|
|
|
|
Electric car
|
| |
|
| |
An electric car is a type of alternative fuel car that utilizes electric motors and motor controllers instead of an internal combustion engine (ICE). Currently, in most cases, electrical power is derived from battery packs carried on board the vehicle. Other energy storage methods that may come into use in the future include the use of ultracapacitors, or storage of energy in a spinning flywheel.
Vehicles that make use of both electric motors and other types of engine are known as hybrid electric vehicles and are not considered pure electric vehicles (EVs) because they operate in a charge-sustaining mode.
Discussion
Ask a question about 'Electric car' Start a new discussion about 'Electric car' Answer questions from other users |
Encyclopedia
An electric car is a type of alternative fuel car that utilizes electric motors and motor controllers instead of an internal combustion engine (ICE). Currently, in most cases, electrical power is derived from battery packs carried on board the vehicle. Other energy storage methods that may come into use in the future include the use of ultracapacitors, or storage of energy in a spinning flywheel.
Vehicles that make use of both electric motors and other types of engine are known as hybrid electric vehicles and are not considered pure electric vehicles (EVs) because they operate in a charge-sustaining mode. Hybrid vehicles with batteries that can be charged externally from an external source are called plug-in hybrid electric vehicles (PHEV), and become pure battery electric vehicles (BEVs) during their charge-depleting mode. Other types of electric vehicles besides cars include light trucks and neighborhood electric vehicles.
History
The electric car was among the oldest automobiles — small electric vehicles predate the Otto cycle upon which Diesel (diesel engine) and Benz (gasoline engine) based the automobile. Between 1832 and 1839 (the exact year is uncertain), Scottish businessman Robert Anderson invented the first crude electric carriage. Professor Sibrandus Stratingh of Groningen, the Netherlands, designed the small-scale electric car, built by his assistant Christopher Becker in 1835.
Practical and more successful electric road vehicles were invented by both American Thomas Davenport and Scotsmen Robert Davidson in 1842. Both inventors were the first to use non-rechargeable electric cells.
Frenchmen Gaston Plante invented a better storage battery in 1865 and his fellow countrymen Camille Faure improved the storage battery in 1881. This improved-capacity storage battery paved the way for electric vehicles to flourish. An electric-powered two-wheel cycle was put on display at the World Exhibition 1867 in Paris by the Austrian inventor Franz Kravogl.
France and Great Britain were the first nations to support the widespread development of electric vehicles. In November 1881 French inventor Gustave Trouvé demonstrated a working three-wheeled automobile at the International Exhibition of Electricity in Paris.
Just prior to 1900, 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).
It was not until 1895 that Americans began to devote attention to electric vehicles after an electric tricycle was built by A. L. Ryker and William Morrison built a six-passenger wagon both in 1891. Many innovations followed and interest in motor vehicles increased greatly in the late 1890s and early 1900s. In 1897, the first commercial application was established as a fleet of New York City taxis built by the Electric Carriage and Wagon Company of Philadelphia. Electric cars, produced in the USA by Anthony Electric, Baker, Detroit, Edison, Studebaker, and others during the early 20th century for a time out-sold gasoline-powered vehicles.
These vehicles were successfully sold as city cars to upper-class customers and were often marketed as suitable vehicles for women drivers due to their clean, quiet and easy operation. Due to technological limitations and the lack of transistor-based electric technology, the top speed of these early electric vehicles was limited to about 32 km/h (20 mph).
By the turn of the century, America was prosperous and cars, now available in steam, electric, or gasoline versions, were becoming more popular. The years 1899 and 1900 were the high point of electric cars in America, as they outsold all other types of cars. Electric vehicles had many advantages over their competitors in the early 1900s. They did not have the vibration, smell, and noise associated with gasoline cars. Changing gears on gasoline cars was the most difficult part of driving, and electric vehicles did not require gear changes.
While steam-powered cars also had no gear shifting, they suffered from long start-up times of up to 45 minutes on cold mornings. The steam cars had less range before needing water than an electric car's range on a single charge. The only good roads of the period were in town, causing most travel to be local commuting - a perfect situation for electric vehicles, since their range was limited.
The electric vehicle was the preferred choice of many because it did not require the manual effort to start, as with the hand crank on gasoline vehicles, and there was no wrestling with a gear shifter. While basic electric cars cost under $1,000, most early electric vehicles were ornate, massive carriages designed for the upper class. They had fancy interiors, with expensive materials, and averaged $3,000 by 1910. Electric vehicles enjoyed success into the 1920s with production peaking in 1912.
The decline of the electric vehicle was brought about by several major developments:
- By the 1920s, America had a better system of roads that now connected cities, bringing with it the need for longer-range vehicles.
- The discovery of Texas crude oil reduced the price of gasoline so that it was affordable to the average consumer.
- The invention of the electric starter by Charles Kettering in 1912 eliminated the need for the hand crank.
- The initiation of mass production of internal combustion engine vehicles by Henry Ford made these vehicles widely available and affordable in the $500 to $1,000 price range. By contrast, the price of the less efficiently produced electric vehicles continued to rise. In 1912, an electric roadster sold for $1,750, while a gasoline car sold for $650.
