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Essay on Vehicular Emissions and Global Warming
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Essay Contents:
- Essay on the Introduction to Vehicular Emissions and Global Warming
- Essay on the Fuel Efficiency in Vehicles
- Essay on the Corporate Average Fuel Economy (CAFE) Standards
- Essay on the Vehicle Features Affecting Fuel Economy
- Essay on the Rolling Resistance of the Vehicles
- Essay on the Engine Design and Technology Affecting Fuel Economy
- Essay on Aero Dynamic Drag
- Essay on Road Characteristics
- Essay on Driving Habits and Fuel Economy
- Essay on Vehicle Maintenance and Fuel Economy
- Essay on Reducing Transport Demand-Traffic and Transportation Management
Essay # 1. Introduction
to Vehicular Emissions and Global Warming:
Among the potential effects of fossil fuel combustion are urban air pollution, acid rain and changes in global climate. In recent years, serious concern has emerged that the earth’s climate is being altered by increased concentration of certain gases (popularly known as greenhouse gases). The greenhouse gases that are of concern include carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCS) and water vapour.
The earth’s climate is driven by solar radiation. The solar radiation takes the form of short wave radiation and most of it is absorbed before it strikes the earth’s surface. Some radiation however reaches earth’s surface to be converted by plants into food, and some warms the earth and oceans.
Part of this radiation is later re-radiated in the form of long-wave radiation, to be trapped by “greenhouse gases”. Part of this outgoing energy is re- emitted back to the earth by the greenhouse gases, thereby reducing net emission of energy to the space.
The greenhouse gases allows solar radiation to pass through the earth’s atmosphere unimpeded but they absorb the infra-red or long wave radiation from the earth’s surface and then re-radiate back to the earth. To maintain the global energy balance, both the atmosphere and the earth’s surface will warm up until the outgoing energy equals the incoming energy. This warming up of earth’s surface is popularly known as global warming, climate change or greenhouse effect.
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Carbon dioxide is the major contributor to global warming and is responsible for 60% of the effect of greenhouse gases responsible for global warming. Major sources of greenhouse gas production are electric power generation, transportation, industry, forests and farming.
The International Energy Agency estimates that transport accounts for 26 percent of total world-wide production of carbon dioxide and this share is increasing very fast in developing countries, especially China and India. Road transport is responsible for about 17%, rail transport for 7% and air and water transport for 1 each out of this 26% carbon dioxide emissions from the transport sector world-wide.
The global warming has significant impacts on health, agriculture, bio diversity, forests, ecological instability and rise of sea levels. Agriculture, forestry and coastal activities which are dependent on rain fall and temperature, are more significantly affected by climate change and global warming.
Most of the developing countries like India heavily depend on agriculture and hence are more vulnerable to global warming. The higher temperatures due to global warming could influence the incidence of diseases such as malaria, dengue fever, yellow fever and several types of encephalitis. Cold temperatures are often the limiting factors in mosquito survival, so any increase in minimum temperatures would increase mosquitos and consequently diseases connected with it.
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One of the easily imagined impacts of global warming is an increase in the number and intensity of heat waves. During intense heat waves, the death toll attributed to heat stress can be very high. The heat wave in Chicago for 4 days in July 1995 killed 726 people. Severe heat waves occurred in India in 1995 and 2003. The people living in hotter climates may be able to adjust better to heat waves than those living in colder climates.
Climate change is likely to threaten Island economies and low lying countries like Maldives, Bangladesh, Netherlands, etc. It was predicted that one meter rise in the sea level as a result of global warming could lead to loss of coastal land to the extent of about 6 per cent in Netherlands and 17 per cent in Bangladesh.
A one- meter increase in the sea level in Bangladesh would force about 70 million people to move away and would have a dramatic effect on the food security in the country. Approximately half of the current rice production is from the area, which is likely to be inundated due to one-meter rise in sea level in Bangladesh. Rising sea levels would inundate many of the low-lying small islands like Maldives.
