sábado, 6 de junio de 2009

Electric car

Electric car

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The General Motors EV1, a hallmark electric car, had a range of 160 mi (260 km) with NiMH batteries in 1999.

An electric car is an alternative fuel car that uses 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.[1]

The term electric vehicle is often used, implying, in context, an electric road vehicle, though in its broader sense it covers all vehicles with electrical propulsion including trains and trams.

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

1830s to 1900s: Early history

Electric vehicle model by Ányos Jedlik, the inventor of electric motor (1828, Hungary).
German electric car, 1904, with the chauffeur on top
1912 Detroit Electric advertisement
Thomas Edison and an electric car in 1913 (courtesy of the National Museum of American History)

The design of the electric car is one of the oldest for 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.[2]

Practical and more successful electric road vehicles were invented by both Thomas Davenport, an American, and Robert Davidson, a Scotsman, in 1842. Both inventors were the first to use non-rechargeable electric cells.[3]

Gaston Plante invented a better storage battery in France in 1865[4], and his fellow countryman Camille Faure improved the storage battery in 1881.[5] 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.[6]

France and Great Britain were the first nations to support the widespread development of electric vehicles.[7] In November 1881 French inventor Gustave Trouvé demonstrated a working three-wheeled automobile at the International Exhibition of Electricity in Paris.[8] Thomas Parker claimed to have built a working electric car by 1884[9]

Before the pre-eminence of internal combustion engines, electric automobiles held many speed and distance records.[10] 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 US by Anthony Electric, Baker, Detroit Electric (Anderson Electric Car Company), 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.

1920s to 1980s: Oil dominates

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.[11] 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. Forklift trucks were EVs when they were introduced in 1923 by Yale[3]; many battery electric forklifts are still produced. In Europe, especially the United Kingdom, milk floats were common EVs, though they are less so now as distances on delivery rounds have grown. Electric golf carts have been available for many years, including early models by Lektro in 1954.[12] 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[13]

1973 General Motors Urban Electric Car gets a battery charge at the first symposium on low pollution power systems development.

Battery powered electric concept cars continued to appear, such as the Scottish Aviation Scamp (1965),[14] the Enfield 8000 (1966)[15] and the General Motors "Electrovair" (1966) and "Electrovette" (1976).

1990s to present: Revival of mass interest

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 the early 1990s, the California Air Resources Board (CARB) began to push for more fuel efficient vehicles, with the end-goal being a shift to more zero-emissions vehicles.[16][17].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.[18] 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, 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

The Indian REVA 2 doors, in Malta in August 2006.
The Tesla Roadster, the first 650 of which were scheduled for delivery in 2008 uses lithium-ion batteries to achieve 220 miles per charge, while also capable of going 0-60 mph in under 4 seconds.

In the US 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.[19] There are now over 100,000 neighborhood electric vehicles (NEVs) on US streets.[citation needed]

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,[citation needed] 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[20] 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-US), yet accelerates from 0-100 km/h (62 mph) in under 4 seconds on its way to a top speed of 210 km/h (130 mph). The company announced that production of the Roadster had officially begun on March 17. The first Tesla was delivered on February 1, 2008.

In December 2007, Fortune reported[citation needed] 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.[citation needed]

Miles Electric Vehicles, the XS500 capable of 135km/h with an estimated price around $30,000.

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 US in early 2009. The XS500 uses Li-Ion batteries.[21][22]

In early 2008, Dodge announced an electric concept car called Dodge Zeo. There are no official release dates or prices.[23]

In May 2008 Nissan Motor Company announced plans to sell an electric car in the US and Japan by 2010. Nissan's chief executive, Carlos Ghosn said they envisioned a broad range of electric vehicles, starting with small cars.[24]

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.[25]

At the 2009 Detroit Auto Show, Toyota debuted the FT-EV electric car based on the Toyota iQ microcar platform. They said a production version could be available by 2012.[26]

Chrysler subsidiary GEM has announced their Peapod Electric Vehicle, a low-speed neighborhood electric vehicle, will be available in fall of 2010.

Other automakers like Fuji Heavy Industries, which produces the Subaru car brand, are testing versions of electric cars[citation needed], and General Motors is working on battery-powered vehicles that have small gasoline engines for recharging.[citation needed]

Acceptance of electric cars

Electric vehicles which store electrical energy in a capacitor or battery would not be able to immediately replace all gasoline cars given the available transportation infrastructure. For example, while a gasoline car could undertake a road trip which would require several short (around five 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. According to the movie, Who Killed the Electric Car, the EV1 was "only" suitable for 90% of consumers.