Electric vehicles became popular for some limited range applications. Forklifts were EVs when they were introduced in 1923 by Yale; many battery electric fork lifts are still produced. Electric golf carts have been available for many years, including early models by Lektra in 1954. Their popularity led to their use as neighborhood electric vehicles; larger versions are becoming popular and increasingly ruled "street legal".
By the late 1930s, the electric automobile industry had completely disappeared, with battery-electric traction being limited to niche applications, such as certain industrial vehicles. A thorough examination into the social and technological reasons for the failure of electric cars is to be found in Taking Charge: The Electric Automobile in America by Michael Brian Schiffer.
Battery powered electric concept cars continued to appear, such as the Scottish Aviation Scamp (1965), the Enfield 8000 (1966) and the General Motors "Electrovair" (1966) and "Electrovette" (1976). At the 1990 Los Angeles Auto Show, GM President Roger Smith unveiled the "Impact" electric car, the precursor to the EV1, promising that GM would build electric cars for the public.
In California, U.S. in the early 1990s, the California Air Resources Board (CARB) mandated electric car sales by major automakers. In response, makers developed EVs including the Chrysler TEVan, Ford Ranger EV pickup truck, GM EV1 and S10 EV pickup, Honda EV Plus hatchback, Nissan lithium-battery Altra EV miniwagon and Toyota RAV4 EV. Automakers refused to properly promote or sell their EVs, allowed consumers to drive them only by closed-end lease and, along with oil groups, fought the mandate vigorously. Chrysler, Toyota and some GM dealers sued in Federal court; California soon neutered its ZEV Mandate. After public protests by EV drivers' groups upset by the repossession of their EVs, Toyota offered the last 328 RAV4-EVs for sale to the general public during six months (ending on November 22, 2002). All other electric cars, with minor exceptions, were withdrawn from the market and destroyed by their manufacturers. Toyota continues to support the several hundred Toyota RAV4-EV in the hands of the general public and in fleet usage. From time to time, Toyota RAV4-EVs come up for sale on the used market and command prices sometimes over 60 thousand dollars. These are highly prized by solar homeowners, who charge their cars from their solar electric rooftop systems.
In 1994, REVA Electric Car Company Private Ltd. was established in Bangalore, India, as a joint venture between the Maini Group India and AEV LLC, California USA, to manufacture environment-friendly and cost-effective electric vehicles. After seven years of R&D, it launched the REVA, India's first Electric Vehicle, in June 2001.
In the summer of 2003, Martin Eberhard and Marc Tarpenning founded Tesla Motors in San Carlos, California. In 2006, a prototype of the Tesla Roadster was unveiled.
Present and future
In the U.S. as of July, 2006, there were between 60,000 and 76,000 low-speed, battery powered vehicles in use, up from about 56,000 in 2004, according to Electric Drive Transportation Association estimates. There are now over 100,000 neighborhood electric vehicles (NEVs) on U.S. streets.
The REVA is currently commercialized in India, in the UK (since 2003), and in several other European countries (including Cyprus and Greece, Belgium, Germany, Spain, Norway, and Malta). In most countries the REVA is classified as an electric quadricycle, while in the US it is allowed only as an NEV with reduced top speed. More REVAs have been produced than any other currently selling electric car.
Series production of the Tesla Roadster began on March 17, 2008 The Roadster uses Lithium-Ion batteries rather than the lead-acid batteries which had previously been predominant in small-maker BEVs. The vehicle uses 6831 Li-ion batteries to travel 394 km (245 mi) per charge, an equivalent fuel efficiency of 1.74 L/100 km (135 mpg U.S.), yet accelerates from 0-100 km/h in under 4 seconds on its way to a top speed of 210 km/h (135 mph). The company announced that production of the Roadster had officially begun on March 17th. The first Tesla was delivered on February 1, 2008.
In December, 2007, Fortune reported on eleven new companies planning to offer highway-capable electric cars within a few years. Aptera Motors plans to sell both electric and hybrid versions of its Aptera 2 Series in 2009. Mitsubishi Motors will sell its iMiev EV beginning in 2009 in Japan and New Zealand.
In 2007, Miles Electric Vehicles announced that it would produce a highway-speed all-electric sedan named the XS500. The company anticipates that the XS500 will be available for sale in the U.S. in early 2009. The XS500 uses Li-Ion batteries.
In early 2008, Dodge announced an electric concept car called Dodge Zeo. There are no official release dates or prices.
In May 2008 Nissan Motor Company announced plans to sell an electric car in the U.S. and Japan by 2010. Nissan's chief executive, Carlos Ghosn said they envisioned a broad range of electric vehicles, starting with small cars.
In November 2008 Ford and PML Flightlink joined together to produce the Hi-Pa Drive Ford F150 pick up truck proving that a vehicle does not have to be small, underpowered and unprofitable to be green.
Other automakers like Fuji Heavy Industries are testing versions of electric cars, and General Motors and Toyota are working on battery-powered vehicles that have small gasoline engines for recharging.