Delta regions such as the Ganga-Brahmaputra delta in India and Bangladesh, the Nile delta in Egypt etc., could suffer from greenhouse effect. According to some scientific studies , one alarming possibility is the melting and eventual disappearance of Himalayan glaciers in about 40 years from now, leading initially to flooding and then to the drying up of the rivers like Ganga, Yamuna and Sindh feeding the Indian Plains. This may affect more than 50 million people by about 2035.
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Although the share of greenhouse gases (especially carbon dioxide) from vehicles in developing countries like India is small compared to developed countries (in 1997, share of carbon dioxide from vehicles is 13% in India against 31% in U.S.A), there are serious concerns about the future trends.
From 1990 to 1997, GHG emissions from transportation sector have grown by 9 percent in U.S.A (i.e., from 23 to 31%). In developing countries like India and China, the economies and the number of vehicles are growing more rapidly and hence greenhouse gases from vehicles in these countries are forecast to overtake those from the developed countries within a fairly short period.
Essay # 2. Fuel Efficiency in Vehicles
:
Fuel efficiency has been defined as the distance traveled by vehicle per unit of fuel consumed. The unit for fuel efficiency is kilometers per litre (KMPL). Fuel economy is a key factor influencing not only the decision of the buyer in the choice of the vehicle due to obvious cost benefits, but also has obvious environmental benefits. Pollutants per km. from vehicles like CO, HC and CO2 are greatly influenced by the fuel efficiency of the vehicle, and thus, in general, the more fuel efficient a vehicle is, fewer are the emissions (except NOx).
Over the last few years, various design and technology developments in engines, vehicles, aerodynamic designs, improvements in rolling resistance etc., have enabled significant improvement in fuel economy, reduction in local emissions and greenhouse gases. Improving the quality of fuel and better roads have also contributed to improved fuel economy. Better maintenance of vehicles and better driving can significantly reduce fuel consumption and consequently CO2 emissions in vehicles.
The most important areas for improvements involve increasing the efficiency of the drive train (i.e. engine, transmission and axles) and reducing the work needed to move the vehicle (tractive effort) by reducing the rolling resistance. The variable or operating factors affecting the fuel efficiency are its maintenance, driving style, road condition, weather condition, use of air conditioner, etc.
Application of available technologies could significantly improve fuel economy in Indian vehicles. Retrofits — including turbo chargers and latest engines, radial tyres, better ignition and fuel injection systems, aerodynamic designs etc., could yield substantial fuel savings in Indian vehicles.
Essay # 3. Corporate Average Fuel Economy (CAFE) Standards
:
Enforcing fuel economy standards on vehicle manufacturers can significantly improve fuel efficiency, reduce local pollutants and greenhouse gases in vehicles. The U.S.A has mandatory fuel efficiency standards for vehicles, called Corporate Average Fuel Economy (CAFE) standards.
CAFE standards require vehicle manufacturers to maintain a minimum fleet average fuel efficiency for all the cars and the light trucks sold in a given year. It is estimated that if CAFE standards of 42 mpg are increased to 58 in U.S.A, carbon dioxide emissions are likely to reduce by about 3.8 per cent.
CAFE standards have resulted in a significant improvement in fuel economy in U.S.A. Introducing CAFE standards and tightening them is the single most important regulatory measure to improve fuel economy, oil security and for reduction of CO2 emissions in India.
Essay # 4. Vehicle Features Affecting Fuel Economy
:
Engine and transmission plays an important role in fuel economy. In transmission, gear box and the rear axle are the components which have strong influence on the fuel performance of a vehicle. Consideration of engine, gear box and rear axle independently and together is necessary to study the fuel performance of a vehicle.
Significant fuel economy improvements are possible through effective engine and transmission matching. It is necessary to select the engine, gear box and rear axle combination, such that sufficient power is available at the road wheels to provide the desired acceleration and gradability under the most efficient speed ranges of the engine.
