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Alternative Transportation
Electric Vehicles
Electric vehicles have a long, interesting history since they were first developed. The very first one was made in 1835 and was a small rail cart. It wasn’t long after that, that a motorized carriage was invented that ran on a non rechargeable battery. Interest and development in electric vehicles rose quickly after that but then started to taper down after the turn of the century. Once Ford Motor Company started mass producing the Model-T, electric automobiles started to disappear.
The term Electric Vehicle can basically include any form of transportation that operates on electricity. Therefore we can have cars, trucks, trains, planes, boats, and spacecraft that fall under this category. Trains are fortunate where they may connect directly to a power grid in some cases. Satellites are almost solely powered on solar power. Smaller planes may also operate on solar created energy; most of them are unmanned though.
When it comes to cars and trucks, some sort of energy storage is required. You could have batteries, or use fuel cells, and then there are ultracapacitors which are a new technology with great potential for storing energy in vehicles. If you do the math, electrical energy is much cheaper to use in transportation than fossil fuels, so it makes economical sense. It won’t produce any direct greenhouse gases, so there is the environmental benefit, although indirect pollution is dependent on where the energy comes from.
Batteries are the primary energy storage at this point for electric vehicles and once the batteries are no longer useful they will have to be replaced. This is a possible mode for pollution if not handled correctly. This is where ultracapacitors really outshine batteries, they are basically good forever, and they aren’t made of hazardous materials.
Electric vehicle
An electric vehicle (EV), also referred to as an electric drive vehicle, is a vehicle which uses one or more electric motors for propulsion. Depending on the type of vehicle, motion may be provided by wheels or propellers driven by rotary motors, or in the case of tracked vehicles, by linear motors. Electric vehicles can include electric cars, electric trains, electric lorries, electric airplanes, electric boats, electric motorcycles and scooters, and electric spacecraft.
Electric vehicles first came into existence in the mid-19th century, when electricity was among the preferred methods for automobile propulsion, providing a level of comfort and ease of operation that could not be achieved by the gasoline cars of the time. At one time the internal combustion engine (ICE) had completely replaced the electric drive as a propulsion method for automobiles, but electric power has remained commonplace in other vehicle types, such as trains and smaller vehicles of all types.
Electric vehicles are different from fossil fuel-powered vehicles in that
• They can receive their power from a wide range of sources, including fossil fuels, nuclear power, and renewable sources such as tidal power, solar power, and wind power or any combination of those. However it is generated, this energy is then transmitted to the vehicle through use of overhead lines, wireless energy transfer such as inductive charging, or a direct connection through an electrical cable. The electricity may then be stored onboard the vehicle using a battery, flywheel, supercapacitor, or fuel cell.
• Instead, vehicles making use of engines working on the principle of combustion can usually only derive their energy from a single or a few sources, usually non-renewable fossil fuels. A key advantage of electric or hybrid electric vehicles is their ability to recover braking energy as electricity to be restored to the on-board battery (regenerative braking) or sent back to the grid (V2G).
At the beginning of the 21st century, increased concern over the environmental impact of the petroleum-based transportation infrastructure, along with the spectre of peak oil, led to renewed interest in an electric transportation infrastructure. As such, vehicles which can potentially be powered by renewable energy sources, such as hybrid electric vehicles or pure electric vehicles, are becoming more popular.