Acceptance of electric cars
As with any new technology that requires mass uptake by the public to succeed, there is a great incentive to convince people that electric cars are a good thing. This is not always done in the most honest way possible. There are many objections both from an engineering point of view and from an economic point of view.
In addition, several automobile companies which sell electric cars have been accused of dishonest business practices, which include providing misleading information about their own products, as well as failure to produce, market, and deliver the cars.
Electric vehicles which store electrical energy in a capacitor or battery would not be able to immediately replace gasoline cars given the available transportation infrastructure. For example, while a gasoline car could undertake a road trip which would require several short (around ten minutes) fuel stops to complete, current electric car technology would not be capable of completing the trip in the same length of time; in addition to the limited range of current electric cars, they are not as quick or as practical to recharge. Even a practically comparable capacitor-based car, which would conceptually permit much faster recharging times than a battery car can, would require an electrical infrastructure that could "quick-charge" the car; provide a significant amount of energy, at very high current, to the car at its charging station, for a similar amount of time to that required to refuel a gasoline car.
Today's infrastructure is suited to the slower charging cycle of battery electric cars, which must be parked for several hours while they recharge, making them suited for a commuter role but unsuitable for the long-distance driving which less frequent but still a factor in many markets.
The unit of measurement known as miles per gallon of gasoline equivalent (MPGe) may be misleading if used to compare the overall efficiency of electric and internal combustion vehicles. The MPGe formula[28] can sometime use the pump to wheels energy for gasoline, but the battery to wheels energy for EVs, ignoring the loss of power when charging a battery with AC. However, the MPGe formula for gasoline also ignores the fuel used to pump, refine and transport the gasoline to the gas station.
Solutions
Improvements to the electrical infrastructure could lead to mitigation of this issue; if charging stations were to adopt high-power connections to the electrical grid, and charge drivers by the kilojoule, supercapacitor-equipped electric cars could reach the goal of refueling in under ten minutes. It should be noted that this infrastructure change would be akin to the availability of cellular communications technology on a nationwide level; in the same way that rural locations are the last to receive access to high-speed data networks and up-to-date technology, those same locations would be the last to receive adequate electric-vehicle charging facilities. Being able to refuel in remote locations is necessary for a vehicle that is capable of undergoing long-distance, cross-country travel.
The possibility to standardize replaceable battery packs should also be considered. The battery would be charged at the energy station over several hours and the vehicle's empty battery would be replaced with the fully charged one, for a fee covering the energy stored.
Because of the weight (several hundred kilos), the vehicle and the energy station need to be adapted with a simple lift-and-slide-in mechanism to facilitate the replacement. It should not take longer time to switch batteries than filling up a gasoline car. Small car = one battery. Big car = several batteries.
Another means of mitigating the infrastructure issue is through use of different energy storage technology, or through hybrid vehicle technology. The goal of the former is to find a method of storing electrical energy on board the car, in a manner more efficient than in a battery or capacitor. One proposed solution is the hydrogen fuel cell vehicle, which uses a hydrogen-based fuel cell to produce electricity while consuming hydrogen stored in a pressurized tank. This arrangement brings its own problems to the issue; cryogenic, compressed storage of hydrogen gas does not provide the energy density required to overcome gasoline as an onboard energy source; hydrogen infrastructure allows for quick refueling of hydrogen vehicles, but lags behind gasoline and electricity in terms of available refueling locations.
Alternative energy storage is fast becoming the norm for achieving fuel efficiency without sacrificing range and performance. The most common example of synergy in the area of electric vehicles today is found in hybrid cars, vehicles which use a small auxiliary gasoline or diesel engine to provide performance beyond that of what their electric drivetrains can provide when necessary, as well as eliminating the concern of having to find a charging station to replenish the car's batteries (most currently available hybrid cars are not plug-in hybrids), since it is much easier to find a gasoline refueling station today. In turn, the electric drivetrain can be seen to be assisting the ICE in delivering the greatest possible range and performance from each gallon of fuel consumed. Regenerative braking and other forms of energy management help hybrid cars fulfill this goal.
Relation with hybrid electric vehicles
Vehicles using both electric motors and Internal Combustion Engines are examples of hybrid vehicles, and are not considered pure electric vehicles (also called all-electric vehicles) because they operate in a charge-sustaining mode. Hybrid vehicles with batteries that can be charged externally to displace some or all of their ICE power and gasoline fuel are called plug-in hybrid electric vehicles (PHEV), and are pure EVs during their charge-depleting mode. The coming Chevrolet Volt is of this type. If batteries cannot be charged externally, the vehicles are called regular hybrids.
Comparison with internal combustion engine vehicles (ICEVs)
Running costs
Electric car operating costs can be directly compared to the equivalent operating costs of a gasoline-powered vehicle. A litre of gasoline contains about 8.9 kW·h of energy. To calculate the cost of the electrical equivalent of a liter of gasoline, multiply the utility cost per kW·h by 8.9. Because automotive internal combustion engines are only about 20% efficient, then at most 20% of the total energy in that liter of gasoline is ever put to use.
