It is a well known fact that a major contribution to pollution is the use of automobiles which are powered by internal combustion engines, running on either petrol or diesel.

When such fuels are burned by the engine they emit certain toxic gases which harm the environment, and are also a detriment to the public health. Such gases include carbon and sulphur-based gases.

Since the inception of the motor car, around a century ago, people from all corners of the world found this means of transportation quite attractive and comfortable in their daily lives.

Most people are not ready to relinquish the use of their car and the majority prefer to use this form of transportation to any other. On the other hand more people are becoming conscious of the health hazards and environmental threats from the gases emitted from internal combustion engines.

With the continuous steep increase in the number of cars on the roads, the amount of toxic gases produced is proportionally augmented. If this trend continues in the future, the use of cars, beyond any reasonable doubt, would be environmentally unsustainable.

Therefore, world-wide car manufacturers are doing their utmost to develop new models of automobiles which utilise alternative fuels, offer the same performance to motorists, and with a price which is competitive to the classical models of propulsion. Several legislators around the world are also encouraging the use of these new forms of green transportation.

There are several methods of propulsion which can substitute an internal combustion engine. These include the Electric Vehicle (EV), Hybrid Electric Vehicle (HEV), and Hydrogen Powered Vehicle (HPV). The EV and HPV are also referred to as Zero-Emission Vehicle (ZEV), as they do not emit any gases.

The EV is one form of green transportation which drew a lot of attention during the last years. The main source of energy is derived from the batteries installed inside the car.

The battery pack is then charged at home during the night or at some specific charging stations that charges the automobile when it is parked. The power to drive the car is obtained by means of an electric motor and its associated power-electronic converter.

The electricity which is used to charge the batteries of the electric car is often derived from the power stations that burn fossil fuel as their primary source of energy.

Although such power plants do emit toxic gases, the quantities that they emit are obviously less than the cumulative sum of all individual automobiles running on either petrol or diesel.

Also the efficiencies of power plants are higher than that of the individual vehicle, while the gases within a power plant are much more controllable than those emitted haphazardly in the streets by vehicles.

To further enhance the respect for the environment in some cases the trend is to have an electric charger that derives energy from renewable energy sources, which include wind energy, solar energy or hydropower.

This offers the advantage of having a free source of energy with absolutely no emissions, while reducing the dependence on fossil fuel.

The implementation of the electric car offers a number of technical challenges. Perhaps the biggest hurdle is in the storage system and normally batteries which are connected in a pack are employed.

The most common type used is the lead-acid battery. Nickel-cadmium batteries are a better improved form for the storage of energy, while new technologies are based on Lithium-Ion.

Such batteries have a limited storage of energy, and the range of the distance that can be accomplished from a single charge is somehow limited.

Presently a lot of research is being carried out in order to develop batteries which can store much more energy and are much more efficient. It has to be said that the performance of the electric car and the development of the market is very much hindered by the battery technology.

In the future it is expected that a new generation of batteries with better storage and performance would be available on the market greatly improving the electric vehicle's performance. Reducing the weight of the battery pack is another objective which researchers aim to achieve.

With an electric car the braking system is slightly different. In the normal petrol or diesel automobile, the car is brought to a standstill by the use of friction in the braking mechanism.

This is somehow a waste of energy, and in the electric vehicle braking is effected by running the driving motor as a generator and the energy is stored back in the batteries. This is technically called regenerative breaking.

Another version is the Hybrid Electric Vehicle. This is composed of an electric car as described above, with the addition of a small internal combustion engine, running on petrol.

The rating of this engine is much smaller than those which are normally installed, to propel a car. Under normal circumstances this engine is not started but is only used to charge the batteries when the batteries become discharged and the car is away from the charging station.

Thus, this engine would power the alternator that charges the batteries in order to have enough energy to arrive at the charging station. This type of propulsion is becoming quite an alternative until a better method of energy storage than batteries is discovered.

Hydrogen Power Vehicles are also another form of cars which are termed as 'clean'. The main driving force is the same as in the case of the electric car, that is an electric motor.

Instead of the batteries they have a fuel cell and some storage for hydrogen gas. HPVs do not require any charging but they are filled with hydrogen gas.

In principle the hydrogen is combined with the oxygen (which is available freely in the air) in order to form electrical energy and water. The electrical energy is then used to power the drive motor of the car.