The unit of measurement known as miles per gallon of gasoline equivalent (MPGe) may be misleading if used to compare the overall fuel efficiency of electric and internal combustion vehicles. The MPGe formula uses the pump to wheels energy for gasoline, and 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. A small car would use one battery pack, while a larger car might use several of the standardized battery packs.

Other ways to mitigate the infrastructure issue are to use a different energy storage technology, or 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 hybrid vehicles, and are not considered electric vehicles because they do not operate solely by electricity; and normally operate in a charge-sustaining mode. Hybrid vehicles that can be charged externally to displace some or all of their ICE power and fuel source are called plug-in hybrid electric vehicles (PHEV), and are EVs during their charge-depleting mode. 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. The energy generated by complete combustion of 1 liter gasoline is about 9.7 kWh. Accounting for inefficiencies of gasoline vs. electric engines and transmission and battery losses, 1 liter gasoline is equivalent to 2.7 kWh energy from batteries.[27]

The Tesla uses about 13 kW·h/100 km[citation needed], the EV1 used about 11 kW·h/100 km.[28]

Servicing costs are lower for an electric car. The documentary film Who Killed the Electric Car? 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 miles, rotate the tires, fill the windshield washer fluid and send them back out again. Even the hydraulic brakes require less maintenance because regenerative braking itself also slows the vehicle, as it does with a hybrid.

Electric cars using lead-acid batteries require their regular replacement, while with routine maintenance internal combustion engines can last the lifetime of the vehicle. NiMH batteries typically last the life of the vehicle. Toyota Prius vehicles have been known to go over 300,000 kilometres (190,000 mi) without needing a battery replacement, though the Toyota warranty is for 10 years/150,000 miles (240,000 km) or 8 years/100,000 miles (160,000 km), and new batteries cost around £2,300 to $2,600 in 2008 and are expected to fall in price over time.[29][30]

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 US 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.[31] 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).[28][32] 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 Li-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).[33] The US fleet average of 10 l/100 km (24 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). While hybrid electric vehicles are relatively energy efficient, battery electric vehicles are much more energy efficient.

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/100 km of energy is only using 19.2kW·h/100 km for motion.

Sources of electricity in the US 2006[2]

Carbon dioxide emissions

While electric cars produce no emissions at the tailpipe— indeed don't have one— their use increases demand for electrical generation. Generating electricity and producing liquid fuels for vehicles are different categories of the energy economy, with different inefficiencies and environmental harms, but both emit carbon dioxide into the environment. The well-to-wheel (WTW) carbon dioxide (CO2) emissions of electric cars is always lower than those of conventional cars, but the amount of savings depend on the emissions intensity of the existing electricity infrastructure. An electric car's WTW emissions are much lower in a country like Canada, which whose electricity supply is dominated by hydro and nuclear, than in countries like China and the US that rely heavily on coal.

An EV recharged from the existing US grid electricity emits about 115 grams of CO2 per km driven, (g(CO2)/km) whereas a conventional gasoline powered car emits 250 g(CO2)/km.[34] The savings are smaller relative to hybrid or diesel cars, 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 WWF and IZES found that a mid-size EV would emit roughly 200 g(CO2)/km, compared with an average of 170 g(CO2)/km for a gasoline powered compact car.[35] 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.[35]

Like any other vehicles, EVs themselves of course differ in their fuel efficiency and their total cost of ownership, including the environmental costs of their manufacture and disposal.

According to the US Department of Energy, most electricity generation in the United States is from fossil sources, and half of that is from coal.[31] Coal is more carbon-intensive than oil. Overall average efficiency from US power plants (33% efficient) to point of use (transmission loss 9.5%) is 30%. [31] Accepting a 70% to 80% efficiency for the electric vehicle gives a figure of only around 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.[36][37]. This is much lower than the efficiency when running at constant load and optimal rotational speed, which gives efficiency around 30% and 45% respectively.[38]. The electric battery suffers from similar decrease in efficiency when running at variable load[39], which accounts for the modest increased efficiency of hybrid vehicles. 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 in 2006, one team entered both a solar & wind-powered EV and a TDI biodiesel car; they scored the equivalent of 68 mpg-US (3.5 l/100 km) and 51 mpg-US (4.6 l/100 km), respectively.[40] 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 100% biodiesel ("B100") did. [41] 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 cars running on commercial B100.[42]

If solar, wind, hydro, or nuclear electric generation, or carbon capture for fossil fuel powered plants were to become prevalent, electric vehicles could produce less CO2, potentially zero. Based on GREET simulations, electric cars can achieve up to 100% reductions with renewable electric generation, against 77% with a B100 car. At present only a 32% reduction of CO2 is available for electric cars recharging from non-renewable utilities on the US Grid, because of the majority use of fossil fuels in generation, and inefficiency in the grid itself.[31][43][44]

Smog

The Ontario Medical Association announced that smog is responsible for an estimated 9,500 premature deaths in the province each year [45]. 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 vehicles with internal combustion engines. 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).

