An electric car is a plug-in battery powered automobile which is propelled by electric motor(s). Electric cars have the potential of significantly reducing city pollution by having zero tail pipe emissions.[1][2][3] Vehicle greenhouse gas savings depend on how the electricity is generated. With the current U.S. energy mix, using an electric car would result in a 30% reduction in carbon dioxide emissions.[4][5][6][7] Given the current energy mixes in other countries, it has been predicted that such emissions would decrease by 40% in the UK,[8] 19% in China,[9] and as little as 1% in Germany.[10][11]
Electric cars are expected to have a major impact in the auto industry[12][13] given advantages in city pollution, less dependence on oil, and expected rise in gasoline prices.[14][15][16] World governments are pledging billions to fund development of electric vehicles and their components. The U.S. has pledged US$2.4 billion in federal grants for electric cars and batteries.[17] China has announced it will provide US$15 billion to initiate an electric car industry.[18] Nissan CEO Carlos Ghosn has predicted that one in 10 cars globally will run on battery power alone by 2020.[19] Additionally a recent report claims that by 2020 electric cars and other green cars will take a third of the total of global car sales.[20]
Electric cars are a variety of electric vehicle (EV); the term “electric vehicle” refers to any vehicle that uses electric motors for propulsion, while “electric car” generally refers to road-going automobiles powered by electricity. While an electric car’s power source is not explicitly an on-board battery, electric cars with motors powered by other energy sources are generally referred to by a different name: an electric car powered by sunlight is a solar car, and an electric car powered by a gasoline generator is a form of hybrid car. Thus, an electric car that derives its power from an on-board battery pack is a form of battery electric vehicle (BEV). Most often, the term “electric car” is used to refer to pure battery electric vehicles.
Electric cars enjoyed popularity between the mid-19th century and early 20th century, when electricity was among the preferred methods for automobile propulsion, providing a level of comfort and ease of operation that could not be achieved by the gasoline cars of the time. Advances in internal combustion technology soon rendered this advantage moot; the greater range of gasoline cars, quicker refueling times, and growing petroleum infrastructure, along with the mass production of gasoline vehicles by companies such as the Ford Motor Company, which reduced prices of gasoline cars to less than half that of equivalent electric cars, led to a decline in the use of electric propulsion, effectively removing it from important markets such as the United States by the 1930s. However, in recent years, increased concerns over the environmental impact of gasoline cars, along with reduced consumer ability to pay for fuel for gasoline cars, and the prospect of peak oil, has brought about renewed interest in electric cars, which are perceived to be more environmentally friendly and cheaper to maintain and run, despite high initial costs. Electric cars currently enjoy relative popularity in countries around the world, though they are notably absent from the roads of the United States, where electric cars briefly re-appeared in the late 90s as a response to changing government regulations.
before the pre-eminence of internal combustion engines, electric automobiles held many speed and distance records. Among the most notable of these records was the breaking of the 100 km/h (62 mph) speed barrier, by Camille Jenatzy on April 29, 1899 in his ‘rocket-shaped’ vehicle Jamais Contente, which reached a top speed of 105.88 km/h (65.79 mph). Before the 1920s, electric automobiles were competing with petroleum-fueled cars for urban use of a quality service car.[21]
Proposed as early as 1896 in order to overcome the lack of recharging infrastructure, a exchangeable battery service was first put into practice by Hartford Electric Light Company for electric trucks. The vehicle owner purchased the vehicle from General Electric Company (GVC) without a battery and the electricity was purchased from Hartford Electric through an exchangeable sell house fast battery. The owner paid a variable per-mile charge and a monthly service fee to cover maintenance and storage of the truck. The service was provided between 1910 to 1924 and during that period covered more than 6 million miles. Beginning in 1917 a similar service was operated in Chicago for owners of Milburn Light Electric cars who also could buy the vehicle without the batteries.[22]
In 1897, electric vehicles found their first commercial application in the U.S. as a we buy any house fleet of electrical New York City taxis, built by the Electric Carriage and Wagon Company of Philadelphia. Electric cars were produced in the US by Anthony Electric, Baker, Columbia, Anderson, Edison [disambiguation needed], Fritchle, Studebaker, Riker, Milburn, and others during the early 20th century.
Despite their relatively slow speed, electric vehicles had a number of advantages over their early-1900s competitors. They did not have the vibration, smell, and noise associated with gasoline cars. They did not require gear changes, which for gasoline cars was the most difficult part of driving. Electric cars found popularity among well-heeled customers who used them as city cars, where their limited range proved to be even less of a disadvantage. The cars were also preferred because they did not require a manual effort to start, as did gasoline cars which featured a hand crank to start the engine. Electric cars were often marketed as suitable vehicles for women drivers due to this ease of operation.
