100%market share ofEVs was achieved. Even without a decarbonizedpower sector through carbon pricing or renewableenergy policies, transport electrification alignedwith SSP1 was able to meet the CO2 emission reduc-tion target.

Figure 9.Emission trajectories for different EVmarket shares. Between LoEV (no EVpolicy) andHiEV (100%EVmarket share), threeadditional EVmarket penetrations were assumed: EV30, EV50, and EV70 (i.e. 30%, 50%, and 70%market shares, respectively).

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4.Discussion and conclusion

Many governments have encouraged the adoption ofEVs as an important step toward a clean energy futurebecause of their contribution toward reducing directemissions from transport. However, our researchconfirmed that an EV policy without decarbonizingpower generation fails to contribute to emissionreduction, although direct emissions from transportcan be reduced significantly because an EV policywould shift emissions from the transport sector to thepower sector (figure 11). Despite the rapid technologi-cal progress made with EV technologies, an analysis ofcombined transport electrification and energy policiesrevealed an uncomfortable truth—transport electrifi-cation alone does not successfully reduce emissionsandmitigate climate change. Instead, tomeet stringentclimate targets, the linkages between the transportsector and energy sector deserve attention. Renewableenergy as a means to decarbonize power generationneeds to play a key role when electrifying the transportsector.

Although homogenous targets of 100% marketshare were established for the stringent EV scenariosin 17 regions, governments have actually set differenttimelines for the phase-out of ICE vehicles (see supple-mentary table S4). According to these differentnational transport electrification goals, heterogeneousmarket shares for EV scenarios were designed toreflect policy variation and estimate the emission tra-jectories considering regional heterogeneity in policytimelines and goals. Figure 12 shows the emission tra-jectories with the setting of regionally specific ICEbans. It was assumed that more ambitious targets forEV penetration would be established in the EU,Canada, and India, in view of their national strategiesfor transport electrification, while default values fordeploying EVs were set for other countries and regionssuch as the US, China, and Japan. Regardless of whe-ther carbon pricing and renewable energy policieswere deployed, additional emission reductions couldbe realized globally due to the different regional EVdiffusion policies. Because transport emissions in theEU, Canada, and India account for approximately a

Figure 10.Emission profiles in three Shared Socioeconomic Pathways (SSP1-3) scenarios.

Figure 11.An electric vehicle (EV) policy alone shifts emissions from the transport sector to the power sector.

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quarter of global transport emissions, earlier timelinesfor ICE bans in these three regions would acceleratethe global emission reduction. The regional emissiontrajectories considering these policy variations areprovided in supplementary figure S8.

Our findings should not be interpreted to down-play the contribution of transport electrification to cli-mate change mitigation or to deemphasize the role ofEVs as a potential solution toward a low-carbon trans-ition. Rather, we highlight the interaction requiredbetween transport electrification and the power sectorto formulate more harmonized and inclusive policies.Combining transport electrification with energy poli-cies, such as carbon pricing, could facilitate emissionreductions from transport and a simultaneous trans-ition to a low-carbon future. Interestingly, transportelectrification can also be considered a potential policytool to alleviate the negative impacts of biofuel devel-opment on food security due to ambitious climatechangemitigation targets. Moreover, it was found thatthe emission reduction effect of stringent EV goals wasnot dependent on the decarbonized power sector oraccompanying energy policies in SSP1, which depictsfeatures of a sustainable future, with low fossil-fueldependence and an increasing share of renewables.SSP1 is characterized as ‘Taking the Green Road’, withlow population projections but high productivity,leading to lower CO2 emissions and fewer challengesto climate change mitigation. Because the world isoriented toward lower resource use and energy inten-sity in SSP1, a widespread transition to a zero-carbonroad transport sector might not have side effects.Because the effectiveness of transport electrificationpolicy is determined by socioeconomic pathways,transport planners, energy experts, policymakers,economists, and stakeholders need towork together todevelop a joint strategy for transport electrification toreduceCO2 emissions quickly and effectively.

Mitigation cost measures represent the econom-ical attractiveness of transport electrification as a miti-gation opportunity, because it reduces the loss rates of

economic growth due to imposition of a carbon tax forachieving climate change mitigation targets. Theimpact on the dynamics of the macroeconomy oftransport electrification needs to be considered whenevaluating the feasibility and cost-effectiveness of EVpolicies. Climate action does not have to decrease eco-nomic growth and it is not certain that economicsacrifice will be required. It is possible to propose awin-win strategy of low-carbon transition and eco-nomic development. On the other hand, from theviewpoint of consumers, an electrified transport sectorrequires additional vehicle purchase costs for EVscompared to a conventional ICE driven vehicle,mainly because of the cost of the battery. Althoughbattery costs are projected to decrease due to improve-ments in the materials used as well as the potential forlarge-scale manufacturing [22], economic policyincentives such as subsidies for EVs need to be con-sidered to reduce the additional costs of EVs directlyand stimulate consumers to purchase them. In thisstudy, scenario settings for stringent EV penetrationwere represented only by ICE vehicle bans, and did notinvolve other specific EV policies, such as purchasingsubsidies, exemptions from tolls, and registration fees.Further studies are needed to determine how financialincentives for EV use would modify the market shareof EVs in the coming decades.