Steady speed fuel economy

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, 15 kW (20 hp) 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 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'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.

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.

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 transmissions to improve top speed[46]. The Tesla Roadster prototype can reach 100 km/h (62 mph) in 4 seconds with a motor rated at 185 kW (248 hp). [47]

Safety

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. 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 despite having a negative effect on the car's performance. 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.[48][49] Some electric cars use low rolling resistance tires, which typically offer less grip than normal tires.[50][51][52]

Hazard to pedestrians

Electric cars produced much less roadway noise as compared to vehicles propelled by a internal combustion engine. However, the reduced noise level from electric engines may not be beneficial for all road users, as 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.[53][54] Tests have shown that this is a valid concern, as vehicles operating in electric mode can be particularly hard to hear below 20mph (32kph) 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 more audible noise.[54] The U.S. Congress and the European Commission are exploring legislation to establish a minimum level of sound for electric and hybrid 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.[54]

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[55] is also attractive for its simplicity - this kind of system is used for example in the Tesla Roadster. However some electric cars, for example the Citroën Berlingo Electrique, use an auxiliary heating system (for example gasoline-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). Two models of the 2010 Toyota Prius include this feature as an option.[56]

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

Prototypes of 75 watt-hour/kilogram lithium ion polymer battery. Newer Li-ion cells can provide up to 130 W·h/kg and last through thousands of charging cycles.

Rechargeable battery materials 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. The amount of electricity stored in batteries is measured in ampere hours or coulombs, with the total energy often measured in watt hours.

Historically, EVs and PHEVs have had issues with high battery costs, limited range between battery recharging, charging time, and battery lifespan, which have limited their widespread adoption. Ongoing battery technology advancements have addressed many of these problems; many models have recently been prototyped, and a few future production models have been announced.

Charging

Ultra-light design by IWK

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 kW (in the US, Canada, Japan, and other countries with 110 volt supply) to 3 kW (in countries with 220/240V supply). The main connection to a house might be able to sustain 10 kW, and special wiring can be installed to use this. At this higher power level charging even a small, 7 kW·h (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 kW. Even if the supply power can be increased, most batteries do not accept charge at greater than their charge rate ("1C"), because high charge rates have an adverse effect on the discharge capacities of batteries.[57]

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.[58]

In 2005, mobile device battery designs by Toshiba were claimed to be able to accept an 80% charge in as little as 60 seconds.[59] Scaling this specific power characteristic up to the same 7 kW·h EV pack would result in the need for a peak of 340 kW 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. [60][61]

Many 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. The charging does not require attention so it takes only a few seconds of the owner's time for plugging and unplugging the charging source. 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 and set with circuit breakers that prevent large current draws for other uses.[62]

Connectors

The charging power can be connected to the car in two ways using an (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 the high voltage. 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 an electromagnetic 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.[63]

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 RCDs (ground fault detectors) can make conductive coupling nearly as safe. Inductive charging can also reduce vehicle weight, by needing fewer components of the charging system on the vehicle itself.[64] 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.[citation needed] 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.[64]

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. The range of an electric vehicle conversion depends on the battery type:

  • Lead-acid batteries are the most available and inexpensive. Such conversions generally have a range of 30 to 80 kilometres (20 to 50 mi). Production EVs with lead-acid batteries are capable of up to 130 kilometres (80 mi) per charge.
  • NiMH batteries have higher energy density and may deliver up to 200 kilometres (120 mi) of range.
  • New lithium-ion battery-equipped EVs provide 400 to 500 kilometres (200 to 300 mi) of range per charge.[65] Lithium is also less expensive than nickel.[66]

Finding the economic balance of range against 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 heavy but not stop-start traffic conditions. Otherwise, the range is extended by about 10 to 15% in city driving, and only negligibly in highway driving, depending upon terrain.

Replacing

An alternative to quick recharging is simply to exchange the drained or nearly drained batteries (or battery range extender modules) with fully charged batteries, rather like stagecoach horses were changed at coaching inns. Batteries could be leased or rented instead of bought, and then maintenance deferred to the leasing or rental company, and ensures availability (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. The company Better Place is one potential player in this market, and though some vehicle manufacturers and other companies are also investigating the possibility, none yet seems to have entered the market.