In 1911, the New York Times stated that the electric car has long been recognized as “ideal” because it was cleaner, quieter and much more economical than gasoline-powered cars. Reporting this in 2010, the Washington Post commented that “the same unreliability of electric car batteries that flummoxed Thomas Edison persists today.”[23]
[edit] 1990s to present: Revival of mass interest
Main article: 1990s to present: Revival of mass interest
The energy crises of the 1970s and 80s brought about renewed interest in the perceived independence electric cars had from the fluctuations of the hydrocarbon energy market. In the early 1990s, the California Air Resources Board (CARB), the government of California’s began a push for more fuel-efficient, lower-emissions vehicles, with the ultimate goal being a move to zero-emissions vehicles such as electric vehicles.[24][25] In response, automakers developed electric models, including the Chrysler TEVan, Ford Ranger EV pickup truck, GM EV1 and S10 EV pickup, Honda EV Plushatchback, Nissan lithium-battery Altra EV miniwagon and Toyota RAV4 EV.
The global economic recession in the late 2000s led to increased calls for automakers to abandon fuel-inefficient SUVs, which were seen as a symbol of the excess that caused the recession, in favor of small cars, hybrid cars, and electric cars. California electric car maker Tesla Motors began development in 2004 on the Tesla Roadster, which was first delivered to customers in 2008. As of January 2011 Tesla had produced more than 1,500 Roadsters sold in at least 31 countries.[26] The Mitsubishi i MiEV was launched for fleet customers in Japan in July 2009, and for individual customers in April 2010,[27][28][29] followed by sales to the public in Hong Kong in May 2010,[30] and Australia in July 2010 via leasing.[31] As of November 2010 Mitsubishi reported 5,000 units produced.[32]
Retail customer deliveries of anything goes diet the Nissan Leaf in Japan and the United States began in December 2010, allowing the Leaf to become the first modern all electric car to be produced for the mass market from a major manufacturer,[33][34][35] though initial availability is restricted to a few launch markets and in limited quantities. As of January 2011 other electric automobiles and city cars available in some markets included the Th!nk City, REVAi, Buddy, Citroën C1 ev’ie, and several neighborhood electric vehicles.
Electric cars are generally more expensive than gasoline cars. The primary reason is the high cost of car batteries. US and British car buyers seem to be unwilling to pay more for an electric car.[36][37] This prohibits the mass transition from gasoline cars to electric cars. A survey taken by Nielsen for the Financial Times has shown that 65 percent of Americans and 76 percent of Britons are not willing to pay more for an electric car above the price of a gasoline car.[38] also a report by J.D. Power and Associates claims that about 50 percent of U.S. car buyers are not even willing to spent more than US$5,000 on a green vehicle above the price of a petrol car despite their concern about the environment.[39]
The Nissan LEAF is the most affordable five door family electric car in the U.S. at a price of US$32,780 going down to US$25,280 after federal tax rebate of US$7,500, going further down to US$20,280 after the US$5,000 tax rebate in California and similar incentives in other states.
The Renault Fluence Z.E. five door family saloon electric car will be priced at less than US$20,000 before any U.S. federal and state tax rebates are applied.[40] It will be sold without the battery thus the significant price difference. The customer will buy the Renault Fluence Z.E. with a contract to lease the battery from the company Better Place.
The electric car company Tesla Motors is using laptop battery technology for the battery packs of their electric cars that are 3 to 4 times cheaper than dedicated electric car battery packs that other auto makers are using. While dedicated battery packs cost $700–$800 per kilowatt hour, battery packs using small laptop cells cost about $200. That could potentially drive down the cost of electric cars that are using Tesla’s battery technology such as theToyota RAV4 EV and the Smart ED as well as their own upcoming 2014 models such as the Model X.[41][42][43]
Most of the running cost of an electric vehicle can be attributed to the maintenance and replacement of the battery pack because an electric vehicle has only around 5 moving parts in its engine, compared to a gasoline car that has hundreds of parts in its internal combustion engine.[44] Electric cars have expensive batteries that must be replaced but otherwise incur very low maintenance costs, particularly in the case of current Lithium based designs.
To calculate the cost per kilometer of an electric vehicle it is therefore necessary to assign a monetary value to the wear incurred on the battery. This can be difficult due to the fact that it will have a slightly lower capacity each time it is charged and is only considered to be at the end of its life when the owner decides its performance is no longer acceptable. Even then an ‘end of life’ battery is not completely worthless as it can be re-purposed, recycled or used as a spare.