Although this study was aimed at determining therole of transport electrification using a global trans-portmodel coupled with economic and climatemod-els, there are limitations to the study that should benoted. The temporal dynamics associated with EVcharging were not taken into consideration and,therefore, the current model framework did not con-duct an analysis of the hourly balance between EVcharging loads and electricity generation. In futurestudies, a detailed hourly profile of EV chargingshould be explicitly represented. In addition, theemissions produced from the EVmanufacturing pro-cess were not included in the global transport model,and will need to be incorporated when estimating the

Figure 12.Emission trajectories after setting regionally specific targets on electric vehicle (EV) sales.Homogeneous targets for EV salesindicated that a 100%market sharewill be achieved by 2050 for all regionsworldwide. Regionally specific targets were set for 100%market shares by 2030 (the EU and India), 2040 (Canada), and 2050 (other regions such as theUS, China, Japan, etc).

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life-cycle emissions of EVs, because a considerableproportion of a vehicle’s carbon footprint is gener-ated at the factory, before the vehicle travels on theroad. Because EV studies are cutting edge and presentinterdisciplinary challenges, this study constitutesonly the first step toward understanding the impor-tant potential tradeoffs between efforts to electrifythe transport sector and decarbonize the power sec-tor. Further research is required to improve the inter-disciplinary methodological framework, extend thescope of EV studies to the field of climate change, andassess how global and national transport electrifica-tion policies should develop in the coming decades.In particular, transport electrification studies couldeasily be extended to include energy security, dis-ruptive technological innovations (e.g. autonomouscars, car-sharing, artificial intelligence, etc), and localair quality and health risks associated with air pollu-tion to enable climate target-oriented transport plan-ning and policymaking.

Acknowledgments

The author acknowledges support from the JapanSociety for the Promotion of Science (JSPS)KAKENHIGrant No. 19K20507, and the Environment Researchand Technology Development Fund (2-1908) of theEnvironmental Restoration and Conservation Agencyof Japan.

Data availability statement

Any data that support the findings of this study areincluded within the article. Scenario data for all thescenarios are available within the supplementarymaterial.

ORCID iDs

RunsenZhang https://orcid.org/0000-0001-9841-8453

References

[1] ChapmanL 2007Transport and climate change: a reviewJ. Transp. Geogr. 15 354–67

[2] EdelenboschOY et al 2017Decomposing passenger transportfutures: comparing results of global integrated assessmentmodelsTransp. Res.D 55 281–93

[3] GirodB, vanVuurenDP,GrahnM,Kitous A, Kim SH andKyle P 2013Climate impact of transportationAmodelcomparisonClim. Change 118 595–608

[4] IPCC2015TransportClimate Change 2014:Mitigation ofClimate Change:WorkingGroup III Contribution to the IPCCFifth Assessment Report (Cambridge: CambridgeUniversityPress) pp 599–670

[5] McCollumDL et al 2018 Interaction of consumer preferencesand climate policies in the global transition to low-carbonvehiclesNat. Energy 3 664

[6] Creutzig F et al 2015Transport: a roadblock to climate changemitigation? Science 350 911–2

[7] Pietzcker RC et al 2014 Long-term transport energy demandand climate policy: alternative visions on transportdecarbonization in energy-economymodels Energy 64 95–108

[8] WeissM,Dekker P,MoroA, ScholzH and PatelMK2015Onthe electrification of road transportation–a review of theenvironmental, economic, and social performance of electrictwo-wheelersTransp. Res.D 41 348–66

[9] Andwari AM, Pesiridis A, Rajoo S,Martinez-Botas R andEsfahanianV 2017A review of Battery Electric Vehicletechnology and readiness levelsRenew. Sustain. Energy Rev. 78414–30

[10] WeissM, PatelMK, JungingerM, Perujo A, Bonnel P andvanGrootveldG 2012On the electrification of road transport-learning rates and price forecasts for hybrid-electric andbattery-electric vehicles Energy Policy 48 374–93

[11] Plotz P, Axsen J, Funke S A andGnannT 2019Designing carbans for sustainable transportationNat. Sustain. 2 534–6

[12] Nykvist B andNilssonM2015Rapidly falling costs of batterypacks for electric vehiclesNat. Clim. Change 5 329–32