1. Electricity sources
There are many ways to generate electricity, some of them more ecological than others:
• On-board rechargeable electricity storage system (RESS), called Full Electric Vehicles (FEV). Power storage methods include:
o chemical energy stored on the vehicle in on-board batteries: Battery electric vehicle (BEV)
o static energy stored on the vehicle in on-board electric double-layer capacitors
o kinetic energy storage: flywheels
• direct connection to generation plants as is common among electric trains, trolley buses, and trolley trucks (See also : overhead lines, third rail and conduit current collection)
• renewable sources such as solar power: solar vehicle
• generated on-board using a diesel engine: diesel-electric locomotive
• generated on-board using a fuel cell: fuel cell vehicle
• generated on-board using nuclear energy: nuclear submarines and aircraft carriers
It is also possible to have hybrid electric vehicles that derive electricity from multiple sources. Such as:
• on-board rechargeable electricity storage system (RESS) and a direct continuous connection to land-based generation plants for purposes of on-highway recharging with unrestricted highway range
• on-board rechargeable electricity storage system and a fueled propulsion power source (internal combustion engine): plug-in hybrid
Batteries, electric double-layer capacitors and flywheel energy storage are forms of rechargeable on-board electrical storage. By avoiding an intermediate mechanical step, the energy conversion efficiency can be improved over the hybrids already discussed, by avoiding unnecessary energy conversions. Furthermore, electro-chemical batteries conversions are easy to reverse, allowing electrical energy to be stored in chemical form.
Another form of chemical to electrical conversion is fuel cells, projected for future use.
For especially large electric vehicles, such as submarines, 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. See Nuclear Power
A few experimental vehicles, such as some cars and a handful of aircraft use solar panels for electricity.
2. Vehicle types
It is generally possible to equip any kind of vehicle with an electric powertrain.
• Hybrid electric vehicle
A hybrid electric vehicle combines a conventional (usually fossil fuel-powered) powertrain with some form of electric propulsion. Common examples include hybrid electric cars such as the Toyota Prius.
• On- and off-road electric vehicles
Electric vehicles are on the road in many functions, including electric cars, electric trolleybuses, electric bicycles, electric motorcycles and scooters, neighborhood electric vehicles, golf carts, milk floats, and forklifts. Off-road vehicles include electrified all-terrain vehicles and tractors.
• Railborne electric vehicles
The fixed nature of a rail line makes it relatively easy to power electric vehicles through permanent overhead lines or electrified third rails, eliminating the need for heavy onboard batteries. Electric locomotives, electric trams/streetcars/trolleys, electric light rail systems, and electric rapid transit are all in common use today, especially in Europe and Asia.
Since electric trains do not need to carry a heavy internal combustion engine or large batteries, they can have very good power-to-weight ratios. This allows high speed trains such as France's double-deck TGVs to operate at speeds of 320 km/h (200 mph) or higher, and electric locomotives to have a much higher power output than diesel locomotives. In addition they have higher short-term surge power for fast acceleration, and using regenerative braking can put braking power back into the electrical grid rather than wasting it.
Maglev trains are also nearly always electric vehicles.
• Airborne electric vehicles
Since the beginning of the era of aviation, electric power for aircraft has received a great deal of experimentation. Currently flying electric aircraft include manned and unmanned aerial vehicles.
• Seaborne electric vehicles
Electric boats were popular around the turn of the 20th century. Interest in quiet and potentially renewable marine transportation has steadily increased since the late 20th century, as solar cells have given motorboats the infinite range of sailboats. Submarines use batteries (charged by diesel or gasoline engines at the surface), nuclear power, or fuel cells [7] run electric motor driven propellers.
• Spaceborne electric vehicles
Electric power has a long history of use in spacecraft. The power sources used for spacecraft are batteries, solar panels and nuclear power. Current methods of propelling a spacecraft with electricity include the arcjet rocket, the electrostatic ion thruster, the Hall effect thruster, and Field Emission Electric Propulsion. A number of other methods have been proposed, with varying levels of feasibility.
3. Energy and motors
Most large electric transport systems are powered by stationary sources of electricity that are directly connected to the vehicles through wires. Electric traction allows the use of regenerative braking, in which the motors are used as brakes and become generators that transform the motion of, usually, a train into electrical power that is then fed back into the lines. This system is particularly advantageous in mountainous operations, as descending vehicles can produce a large portion of the power required for those ascending. This regenerative system is only viable if the system is large enough to utilize the power generated by descending vehicles.
In the systems above motion is provided by a rotary electric motor. However, it is possible to "unroll" the motor to drive directly against a special matched track. These linear motors are used in maglev trains which float above the rails supported by magnetic levitation. This allows for almost no rolling resistance of the vehicle and no mechanical wear and tear of the train or track. In addition to the high-performance control systems needed, switching and curving of the tracks becomes difficult with linear motors, which to date has restricted their operations to high-speed point to point services.