Since a battery is made of many individual cells that do not necessarily wear evenly periodically replacing the worst of these can retain the vehicle’s range.
The Tesla Roadster’s very large battery pack is expected to last seven years with typical driving and costs US$12,000 when pre-purchased today.[45][46] Driving 40 miles (64 km) per day for seven years or 102,200 miles (164,500 km) leads to a battery consumption cost of US$0.1174 per 1 mile (1.6 km) or US$4.70 per 40 miles (64 km). The company Better Place provides another cost comparison as they anticipate meeting contractual obligations to deliver batteries as well as clean electricity to recharge the batteries at a total cost of US$0.08 per 1 mile (1.6 km) in 2010, US$0.04 per mile by 2015 and US$0.02 per mile by 2020.[47] 40 miles (64 km) of driving would initially cost US$3.20 and fall over time to US$0.80.
In 2010 the U.S. government estimated that a battery with a 100 miles (160 km) range would cost about US$33,000. Concerns remain about durability and longevity of the battery.[48]
Nissan estimates that the Leaf’s 5 year operating cost will be US$1,800 versus US$6,000 for a gasoline car.[49] The documentary film Who Killed the Electric Car?[50] shows a comparison between the parts that require replacement in a gasoline powered cars and EV1s, with the garages stating that they bring the electric cars in every 5,000 mi (8,000 km), rotate the tires, fill the windshield washer fluid and send them back out again.
[edit] Electricity vs. Fuel
“Fuel” cost comparison: the Tesla Roadster sport car’s plug-to-wheel energy use is 280 W·h/mi. In Northern California, the local electric utility company PG&E says that “The E-9 rate is mandatory for those customers that are currently on a residential electric rate and who plan on refueling an EV on their premises.”[51] Combining these two facts implies that driving a Tesla Roadster 40 miles (64 km) a day would use 11.2 kW·h of electricity costing between US$0.56 and US$3.18 depending on the time of day chosen for recharging.[51] For comparison, driving an internal combustion engine-powered car the same 40 miles (64 km), at a mileage of 25 miles per US gallon (9.4 L/100 km; 30 mpg-imp), would use 1.6 US gallons (6.1 l; 1.3 imp gal) of fuel and, at a cost of US$3 per 1 US gallon (3.8 l; 0.83 imp gal), would cost US$4.80.
The Tesla Roadster uses about 17.4 kW·h/100 km (0.63 MJ/km; 0.280 kW·h/mi),[52] the EV1 used about 11 kW·h/100 km (0.40 MJ/km; 0.18 kW·h/mi).[53]
[edit] Range
“Range anxiety” is a reason that many automakers marketed EVs as “daily drivers” suitable for city trips and other short hauls.[54] The average American drives less than 40 miles (64 km) per day; so the GM EV1 would have been adequate for the daily driving needs of about 90% of U.S. consumers.[50]
The Tesla Roadster gets 245 miles (394 km) per charge;[55] more than double that of prototypes and evaluation fleet cars currently on the roads.[56] The Roadster can be fully recharged in about 3.5 hours from a 220-volt, 70-amp home outlet.[57]
One way automakers can extend the short range of electric vehicles is by building them with battery switch technology. An EV with battery switch technology and a 100 miles (160 km) driving range will be able to go to a battery switch station and switch a depleted battery with a fully charged one in 59.1 seconds[58] giving the EV an additional 100 miles (160 km) driving range. The process is cleaner and faster than filling a tank with gasoline and the driver remains in the car the entire time.[59] As of late 2010 there are only 2 companies with plans to integrate battery switching technology to their electric vehicles.[60][61][62] The company Better Place is already operating a battery switch station in Japan up to the end of 2010[63] and announced a commitment to open four battery switch stations in the US from San Francisco toSan Jose in California.[64]
Another way is the installation of DC Fast Charging stations with high-speed charging capability from three-phase industrial outlets so that consumers could recharge the 100 mile battery of their electric vehicle to 80 percent in about 30 minutes.[65][66] A nationwide fast charging infrastructure is currently being deployed in the US that by 2013 will cover the entire nation.[67] DC Fast Chargers are going to be installed at 45 BP and ARCO locations and will be made available to the public as early as March 2011.[68] The EV Project will deploy charge infrastructure in 16 cities and major metropolitan areas in six states.[69][70] Nissan has announced that 200 of its dealers in Japan will install fast chargers for the December 2010 launch of its Leaf EV, with the goal of having fast chargers everywhere in Japan within a 25 mile radius.[71]
Electric cars produce no pollution at the tailpipe which will contribute to cleaner air in cities, but their use increases demand for electricity generation. 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.