A car powered by an internal combustion engine at 20% efficiency, getting 8 L/100 km (30 mpg), will require (8.9*8)*0.20 = 14.2 kW·h/100 km of energy to push air aside and overcome rolling resistance. At a cost of $1/L, 8 L/100 km is $8 per 100 km. A battery electric version of that same car with a charge/discharge efficiency of 81%, and charged at a cost of $0.10 for kW·h would cost (14.2/0.81)*0.10 = $1.75 per 100 km, or would be paying the equivalent of $0.22/L. The Tesla uses about 13 kW·h/100 km, the EV1 used about 11 kW·h/100 km.
Servicing costs are lower for an electric car. The movie Who Killed the Electric Car shows a comparison between the parts that require replacement in a gasoline powered car and the EV1 (none), stating that they bring the cars in every 5,000 miles, rotate the tires, fill the windshield washer fluid and send them back out again. Even brakes require less maintenance because of the regenerative braking, the same as with a hybrid.
Electric cars using lead-acid batteries require replacement of the battery pack on a regular basis, while internal combustion engines can last the life of the vehicle, with routine repairs. NiMH batteries typically last the life of the vehicle. Toyota Prius vehicles have been known to go over 300,000km without needing a battery replacement.
Energy efficiency
An electric car's efficiency is affected by its charging and discharging efficiencies, which ranges from 70 to 85%. The electricity generating system in the USA loses 9.5% of the power transmitted between the power station and the socket, and the power stations are 33% efficient in turning the calorific value of fuel at the power station to electrical power. Overall this results in an efficiency of 20% to 25% from fuel into the power station, to power into the motor of the grid-charged EV, comparable or slightly better the average 20% efficiency of gasoline-powered vehicles in urban driving.
Production and conversion electric cars typically use 10 to 23 kW·h/100 km (0.17 to 0.37 kW·h/mi). Approximately 20% of this power consumption is due to inefficiencies in charging the batteries. Tesla Motors indicates that the well-to-wheels energy consumption of their li-ion powered vehicle is 10.9 kW·h/100 km (0.176 kW·h/mi). The US fleet average of 10 L/100 km (23 mpg US) of gasoline is equivalent to 96 kW·h/100 km (1.58 kW·h/mi), and the 3.4 L/100 km (70 mpg US) Honda Insight uses 32 kW·h/100 km (0.52 kW·h/mi) (assuming 9.6 kW·h per liter of gasoline), so hybrid electric vehicles are relatively energy efficient, and battery electric vehicles are much more energy efficient. Note that the greater efficiency of electric vehicles is primarily because most energy in a gasoline-powered vehicle is released as waste heat. With an engine getting only 20% thermal efficiency, a gasoline-powered vehicle using 96kW·h/100km of energy is only using 19.2kW·h/100km for motion.
]
Carbon dioxide emissions
While electric cars are considered zero-emission-at-tailpipe-vehicles, their widespread uptake will eventually cause an increase in electrical generation needs. Generating electricity and providing liquid fuels for vehicles are different categories of the energy economy, with different inefficiencies and environmental harms.
If the aim of looking at electric vehicles as alternatives to conventional vehicles is to reduce CO2 emissions, then that has to mean using the most carbon-efficient vehicle and fuel you can buy. An EV recharged from conventional grid electricity is not significantly less polluting than efficient gasoline, hybrid or diesel cars.
Most electricity generation in the United States is from fossil sources, and half of that is from coal, according to the U.S. Department of Energy. Coal is more carbon-intensive than oil. Overall average efficiency from US power plants (33% efficient) to point of use (transmission loss 9.5%), (US DOE figures) is 30% . Accepting 70% to 80% efficiency for the electric vehicle gives a figure of only 20% overall efficiency when recharged from fossil fuels. That is comparable to the efficiency of an internal combustion engine running at variable load. The efficiency of a gasoline engine is about 16 %, and 20 % for a diesel engine.. This is much lower than the efficiency when running at constant load and optimal rotational speed, which gives efficiency around 30 and 45 % respectively (Volvo figures). The electric battery suffers from similar decrease in efficiency when running at variable load, which accounts for the modest increased efficiency of hybrid vehiclesJkolle (talk) 02:36, 26 February 2009 (UTC).
The actual result in terms of emissions depends on different refining and transportation costs getting fuel to a car versus a power plant. Diesel engines can also easily run on renewable fuels, biodiesel, vegetable oil fuel, with no loss of efficiency. Using fossil based grid electricity entirely negates the in vehicle efficiency advantages of electric cars. The major potential benefit of electric cars is to allow diverse renewable electricity sources to fuel cars.