Automotive engines have a wide speed range but, are fuel efficient only over a narrow band or range. Most of the engines used on heavy vehicles have their best fuel efficiency in the range of two-thirds of their maximum speed. It will therefore, be conducive to fuel saving if the engine could be operated in this range for maximum duration during the operation.
The gear box is a tool to transform torque and power of the engine into driving performance. For best—fuel economy, the gear box must enable the driver to keep the vehicle running such that the engine speed is in the most economic range. The rear axle transfers the power from the engine and gear box to the road wheels.
Based on the horse power of the engine, type of operation, load on the vehicle, etc.; rear axle ratios can be selected for best performance of the vehicle, including fuel performance. Most of the vehicle manufacturers offer rear axles with different axle ratios for a given engine and chassis combination. Lower the ratio, better the fuel economy, though it may result in slight sacrifice in acceleration.
Essay # 5. Rolling Resistance
of the Vehicles:
Rolling resistance is influenced by weight of the vehicle, speed, tyre construction and size, type of road surface, etc. The rolling resistance is higher at low speeds and is almost constant at the normal operating speed range.
The most effective route to better fuel economy is weight reduction. The rolling resistance is directly proportional to the weight of the vehicle. Weight reduction is possible through the use of low weight, high strength materials like reinforced plastics. An OECD study has reported a fuel saving of 5% for 100 kgs of weight reduction in cars.
While running on the road, there is deformation of the tyre at the areas of road contact. Energy is lost in the deformation of a tyre. Lesser the deformation, lesser the rolling resistance and hence better the fuel economy. In radial tyres, the arrangement of plies results in lesser deformation, lesser energy losses and hence better fuel economy.
Radial tyres fitment on the buses of State Transport undertakings in India have shown fuel savings of 4-7% compared to buses operating on bias ply tyres.
Essay # 6. Engine Design and Technology Affecting Fuel Economy
:
During about 100 years of development of internal combustion engines used on vehicles, main emphasis was on improvement of power, torque characteristics, reliability, durability, etc. For about two decades (during 1970s and 1980s), emphasis in engine development shifted to fuel economy.
After 1990s, the focus is on emissions. Electronic engine management, electronic fuel injection, increased compression- ratios, improved combustion chamber design, 4 valves per cylinder, etc.; have improved fuel efficiency and reduced emissions considerably.
Turbo-charged and inter-cooled turbo charged diesel engines have not only improved fuel economy significantly, but have also reduced pollutant emissions substantially, enabling vehicle manufacturers to meet Euro-2 and Euro-3 emission standards. About 10 percent fuel economy is possible in a turbo charged diesel engine, compared to an equivalent naturally aspirated engine.
Fuel efficiency improvements of about 8% can be obtained for every unit increase of compression-ratio in diesel vehicles. Most of the modern diesel engines with better fuel and emission characteristics are designed with compression-ratios around 22 compared to about 16 in the conventional engines. Apart from changes in engine design, higher compression ratios require better fuel. The octane and cetane number of gasoline and diesel fuels respectively can significantly affect the choice of compression ratio.
Engines with 4 valves per cylinder produces not only higher outputs and better torque, but also improves fuel efficiency by about 10% compared to a 2-valve design in internal combustion engines. The performance is better in part load conditions.
Significant improvement in fuel efficiency can be achieved through high torque engines especially while operating in frequent stop-start city operation, steep gradients, etc. According to Automotive Research Association of India (ARAI), Pune, improvement of fuel consumption upto 20% is possible by improving the torque characteristics.
Studies have shown that friction modifiers (additives in engine oils) can give additional fuel efficiency of about 3% compared to the same grade oil without friction modifiers. Engine oil viscosity is an important parameter affecting fuel economy. Studies have indicated a fuel saving of about 5% when SAE10 Engine oil was used in place of SAE30.
