In this essay we will discuss about:- 1. Introduction to Hybrid Electric Vehicles 2. Status of Electric Hybrid Vehicles 3. Advantages.
Essay on Hybrid Electric Vehicles
Essay # 1. Introduction to Hybrid Electric Vehicles:
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Hybrid Electric vehicles use electrical and mechanical means to propel the vehicle. They combine the efficiency and lower emissions of electrical vehicles and longer driving range of gasoline and diesel vehicles. The most traditional hybrid – electric vehicles are the diesel electric trains.
Most of the vehicle manufacturers have brought out electric hybrid cars and buses. The experience to date with hybrid electric cars and buses has been largely positive. Hybrid electric vehicles are now at the forefront of transportation technology development.
Hybrid electric vehicles employ a small internal combustion engine (gasoline, diesel engine or gas turbine) running continuously at constant speed under conditions of maximum efficiency and least exhaust emissions.
The energy produced by the internal combustion engine is converted to electricity in a generator (coupled to the engine) and fed direct to hub motors on the wheels of the vehicle or to batteries or to a combination, according to the power required by the vehicle. The vehicle can operate only on batteries in city limits and the internal combustion engine is switched “on” in the suburbs. Hence hybrid electric vehicle is both a “zero-emission” and an “ultra-low” pollution vehicle.
Electric hybrid vehicles have considerable advantage in fuel economy and pollutant emissions over conventional gasoline or diesel vehicles. In hybrid electric vehicles, the battery pack stores the energy recovered through “regenerative braking” increasing its fuel economy.
The engines in conventional vehicles are relatively inefficient under average driving conditions because they are designed for peak demand situations which occur when a vehicle is accelerating or climbing a steep hill.
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By contrast, the internal combustion engines that run generators in hybrid electric vehicles are tailored to efficiently meet the average power requirements of the vehicle, since onboard batteries handle surge power requirements.
This would allow the prime mover to be sized for the average power demand over the driving cycle (with some reserve), rather than the peak power demand. Since the prime-mover would operate at its designed power output most of the time, its average efficiency over the driving cycle would be much greater than that of the conventional engines.
The higher efficiency and the decoupling of the engine and the wheels should result in much lower emissions than a conventional engine. Decoupling the engine from the wheels (and thus the need to respond to the rapid changes in speed and the power output) would also make possible the use of new, lower-emitting , and more efficient prime movers such as Stirling engines, gas turbines etc., Most of the EHVS are also powered by natural gas, methanol, etc. to reduce emissions.
Essay # 2. Status of Electric Hybrid Vehicles
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Electric hybrid vehicles have been under development for light and heavy duty vehicle applications for the past several years. Most of the vehicle manufacturers have brought out electric hybrid cars and buses. The experience to date with hybrid electric cars and buses has been largely positive.
Toyota launched the first gasoline – electric hybrid car six years ago (in 1997) — Prius. Its performance was as good as an equivalent gasoline vehicle, and was capable of a fuel consumption of 28kms per litre. Till date it has produced 130,000 vehicles and the Toyota Prius is seen as a vehicle that might change the automotive world.
Toyota plans to introduce hybrid versions of virtually every model in its range, starting with its luxury model Lexus, encouraged by demand for the new Prius that is running far in excess of its own expectations. It is considering putting 6000 to 10,000 hybrid vehicles per month during the year 2004. During acceleration, HC, CO and NOx emissions are reduced to about one-tenth of the vehicle fitted with conventional engine.
Chrysler Corporation has come up with a new concept hybrid electric car with a drastic cost reduction compared to its earlier models of hybrid vehicles. The cost of Esx2 hybrid car will be closer to a conventional vehicle-U.S $15,000. The main features of this new concept car are a small battery to provide a boost to the vehicle during the acceleration as well as to power the accessories. The battery power pack used in this new hybrid car is only 60 kgs.
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General Motors has come out with a plan to have production of electric hybrid vehicles. Fitted with a turbine engine and nickel- metal hydride batteries, the vehicle can attain 60 miles per gallon on the high way and accelerates from 0 to 96 kms per hour in 9 seconds and the range of the vehicle will be 64kms running on batteries only giving zero emissions.
The Honda Insight and Honda civic hybrids are available in U.S and many other countries and have been getting a lot of attention. Honda Insight is a petrol-electric hybrid two seater coupe that blends a number of new technologies to achieve the world’s lowest fuel consumption for mass produced petrol engine car.
Honda-Insight has the world’s lightest 1.0 litre, 3-cylinder gasoline engine, which uses advanced lean burn technology, low friction characteristics and lightweight materials in combination with a new lean-burn compatible NOx catalyst. It has ultra-low fuel consumption of 3.4 litres for 100 kms.
The CO2 emissions stand at an extremely low 80 grams/km (the lower-value ever achieved by a mass produced car). With emissions less than half the Euro-3 limits, it has highly respectable performance of 0 to 100 Kms per hour in 12 seconds and a top speed of 180 kms/hour.
In the New York City Transit, the electric hybrid buses with diesel engines (equipped with particulate filters) are delivering emissions comparable to CNG buses. The hybrid buses are delivering 16 percent fuel economy benefits over the conventional diesel buses.
Hybrid electric vehicles are poised for exponential growth and significant market penetration, provided that the incremental cost for hybridization can be reduced. Bulk of the incremental costs is due to batteries, electric motors, and power electronics.
Essay # 3. Advantages of Hybrid Electric Vehicles
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Hybrid electric vehicles were conceived as a way to compensate the range and cost problems of battery-powered electric vehicles. The “ultra-low emission” hybrid electric vehicles can cut emissions of global warming pollutants by a third to a half, and later models may cut emissions by even more. The practical benefits of hybrid electric vehicles include improved fuel economy and lower emissions compared to conventional vehicles.
The inherent flexibility of hybrid electric vehicles will allow them to be used in a wide range of applications, from personal cars to buses and trucks. Hybrid electric vehicles do not require any changes to the fuel and power infrastructure. The hybrid electric vehicles now available for sale are very competitive with similar conventional vehicles. Any cost premium that may be associated with hybrid electric vehicles can be off-set by the overall fuel savings.
The generators in hybrid electric vehicles can also be used as emergency electric generators. The availability of thousands of mobile distributed generation systems could mean improved power reliability, emergency backup power for homes and businesses and a potential source to reduce peak demands.
Hybrid electric vehicles have some major advantages over internal combustion engines and battery powered electric vehicles.
The following are some of the advantages:
1. The internal combustion engine or the gas turbine used on hybrid electric vehicles can be smaller because it shares the work load with the batteries during peak load demand.
2. The engine can be optimized to operate within a specific speed range where fuel economy is greatest and emissions are least. In this way, the higher emissions and poor fuel economy associated with internal combustion engines are avoided.
3. Hybrid electric vehicles use liquid fuels (gasoline, diesel, bio-diesel, methanol or ethanol) or gaseous fuels (natural gas, LPG, etc.) in addition to battery power, which provides for more driving range than just batteries alone.
4. The wheel hub motors and regenerative braking, possible with hybrid electric vehicles result in lower energy losses compared to conventional internal combustion engines.
5. Hybrid electric vehicles can reduce dependency on fossil fuels because they can run on alternative fuels.
These advantages, combined with advances in battery, motor and material technologies in recent years, have led to a large expansion of development work and reduced costs leading to greater market acceptance of electric hybrid vehicles.