For mains electricity the emission intensity varies significantly per country and within a particular country it will vary depending on demand,[72] the availability of renewable sources and the efficiency of the fossil fuel-based generation used at a given time.[73] Charging a vehicle using off-grid renewable energy yields very low carbon intensity (only that to produce and install the off-grid generation system e.g. domestic wind turbine).
An EV recharged from the existing US grid electricity emits about 115 grams of CO2 per kilometer driven (6.5 oz(CO2)/mi), whereas a conventional US-market gasoline powered car emits 250 g(CO2)/km (14 oz(CO2)/mi) (most from its tailpipe, some from the production and distribution of gasoline).[74] 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[75]), but would be more significant in countries with cleaner electric infrastructure. 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.[76] 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.[76]
In France, which has a clean energy grid, CO2 emissions from electric car use would be about 12g per kilometer.[77]
A study done in the UK in 2008 has concluded that electric vehicles have the potential to cut down carbon dioxide and greenhouse gas emissions by at least 40% even when taking into account the emissions of current electricity generation in the UK and emissions relating to the production and disposal of electric vehicles.[78]
[edit] Acceleration and drivetrain design
Electric motors can provide high power to weight ratios, and batteries can be designed to supply the large currents to support these motors.
Although some electric vehicles have very small motors, 15 kW (20 hp) or less and therefore have modest acceleration, many electric cars have large motors and brisk acceleration. In addition, the relatively constant torque of an electric motor, even at very low speeds tends to increase the acceleration performance of an electric vehicle relative to that of the same rated motor power internal combustion engine. Another early solution was American Motors’ experimental Amitron piggyback system of batteries with one type designed for sustained speeds while a different set boosted acceleration when needed.[79]
Electric vehicles can also use a direct motor-to-wheel configuration which increases the amount of available power. Having multiple motors connected directly to the wheels allows for each of the wheels to be used for both propulsion and as braking systems, thereby increasing traction. In some cases, the motor can be housed directly in the wheel, such as in the Whispering Wheel design, which lowers the vehicle’scenter of gravity and reduces the number of moving parts. When not fitted with an axle, differential, or transmission, electric vehicles have less drivetrain rotational inertia.
[edit] Transmission
A gearless or single gear design in some EVs eliminates the need for gear shifting, giving such vehicles both smoother acceleration and smoother braking. Because the torque of an electric motor is a function of current, not rotational speed, electric vehicles have a high torque over a larger range of speeds during acceleration, as compared to an internal combustion engine. As there is no delay in developing torque in an EV, EV drivers report generally high satisfaction with acceleration.
For example, the Venturi Fetish delivers supercar acceleration despite a relatively modest 220 kW (295 hp), and top speed of around 160 km/h (100 mph). Some DC motor-equipped drag racer EVs, have simple two-speed manual transmissions to improve top speed.[80] The Tesla Roadster 2.5 Sport can accelerate from 0 to 60 mph (97 km/h) in 3.7 seconds with a motor rated at 215 kW (288 hp).[81]
Also the Wrightspeed X1 prototype created by Wrightspeed Inc is the worlds fastest street legal electric car.[82] With an acceleration of 0-60 mph in 2.9 seconds[83] the X1 has bested some of the worlds fastest sports cars.[84]
[edit] Energy efficiency
Main articles: Fuel efficiency, Electrical efficiency, Thermal efficiency, and Energy conversion efficiency
Internal combustion engines are relatively inefficient at converting on-board fuel energy to propulsion as most of the energy is wasted as heat. On the other hand, electric motors are more efficient in converting stored energy into driving a vehicle, and electric drive vehicles do not consume energy while at rest or coasting, and some of the energy lost when braking is captured and reused through regenerative braking, which captures as much as one fifth of the energy normally lost during braking.[85][86] Typically, conventional gasoline engines effectively use only 15% of the fuel energy content to move the vehicle or to power accessories, and diesel engines can reach on-board efficiencies of 20%, while electric drive vehicles have on-board efficiency of around 80%.[85]
Production and conversion electric cars typically use 10 to 23 kW·h/100 km (0.17 to 0.37 kW·h/mi).[53][87] Approximately 20% of this power consumption is due to inefficiencies in charging the batteries. Tesla Motors indicates that the vehicle efficiency (including charging inefficiencies) of their lithium-ion battery powered vehicle is 12.7 kW·h/100 km (0.21 kW·h/mi) and the well-to-wheels efficiency (assuming the electricity is generated from natural gas) is 24.4 kW·h/100 km (0.39 kW·h/mi).[88]
[edit] Safety
The safety issues of BEVs are largely dealt with by the international standard ISO 6469. This document is divided in three parts dealing with specific issues:
* On-board electrical energy storage, i.e. the battery
* Functional safety means and protection against failures
* Protection of persons against electrical hazards.