A modern TDI diesel vehicle is almost as efficient as an electric vehicle. At Tour de Sol 2006, one team entered both a solar & wind-powered EV and a TDI biodiesel car; they earned 68 and 51 MPGe, respectively. Either type of vehicle is able to run on 100% renewable energy sources, which sets them apart from hybrid and conventional gasoline cars. Electric vehicles did not win the US 'Tour de Sol' competitions for greenest car in 2005 and 2006; a VW TDI running on biodiesel (B100) did. (Bianchi, M. :, Retrieved on 2008 -19-12.) The range limitations and higher mass of electric vehicles put them at a significant performance disadvantage to biodiesels, yet the low cost and wide availability of 100% renewable electricity to US grid customers makes electric vehicles cheaper to operate than biodiesel cars running on commercial B100.
The use of solar, wind, nuclear electric generation along with carbon capture for fossil fuel powered plants means that in the long run, electric vehicles will produce less carbon dioxide over their life time since it is impractical to reduce carbon dioxide and NOx at the tailpipe of diesel/bio fueled cars. Based on GREET simulations, electric cars can achieve up to 100% reductions with renewable electric generation vs 77% will B100 (100% bio-diesel car). At present only 32% reductions of carbon dioxide is available for electric cars recharging from non-renewable utilities on the US Grid, due to heavy fossil fuel use and inefficiencies.
Smog
The Ontario Medical Association announced that smog is responsible for an estimated 9,500 premature deaths in the province each year . Electric cars or plug-in hybrids, especially in emission-free electric mode, could vastly reduce this number.
Range vs cruising speed
The trade-off for range against cruising speed is well known for IC vehicles, typically a cruising speed of around 80 km/h (50 mph) is near-optimal, although for specific cars it could fall as low as 40 km/h (25 mph), or as high as 100 km/h (60 mph).
For electric vehicles the equation is less complex, and maximum range is achieved at comparatively low speeds.
Acceleration and drivetrain design
Although some electric vehicles have very small motors, or less and therefore have modest acceleration, the relatively constant torque of an electric motor even at very low speeds tends to increase the acceleration performance of an electric vehicle for the same rated motor power. 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.
Electric vehicles can also utilize 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's center 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.
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 , and a top speed of around 160 km/h. Some DC motor-equipped drag racer EVs, have simple two-speed transmissions to improve top speed. The Tesla Roadster prototype can reach in 4 seconds with a motor rated at .
Safety
One way to increase the range of an electric vehicle is to decrease the mass of the vehicle. Though due to the high weight of batteries, this typically still results in an EV with higher mass than an equivalent gas vehicle. 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. An accident in a 2000 lb (900 kg) vehicle will on average cause about 50% more injuries to its occupants than a 3000 lb (1350 kg) vehicle
Some electric cars use low rolling resistance tires, which typically offer less grip than normal tires. The weight (and price) of safety systems such as airbags, ABS and ESC may encourage manufacturers not to include them if it weren't for laws mandating their use.
Cabin heating and cooling
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 Constant (PTC) junction cooling is also attractive for its simplicity - this kind of system is used for example in Tesla Roadster. However some electric cars, for example Citroën Berlingo Electrique use auxiliary heating system (for example petrol-fueled units manufactured by Webasto or Eber). 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).
Regenerative braking
Using regenerative braking, a feature which is present on many electric and hybrid vehicles, a significant portion of the energy expended during acceleration may be recovered during braking, increasing the efficiency of the vehicle.
Batteries
Rechargeable batteries used in electric vehicles include lead-acid ("flooded" and VRLA), NiCd, nickel metal hydride, lithium ion, Li-ion polymer, and, less commonly, zinc-air and molten salt batteries. The amount of electricity stored in batteries is measured in ampere hours or in coulombs, with the total energy often measured in watt hours.
Historically, EVs and PHEVs have had issues with high battery costs, limited travel distance between battery recharging, charging time, and battery lifespan, which have limited widespread adoption. Ongoing battery technology advancements have addressed many of these problems; many models have recently been prototyped, and a handful of future production models have been announced.
Charging
Batteries in BEVs must be periodically recharged (see also Replacing, below).
BEVs most commonly charge from the power grid (at home or using a street or shop recharging point), which is in turn generated from a variety of domestic resources; such as coal, hydroelectricity, nuclear and others. Home power such as roof top photovoltaic solar cell panels, micro hydro or wind may also be used and are promoted because of concerns regarding global warming.
Charging time is limited primarily by the capacity of the grid connection. A normal household outlet is between 1.5 kilowatts (in the US, Canada, Japan, and other countries with 110 volt supply) to 3 kilowatts (in countries with 240 V supply). The main connection to a house might be able to sustain 10 kilowatts, and special wiring can be installed to use this. At this higher power level charging even a small, 7 kilowatt-hour (22–45 km) pack, would probably require one hour. This is small compared to the effective power delivery rate of an average petrol pump, about 5,000 kilowatts. Even if the supply power can be increased, most batteries do not accept charge at greater than their charge rate ("1C"), because high charge rate has adverse effect on the discharge capacities of batteries.
In 1995, some charging stations charged BEVs in one hour. In November 1997, Ford purchased a fast-charge system produced by AeroVironment called "PosiCharge" for testing its fleets of Ranger EVs, which charged their lead-acid batteries in between six and fifteen minutes. In February 1998, General Motors announced a version of its "Magne Charge" system which could recharge NiMH batteries in about ten minutes, providing a range of sixty to one hundred miles.
