Environmental And Economic Impacts Of The Large-Scale Development Of Urban Electric Vehicles

The sustained and rapid development of the national economy and the improvement of residents’living standards have led to a substantial increase in vehicle population.Road traffic emissions have become a major source of air pollution in urban areas in China,and also an important source of greenhouse gas CO₂ that causes climate change.Promotion and use of electric vehicles（EVs）are thought to be an effective way to cope with air pollution and climate change relating to traffic emissions.The national and local governments at all levels have introduced a large number of policy incentives to promote the development of EVs.But large-scale development of EVs may not only affect the stability of grid operations,but also increase emissions from the power sector.In this context,comprehensive assessment of the impacts of large-scale development of EVs on air pollutants and CO₂ emissions and the cost effectiveness of carbon abatement is not only an important topic in the studies of energy and environment,but also has significant implications for policy makers in formulating the development strategies for EVs.Taking Nanjing in Yangtze River Delta as the research object,2018 as the year of study,this study comprehensively applied scenario analysis,charging behavior survey,Monte Carlo simulation,chronological operation simulation,COPERT model and cost effectiveness analysis to evaluate the impacts of electric private cars,taxis and buses on emissions from transportation and power sectors,as well as the carbon abatement cost of EVs.The main results include:In terms of the charging load of large-scale development of EVs,on the weekday,charging demand of electric private cars is concentrated,with the peak from 8:00 to10:00 am and from 19:00 to 22:00 pm.On the weekend,the load is dispersed,with a peak at around 18:30 pm.The peak load of electric taxis is at 12:00-14:00 pm and20:00-22:00 pm,while the peak charging demand of electric buses appear in 12:00-15:00 pm and 19:00-21:00 pm.Under the scenario that private cars are 50%electrified and taxis and buses are 100%electrified,charging load peaks around 20:30 pm on weekdays,with a peak load of 1070 MW,accounting for 10%of the highest load of the whole year in Nanjing,and a peak load of 800 MW on the weekend.No matter on weekdays or weekends,the load peak of EVs coincides with the peak of power grid,resulting in"peak plus peak"of power grid load.In the orderly charging scenarios,the charging load moves to 1:00 am to achieve the effect of"peak cutting and valley filling".From the perspective of the environmental impacts of the development of EVs,compared with the BAU scenario,the emission reductions of SO₂,CO,NO_X,PM_2.5,PM₁₀ and VOCs in the transport sector are 49 t,20223 t,2568 t,434 t,773 t and 3649t,respectively,in the scenario that private cars are 50%electrified and taxis and buses are 100%electrified.The corresponding emission reduction ratios are 33%,33%,7%,23%,25%and 35%,respectively.In this scenario,SO₂,NO_X,PM_2.5,PM₁₀ and CO₂emissions in the power sector increase by 874 t,1795 t,99 t,178 t and 2.29 Mt,respectively,with an increase rate of 4.1%,4.6%,4.3%,4.3%and 4.0%.In general,in this scenario,all pollutant emissions except SO₂ will decrease.Orderly charging according to time-of-use price can further improve the emission reduction effect of EVs.In terms of total cost and carbon abatement cost of the large-scale development of EVs,private cars,taxis and buses electric will increase their personal and social total cost（including the cost of purchase and use）with 29600 yuan,95000 yuan and 1.17million yuan,respectively.The cost increase is mainly due to the increase in its purchase and insurance cost excel the cost of fuel and purchase and use tax savings.Considering private cost only,electric cars cost less than conventional cars,while electric taxis and buses still cost more.With the increase of the electrification of private cars,the carbon abatement cost decreases.When the penetration rate of private cars increases from 20%to 50%,the carbon abatement cost decreases from 893 yuan/t to 484 yuan/t respectively.Orderly charging can further reduce the carbon abatement cost to 364 yuan/t.According to the evaluation results,the key to affect the emission reduction benefits of EVs is the emission factor of the power sector.Therefore,on the one hand,it is necessary to reduce the emission level of the traditional power sector.The government can continue to promote the transformation of the power sector to meet“ultra-low emissions”standard.On the other hand,through vehicle-to-grid,the energy storage of a large number of EVs can be used as a buffer for the power grid and renewable energy,so as to reduce the waste of clean energy and achieve low emission of EVs.In addition,the city management department can regulate the charging time of EVs through policies such as time-of-use price and technical measures such as intelligent regulation,so as to achieve the effect of"peak cutting and valley filling"and comprehensively improve the energy and environmental benefits.To promote the large-scale development and lower the carbon abatement cost of EVs,the key point is reducing the cost of electrification.The manufactures need to put more efforts on the research and development of EVs,so as to promote reduction of the battery and production cost.Purchase subsidies and tax incentives from government are necessary for the development of EVs at the present stage.