4. Energy sources
Although electric vehicles have few direct emissions, all rely on energy created through electricity generation, and will usually emit pollution and generate waste, unless it is generated by renewable source power plants. Since electric vehicles use whatever electricity is delivered by their electrical utility/grid operator, electric vehicles can be made more or less efficient, polluting and expensive to run, by modifying the electrical generating stations. This would be done by an electrical utility under a government energy policy, in a timescale negotiated between utilities and government.
Fossil fuel vehicle efficiency and pollution standards take years to filter through a nation's fleet of vehicles. New efficiency and pollution standards rely on the purchase of new vehicles, often as the current vehicles already on the road reach their end-of-life. Only a few nations set a retirement age for old vehicles, such as Japan or Singapore, forcing periodic upgrading of all vehicles already on the road.
Electric vehicles will take advantage of whatever environmental gains happen when a renewable energy generation station comes online; a fossil fuel station is decommissioned or upgraded. Conversely, if government policy or economic conditions shifts generators back to use more polluting fossil fuels and internal combustion engine vehicles (ICEVs), or more inefficient sources, the reverse can happen. Even in such a situation, electrical vehicles are still more efficient than a comparable amount of fossil fuel vehicles. In areas with a deregulated electrical energy market, an electrical vehicle owner can choose whether to run his electrical vehicle off conventional electrical energy sources, or strictly from renewable electrical energy sources (presumably at an additional cost), pushing other consumers onto conventional sources, and switch at any time between the two.
5. Charging stations
Electric vehicles typically charge from conventional power outlets or dedicated charging stations, a process that typically takes hours, but can be done overnight and often gives a charge that is sufficient for normal everyday usage.
One proposed solution for daily recharging is a standardized inductive charging system such as Evatran's Plugless Power. Benefits are the convenience of automatic occurrence with parking over the charge station and minimized cabling and connection infrastructure.
Another proposed solution for the typically less frequent, long distance travel is "rapid charging", such as the Aerovironment PosiCharge line (up to 250 kW) and the Norvik MinitCharge line (up to 300 kW). Ecotality is a manufacturer of Charging Stations and has partnered with Nissan on several installations. Battery replacement is also proposed as an alternative, although no OEM's including Nissan/Renault has any production vehicle plans. Swapping requires standardization across platforms, models and manufacturers. Swapping also requires many times more battery packs to be in the system.
One type of battery "replacement" proposed is much simpler: while the latest generation of vanadium redox battery only has an energy density similar to lead-acid, the charge is stored solely in a vanadium-based electrolyte, which can be pumped out and replaced with charged fluid. The vanadium battery system is also a potential candidate for intermediate energy storage in quick charging stations because of its high power density and extremely good endurance in daily use. System cost however, is still prohibitive. As vanadium battery systems are estimated to range in between $350–$600 per kWh, a battery that can service one hundred customers in a 24 hour period at 50 kWh per charge would cost $1.8-$3 million.
6. Disadvantages of electric vehicles
Many electric designs have limited range, due to the low energy density of batteries compared to the fuel of internal combustion engined vehicles. Electric vehicles also often have long recharge times compared to the relatively fast process of refueling a tank. This is further complicated by the current scarcity of public charging stations, although these are far less necessary for electric vehicles in everyday use. "Range anxiety" is coming into use as a label for part of this situation.
Contrary to widespread belief, according to Department of Energy research conducted at Pacific National Laboratory, 84% of existing vehicles could be switched over to plug-in hybrids without requiring any new grid infrastructure. In terms of transportation, the net result would be a 27% reduction in carbon dioxide emissions, a slight reduction in nitrous oxide emissions, an increase in particulate matter emissions, the same sulfur dioxide emissions, and the near elimination of carbon monoxide and volatile organic compound emissions. The emissions would be displaced away from street level and have correspondingly less effect on human health.