In 2005, handheld device battery designs by Toshiba were claimed to be able to accept an 80% charge in as little as 60 seconds. Scaling this specific power characteristic up to the same 7 kilowatt-hour EV pack would result in the need for a peak of 340 kilowatts of power from some source for those 60 seconds. It is not clear that such batteries will work directly in BEVs as heat build-up may make them unsafe.
Altairnano's NanoSafe batteries can be recharged in several minutes, versus hours required for other rechargeable batteries. A NanoSafe cell can be charged to around 95% charge capacity in approximately 10 minutes.
Most people do not always require fast recharging because they have enough time, 30 minutes to six hours (depending on discharge level) during the work day or overnight to recharge. As the charging does not require attention it takes a few seconds for an owner to plug in and unplug their vehicle much like a cell phone. Many BEV drivers prefer recharging at home, avoiding the inconvenience of visiting a fuel station. Some workplaces provide special parking bays for electric vehicles with chargers provided - sometimes powered by solar panels. In colder areas such as Minnesota and Canada there already exists some infrastructure for public power outlets, in parking garages and at parking meters, provided primarily for engine pre-heating.
Connectors
The charging power can be connected to the car in two ways (electric coupling). The first is a direct electrical connection known as conductive coupling. This might be as simple as a mains lead into a weatherproof socket through special high capacity cables with connectors to protect the user from high voltages. The second approach is known as inductive charging. A special 'paddle' is inserted into a slot on the car. The paddle is one winding of a transformer, while the other is built into the car. When the paddle is inserted it completes a magnetic circuit which provides power to the battery pack.
In one inductive charging system, one winding is attached to the underside of the car, and the other stays on the floor of the garage.
The major advantage of the inductive approach is that there is no possibility of electric shock as there are no exposed conductors, although interlocks, special connectors and ground fault detectors can make conductive coupling nearly as safe. Inductive charging can also reduce vehicle weight, by moving more charging components offboard. However there is no reason that conductive coupling equipment cannot take advantage of the same concept. Conductive coupling equipment is lower in cost and much more efficient due to a vastly lower component count. An inductive charging proponent from Toyota contended in 1998 that overall cost differences were minimal, while a conductive charging proponent from Ford contended that conductive charging was more cost efficient.
Travel range before recharging and trailers
The range of an electric car depends on the number and type of batteries used, and the performance demands of the driver. The weight and type of vehicle also have an impact just as they do on the mileage of traditional vehicles. Electric vehicle conversions depends on the battery type:
- Lead-acid batteries are the most available and inexpensive. Such conversions generally have a range of 30 to 80 km (20 to 50 mi). Production EVs with lead-acid batteries are capable of up to 130 km (80 mi) per charge.
- NiMH batteries have higher energy density and may deliver up to 200 km (120 mi) of range.
- New lithium-ion battery-equipped EVs provide 400–500 km (250–300 mi) of range per charge. Lithium is also less expensive than nickel.
Finding the economic balance of range versus performance, battery capacity versus weight, and battery type versus cost challenges every EV manufacturer.
With an AC system regenerative braking can extend range by up to 50% under extreme traffic conditions without complete stopping. Otherwise, the range is extended by about 10 to 15% in city driving, and only negligibly in highway driving, depending upon terrain.
BEVs (including buses and trucks) can also use genset trailers and pusher trailers in order to extend their range when desired without the additional weight during normal short range use. Discharged battery set trailers can be replaced by recharged ones along a route. If rented then maintenance costs can be deferred to the agency.
Such BEVs can become Hybrid vehicles depending on the trailer and car types of energy and powertrain.
Replacing
An alternative to recharging is to exchange drained or nearly drained batteries (or battery range extender modules) with fully charged batteries. Batteries could be leased or rented instead of bought (see Think Nordic). In 1947, in Nissan's first electric car, the batteries were removable so that they could be replaced at filling stations with fully charged ones. Replaceable batteries were used in the electric buses used at the 2008 Olympics.
Re-filling
Zinc-bromine flow batteries or Vanadium redox batteries can be re-filled, instead of recharged, saving time. The depleted electrolyte can be recharged at the point of exchange, or taken away to a remote station.
V2G: uploading and grid buffering
Smart grid allows BEVs to provide power to the grid, specifically:
- During peak load periods, when the cost of electricity can be very high. These vehicles can then be recharged during off-peak hours at cheaper rates while helping to absorb excess night time generation. Here the vehicles serve as a distributed battery storage system to buffer power.
- During blackouts, as an emergency backup supply.
Lifespan
Individual batteries are usually arranged into large battery packs of various voltage and ampere-hour capacity products to give the required energy capacity. Battery life should be considered when calculating the extended cost of ownership, as all batteries eventually wear out and must be replaced. The rate at which they expire depends on a number of factors.
The depth of discharge (DOD) is the recommended proportion of the total available energy storage for which that battery will achieve its rated cycles. Deep cycle lead-acid batteries generally should not be discharged below 80% capacity. More modern formulations can survive deeper cycles.