[13] PearreN S, KemptonW,Guensler R L and ElangoVV 2011Electric vehicles: howmuch range is required for a day’sdriving?Transp. Res.C 19 1171–84

[14] DalyHE, RameaK, Chiodi A, Yeh S, GargiuloMandGallachoir BO 2014 Incorporating travel behaviour and traveltime into TIMES energy systemmodelsAppl. Energy 135429–39

[15] GirodB, vanVuurenDP and deVries B 2013 Influence oftravel behavior on global CO2 emissionsTransp. Res.A 50183–97

[16] GirodB, vanVuurenDP andDeetrnan S 2012Global travelwithin the 2 degrees C climate targetEnergy Policy 45 152–66

[17] Karkatsoulis P, Siskos P, Paroussos L andCapros P 2017Simulating deepCO2 emission reduction in transport in ageneral equilibrium framework: theGEM-E3TmodelTransp.Res.D 55 343–58

[18] Kyle P andKimSH2011 Long-term implications ofalternative light-duty vehicle technologies for globalgreenhouse gas emissions and primary energy demands EnergyPolicy 39 3012–24

[19] MuratoriM, Smith S J, Kyle P, LinkR,Mignone BK andKheshgiH S 2017Role of the freight sector in future climatechangemitigation scenarios Environ. Sci. Technol. 51 3526–33

[20] WaismanHD,GuivarchC and Lecocq F 2013Thetransportation sector and low-carbon growth pathways:modelling urban, infrastructure, and spatial determinants ofmobilityClim. Policy 13 106–29

[21] EdelenboschO,McCollumD, PettiforH,WilsonC andVanVuurenD2018 Interactions between social learning andtechnological learning in electric vehicle futures Environ. Res.Lett. 13 124004

[22] EdelenboschOY,Hof A F,Nykvist B, Girod B andvanVuurenDP 2018Transport electrification: the effect ofrecent battery cost reduction on future emission scenariosClim. Change 151 95–108

[23] McCollumDL et al 2016 Improving the behavioral realism ofglobal integrated assessmentmodels: an application toconsumers’ vehicle choicesTransp. Res.D 55 322–42

[24] Liu J and SantosG 2015 Plug-in hybrid electric vehicles’potential for urban transport in china: the role of energysources and utility factors Int. J. Sustain. Transp. 9 145–57

[25] MeyerG, Bucknall R andBreuil D 2017Electrification of theTransport System Studies andReportsEuropeanCommissionDirectorate General for Research and Innovation

[26] Giannakidis G, KarlssonK, LabrietM andGallachóir BÓ 2018Limiting GlobalWarming toWell Below 2 °C: Energy SystemModelling and PolicyDevelopment (Berlin: Springer)

[27] MeyerG, Bucknall R andBreuil D 2016TransportelectrificationTransport Research and InnovationMonitoringand Information System SRIARoadmap EuropeanCommission

[28] ZhangR, Fujimori S, DaiH andHanaoka T 2018Contributionof the transport sector to climate changemitigation: Insightsfrom a global passenger transportmodel coupledwith a

11

Environ. Res. Lett. 15 (2020) 034019

A Self-archived copy inKyoto University Research Information Repository

https://repository.kulib.kyoto-u.ac.jp

computable general equilibriummodelAppl. Energy 21176–88

[29] ZhangR, Fujimori S andHanaoka T 2018The contribution oftransport policies to themitigation potential and cost of 2 °Cand 1.5 °CgoalsEnviron. Res. Lett. 13 054008

[30] Fujimori S,Masui T andMatsuoka Y 2014Development of aglobal computable general equilibriummodel coupledwithdetailed energy end-use technologyAppl. Energy 128 296–306

[31] FrickoO,Havlik P, GustiM and JohnsonN2017Themarkerquantification of the Shared Socioeconomic Pathway 2: Amiddle-of-the-road scenario for the 21st century.GlobalEnvironmental Change 42 251–67

[32] TimilsinaGR 2014 Biofuels in the long-run global energysupplymix for transportation Phil. Trans. R. Soc.A 372 1–19

[33] BauerN et al 2018Global energy sector emission reductionsand bioenergy use: overview of the bioenergy demand phase ofthe EMF-33model comparisonClim. Change (https://doi.org/10.1007/s10584-018-2226-y)

[34] HasegawaT et al 2018Risk of increased food insecurity understringent global climate changemitigation policyNat. Clim.Change 8 699–703

[35] HasegawaT, Fujimori S, Shin Y, Tanaka A, Takahashi K andMasui T 2015Consequence of climatemitigation on the risk ofhunger Environ. Sci. Technol. 49 7245–53

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https://repository.kulib.kyoto-u.ac.jp