Russell Bolton Assignment 3.
At the present day, pol...
these high temperatures, so catalytic converters do not work during short journeys which are common
in cities. This is the...
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Pollution Assignment July 2000

Published on: Mar 4, 2016

Transcripts - Pollution Assignment July 2000

  • 1. Russell Bolton Assignment 3. POLLUTION CONTROL OF VEHICLES DURING THE NEXT 20 YEARS. Introduction: At the present day, pollution from road vehicles has undoubtedly become a very serious problem which society in general has yet to come to terms with. This situation we find ourselves in at present has come apon us because of our over-dependence on the combustion engine and our failure to properly investigate the possibilities of alternative zero-emission propulsion systems for road vehicles. The aim of this essay is to attempt to clarify the exact nature of vehicle pollutants and explain how they effect us and our surroundings. The essay will also look at research and development in the field of vehicle pollution control, both at present and in the future. Background: Vehicle pollution is certainly not a new phenomenon, it has been present in large quantities in our streets for at least the past fifty years, basically since cars became mass-produced. On today’s roads you find both petrol and diesel powered vehicles which run on different combinations of hydrocarbon derivatives respectively. It is these hydrocarbon derivatives that when burned produce compounds which are serious pollutants. The gas CO2 is currently a big concern to ecologists as it is responsible for the so called “Greenhouse” effect. The greenhouse effect is the excess build up of CO2 in the upper atmosphere which causes unwanted radiation from the sun to be trapped within the atmosphere. Specifically, radiation from the sun shines through the atmosphere and is absorbed by the earth’s surface, however normally reflected radiation which travels back into space, is trapped by the CO2. Scientists now have evidence that in the near future this effect could cause a two degree rise in global temperature, which would effect ocean levels and induce global climatic changes. This ties into vehicle pollution because one of the products of hydrocarbon combustion is CO2, indeed over 50% of vehicle exhaust gases are CO2. A second very serious pollution problem is the formation of the oxides of nitrogen (NOx) during combustion. In the combustion engine, air and fuel are ignited by an electrical spark of very high voltage. This spark creates extremely hot conditions within the combustion chamber and causes nitrogen and oxygen from the air to combine to form oxides of nitrogen. These oxides combine with water in the upper atmosphere to form nitric acids, which fall to the earth as what we commonly call “Acid rain”. Acid rain seriously effects nature, especially vegetation. The most common example of this is the pine forests in Scandinavia where the trees are exposed to large quantities of acid rain due to winds blowing Nox from mainland Europe’s industrial areas, to Scandinavia. The trees die very quickly and whole forests have been devastated, in a similar was to which forest fires effect America. Carbon Monoxide is a potentially lethal gas if inhaled in large quantities. The gas is formed as a result of incomplete combustion within the petrol engine. High concentrations of the gas at street level can cause eye irritation and respiratory problems, especially for young children. The gas can also cause atmospheric problems as it effects the ozone layer at high altitudes by preventing the formation of ozone. Finally, the fourth main vehicle pollutant is unburned hydrocarbons which escape into the atmosphere. In the average vehicle, the most common leakage areas are the fuel tank and carboretta, but leakage also occurs in the combustion chamber itself. The hydrocarbons escape in vapour form and like carbon monoxide, can cause eye irritation at street level. However the main health risk from hydrocarbon ingestion, is cancer. Because petrol and diesel have benzene derivatives in them which are carcinigenic’s, there is a big risk to the general public especially to city dwellers. Development: In an attempt to remedy the vehicle pollution issue, car manufacturers have invested heavily in development and modern cars are now all fitted with catalytic converters. A catalytic converter is a device which uses the reactive metals (platinum, rhodium and palladium), which cover a honeycomb structure designed to maximise catalyst surface area. Converters are situated in vehicle exhaust systems and effectively oxidise gases like (Nox, CO and H.C’s) into environmentally friendlier compounds. One problem with the current catalyst technology, is that converters only operate efficiently at high temperatures (300 Celsius). Journeys of over five miles are necessary to obtain
  • 2. these high temperatures, so catalytic converters do not work during short journeys which are common in cities. This is the major flaw in converter systems today and much research is needed to improve efficiency. A very encouraging step forward was announced at the 1994 Chinese car show in Beijing (1.). Mercedes-Benz were prepared to invest up to £800 million in a new car plant producing 250,000 F.C.C’s (Family Car China) concept cars a year. The car is a squat, snub nosed prototype with an innovative design, which incorporates alternative propulsion options, such as electric or hydrogen drive. Mercedes also claim that the car has excellent efficiency, with the 1.3 litre petrol engine capable of 800km. on a single tank. However, even with the present improvements on vehicle pollution, the need to research alternative zero-emission energy sources has never been greater. Research: Looking to the future, within the next 20 years I would expect to see many more electric vehicles on British roads, due to stricter emission control limits enforced by our government. Evidence for this statement comes from looking across the Atlantic to America. In a report from the Economist (2.), directives have been drawn up by the Californian Air Resources Board “C.a.r.b”, stating that by 1998, 2% of any car makers Californian sales must be zero-emission vehicles, rising to 10% by 2007. These directives have been copied by five other American states. The penalty for non-compliance could be exclusion from the Californian new car market, which is worth over one million sales per year. No mainstream car maker could contemplate such a prospect, so all are developing electric cars to meet the deadline, despite reservations about the cost. So from taking a distant look at the situation in California, I feel confident that my prediction will be fulfilled. However, in a “EIU” report (2.), which concentrates on what it describes as the “Extreme inefficiency” of batteries as a means of storing energy , maintaining that 150 conventional lead-acid batteries, weighing several tonnes, would be needed to store the equivalent energy of a tankfull of petrol. Even the most advanced forms of battery now at the research and development stage would only improve the situation by a factor of three, according to the report. However each of these batteries suffer from technical problems and of course the very high cost. General motors are providing the most visible evidence that electric cars will be available from 1998. The company has just finished building a fleet of thirty models based on the Impact, a prototype unveiled about three years ago. The car is powered by traditional lead acid batteries and is estimated to have a range of 70 miles. Even if the regulations by “C.a.r.b” are upheld, motorists cannot be forced to by these cars which unsubsidised, could cost double that of conventional family cars. Conclusion: (3.) Looking at a report by “Delbert Borth” and his colleges at the European Pollution Association (E.P.A) back in the early 70’s, 1990 was selected as a target date, where they made predictions of threshold levels of pollutant concentrations above which they believed there were significant health risks to exposed populations. They found the worst current pollutant concentration readings and assumed a growth rate of vehicles between 1967 and 1990 that would yield more than double the automobile population by 1990. They then predicted that the worst pollution concentrations would more than double by 1990, which was a very accurate estimation. A rollback model was then applied to determine the extent to which automobile emissions would have to be reduced so as to reduce pollution concentrations below threshold levels. Whether or not this rollback model has been satisfied is debatable, but one point certain, if this model was used similarly to estimate the extent to which automobile emissions would have to be reduced, I am sure it would become clear just how far we are behind the problem of vehicle pollution control. (1.) Tony Walker,” Designers stress their proletarian credentials”, Financial Times, 23 NOV 94. (2.) John Griffiths,”Power to the petrol-John Griffiths finds battery cars cannot keep up”, Financial Times, Page 14, 05 OCT 94. (3.) Edwin S. Mills and Lawrence J. White, “Government policies towards Automobile Emissions Control”, “Approaches to controlling air Pollution”, Page353,1978.

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