BEVs (including buses and trucks) can also use genset trailers and pusher trailers to extend their range without the additional weight during normal short-range use. Drained battery set trailers can be replaced by charged ones along a route.

Such BEVs can become hybrid vehicles depending on the trailer's and car's types of energy and powertrain.

Replaceable batteries were used in the electric buses at the 2008 Summer Olympics.[67]

Refilling

Zinc-bromine flow batteries or Vanadium redox batteries can be refilled, instead of recharged, saving time. The depleted electrolyte can be recharged at the point of exchange, or taken away to a remote station.

Vehicle-to-grid: uploading and grid buffering

A 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 batteries in the vehicles serve as a distributed storage system to buffer power.
  • During blackouts, as an emergency backup supply.

The basic premise here is similar to Economy 7 in the United Kingdom: incentives to spread the load more evenly across the day reduces the need for expensive peak demand and thus the need to building power stations that can supply it on demand.

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.[68] Quoting that report's concluding assessment:

The five-vehicle test is demonstrating the long-term durability of Nickel Metal Hydride batteries and electric drive trains. Only slight performance degradation has been observed to-date on four out of five vehicles.... EVTC test data provide strong evidence that all five vehicles will exceed the 100,000-mile (160,000 km) mark. SCE’s positive experience points to the very strong likelihood of a 130,000-to-150,000-mile (210,000 to 240,000 km) Nickel Metal Hydride battery and drive-train operational life. EVs can therefore match or exceed the lifecycle miles of comparable internal combustion engine vehicles.

In June 2003 the 320 RAV4 EVs of the SCE fleet were used primarily by meter readers, service managers, field representatives, service planners and mail handlers, and for security patrols and carpools. In five years of operation, the RAV4 EV fleet had logged more than 6.9 million miles, eliminating about 830 tons of air pollutants, and preventing more than 3,700 tons of tailpipe CO2 emissions. Given the successful operation of its EVs to-date, SCE plans to continue using them well after they all log 100,000-mile (160,000 km).

Jay Leno's 1909 Baker Electric still operates on its original Edison cells. Battery replacement costs of BEVs may be partially or fully offset by the elimination of some 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 or mobile phone battery.

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.

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 logistics conglomerate, developed a concept car, called the Bluecar, using Lithium metal polymer batteries developed by a subsidiary, Batscap. It had a range of 250 kilometres (160 mi) and top speed of 125 kilometres per hour (80 mph).[69]

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, breaking even after three years.[70]

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).[71]

Solar cars

Solar cars are electric cars that derive most or all of their electricity from built in solar panels. After the 2005 World Solar Challenge established that solar race cars could exceed highway speeds, the specifications were changed to provide for vehicles that with little modification could be used for transportation.

Electric car use by country

An Italian Carabinieri GEM e2, called the Ovetti (egg), used for patrolling urban areas
GEM e2 NEV used by the Tourist Police in Playa del Carmen, Mexico, being recharged

Australia and New Zealand

In 2008 Australia started producing its first commercial all-electric vehicle. Originally called the Blade Runner, its name was changed to Electron, and is already being exported to New Zealand with one purchased by the Environment Minister Dr. Nick Smith [72][73]. The Electron is based on the Hyundai Getz chassis and has proven popular with government car pools.[74]

Canada

See also: Legalization of ZENN in Canada

British Columbia is the only place where it is legal to drive a LSV electric car on public roads, 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 city streets.

China

The Chinese government adopted a plan with the goal of turning the country into one of the leaders of all-electric and hybrid vehicles by 2012.[75] The government's intention is to create a world-leading industry that will produce jobs and exports, and to reduce urban pollution and its oil dependence. However, a study found that even though local air pollution would be reduced by replacing a gasoline car with a similar-size electric car, it would reduce greenhouse gas emissions by only 19%, as China uses coal for 75% of its electricity production.[75]

The government is providing subsidies for electric car research and also subsidies of up to $8,800 US for each hybrid or all-electric vehicle purchased by taxi fleets and local government agencies in 13 Chinese cities.[75][76] Electricity utilities have been ordered to set up electric car charging stations in Beijing, Shanghai and Tianjin.[75][76] China wants to raise its annual production capacity to 500,000 hybrid or all-electric cars and buses by the end of 2011, from 2,100 in 2008.[75]

As intercity driving is rare in China, electric cars provide several practical advantages because commutes are fairly short and at low speeds due to traffic congestion. These particular local conditions overcome the range limitation of all-electric cars, as the latest Chinese models have a top speed of 100 km/h (60 mph) and a range of 200 km (120 mi) between charges.[75]

