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An electric car is an automobile that is propelled by one or more electric motors, using electrical energy stored in batteries or another energy storage device. Electric motors give electric cars instant torque, creating strong and smooth acceleration.

The first electric cars were produced in the 1880s.[1] Electric cars were popular in the late 19th century and early 20th century, until advances in internal combustion engines and mass production of cheaper gasoline vehicles led to a decline in the use of electric drive vehicles. The energy crises of the 1970s and 1980s brought a short-lived interest in electric cars; although, those cars did not reach the mass marketing stage, as is the case in the 21st century. Since 2008, a renaissance in electric vehicle manufacturing has occurred due to advances in batteries and power management, concerns about increasing oil prices, and the need to reduce greenhouse gas emissions.[2][3] Several national and local governments have established tax credits, subsidies, and other incentives to promote the introduction and adoption in the mass market of new electric vehicles depending on battery size and their all-electric range.

Benefits of electric cars over conventional internal combustion engine automobiles include a significant reduction of local air pollution, as they do not emit tailpipe pollutants,[4] in many cases, a large reduction in total greenhouse gas and other emissions (dependent on the fuel used for electricity generation[2][3]), and less dependence on foreign oil, which in several countries is cause for concern about vulnerability to oil price volatility and supply disruption.[2][5][6] But widespread adoption of electric cars faces several hurdles and limitations, including their higher cost, patchy recharging infrastructure (other than home charging) and range anxiety (the driver's fear that the electric energy stored in the batteries will run out before the driver reaches their destination, due to the limited range of most existing electric cars).[2][3] Recharging can take a long time, however, for long distance driving many cars support fast charging that can give around 80% charge in half an hour using public fast chargers.[7][8][9]

As of November 2014, the number of mass production highway-capable all-electric passenger cars and utility vans available in the market is limited to over 30 models, mainly in the United States, Japan, Western European countries and China. Pure electric car sales in 2012 were led by Japan with a 28% market share of global sales, followed by the United States with a 26% share, China with 16%, France with 11%, and Norway with 7%.[10] The world's highest selling highway-capable electric car is the Nissan Leaf, released in December 2010 and sold in 35 countries, with global sales of over 165,000 units by early March 2015.[11][12][13]

Environmental aspectsEdit

File:EarthRangersCentre6.jpg

Electric cars have several benefits over conventional internal combustion engine automobiles, including a significant reduction of local air pollution, as they have no tailpipe, and therefore do not emit harmful tailpipe pollutants from the onboard source of power at the point of operation;[14][15][16] reduced greenhouse gas emissions from the onboard source of power, depending on the fuel used for electricity generation to charge the batteries.[2][3] Electric vehicles generally, compared to gasoline vehicles show significant reductions in overall well-wheel global carbon emissions due to the highly carbon intensive production in mining, pumping, refining, transportation and the efficiencies obtained with gasoline.[17] While there is some technical superiority of electric propulsion compared with conventional technology, one should be aware that, in many countries, the effect of electrification of vehicles' fleet emissions will predominantly be due to regulation rather than technology.[18] Indeed electricity production is submitted to emission quotas, while vehicles' fuel propulsion is not, thus electrification shifts demand from a non-capped sector to a capped sector. In this context, technical efficiency of EV engine is not the driver of emission reduction.

Many countries are introducing CO2 average emissions targets across all cars sold by a manufacturer, with financial penalties on manufacturers that fail to meet these targets. This has created an incentive for manufacturers, especially those selling many heavy or high-performance cars, to introduce electric cars as a means of reducing average fleet CO2 emissions.[19]

Air pollution and carbon emissionsEdit

Electric cars contribute to cleaner air in cities because they produce no harmful pollution at the tailpipe from the onboard source of power, such as particulates (soot), volatile organic compounds, hydrocarbons, carbon monoxide, ozone, Pb, and various oxides of nitrogen. The clean air benefit is usually local because, depending on the source of the electricity used to recharge the batteries, air pollutant emissions are shifted to the location of the generation plants.[2] Nevertheless, introducing EV would come with a major environmental benefits in most (EU) countries, except those relying on old coal fired power plants.[20] The amount of carbon dioxide emitted depends on the emission intensity of the power source used to charge the vehicle, the efficiency of the said vehicle and the energy wasted in the charging process. This is referred to as the long tailpipe of electric vehicles.

