A
hybrid car or
hybrid electric vehicle is a vehicle which relies not only on batteries but also on an internal combustion engine which drives a generator to provide the electricity and may also drive the wheels directly.
Prior to its modern usage to mean hybrid propulsion, the word
hybrid was used in the United States to mean a vehicle of mixed national origin; generally, a European car fitted with American mechanical components. This is falling out of use as the newer meaning gains more currency.
Overview
Hybrid vehicles are designed to drive like conventionally powered vehicles, while producing significantly lower emissions and increased fuel economy. They combine the power of an internal combustion engine with the power from an electric motor to provide a vehicle that operates more efficiently.
A gasoline engine produces most of its torque at higher rpm, whereas the electric motor can produce maximum torque at very low speeds. Combining both sources of power allows the vehicle to be equipped with a highly efficient, small gasoline engine, and an electric motor that can also double as a generator, allowing the vehicle to recapture energy as the vehicle is slowing down.
This contrasts with all-electric cars which use batteries charged by an external source. Benefits of the hybrid design include the following:
- The vehicle is lighter and roomier than a purely electric vehicle of comparable size and power because fewer heavy batteries are needed.
- The internal-combustion engine in a hybrid vehicle can be much smaller, lighter, and more efficient than the engine in a conventional vehicle, because the electric motor can provide a boost of power for acceleration.
- Braking can be configured to recapture part of the kinetic energy of movement that would otherwise be wasted as heat in a conventional vehicle. This is called regenerative braking.
- Most hybrid powertrains are characterized by a split power path called a powersplit. One side of this split is mechanical and the other side of this power path is electrical.
History
Hybrid technology actually originated with diesel-electric locomotives and diesel electric submarines. Both operate in essentially the same manner as hybrid electric cars.
The first successful hybrid electric car was engineered by Ferdinand Porsche in 1928. Since then, hobbyists have continued to build such cars but none was put into production by a major manufacturer until the waning years of the 20th century.
Automotive hybrid technology became commercially successful in the 1990s when the Honda Insight and Toyota Prius became available. These vehicles have a direct linkage from the internal combustion engine to the driven wheels, so the engine can provide acceleration power. Prototypes of plug-in hybrid cars, with larger battery packs that can be re-charged from the power grid, have been built in the U.S., and one production PHEV, the Renault Kangoo, went on sale in France in 2003. DaimlerChrysler is currently building a small number of PHEVs based on the Sprinter van.
Earlier hybrid designs tended to use the electric motor for all power, due to simplicity. The engine would charge batteries from which the motor drew power, running only when needed to charge them back up. The engine would only run at its most efficient speed when doing so. However, this design was actually less efficient because of losses accrued in converting the kinetic energy of the engine into electrical energy, and back into kinetic energy at the wheels.
Recent developments
More modern designs reverse this to some degree, using the gasoline engine for primary power, but using one that is smaller than would otherwise be needed. The electric motor is essentially a very large starter motor, which operates not only when the engine needs to be turned over, but also when the driver "steps on the gas" and requires extra power. Instead of the engine solely charging the batteries, the motor acts as a generator during braking, using the momentum of the car to generate electricity. Thus the energy that would normally be lost when stopping is used to speed the car back up. Since the amount of electrical power needed is much smaller, the size of the battery systems is reduced.
Such designs were released in the late 1990s in the Honda Insight and Toyota Prius. The Insight sold poorly due to its high price and small size, but the Prius has been in high demand since its introduction. Newer designs are considerably more conventional and slightly cheaper, often appearing and performing identically to their non-hybrid counterparts while delivering 50% better fuel efficiency. The Honda Civic Hybrid appears identical to the non-hybrid version, for instance, but delivers about 50 mpg (US). The redesigned 2004 Toyota Prius improved passenger room, cargo area, and power output, while increasing energy efficiency and reducing emissions. The Honda Insight is still on sale and has a devoted base of owners, similar to the phenomenon observed with Apple computer.
Ford Motor Company is making the first hybrid SUV, the Ford Escape Hybrid. Toyota reportedly has plans to add hybrid drivetrains to every model it sells in the coming decades. Honda has also announced that they would release a hybrid version of the Accord.
An R.L. Polk & Co. Survey of 2003 automobiles showed that hybrid car registrations in the United States rose to 43,435 automobiles, a 25.8 percent increase from 2002 numbers. California had the most hybrid vehicles registered with 11,425, which may be partially due to its higher gasoline prices and emissions rules, which hybrids generally have little trouble passing.