In real world use, some fleet Toyota RAV4 EVs, using NiMH batteries, will exceed 160 000 km (100,000 mi), and have had little degradation in their daily range. Quoting that report's concluding assessment:
Jay Leno's 1909 Baker Electric (see Baker Motor Vehicle) still operates on its original Edison cells. Battery replacement costs of BEVs may be partially or fully offset by the elimination of certain regular maintenance, such as oil and filter changes required for ICEVs, and by the greater reliability of BEVs due to their fewer moving parts. They also do away with many other parts that normally require servicing and maintenance in a regular car, such as on the gearbox, cooling system, and engine tuning. And by the time batteries do finally need definitive replacement, they can be replaced with later generation ones which may offer better performance characteristics, in the same way one might replace an old laptop battery.
Safety
The safety issues of battery electric vehicles 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.
Future
Battery technology
The future of battery electric vehicles depends primarily upon the cost and availability of batteries with high energy densities, power density, and long life, as all other aspects such as motors, motor controllers, and chargers are fairly mature and cost-competitive with internal combustion engine components. Li-ion, Li-poly and zinc-air batteries have demonstrated energy densities high enough to deliver range and recharge times comparable to conventional vehicles.
Bolloré, a French automotive parts group, developed a concept car, called the Bluecar, using Lithium metal polymer batteries developed by a subsidiary, Batscap. It had a range of 250 km and top speed of 125 km/h.
The cathodes of early 2007 lithium-ion batteries are made from lithium-cobalt metal oxide. That material is expensive, and can release oxygen if its cell is overcharged. If the cobalt is replaced with iron phosphates, the cells will not burn or release oxygen under any charge. The price premium for early 2007 hybrids is about US $5000, some $3000 of which is for their NiMH battery packs. At early 2007 gasoline and electricity prices, that would break even after six to ten years of operation. The hybrid premium could fall to $2000 in five years, with $1200 or more of that being cost of lithium-ion batteries, providing a three-year payback.
Other methods of energy storage
Experimental supercapacitors and flywheel energy storage devices offering comparable storage capacity, higher charging rates, and lower volatility have the potential to overtake batteries as the prominent rechargeable storage for EVs. The FIA has included their use in its sporting regulations of energy systems for Formula One race vehicles in 2007 and 2009, respectively.
EEStor claims to have developed a supercapacitor for electricity storage. These units titanate coated with aluminum oxide and glass to achieve a level of capacitance claimed to be much higher than what is currently available in the market. The claimed energy density is 1.0 MJ/kg (existing commercial supercapacitors typically have an energy density of around 0.01 MJ/kg, while lithium ion batteries have an energy density of around 0.59–0.95 MJ/kg). EEStor claims a less than 5 minute charge should give the supercapacitor sufficient energy to drive a car 400 km (250 mi).
Solar Cars
See Solar taxi and Solar vehicle
Electric car use by country
Canada
British Columbia is the only place where you can drive an LSV electric car, although it also requires low speed warning marking and flashing lights. Quebec is allowing LSVs in a three year pilot project. These cars will not be allowed on the highway, but will be allowed on inter city streets. See ZENN#Legalization in Canada
Israel
Israel's Shai Agassi has reached agreements with Renault-Nissan and the Israeli government for a plan called Project Better Place to install recharging and battery replacement stations nationwide and put 100,000 electric cars on the roads beginning in 2011. Israel is considered a practical choice for the first large-scale use of electric vehicles because 90 percent of car owners drive less than 70 kilometers per day and the major cities are fewer than 150 kilometers apart.
Portugal
Portugal has also reached agreements with French car maker Renault and its Japanese partner Nissan to boost the use of electric cars by creating a national recharging network.
The aim is to make Portugal, one of the first countries to offer drivers the possibility of nationwide charging stations.
United States
Since the late 1980s, electric vehicles have been promoted in the US through the use of tax credits. Electric cars are the most common form of what is defined by the California Air Resources Board (CARB) as zero emission vehicle (ZEV) passenger automobiles, because they produce no emissions while being driven. The CARB had set progressive quotas for sales of ZEVs, but most were withdrawn after lobbying and a lawsuit by auto manufacturers complaining that EVs were economically infeasible due to an alleged "lack of consumer demand". Many of these lobbying influences are discussed in the documentary Who Killed the Electric Car?.
The California program was designed by the CARB to reduce air pollution and not specifically to promote electric vehicles. Under pressure from various manufactures, CARB replaced the zero emissions requirement with a combined requirement of a very small number of ZEVs to promote research and development, and a much larger number of partial zero-emissions vehicles (PZEVs), an administrative designation for a super ultra low emissions vehicle (SULEV), which emit about ten percent of the pollution of ordinary low emissions vehicles and are also certified for zero evaporative emissions. While effective in reaching the air pollution goals projected for the zero emissions requirement, the market effect was to permit the major manufacturers to quickly terminate their electric car programs and crush the vehicles.