Firefighters and rescue personnel receive special training to deal with the higher voltages and chemicals encountered in electric and hybrid electric vehicle accidents. While BEV accidents may present unusual problems, such as fires and fumes resulting from rapid battery discharge, there is apparently no available information regarding whether they are inherently more or less dangerous than gasoline or diesel internal combustion vehicles which carry flammable fuels.
[edit] Vehicle safety
Great effort is taken to keep the mass of an electric vehicle as low as possible, in order to improve the EV’s range and endurance. Despite these efforts, the high density and weight of the electric batteries usually results in an EV being heavier than a similar equivalent gasoline vehicle leading to less interior space, and longer braking distances. However, in a collision, the occupants of a heavy vehicle will, on average, suffer fewer and less serious injuries than the occupants of a lighter vehicle; therefore, the additional weight brings safety benefits[89] despite having a negative effect on the car’s performance.[90] An accident in a 2,000 lb (900 kg) vehicle will on average cause about 50% more injuries to its occupants than a 3,000 lb (1,400 kg) vehicle.[91][92] In a single car accident,[citation needed] and for the other car in a two car accident, the increased mass causes an increase in accelerations and hence an increase in the severity of the accident. Some electric cars use low rolling resistance tires, which typically offer less grip than normal tires.[93][94][95] Many electric cars have a small, light and fragile body, though, and therefore offer inadequate safety protection. Because of this, the Insurance Institute for Highway Safety in America had condemned the use of such vehicles.[96]
[edit] Hazard to pedestrians
See also: Electric vehicle warning sounds
At low speeds, electric cars produced less roadway noise as compared to vehicles propelled by a internal combustion engine. Blind people or the visually impaired consider the noise of combustion engines a helpful aid while crossing streets, hence electric cars and hybrids could pose an unexpected hazard.[97][98] Tests have shown that this is a valid concern, as vehicles operating in electric mode can be particularly hard to hear below 20 mph (30 km/h) for all types of road users and not only the visually impaired. At higher speeds the sound created by tire friction and the air displaced by the vehicle start to make sufficient audible noise.[98]
The US Congress, the European Commission and the Government of Japan are exploring legislation to establish a minimum level of sound for hybrids and plug-in electric vehicles when operating in electric mode, so that blind people and other pedestrians and cyclists can hear them coming and detect from which direction they are approaching.[98][99] The Nissan Leaf is the first electric car to include Nissan’s Vehicle Sound for Pedestrians system, which will include one sound for forward motion and another for reverse.[100][101]
[edit] Differences in controls
Presently most EV manufacturers do their best to emulate the driving experience as closely as possible to that of a car with automatic transmission that American motorists are most familiar with. Most models have the PRNDL gate or PRND push-buttons traditionally found in cars with automatic transmission despite the underlaying mechanical differences. Push buttons are the easiest to implement as all modes are implemented through software on the vehicle’s controller.
Even though the motor may be permanently connected to the wheels through a fixed-ratio gear and no parking pawl may be present the modes “P” and “N” will still be provided on the selector. In this case the motor is disabled in “N” and an electrically actuated handbrake provides the “P” mode.
In some cars the motor will spin slowly to provide a small amount of creep in “D”, similar to a traditional automatic.[102]
When the foot is lifted from the accelerator of an ICE, engine braking causes the car to slow. An EV would coast under these conditions, and applying mild regenerative braking instead provides a more familiar response. Selecting the “B” (Brake) mode will increase this effect for sustained downhill driving.
[edit] Cabin heating and cooling
Electric vehicles generate very little waste heat and resistance electric heat may have to be used to heat the interior of the vehicle if heat generated from battery charging/discharging can not be used to heat the interior.
While heating can be simply provided with an electric resistance heater, higher efficiency and integral cooling can be obtained with a reversible heat pump(this is currently implemented in the hybrid Toyota Prius). Positive Temperature Coefficient (PTC) junction cooling[103] is also attractive for its simplicity – this kind of system is used for example in the Tesla Roadster.
Some electric cars, for example the Citroën Berlingo Electrique, use an auxiliary heating system (for example gasoline-fueled units manufactured by Webasto or Eberspächer) but sacrifice “green” and “Zero emissions” credentials. Cabin cooling can be augmented with solar power, most simply and effectively by inducting outside air to avoid extreme heat buildup when the vehicle is closed and parked in the sunlight (such cooling mechanisms are available as aftermarket kits for conventional vehicles). Two models of the 2010 Toyota Prius include this feature as an option.[104]