Diesel
One particularly interesting combination uses a diesel engine for power. Diesels are excellent at delivering constant power for long periods of time, suffering less wear while delivering higher efficiency. However, the engines also suffer from poor acceleration due to having a limited RPM range. This poor acceleration can be addressed with the hybrid technique, and such designs may offer performance in a car of over 100 mpg (2.35 liter/100km).
Diesel hybrid have the advantage they can use 100% pure biofuels (biodiesel), so they don´t need petroleum at all.
However, there are no diesel production models as of 2003.
Battery technology
Because battery technology has not advanced dramatically enough to enable battery-only vehicles to have range on a single charge comparable to gasoline cars, and because major automakers have not been interested in marketing vehicles that have enough range for daily commuting and errands but not for interstate journeys, all major automakers involved in such research have since given up, and moved to fuel cells and hybrids. Toyota has announced that it intends that all its vehicles will have a hybrid electric version by 2012. It appears many European companies, where diesel is much more common, will follow Toyota's lead and move in the same direction.
Hybrid Types
In the earliest hybrid cars, prior to the Prius and Insight, the internal combustion engine only serves as an on-board generator to supply power to the electric motor which provide the sole driving force to the wheels. This is referred to as a "Series Hybrid" system.
In the second generation, the internal combustion engine drives the wheels directly with the electric motor serving as a power assist when extra power is needed, and to recapture the kinetic energy usually lost during braking. This is known as a "Parallel Hybrid" system. The extra power from the electric motor enables the manufacturers to reduce the engine size to achieve fuel economy. Either approach has its limitations.
Starting from 2004 model year, the Toyota Prius uses the third-generation hybrid design. In this new design, the wheels can be driven by either the internal combustion engine or the electric motor using a planetary gear system to draw power from either source. The on-board computer optimizes the fuel usage by shutting off the internal combustion engine when the electric motor is sufficient to provide the power. The internal combustion engine starts up whenever extra power is needed or the battery needs recharging. The electric motor serves as the main driving force and a generator. The more efficient new design enabled Toyota to build the new Prius as a mid-size car without sacrificing fuel economy.
Full hybrids
A "full hybrid", sometimes also called the "strong hybrid", is a vehicle that can run on just the engine, just the batteries, or a combination of both. The Prius and the Escape are examples of this. A large, high voltage battery pack is usually needed for battery-only operation.
Assist hybrids
Assist hybrids use a battery and electric motors to accelerate the car, but only in combination with the internal combustion engine. The Honda Insight is an example of an assist hybrid.
A variation on this type is Mazda's
e-4WD system, offered on the Japan-market Mazda Demio. This front wheel drive vehicle has an electric motor which can drive the rear wheels when extra traction is needed. The system is entirely disengaged in all other driving conditions, so it does not enhance performance or economy.
Plug-In hybrids
These are full hybrids, able to run in electric-only mode, with larger batteries and the ability to recharge from the electric power grid (some call it griddable hybrid.) Their benefit is that they can be gasoline-independent for daily commuting, while they have the extended range of a hybrid for long trips. The Electric Power Research Institute's research indicates a lower total cost of ownership for PHEVs due to reduced service costs and gradually improving batteries. Some critics argue that unless the electric power is generated by clean energy source (such as solar, wind, hydro, geo-thermal etc.), a gasoline hybrid car may be cleaner and more energy efficient than a PHEV when the entire powerplant-to-tailpipe energy conversion cycle is considered.
Hydraulic hybrids
A hydraulic hybrid vehicle uses hydraulic and mechanical components instead of electrical ones. A variable displacement pump replaces the motor/generator, and a hydraulic accumulator replaces the batteries. The hydraulic accumulator, which is essentially a pressure tank, is potentially cheaper and more durable than batteries. Hydraulic hybrid technology is being actively developed by Eaton and several other companies, primarily in heavy vehicles like buses, trucks and military vehicles. Many cities, including New York City and Seattle, Washington have purchased hybrid electric/diesel buses.