Israel

Israel’s Shai Agassi, CEO of the electric vehicle services, systems, and infrastructure provider Better Place, has reached agreements with Renault-Nissan and the Israeli government to begin the first phases of the company’s efforts to make Israel the world’s first integrated electric car network. Better Place, whose aim is to reduce global dependency on oil by creating an infrastructure to support the implementation of a world-wide network of electric vehicles, was started in 2007 with the encouragement of Israeli President Shimon Peres.[77] Israel is considered a viable site for this groundbreaking endeavor due to the country’s relatively small size and the fact that approximately 90% of the nation’s car owners drive less than 40 miles per day.[78]

Agassi has designed an infrastructure consisting of 500,000 charging points and almost 200 battery-exchange stations. In December of 2008, Better Place revealed its first plug-in parking lot in Tel Aviv. Additionally, in May of 2009, the company unveiled its patented battery swap system, which is designed for drivers taking longer road trips who lack the time needed to recharge their existing battery.[79] Better Place has currently opened 17 of the 150,000 charging stations planned Israel by 2011.[80]

Ireland

Ireland like Portugal has reached agreements with French car maker Renault and its Japanese partner Nissan to boost the use of electric cars. Electric cars will be a feature on Irish roads within two years [before 2010], Eamon Ryan Ireland's Minister for Communications, Energy and Natural Resources said at the unveiling of a collaboration between the Electricity Supply Board, the Government and the two manufacturers.

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 nationwide charging stations.[81]

United Kingdom

Speaking at the G8 summit in 2008, British Prime Minister Gordon Brown announced plans for Britain to be at the forefront of a "green car revolution". Brown suggested that by 2020 all new cars sold in Britain could be electric or hybrid vehicles producing less than 100 g/km of CO2.[82]

In preparation for the introduction of mass-produced electric vehicles to Britain's roads, trials of electric cars are taking place from 2009, with further trials in cities across the UK from 2010. Local British councils are being invited to submit bids to become Britain's first "green cities". One example is Glasgow, where a Scottish consortium has been awarded more than £1.8m to run a pilot electric car scheme from 2009-11.[83]

In January 2009, transport secretary Geoff Hoon said the British government would make £250 million available for consumer incentives to bring electric cars to market in the UK.[84] Nissan's Sunderland plant — the largest car factory in the UK — has been granted a £380m EU-backed loan to develop electric car technology. This will potentially generate 4,500 jobs and make the North-East of England a major producer of electric cars.[85]

London mayor Boris Johnson has also announced plans to deliver 25,000 electric car-charging places across the capital by 2015, in order to make London the "electric car capital of Europe". His target is to get 100,000 electric vehicles on to London's streets. Mr Johnson has also pledged to convert at least 1000 Greater London Authority fleet vehicles to electric by 2015.[83][84]. There has been criticism that although electric vehicles are available, places to charge them are not.[86]

In April 2009, the UK Government set out plans to offer subsidies of up to £5,000 to encourage them to buy electric or plug-in hybrid cars. However, these subsidies are not expected to be available until there is a "mass market" in "around 2011". [87] In a separate Budget initiative, in April 2009 the UK Chancellor of the Exchequer Alistair Darling detailed a £2,000 subsidy for scrapping a vehicle over 10 years old for an electric or hybrid vehicle.[88]

On 30 April 2009, the Electric Car Company put on sale the Citroën C1 ev'ie, an adapted Citroën C1 intended for city driving. On that date, it had a list price of £16,850 ($24,989 US).[86][89][90][91]

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".[citation needed] Many of these lobbying influences are discussed in the documentary Who Killed the Electric Car?.

The California program was designed by 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 emits about 10% 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.[citation needed]

The chart and table are based on Department of Energy tables.[92] (Table V1 and 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 ... 20 to 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."[93] 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.[94][95]

Number of battery electric vehicles in use each year (red), and year-to-year percentage increase (blue), per table at left
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
2007 55,730
Average growth 26.7%

Hobbyists, conversions, and racing

Eliica prototype

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 (62 to 81 mi) range. The result is a vehicle with about a 50 km (31 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 (where 60 to 70 kilometres per hour (37 to 43 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 180 to 240 km (110 to 150 mi). After a 7 hour charge, the car should also be able to run up to a speed of 100 km/h (60 mph). As electricity is supplied to Gaza by Israel, this may be seen not only as a way to combat climate changes and fuel shortage, but also as a way of making peace.[96][97]

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 kW hub motors (8WD) with an output of 470 kW and zero emissions, a top speed of 370 km/h (230 mph), and a maximum range of 320 kilometres (200 mi) provided by lithium-ion-batteries[98]. 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.

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