Essay # 7. Aero Dynamic Drag
:
Aerodynamic drag is the resistance to the motion of a vehicle offered by air. The aerodynamic drag varies as the cube of the speed of the vehicle and reaches significant proportions after 60 Kms. per hour speed. Studies have indicated that in vehicles moving at 100 Kms. per hour, half the power from the engine is accounted for overcoming aerodynamic drag.
Factors influencing aerodynamic drag includes the vehicle speed, frontal area of the vehicle and aerodynamic drag coefficient. Aerodynamic drag which depends on the frontal shape of the vehicle can be improved by adopting aerodynamic principles in designing the frontal areas of vehicles. Wind tunnels are particularly suited for systematic investigations in improving cab designs with lower coefficient of drag.
According to Waters, by developing suitable aerodynamic shape to heavy – duty trucks, fuel saving of about 10-14% was achieved in UK in the recent years. Bus body designs developed by Automotive Research Association of India (ARAI) and Central Institute of Road Transport, enabled some of the State Road Transport undertakings to achieve a fuel saving of 6.8 percent diesel.
Aerodynamic drag plays an important role in the consumption of energy in vehicles operating at high speeds on high ways. It will have very limited impact on city buses and cars operating in the city centers at slow speeds.
Essay # 8. Road Characteristics
:
If the road surface is poor, the force acting against the movement will be high, resulting in higher fuel consumption. Research studies indicate that fuel consumption increases as the roughness of the road increases. Fuel consumption on earthen roads and unpaved surface roads will be very high. Various studies have revealed that fuel economy to the extent of about 20% can be brought about by converting the unpaved roads to paved roads of a smooth nature.
Road gradient is a significant factor which affects the fuel consumption of a vehicle. The fuel consumption is greater on up gradients than on level stretches. When a vehicle operates on an up gradient, it has to overcome the natural forces of gravity. Hence steeper the upward gradient, greater is the fuel consumption. Studies indicate that 4% upward gradient roads consume 200% of the fuel consumed on plain roads.
There should be sufficient road width to accommodate traffic with required level of service. Otherwise congestion will occur resulting in loss of speed, frequent gear changes and consequent higher consumption of fuel. Studies have revealed that fuel saving of about 6% is possible by widening single lane roads to two lane roads.
Essay # 9. Driving Habits
and Fuel Economy:
Driver plays a very important role in the fuel economy of a vehicle. Studies have shown that different drivers using the same vehicle over the same road and weather conditions experience about 20 percent variation in fuel consumption. According to Petroleum Conservation Research Association (PCRA), about 15% fuel saving is possible through effective driver training.
Fuel efficiency is possible over a very narrow range of speed band of an engine. The engine can be operated in this range for maximum duration during the vehicle operation. A driver who manages to operate his vehicle in most fuel efficient speed range of the engine will consume least quantity of fuel. A fuel efficient driver through effective gear changing, speed control, etc.; will operate his vehicle, majority of the time in the fuel efficient zone.
Bad driving habits, such as improper selection of gears, frequent application of brakes, prolonged idling, over speeding, etc.; affects fuel consumption of a vehicle significantly. Sudden acceleration results in increased fuel entering the cylinder without proportionate speed increase which alters the air-fuel ratio resulting in excess fuel consumption and black smoke even in a well maintained vehicle.
The driving habits which have pronounced effect on fuel economy are:
1. Over speeding and unnecessary brake applications
2. Gear changing
3. Clutch riding
4. Unnecessary idling of the engine
5. Jack Rabbit start and racing in lower gears
6. Anticipation of Stops.
A driver must be aware of the driving habits for the best fuel economy and this is possible only if he is required to undergo a properly evaluated training and education programme. The training should include some essential elements regarding the engine performance and fuel economy under different operating conditions of the vehicle.
Studies indicate that driving characteristics have more influence on fuel economy than any other single factor. The variations in driving habits between different drivers can result in a fuel consumption variations of 15-20%. Scientifically designed training modules will be useful in upgrading driving skills for fuel economy.
Essay # 10. Vehicle Maintenance and Fuel Economy
:
A well maintained vehicle can significantly improve its fuel economy and reduce pollutant emissions. Even new vehicles with state of the art technology will deteriorate, if not maintained properly.