Mild hybrids
There is another kind of cars that are marketed as hybrids, but technically they are not. The critics called these mild hybrid cars to distinguish from a real hybrid design. One example is the 2005 Chevrolet Silverado Hybrid fullsize pickup truck. Some people argue that it is not really hybrid since the electric motor/generator does not drive the wheels at all. In these mild hybrid cars, an oversize, large starter motor spins up the engine to operating rpm before fuel is injected into the combustion chambers. At high rpm, an engine can be restarted efficiently and cleanly. This allows the car to shut down the internal combustion engine whenever the car is coasting, braking, or stopped but the accessories can continue to run on electrical power. The motor/generator is also used to recapture energy through regenerative braking. Chevrolet was able to get a 10% improvement on the Silverado's fuel efficiency by shutting down and restarting the engine on demand. Mild hybrids often use 48 Volt systems to supply the power needed for the startup motor, as well as to compensate for the increasing number of electronic accessories on modern vehicles. These vehicles do not achieve the fuel mileage of "true" hybrid models.
Perks of owning a hybrid car in the US
Government agencies in the US offer benefits to encourage the purchase of certain qualifying hybrid or electrical vehicles.
- The purchase of certain hybrid cars qualifies for a $2000 tax deduction on the IRS 1040 form for the year of 2003. The deduction reduces by $500 each year until it reaches zero. United States House of Representatives 1308 Sec. 319 proposed the phasing out of the deduction to put on hold for the year 2004 and 2005. i.e. hybrid car buyers can enjoy the $2000 deduction before the phasing out resumes at $500 in 2006.
- Certain states give tax credits to hybrid car buyers.
- Certain states, e.g. Virginia and Florida, allow singly occupied hybrid vehicles to enter the HOV lanes on the highway.
- Certain states, e.g. California, exempt hybrid cars from the bi-annual smog inspection, which costs over US$50 in 2004.
- Hybrid cars can go on certain toll roads for free.
- City of San Jose, CA issues a free parking tag for hybrid cars that were purchased at a San Jose dealership. The qualified owners do not have to pay for parking in any city garage or road side parking meters.
- City of Los Angeles, CA runs a six month experiment to offer free parking to all hybrid vehicles starting on Oct 1, 2004. The experiment is an extention to an existing offer of free parking for all electrical vehicle.
An
electric vehicle is a vehicle that is propelled by electric motors. This is the case for metros and usually trams, and for some trains (i.e. for some locomotives and often for multiple units), and for electric trolleybuses. Helios Prototype is the name of a solar- and fuel cell system-powered unmanned aerial vehicle. Some rocket propulsion systems use electricity, e.g. the ion thruster.
The term is used in particular for electric automobiles. The rest of the article will pertain to those.
Variety
The energy used to power the motors can be obtained from a variety of sources including fuel cells and batteries. Strictly Solar Powered passenger carrying electric cars and model cars are used only for technology-proving races.
There are a variety of battery electric vehicles that have been produced ranging from SUVs to sports cars. The chief problem with battery electric vehicles is their limited range in comparison with gasoline powered vehicles and the limited number of charge–discharge cycles provided before battery replacement is required. The problem of range could be addressed through the use of gas-electric hybrid vehicles which use an electric engine and grid-rechargeable batteries for acceleration and slow speed driving, with the ability to switch to gasoline power for cruising (no such production vehicles are available, but prototypes have been demonstrated). The future of electric vehicles is dependent upon the availability of batteries with higher energy densities and longer life at reasonable cost, as all other engineering problems of motor control, power delivery, and regenerative braking have been solved. While auto manufacturers have active programs developing fuel cells which could replace batteries to power electric cars, electric vehicles would have an advantage over fuel cells because fuel cell cars require as much as four times more energy per unit distance than an electric car when hydrogen production energy is included (assuming both vehicles use the same electric motors, the same tires, the same rim size, have the same weight, and share aerodynamic characteristics). Battery electric vehicles also have an advantage over fuel cell electric vehicles because they do not need expensive membranes made of platinum and other rare metals in which to develop their energy, although batteries have a relatively high life–cycle cost and most have environmental disposal issues.
Electric vehicles have been noted for being more environmentally friendly than conventional internal combustion engine (ICE) automobiles. Although the power for the car still has to be generated from a source, this energy can be provided by environmentally friendly technologies such as tidal, solar, wind or hydroelectric power. In addition, electric engines are several times more efficient than an ICE because they are not limited by thermodynamic (heat difference) considerations and have no significant friction creating sliding mechanisms. Electric vehicles can also reclaim kinetic energy when braking through a regenerative process (as can hybrid vehicles). Electric vehicles can potentially last longer as their motors have one moving part and do not require the large number of pressure sealing devices of an ICE. They also often do not require a transmission, and without a transmission they do not require a clutch. Overall system efficiency may be reduced by transmission losses from electricity distribution, but this is less of a consideration if the vehicle owner adds photovoltaic power production.