The following chart and table are based on Department of Energy tables on , from table V1 and from the Historical Data. Figures for electric vehicles do not include privately owned vehicles, but do include Low-Speed Vehicles (LSVs), defined as "four-wheeled motor vehicles whose top speed is between 20 and 25 miles per hour [32 to 40 km/h]...to be used in residential areas, planned communities, industrial sites, and other areas with low density traffic, and low-speed zones." LSVs, more commonly known as neighborhood electric vehicles (NEVs), were defined in 1998 by the National Highway Traffic Safety Administration's Federal Motor Vehicle Safety Standard No. 500, which required safety features such as windshields and seat belts, but not doors or side walls.
Electric Cars
in the United States |
|---|
| Year | Number |
|---|
| 1992 | 1,607 | | 1993 | 1,690 | | 1994 | 2,224 | | 1995 | 2,860 | | 1996 | 3,280 | | 1997 | 4,453 | | 1998 | 5,243 | | 1999 | 6,964 | | 2000 | 11,830 | | 2001 | 17,847 | | 2002 | 33,047 | | 2003 | 47,485 | | 2004 | 49,536 | | 2005 | 51,398 | | 2006 | 53,526 | Average growth | 28.5% | |
Hobbyists, conversions, and racing
Hobbyists often build their own EVs by converting existing production cars to run solely on electricity. There is a cottage industry supporting the conversion and construction of BEVs by hobbyists. Universities such as the University of California, Irvine even build their own custom electric or hybrid-electric cars from scratch.
Short-range battery electric vehicles can offer the hobbyist comfort, utility, and quickness, sacrificing only range. Short-range EVs may be built using high-performance lead–acid batteries, using about half the mass needed for a 100 to 130 km (60 to 80 mi) range. The result is a vehicle with about a 50 km (30 mi) range, which, when designed with appropriate weight distribution (40/60 front to rear), does not require power steering, offers exceptional acceleration in the lower end of its operating range, and is freeway capable and legal. But their EVs are expensive due to the higher cost for these higher-performance batteries. By including a manual transmission, short-range EVs can obtain both better performance and greater efficiency than the single-speed EVs developed by major manufacturers. Unlike the converted golf carts used for neighborhood electric vehicles, short-range EVs may be operated on typical suburban throughways (60 to 70 km/h (40 to 45 mph) speed limits are typical) and can keep up with traffic typical on such roads and the short "slow-lane" on-and-off segments of freeways common in suburban areas.
Faced with chronic fuel shortage on the Gaza Strip, Palestinian electrical engineer Waseem Othman al-Khozendar invented in 2008 a way to convert his car to run on 32 electric batteries. According to al-Khozendar, the batteries can be charged with $2 worth of electricity to drive from 180km to 240km. After a 7 hour charge, the car should also be able to run up to a speed of 100kph.
Japanese Professor Hiroshi Shimizu from Faculty of Environmental Information of the Keio University created an electric limousine: the Eliica (Electric Lithium Ion Car) has eight wheels with electric 55 kilowatt hub motors (8WD) with an output of 470 kilowatts and zero emissions, a top speed of 370 kilometers per hour (230mph), and a maximum range of 320 kilometers provided by lithium-ion-batteries (). However, current models cost approximately $300,000 US, about one third of which is the cost of the batteries.
Alternative green vehicles
Other types of green vehicles include vehicles that move fully or partly on alternative energy sources rather than fossil fuel. Another option is to use alternative fuel composition in conventional fossil fuel-based vehicles, making them go partly on renewable energy sources.
Other approaches include personal rapid transit, a public transportation concept that offers automated on-demand non-stop transportation, on a network of specially-built guideways.
Currently available electric cars
, the following electric cars can be ordered.
Low speed
Cars not capable of reaching 60 km/h, required by the Autobahn
City speed
Cars capable of at least 60 km/h, but not 80 km/h
| Model | Top speed | Capacity
(Adults) | Charging time | Range |
|---|
| CityEl | | 1 | | | | NICE Mega City | | 4 | | | | ZAP Xebra SD and PK | | PK 2 person - SD 4 | 4 hours 120 volt 20 amp 220 volt compatible | |
Highway capable
Cars capable of at least 80 km/h
| Model | Top speed | Acceleration | Capacity
Adults+kids | Charging time | Nominal range | Market Release Date |
|---|
| Kewet Buddy | | | | | | | | Stevens Zecar | | | | | | | | REVA i | | | 2 + 2 | 8 hrs (80% in 2 hrs) | | Available | | REVA L-ion | | | 2 + 2 | 6 hrs with onboard charger
1 hrs with external charger | | Available | | Tesla Roadster | | | 2 | 3˝ hours | | Available | | Th!nk City | | | | | | | | Venturi Fétish | | | | | | |
Gallery of electric cars
See also
Further reading
External links
Patents
Organizations
- by Society for Sustainable Mobility
- and
-
Electric vehicle comparison websites
- Complete electric vehicle comparison rating website
- Electric car and van resource including comparisons of electric cars available in the UK
News stories
- September 2008
- 7 November 2006
|
| |
|
|