For mains electricity the emission intensity varies significantly per country and within a particular country it will vary depending on demand,[21] the availability of renewable sources and the efficiency of the fossil fuel-based generation used at a given time.[20][22]

Charging a vehicle using renewable energy yields very low carbon footprint (only that to produce and install the generation system e.g. wind power).

United States
File:U.S. 2013 Electricity Generation By Type crop.png

The following table compares tailpipe and upstream CO2 emissions estimated by the U.S. Environmental Protection Agency for all series production model year 2014 all-electric passenger vehicles available in the U.S. market. Since all-electric cars do not produce tailpipe emissions, for comparison purposes the two most fuel efficient plug-in hybrids and the typical gasoline-powered car are included in the table. Total emissions include the emissions associated with the production and distribution of electricity used to charge the vehicle, and for plug-in hybrid electric vehicles, it also includes emissions associated with tailpipe emissions produced from the internal combustion engine. These figures were published by the EPA in October in its 2014 report "Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends."[24]

In order to account for the upstream CO2 emissions associated with the production and distribution of electricity, and since electricity production in the United States varies significantly from region to region, the EPA considered three scenarios/ranges with the low end scenario corresponding to the California powerplant emissions factor, the middle of the range represented by the national average powerplant emissions factor, and the upper end of the range corresponding to the powerplant emissions factor for the Rocky Mountains. The EPA estimates that the electricity GHG emission factors for various regions of the country vary from 346 g CO2/kWh in California to 986 g CO2/kWh in the Rockies, with a national average of 648 g CO2/kWh.[24] In the case of plug-in hybrids, and since their all-electric range depends on the size of the battery pack, the analysis introduced a utility factor as a projection of the share of miles that will be driven using electricity by an average driver.[24]

Comparison of tailpipe and upstream CO2 emissions(1) estimated by EPA
for the MY 2014 all-electric vehicles available in the U.S. market[24]
Vehicle Overall
fuel
economy
(mpg-e)
Utility
factor(2)
(share EV
miles)
Tailpipe CO2
(g/mi) ||style="background:#cfc;" colspan="3"|Tailpipe + Total Upstream CO2
Low
(g/mi)
Avg
(g/mi)
High
(g/mi)
BMW i3124 1 0 93 175 266
Chevrolet Spark EV 119 1 0 97181 276
Honda Fit EV 118 1 0 99 185 281
Fiat 500e 116 1 0 101 189 288
Nissan Leaf 114 1 0 104 194 296
Mitsubishi i 112 1 0 104 195 296
Smart electric drive 107 1 0 109 204 311
Ford Focus Electric 105 1 0 111 208 316
Tesla Model S (60 kWh) 95 1 0 122 229 348
Tesla Model S (85 kWh)89 1 0 131 246 374
BMW i3 REx(3)880.83 40134207 288
Mercedes-Benz B-Class ED 84 1 0 138 259 394
Toyota RAV4 EV 76 1 0 153 287 436
BYD e663 1 0 187 350 532
Chevrolet Volt plug-in hybrid620.66 81 180 249 326
Average 2014 gasoline-powered car24.2 0 367 400400400
Notes: (1) Based on 45% highway and 55% city driving. (2) The utility factor represents, on average, the percentage of miles that will be driven
using electricity (in electric only and blended modes) by an average driver. (3) The EPA classifies the i3 REx as a series plug-in hybrid.[25][24]

The Union of Concerned Scientists (UCS) published in 2012 a report with an assessment of average greenhouse gas emissions resulting from charging plug-in car batteries considering the full life-cycle (well-to-wheel analysis) and the fuel used to generate electric power by region in the U.S. The study used the Nissan Leaf all-electric car to establish the analysis's baseline. The UCS study expressed the results in terms of miles per gallon instead of the conventional unit of grams of carbon dioxide emissions per year. The study found that in areas where electricity is generated from natural gas, nuclear, or renewable resources such as hydroelectric, the potential of plug-in electric cars to reduce greenhouse emissions is significant. On the other hand, in regions where a high proportion of power is generated from coal, hybrid electric cars produce less CO2 emissions than plug-in electric cars, and the best fuel efficient gasoline-powered subcompact car produces slightly less emissions than a plug-in car. In the worst-case scenario, the study estimated that for a region where all energy is generated from coal, a plug-in electric car would emit greenhouse gas emissions equivalent to a gasoline car rated at a combined city/highway fuel economy of 30 mpg-US (7.8 L/100 km; 36 mpg-imp). In contrast, in a region that is completely reliant on natural gas, the plug-in would be equivalent to a gasoline-powered car rated at 50 mpg-US (4.7 L/100 km; 60 mpg-imp) combined.[26][27]