In this case there are no emissions and this makes the car environmentally compatible. The only by-product is water. Hydrogen could easily be obtained from filling stations, and can also be derived from renewable energy resources, which makes this kind of transportation emission-free.

Besides, being environment-friendly these vehicles are much more silent than conventional cars. It is also noted that the electric motor is only active when the car is in motion.

When the cars are at a standstill, say in a traffic jam, or at the junction controlled by traffic lights the motor is switched off. This indirectly helps to reduce the noise pollution on the roads and increase in efficiency.

Green transportation is also becoming more popular for use in public transportation networks. Since the traffic within a city centre tends to move slower than other areas, the pollution created as a result of the emissions become notably high.

Therefore many cities together with manufacturers of buses are investigating ways by which zero-emission vehicles would be introduced for public transport applications.

Several global leading car manufacturers have released some version of the electric/hybrid/hydrogen power car in recent years. Several models ranging from the small family car to large vehicles and even buses have been considered.

It is estimated that 60 per cent of the world's green fleet vehicles are found in Europe. Some of these are vehicles whose engines have been converted to run on electricity instead of petroleum fuel.

The European market is starting to develop mainly in Germany and France. Japan dominates the non-European market. Market potential is primarily dependent on more stringent pollution laws.

The laws which were introduced in California aim for green transportation to make up 10 per cent of all passenger cars.

The European Association of Electric Road Vehicles, AVERE, was founded in 1978 as a European network of industrial manufacturers and suppliers for electric vehicles.

It is a non-profit organisation, incorporated under the aegis of the European Community. AVERE specifies that in most cases mass-produced electric vehicles have a range of around 80 to 100 km per single charge.

It also quotes that presently on average an electric car can make around 100 km with 1 Euro worth of charge. This is one of the biggest advantages when compared with cars running on fossil fuels.

AVERE says that such cars require almost zero maintenance and the motor has an infinite lifetime. However, the batteries need to be changed every three to five years.

The first mass production electric vehicle was launched in 1995 and since then several models were produced. In the year 2000 over 16,000 electric vehicles were produced in Europe.

Considering the number of cars presently running on fossil fuel, the number of electric cars is still minute. However, AVERE is confident that in future the number of alternative vehicles is set to increase once more people become aware of the benefits associated with choosing this new kind of transportation.

eMobile, the Swiss Association of Electric and Efficient Vehicles, took several initiatives in collaboration with several Swiss cantons to promote the use of green transportation in Switzerland.

eMobile reports that the Zurich police, for example, are using a three-wheeler electric vehicle to patrol the parks on the shore of the lake without annoying pedestrians with noise and fumes.

The Electric Vehicles Association of America, EVAA, aims to promote green transportation in the United States and in Latin America, while it helps to disseminate information on this subject.

Last February, the US Senate approved the Energy Tax Incentives Act, which among other things extends the present fiscal incentives for electric and hybrid cars till December 31, 2006, and till December 31, 2011 for fuel cell cars. This was overwhelmingly welcomed by the EVAA, which hopes that by these incentives the number of green cars would rise.

Considering that Malta is a small island and that distances are relatively short when compared to other countries, the idea of using such an environment-friendly form of transportation should be quite attractive.

The fact that the government reduced the importation tax on electric vehicles is a positive step to favour the diffusion of such means of transportation.

However, to date no electric vehicle has appeared on the Maltese roads, and car importers still prefer to sell their classical models which burn fossil fuel.

Although the importation tax is lower for electric cars, the initial car price is more expensive than the competition, and therefore there is the need for further incentives in order to encourage the use of environment-friendly means of transport.

Such incentives could for example, offer free-privileged parking spaces with charging facilities for electric cars, reduction in the yearly licences and insurance premium subsidies, among other things.

The use of alternative power for public transportation should be seriously considered in Malta, if the present buses are replaced.

Nevertheless, the success of green transportation will certainly depend on its diffusion and popularity. The technology of green transportation is already at hand and given the right conditions and promotion, in future its use would certainly increase.

The benefits of using this means of transportation, which is compatible with the environment, would thus be harvested. It is then that people can enjoy a better and healthier environment with less noise, while most cities would certainly be cleaner.

Dr Richard Blundell, B. Eng. (Hons.), Ph.D., can be reached by e-mail at blundell@iee.org

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