Recent studies conducted by Automotive Research association of India (ARAI) show that of a batch of 34 vehicles of various ages, comprising of cars, two and three wheelers, simple and relatively inexpensive maintenance action consisting of cleansing and tuning and adjusting of carburetor and ignition systems reduced HC and CO emissions by 60 percent. As a result, there was improvement in fuel consumption by 20 percent.
According to Petroleum Conservation Research Association (PCRA), a poorly maintained vehicle consumes upto 15 percent more fuel and significant improvements in fuel economy are possible through efficient fleet maintenance.
During operation, even a fairly new truck or a bus can produce poor fuel economy and higher levels of emissions if the air cleaners are dirty, if the injectors start leaking, if the injection timing is retarded or if the tyres are under inflated. Periodic inspection and effective maintenance can be one of the important strategies to achieve better fuel economy and reduced emissions. Identifying the causes that affect fuel economy and emissions is essential if the remedies are to be planned in advance.
Some of the major causes that affect diesel economy-in trucks and buses are under inflated tyres, choked air cleaners, binding brakes, improper injection timing, clutch slippage, defective injectors and fuel injection pump, diesel leakages, clogged silencer, idling of engine, lubrication of the vehicle etc. Some of the large transport undertakings in India like Andhra Pradesh and Gujrat state Transport undertakings could achieve about 20 percent improvement in diesel performance though effective fleet maintenance during 1980s.
Essay # 11. Reducing Transport Demand-Traffic and Transportation Management
:
High levels of motor vehicle ownership, sprawling land use patterns, limited and inefficient public transport service, and lower gasoline prices have been major factors in increasing vehicle kilometers traveled (VKT), and as a result increase in GHG emissions from vehicles over the last decade. Studies indicate that between 1990 and 1997, GHG emissions from vehicles in U.S.A have grown by 9 percent.
Fuel consumption and emissions are significantly higher in start-stop conditions. Vehicles under stop-start conditions use about three times more fuel and cause about three times more pollutant emissions than those in free flowing traffic. Several factors such as road activities, slow moving traffic, lack of road space, ineffective traffic control at signals, an urban infrastructure which is not suitable for motor traffic, bad road conditions etc., can create traffic congestion frequently.
Low cost traffic engineering measures such as optimization of traffic signals, better inter sections, separate bus ways, bus bays, etc. can improve traffic movement on urban roads and significantly improve fuel economy and reduce greenhouse gases.
Reducing travel demand and travel trip lengths can result in substantial fuel economy and reduced emissions. Through effective land use planning and transport policy, if people can be made to live closer to their work places by providing facilities like good educational institutions and shopping complexes in major residential areas, travel demand as well as travel distances can be cut down substantially.
In China, land use policies in the 1950s enforced juxtaposition of work places and residences, reducing demand for motorized transport and promoting the use of bicycles. This policy significantly reduces the demand for energy while reducing local, regional and greenhouse gases substantially.
Some transport modes are more energy efficient and less environmentally damaging than others. Walking and use of bicycles consume no fuel and totally emission free. Water transport and rail transport are fuel efficient and less polluting than road transport. Within road transport, buses are more fuel efficient and less polluting compared to cars, two and three wheelers for the same travel demand.
A recent study in London has indicated that CO2 emissions in grams per passenger km. varies from 89 grams/km in buses to 115 grams/km in two wheelers to 197 grams/km. in cars. A recent study indicated that the share of public transport in Delhi is about 62%, but the contribution of buses to pollution is only about 2%.
As question of energy and environment policies are playing an important role, the transport policy should put priority in integrating all modes of transport and provide incentives and priority in encouraging people to switch over to public transport in preference to personalized transport.
For this purpose, the transport policy should aim at raising the quality of public transport to high standards. “Bus-ways”, bus bays, preference for public transport at traffic signals, etc. can significantly encourage public transport usage.