The study found that for 45% of the U.S. population, a plug-in electric car will generate lower CO2 emissions than a gasoline-powered car capable of a combined fuel economy of 50 mpg-US (4.7 L/100 km; 60 mpg-imp), such as the Toyota Prius. Cities in this group included Portland, Oregon, San Francisco, Los Angeles, New York City, and Salt Lake City, and the cleanest cities achieved well-to-wheel emissions equivalent to a fuel economy of 79 mpg-US (3.0 L/100 km; 95 mpg-imp). The study also found that for 37% of the population, the electric car emissions will fall in the range of a gasoline-powered car rated at a combined fuel economy between 41 to 50 mpg-US (5.7 to 4.7 L/100 km; 49 to 60 mpg-imp), such as the Honda Civic Hybrid and the Lexus CT200h. Cities in this group include Phoenix, Arizona, Houston, Miami, Columbus, Ohio and Atlanta, Georgia. An 18% of the population lives in areas where the power supply is more dependent on burning carbon, and emissions will be equivalent to a car rated at a combined fuel economy between 31 to 40 mpg-US (7.6 to 5.9 L/100 km; 37 to 48 mpg-imp), such as the Chevrolet Cruze and Ford Focus. This group includes Denver, Minneapolis, Saint Louis, Missouri, Detroit, and Oklahoma City.[27][28][29] The study found that there are no regions in the U.S. where plug-in electric cars will have higher greenhouse gas emissions than the average new compact gasoline engine automobile, and the area with the dirtiest power supply produces CO2 emissions equivalent to a gasoline-powered car rated 33 mpg-US (7.1 L/100 km; 40 mpg-imp).[26]

In September 2014 the UCS published an updated analysis of its 2012 report. The 2014 analysis found that 60% of Americans, up from 45% in 2012, live in regions where an all-electric car produce fewer CO2 equivalent emissions per mile than the most efficient hybrid. The UCS study found two reasons for the improvement. First, electric utilities have adopted cleaner sources of electricity to their mix between the two analysis. Second, electric vehicles have become more efficient, as the average 2013 all-electric vehicle used 0.33 kWh per mile, representing a 5% improvement over 2011 models. Also, some new models are cleaner than the average, such as the BMW i3, which is rated at 0.27 kWh by the EPA. In states with a cleaner mix generation, the gains were larger. The average all-electric car in California went up to 95 mpg-US (2.5 L/100 km) equivalent from 78 mpg-US (3.0 L/100 km) in the 2012 study. States with dirtier generation that rely heavily on coal still lag, such as Colorado, where the average BEV only achieves the same emissions as a 34 mpg-US (6.9 L/100 km; 41 mpg-imp) gasoline-powered car. The author of the 2014 analysis noted that the benefits are not distributed evenly across the U.S. because electric car adoptions is concentrated in the states with cleaner power.[30][31]

One criticism to the UCS analysis and several other that have analyze the benefits of PEVs is that these analysis were made using average emissions rates across regions instead of marginal generation at different times of the day. The former approach does not take into account the generation mix within interconnected electricity markets and shifting load profiles throughout the day.[32][33] An analysis by three economist affiliated with the National Bureau of Economic Research (NBER), published in November 2014, developed a methodology to estimate marginal emissions of electricity demand that vary by location and time of day across the United States. The marginal analysis, applied to plug-in electric vehicles, found that the emissions of charging PEVs vary by region and hours of the day. In some regions, such as the Western U.S. and Texas, CO2 emissions per mile from driving PEVs are less than those from driving a hybrid car. However, in other regions, such as the Upper Midwest, charging during the recommended hours of midnight to 4 a.m. implies that PEVs generate more emissions per mile than the average car currently on the road. The results show a fundamental tension between electricity load management and environmental goals as the hours when electricity is the least expensive to produce tend to be the hours with the greatest emissions. This occurs because coal-fired units, which have higher emission rates, are most commonly used to meet base-level and off-peak electricity demand; while natural gas units, which have relatively low emissions rates, are often brought online to meet peak demand.[33]

United Kingdom

A study made in the UK in 2008 concluded that electric vehicles had the potential to cut down carbon dioxide and greenhouse gas emissions by at least 40%, even taking into account the emissions due to current electricity generation in the UK and emissions relating to the production and disposal of electric vehicles.[34]