Electric and hybrid cars are seen as environmentally-friendly. While they do have reduced carbon emissions, the energy they consume are usually produced by means which some believe to be harmful to the environment, such as coal, nuclear, and hydroelectric power. Electric cars may lead consumers to believe that buying such a vehicle is an environmentally-sound choice, whereas the choice that would have nearly zero environmental impact would be to make a lifestyle change in favor of walking, biking or telecommuting. Governments may invest in research and development of electric vehicles with the intention of reducing the impact on the environment where they could instead develop pedestrian-friendly communities.
• Heating of electric vehicles
In cold climates considerable energy is needed to heat the interior of the vehicle, and to defrost the windows. With internal combustion engines this heat already exists due to the combustion process (offsetting the greenhouse gases external costs) from the waste heat from the engine cooling circuit. If this is done with battery electric cars, this will require extra energy from the battery or an additional battery and circuit for accessories. Although some heat could be harvested from the motor(s) and battery, however, due to their greater efficiency, there is not as much waste heat available as from a combustion engine.
However when plugged into the grid electric vehicles can be preheated, or cooled, and need little or no energy from the battery, especially for short trips.
Newer designs are focused on using super-insulated cabins which can heat the car using the body heat of the passengers. This is however not enough in colder climates as a driver only delivers approximately 100 W of heating power. A reversible AC-system, cooling the cabin during summer and heating it during winter seems to be the most practical and promising way of solving the thermal management of the EV. Ricardo Arboix introduced (2008) a new concept based on the principle of combining the thermal-management of the EV-battery with the thermal-management of the cabin using a reversible AC-system. This is done by adding a third heat-exchanger, thermally connected with the battery-core, to the traditional heat pump/air conditioning system used in previous EV-models like the GM EV1 and Toyota RAV4 EV. The concept has proven to bring several benefits such as prolonging the life-span of the battery as well as improving the performance and overall energy-efficiency of the EV.
7. Advantages of electric vehicles
• Mechanical
Electric motors are mechanically very simple.
Electric motors often achieve 90% energy conversion efficiency over the full range of speeds and power output and can be precisely controlled. They can also be combined with regenerative braking systems that have the ability to convert movement energy back into stored electricity. This can be used to reduce the wear on brake systems (and consequent brake pad dust) and reduce the total energy requirement of a trip. Regenerative braking is especially effective for start-and-stop city use.
They can be finely controlled and provide high torque from rest, unlike internal combustion engines, and do not need multiple gears to match power curves. This removes the need for gearboxes and torque converters.
Electric vehicles provide quiet and smooth operation and consequently have less noise and vibration than internal combustion engines. While this is a desirable attribute, it has also evoked concern that the absence of the usual sounds of an approaching vehicle pose a danger to blind, elderly and very young pedestrians. To mitigate this situation, automakers and individual companies are developing systems that produce warning noises or distinctive sounds when electric vehicles are moving slowly, up to a speed when normal motion and rotation (road, suspension, electric motor, etc.) noises become audible.
• Environmental
Electric vehicles release almost no air pollutants at the place where they are operated. In addition, it is generally easier to build pollution control systems into centralized power stations than retrofit enormous numbers of cars.
Another advantage is that electric vehicles typically have less noise pollution than an internal combustion engine vehicle, whether it is at rest or in motion. Electric vehicles emit no tailpipe CO2 or pollutants such as NOx, NMHC, CO and PM at the point of use.
• Energy resilience
Electricity is a form of energy that remains within the continent where it was produced and can be multi-sourced. As a result it gives the greatest degree of energy resilience.
• Energy efficiency
Electric vehicle 'tank-to-wheels' efficiency is about a factor of 3 higher than internal combustion engine vehicles.
• Cost of recharge
The GM Volt will cost "less than purchasing a cup of your favorite coffee" to recharge. The Volt should cost less than 2 cents per mile to drive on electricity, compared with 12 cents a mile on gasoline at a price of $3.60 a gallon. This means a trip from Los Angeles to New York would cost $56 on electricity, and $336 with gasoline. This would be the equivalent to paying 60 cents a gallon of gas.