Critics
Critics of electric vehicles point out that in addition to the contrast in range, the large batteries needed to store energy in the vehicles are a serious environmental hazard. These claims are often refuted by environmentalists because the batteries can be recycled with minimal environmental impact and more advanced batteries such as lithium ion and nickel metal hydride batteries might give the cars the range of conventional gas cars. Due to lack of production volume, these batteries are currently 3-4 times more expensive than conventional Lead Acid or Nickel Cadmium batteries. Firefighters and rescue personnel require special training to deal with the higher voltages encountered in electric vehicle accidents.
Critics also note that years of research have so far failed to yield economical or long-lasting batteries. In addition, battery recharge times are longer than practical in many situations The fastest recharge times being when quick charge technology is utilised, allowing charging times of under 30 minutes but not practical for gas stations.
Fans
The greatest fans of electric vehicles are those who have obtained and used them. Owing to the fact that electric vehicles have not been promoted by the major manufactures in the United States, this is a self-selected group, so their enthusiasm may be misleading. Fans point out the following:
- Range is adequate if not the only vehicle in household or if long commutes are not required. Fans point out that most trips in non-commute vehicles are for shopping, school drop-off/pick-up, visiting, and other errands within a 10 to 20 mile (15 to 30 km) radius. Long range is simply not needed for such trips and an operating range of 30 to 40 miles (50 to 65 km) is quite sufficient.
- Fueling at home by charging batteries may be more convenient than driving to obtain liquid or gaseous fuel and both the availability and the cost of operation is predictable.
- The homeowner can install on-grid solar photovoltaic rooftop power and so produce most of the energy required for personal transportation with true zero pollution. Since the vehicles can be charged during low demand times the photovoltaics provide a larger societal benefit by helping to satisfy local peak demand, greatly reducing overall pollution and reducing transmission line loads. Additional benefits can also flow to the user through time sensitive pricing/payback schemes, significantly reducing the cost of a system that will support transportation needs. Once a commitment to producing power is made becomes an easy decision to commit to producing all household and local transportation power needs. Thus there is a societal benefit from electric vehicles beyond transportation.
- Electric vehicles are quiet. Even if not completely silent, they do not produce the low frequency rumble that can easily penetrate household walls and windows.
- Owners take pride in the non-polluting nature of their vehicles. Some point out that knowing that your vehicle is non-polluting quickly leads to a realization how stinky and noxious even modern, well tuned non-electric vehicles actually are — something that tends to be ignored when you are part of the problem.
- Some EV fans with a left of center political bias or of an extreme "green" inclination claim that when combined with household photovoltaics, electric vehicle users are not assisting (through their fuel purchases) despotic governments in oil-rich countries, nor the politically powerful companies that prepare and distribute their products, nor the politically powerful coal interests, nor the domestic politicians that serve and protect these companies and countries. Many electric vehicle owners and operators express great satisfaction in this aspect of electric vehicle use, even while acknowledging that this use can have only little effect on these matters at the present time.
- Some USA EV fans have accused the three major domestic manufactures, General Motors, Chrysler Corporation and Ford Motor Company of deliberately sabotaging their own electric vehicle efforts through several methods: failing to market, failing to produce appropriate vehicles, failing to satisfy demand, and using lease-only programs with prohibitions against end of lease purchase. By these actions they have managed to terminate their EV development and marketing programs despite operator's offers of purchase and assumption of maintenance liabililties. They also point to the Chrysler "golf cart" program as an insult to the marketplace and to mandates, accusing Chrysler of intentionally failing to produce a vehicle usable in mixed traffic conditions. The manufacturers, in their own defense, have responded that they only make what the public wants. EV fans point out that this response is the same argument used by GM to justify the intensively promoted 8 mpg 6500 lb (2,950 kg) Hummer H2 SUV. Of the various electric vehicles marketed by the "Big Three", only the General Motors EV1 (manufactured by GM) and the Th!nk City (imported and marketed by Ford) came close to being appropriate configurations for a mass market. However, at the end of their programs GM destroyed its fleet, despite offers to purchase them by their drivers. Ford's Norwegian-built "Th!nk" fleet was covered by a three-year exemption to the standard U.S. Motor Vehicle Safety laws, after which time Ford had planned to dismantle and recycle its fleet; the company was, however, persuaded by activists to not destroy its fleet but return them to Norway and sell them as used vehicles.
