102Vehicle Pollution the Effects

Before we look at solving environmental problems it is worth pausing to look at precisely what environmental problems are caused by vehicles.

Electric Vehicle Technology Explained James Larminie and John Lowry © 2003 John Wiley & Sons, Ltd ISBN: 0-470-85163-5

There are two main problems caused by conventional vehicles. Firstly they ruin the immediate environment with noise and pollutants. Secondly they burn irreplaceable fossil fuels producing carbon dioxide which is a major cause of global warming and climate change.

You do not need to be a scientist or engineer to understand that motor cars spoil the immediate environment. You simply need to walk along a busy street or sit at a roadside cafe. The motor vehicle has emerged over a century and we simply accept it as a fact of life. Normally when people who live in the country come to a big city they find both the noise and the fumes quite unacceptable.

The health hazards associated with motor vehicle exhausts are particularly worrying. If you place a stationary diesel engine with the exhaust near a wall, the wall very quickly turns black with what can loosely be described as soot. Again you do not need to be a medical scientist to realise the effect that this might have on your lungs. You would need to smoke a lot of cigarettes to get the same level of deposit, and we all know the health effects of tobacco smoke. Although you do not have to stand behind diesel exhausts, you are bound to inhale a fair amount walking along a busy street and crossing the road, which often involves passing directly through vehicle exhaust.

Accepted health problems associated with car exhausts makes depressing reading and one has to wonder why society keeps quite happily emitting these substances.

The major internal combustion engine pollutants include carbon dioxide, carbon monoxide, nitrous oxides, volatile organic compounds (VOCs), particulate matter, and sulphur dioxide.

Carbon monoxide inhibits the ability of the blood to carry oxygen, and in particular is dangerous to smokers and people with heart disease. It can also cause permanent damage to the nervous system.

Nitrous oxides (NOx) exacerbate asthma, affect the lungs and increase the susceptibility of young children and the elderly to respiratory infections. In the presence of VOCs and sunlight NOx reacts to produce ground level ozone. This in turn irritates the eyes, damages the lungs and causes respiratory problems. NOx contributes to the formation of acid rain whose acidity kills plants and fish. Benzene, a known carcinogen, is an example of a toxic VOC found in vehicle exhaust.

Particulate matter (PM) causes lung problems including shortage of breath, worsens cardiovascular disease, damages lung tissue and causes cancer. Ultra-fine PM makes its way past the upper airway and penetrates the deepest tissue of the lungs and thence to the blood stream. At concentrations above 5 micrograms per cubic metre particulate matter presents a significant cancer risk. Many PMs are recognised as toxicants and carcinogens, as well as hazards to the reproductive and endocrine systems.

New discoveries on the risks of cancer from exhaust fumes continue to emerge. Researchers in Japan have apparently isolated a compound called 3-nitrobenzanthone which is a highly potent mutagen.

Clearly this is cause for alarm. It must also be remembered that new research is constantly emerging and the overall picture may well be extremely grim. Certainly there have been large rises in asthma, many allergies and cancers that may well be linked to exhaust fumes.

The effect of carbon dioxide on the planet is another cause for alarm. The greenhouse effect of carbon dioxide is now well known. Basically, some of the short-wave radiation from the sun is absorbed by the earth and then re-emitted at a longer wavelength. This is absorbed by carbon dioxide and other gases and then re-emitted, the downward radiation warming the surface of the earth. The atmospheric concentration of carbon dioxide has increased by about 25% over the past 100 years.

Although a warmer earth may sound appealing to those living in cold climates, there are side effects which could prove absolutely devastating. Firstly the earth relies on a reasonably set weather pattern for growing food. A change of climate in the grain growing belt of America, for example, could itself have serious consequences on food supply. Secondly the 'warm up' is melting the polar ice caps and this could cause permanent flooding in low-lying areas. Bearing in mind that many major cities, London, New York, Barcelona, San Francisco, Perth (Australia) and scores of others, are built on the coast, this could have very serious repercussions throughout the world.

One significant problem with internal combustion engine vehicles in slow traffic is that fuel consumption rises very dramatically as vehicles crawl along at slow speeds and pollution gets considerably worse. This is illustrated in Figure 10.1. With electric vehicles there will be a small decrease in efficiency of the electric motor when used at low speeds but the efficiency of batteries such as lead acid increases resulting in a fairly steady efficiency across the speed range. In cities such as London and Tokyo the average speeds are normally less than 15 kph and in rush hour are considerably less.

The simplest way of eliminating these problems from town and city streets is to enforce zero emission vehicles into the towns and cities by legislation or other means.


Figure 10.1 Indicative energy use for IC engine and battery powered cars. Obviously the precise figures vary very greatly with size and design of vehicle. These figures are not the whole well-to-wheel energy figures, but just the tank-to-wheel or battery-to-wheel figures


Figure 10.1 Indicative energy use for IC engine and battery powered cars. Obviously the precise figures vary very greatly with size and design of vehicle. These figures are not the whole well-to-wheel energy figures, but just the tank-to-wheel or battery-to-wheel figures

Conventional internal combustion vehicles ruin the environment in their vicinity particularly in towns and cities.

The simplest way of creating zero emission vehicles is to adopt electric vehicles, or at least hybrid vehicles which solely run on electricity when in the town and city environment. However, the total pollution impact of vehicles and their energy use cannot be ignored, and this we consider in the next section.

Electric Car Craze

Electric Car Craze

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