The savings are questionable relative to hybrid or diesel cars (according to official British government testing, the most efficient European market cars are well below 115 grams of CO2 per kilometer driven, although a study in Scotland gave 149.5gCO2/km as the average for new cars in the UK[35]), but since UK consumers can select their energy suppliers, it also will depend on how 'green' their chosen supplier is in providing energy into the grid. In contrast to other countries, in the UK a stable part of the electricity is produced by nuclear, coal and gas plants. Therefore there are only minor differences in the environmental impact over the year.[20]

Germany

In a worst-case scenario where incremental electricity demand would be met exclusively with coal, a 2009 study conducted by the World Wide Fund for Nature and IZES found that a mid-size EV would emit roughly 200 g(CO2)/km (11 oz(CO2)/mi), compared with an average of 170 g(CO2)/km (9.7 oz(CO2)/mi) for a gasoline-powered compact car.[36] This study concluded that introducing 1 million EV cars to Germany would, in the best-case scenario, only reduce CO2 emissions by 0.1%, if nothing is done to upgrade the electricity infrastructure or manage demand.[36] A more reasonable estimate, relaxing the coal assumption, was provided by Massiani and Weinmann taking into account that the source of energy used for electricity generation would be determined based on the temporal pattern of the additional electricity demand (in other words an increase in electricity consumption at peak hour will activate the marginal technology, while an off peak increase would typically activate other technologies). Their conclusion is that natural gas will provide most of the energy used to reaload EV, while renewable energy will not represent more than a few percent of the energy used.[37]

Volkswagen conducted a life-cycle assessment of its electric vehicles certified by an independent inspection agency. The study found that CO2 emissions during the use phase of its all-electric VW e-Golf are 99% lower than those of the Golf 1.2 TSI when powers comes from exclusively hydroelectricity generated in Germany, Austria and Switzerland. Accounting for the electric car entire life-cycle, the e-Golf reduces emissions by 61%. When the actual EU-27 electricity mix is considered, the e-Golf emissions are still 26% lower than those of the conventional Golf 1.2 TSI.[38]

France and Belgium

In France and Belgium, which have a many nuclear power plants, CO2 emissions from electric car use would be about 12g per km (19.2g per US mile).[39] Because of the stable nuclear production, the timing of charging electric cars has almost no impact on their environmental footprint.[20]

Emissions during production

Several reports have found that hybrid electric vehicles, plug-in hybrids and all-electric cars generate more carbon emissions during their production than current conventional vehicles, but still have a lower overall carbon footprint over the full life cycle. The initial higher carbon footprint is due mainly to battery production.[20] As an example, the Ricardo study estimated that 43 percent of production emissions for a mid-size electric car are generated from the battery production.[40]

Environmental impact of manufacturingEdit

Electric cars are not completely environmentally friendly, and have impacts arising from manufacturing the vehicle. Since battery packs are heavy, manufacturers work to lighten the rest of the vehicle. As a result, electric car components contain many lightweight materials that require a lot of energy to produce and process, such as Al and carbon-fiber-reinforced polymers. Electric motors and batteries also add to the energy of electric-car manufacture.[41] Additionally, the magnets in the motors of electric vehicles contain precious metals. In a study released in 2012, a group of MIT researchers calculated that global mining of two rare Earth metals, Template:Neodymium and Template:Dysprosium, would need to increase 700% and 2600%, respectively, over the next 25 years to keep pace with various green-tech plans.[42] Substitute strategies do exist, but deploying them introduces trade-offs in efficiency and cost.[41] The same MIT study noted that the materials used in batteries are also harmful to the environment.[43] Compounds such as Li, Cu, and Ni are mined from the Earth and processed in a manner that demands energy and can release toxic components. In regions with poor legislature, mineral exploitation can even further extend risks. The local population may be exposed to toxic substances through air and groundwater contamination.[41]Script error

A paper published in the Journal of Industrial Ecology named "Comparative environmental life cycle assessment of conventional and electric vehicles" begins by stating that it is important to address concerns of problem-shifting.[1] The study highlighted in particular the toxicity of the electric car's manufacturing process compared to conventional petrol/diesel cars. It concludes that the global warming potential of the process used to make electric cars is twice that of conventional cars. The study also finds that electric cars do not make sense if the electricity they consume is produced predominately by coal-fired power plants.[2]

See alsoEdit

ReferencesEdit

Citations

  1. Script error
  2. Script error

Bibliography

  • Michael H. Westbrook."The Electric and Hybrid Electric Car", The Institution of Mechanical Engineers, 2001, London & SAE, USA. ISBN 0-7680-0897-2

External linksEdit

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