Electric vehicle
Encyclopedia : E : EL : ELE : Electric vehicle
The energy used to propel the vehicle may be obtained from several sources:
- from chemical energy stored on the vehicle in on-board batteries: Battery electric vehicle (BEV)
- from both an on-board rechargeable energy storage system (RESS) and a fueled propulsion power source: hybrid vehicle
- generated on-board using a combustion engine, as in a diesel-electric locomotive
- generated on-board using a fuel cell: fuel cell vehicle
- generated on-board using nuclear energy, on nuclear submarines and aircraft carriers
- from more esoteric sources such as flywheels, wind and solar
- from a direct connection to land-based generation plants, as is common in electric trains and trolley buses
Personal highway-capable EVs are driven by tens of thousands of ordinary people worldwide. According to the (US) Electric Auto Association, as many as ten thousand full-sized electric cars are on American roads today. Most are converted to electric propulsion by owners or small shops, although several hundred of the several thousand (of eight EV models in the US) built by major automakers also survive, mostly Toyota RAV4 EV's. The rest have been repossessed and crushed by their makers, including the General Motors EV1.
Most large electric transport is directly connected to stationary sources of energy through the grid. Due to the extra infrastructure and difficulty in handling arbitrary travel, most directly connected vehicles are owned publicly or by large companies. These forms of transportation are covered in more detail in maglev trains, metros, trams, trains and trolleybuses. A hypothetical electric vehicle design is Personal rapid transit, a cross between cars and trains optimised for independent travel.
In most systems the motion is provided by a rotary electric motor. However, some trains unroll their motors to drive directly against a special matched track. These are known as maglev trains, short for magnetic levitation, which float above the rails through magnetic force. This allows for almost no rolling resistance of the vehicle and no mechanical wear and tear of the train or track. Note that the levitation and the forward motion are independent effects: while the forward motive forces still require external power, although Inductrack achieves levitation at low speeds without any.
Chemical energy is a common independent energy source. Chemical energy is converted to electrical energy, which is then regulated and fed to the drive motors. Chemical energy is usually in the form of diesel or petrol. The liquid fuels are usually converted into electricity by a generator powered by an internal combustion engine or other heat engine. This approach is known as diesel-electric or gas-hybrid locomotion.
Another common form of chemical to electrical conversion is by electro-chemical devices. These include fuel cells and batteries. By avoiding an intermediate mechanical step, the conversion efficiency is dramatically improved over the chemical-thermal-mechanical-electrical-mechanical process already discussed. This is due to the higher carnot efficiency through directly oxidizing the fuel and by avoiding several unnecessary energy conversions. Furthermore, electro-chemical batteries conversions are easy to reverse, allowing electrical energy to be stored in chemical form.
Despite the higher efficiency, electro-chemical vehicles have been beset by many technical issues which have prevented them from replacing the more cumbersome heat engines. Heat engines have been easier to scale up, with the largest electrical generators always being driven by heat engines. Fuel cells are fragile, sensitive to contamination, and require external reactants such as hydrogen. Batteries require highly refined and unstable chemicals that could be harmful to the environment and must be recycled to minimize their impact and maximize their sustainability through material reuse. Both have lower energy and power density than heat engines. However, recent advances in battery efficiency, capacity, materials, safety, toxicity and durability are likely to allow their superior characteristics to be widely applied in car-sized EVs,
For especially large electric vehicles, namely submarines and aircraft carriers, the chemical energy of the diesel-electric can be replaced by a nuclear reactor. The nuclear reactor usually provides heat, which drives a steam turbine, which drives a generator, which is then fed to the propulsion.
There have been a number of experiments using flywheel energy storage in electric vehicles. The flywheels store energy as rotation, which is converted to electricity via a generator, which then drives the wheel motors. It might seem odd to convert rotational energy to electrical energy, only to convert it back again to rotate the vehicle's drive wheels, but in fact it is a necessary step: In order to hold a useful amount of energy, flywheels need to spin extremely fast, and an electric generator is usually a more practical converter for this high speed rotational energy than a mechanical gearing system would be.
Electric motive power started with a small railway operated by a miniature electric motor, built by Thomas Davenport in 1835. In 1838, a Scotsman named Robert Davidson built an electric locomotive that attained a speed of four miles an hour. In England a patent was granted in 1840 for the use of rails as conductors of electric current, and similar American patents were issued to Lilley and Colten in 1847. [link]
Between 1832 and 1839 (the exact year is uncertain), Robert Anderson of Scotland invented the first crude electric carriage, powered by non-rechargable Primary cells. [link]
By the 20th century, electric cars and rail transport were commonplace, with commercial electric automobiles having the majority of the market. Electrified trains were used for coal transport as the motors did not use precious oxygen in the mines. Switzerland's lack of natural fossil resources forced the rapid electrification of their rail network.