- Both Honda and Toyota also manufactured electric only vehicles. Honda followed the lead of the other majors and terminated their lease–only programs. Toyota offered vehicles for both sale and lease, while Ford also sold a few lead-acid battery Ranger EVs, unique among the large manufactures. While Toyota has terminated manufacture of new vehicles it continues to support those manufactured. It is actually possible to see a RAV-4 EV on the road but this is indeed a rare sight.
- There is a minor industry supporting the conversion and building of electric vehicles by hobbyists. Some designers point out that a specific type of electric vehicle offers comfort, utility and quickness, sacrificing only range. This is called a short range electric vehicle. This type may be built using high performance lead–acid batteries, but of only about half the mass that would be expected to obtain a 60 to 80 mile range. The result is a vehicle with about a thirty mile range, but when designed with appropriate weigh distribution (40/60 front to rear) does not require power steering, offers exceptional acceleration in the lower end of its operating range, is freeway capable and legal, and costs less to build and maintain. By including a manual transmission this type of vehicle can obtain both better performance and higher efficiency than the single speed types developed by the major manufactures. Unlike the converted golf carts used for neighborhood electric vehicles these may be operated on typical suburban throughways (40 to 45 MPH speed limits are typical) and can keep up with traffic typical to these roads and to the short on and off segments of freeways that are common in suburban areas.
United States
The United States produced many electric automobiles, such as the Detroit Electric, during the early 20th century, but production dropped to insignificant numbers with the triumph of gasoline powered internal combustion engine vehicles in the 1920s.
In recent years, electric vehicles have been promoted through the use of tax credits. In California, the California Air Resources Board attempted to set a quota for the use of electric cars, but this was withdrawn after complaints by auto manufacturers that the quotas were economically unfeasible due to a lack of consumer demand. However, many believe this complaint to be unwarranted due to the claim that there were thousands waiting to purchase or lease electric cars from companies such as General Motors, Ford, and Chrysler in which these companies refused to meet that demand despite their production capability. Others note that the original electric car leases were at reduced cost and the program could not be expected to draw the high volumes required without selling or renting the cars at a financial loss. Since the California program was designed by California Air Resources Board:CARB to reduce air pollution and not to promote electric vehicles, the zero emissions requirement in California was replaced by a combination requirement of a tiny number of zero-emissions vehicles (to promote research and development) and a much larger number of partial zero-emissions vehicles (PZEVs), which is an administrative designation for an
super ultra low emissions vehicle (SULEV), which emits pollution of about ten percent of that of an ordinary low emissions vehicle.
International
In London, electrically powered vehicles are one of the categories of vehicle exempted from the Congestion Charge.
History
Electric vehicles were among the earliest automobiles, and before the preeminence of internal combustion vehicles, electric automobiles held many vehicle land speed and distance records in the early 1900s. They were produced by Anthony Electric, Baker Electric, Detroit Electric, and others and at one point in history out-sold gasoline-powered vehicles.
Internal combustion engines replaced electric drive with the invention of the electric starter by Cadillac. For more information on this subject, see history of the electric vehicle.
Productions
Recent or current production electric vehicles sold or leased to fleets include:
- AC Propulsion TZero
- Arton Birdie
- Bertone Blitz
- Citroën Berlingo Electrique
- Chevrolet S10 EV
- Chrysler Epic
- Commuter Cars Tango
- Corbin Sparrow
- Elcat
- Ford Ranger EV
- General Motors EV1
- Honda EV Plus
- Hyundai SantaFe EV
- Kewet
- Nissan Altra
- Porsche 550 Spyder replica electric conversion
- Peugeot 106 EV
- Pivco City Bee
- Renault EV
- REVA
- Sinclair C5
- Solectria Force
- Think City
- Toyota RAV4 EV
- Twike
- Zebra Model Z roadster (Formerly Renaissance Tropica))
- Zytec Lotus Elise
Prototypes
Recent prototype EVs include:
- Ford E-Ka
- Lexus EV (Featured in the film Minority Report)
- Pinanfarina Ethos II
- Renault EV Racer
- Solectria Sunrise
- Subaru Zero EV
- Suzuki EV Sport
Hobbyists and racing
Aside from production electric cars, often hobbyists build their own EVs by converting existing production cars to run on electricity. Universities such as the University of California, Irvine even go so far as to build their own custom electric or hybrid-electric cars from scratch.
Electric vehicles are also highly popular in quarter mile (400 m) racing. The National Electric Drag Racing Association regularly holds electric car races and often competes them successfully against exotics such as the Dodge Viper.