Electric vehicles were among the earliest automobiles, and before the preeminence of light, powerful internal combustion engines, 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.
Future
The future of electric vehicles until recently seemed unimpressive due to their low driving range and short lifespan of batteries. However, recent technological advances have made electric vehicles more feasible.
Improved long term energy storage
There have been several developments which could bring back electric vehicles outside of their current fields of application, as scooters, golf cars, neighborhood vehicles, in industrial operational yards and indoor operation. First, advances in lithium-based battery technology, in large part driven by the consumer electronics industry, allow full-sized, highway-capable electric vehicles to be propelled as far on a single charge as conventional cars go on a single tank of gasoline. Lithium batteries have been made safe, can be recharged in minutes instead of hours, and now last longer than the typical vehicle. The production cost of these lighter, higher-capacity lithium batteries is gradually decreasing as the technology matures and production volumes increase.Introduction of Battery Management and Intermediate Storage
Another improvement[link] was to decouple the electric motor from the battery through electronic control while employing ultra-capacitors to buffer large but short power demands and recuperable braking energy. The development of new cell types compared with intelligent cell management improved both weak points mentioned above. The cell management is not only able to monitor the health of the cells but by having a redundant cell configuration (one cell more than needed) and a sophisticated switched wiring it is possible to condition one cell after the other while the rest are on duty.Range extending energy converters on board
Perhaps the most important point is that a monovalent operation (electric only) is no longer considered dogma. Plug-in hybrid electric vehicles can use an engine for longer trips. The use of fuel cells instead of internal combustion engines can create propulsion systems that are nearly emissions-free (regarding local emissions).
Electric vehicles and the automotive industry
Some accuse the major automakers of trying to postpone or prevent the mass production of electric cars. These critics allege that this stems from their being heavily financially invested in today's dominant power technology, the internal combustion engine. At one time during emissions reductions regulations GM produced over 1,100 of their EV1 models, 800 of which were made available through 3-year leases. Upon the expiration of EV1 leases, GM crushed them. The reason for the crushing is not clear, but has variously been attributed to (1) the auto industry's successful challenge to California law requiring zero emission vehicles or (2) a federal regulation requiring GM to produce and maintain spare parts for the few thousands EV1s. A [web site] tracks crushing of other electric vehicles. A movie on the subject was made in 2005-2006, entitled Who Killed the Electric Car? was released theatrically by Sony Pictures Classics in 2006. The film explores the roles of automobile makers, oil industry, the US government, batteries, hydrogen vehicles, and consumers, and each of their roles in limiting the deployment and adoption of this technology.
The Benefits of Electric Vehicles
Electric vehicles have many benefits. One of these benefits is that owners of these cars will be avoiding the rising costs of gasoline. Instead they will be paying less by paying only for the electricity they need to recharge their batteries. Even though the power output and lifespan of batteries is not a great amount at this point, research is being done to boost the numbers of both of these things.Furthermore, since the energy used by electric vehicles is generated at stationary sources, there is far more potential for the use of renewable energy for transportation. Electricity generated from wind, solar, and biomass energy could be used directly to power vehicles. This would be far more efficient than using energy converting biomass into ethanol, transporting it by tanker truck, and then burning it within an internal combustion engine.
Patents
- [U.S. Patent 772571], Hiram Stevens Maxim, Electric motor vehicle
- [U.S. Patent 657046], J. Trier, Multiple motor system for automobile
- [U.S. Patent 594805], H. S. Maxim, Motor vehicle
- [U.S. Patent 523354], E. E. Keller, Electrically Propelled Preambulator
- [U.S. Patent 650014], I. Kitsee, Electric motorcycle
- [U.S. Patent 643258], E. A. Sperry, Motor vehicle
- [U.S. Patent 640968], E. A. Sperry, Electric vehicle
- [U.S. Patent 849146], J. Ledwinka, Automobile
- [U.S. Patent 1017198], E. W. Bender, Electric Motor vehicle
See also
- Battery electric vehicle
- Buckeye Bullet is the world's fastest electric car
- Documentary film: Who Killed the Electric Car?
- Electric scooter
- Electric vehicle conversion
- Electric vehicle production
- Hybrid vehicle
- Fuel Cell Vehicle
- Hydrogen vehicle
- Mitigation of global warming
- Plug-in hybrid electric vehicle
Related Links
- [The PBS newsmagazine NOW] takes a closer look at the life and death of the electric vehicle, including interviews with "Who killed the electric car?" director Chris Paine, and Baywatch actress/EC Enthusiast Alexandra Paul
- [Electric Car Society]
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