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ELECTROMOBILE—TO BE OR NOT TO BE

There are now more than 200 million automobiles on the roads of the world, and the number is growing. The tremendous number of cars makes air pol­lution, especially in the big cities, a real problem. This is one of the reasons why people are talking about eliminating the internal combustion engine altogether as soon as possible or at least reducing exhaust fumes.

So far, years of research have come up with little— searches for new types of engines and new fuels have not pro­duced any basic solutions. True, using a gas fuel (propane-butane) instead of gasoline does cut the carbon dioxide con­tent in the exhaust fumes from 10 to 25 per cent of what it was, as well as the percentage of nitrogen oxides and hy­drocarbons, but the idea has not really caught on yet, although Russia has tens of thousands of cars that run on a gas fuel.

Born Last Century. As a substitute, the electromobile— an essentially new type of a vehicle with an electric engine has drawn the attention of engineers. A very curious thing is that the progress of automobile transport in general was triggered by the electromobile, since the few steam-engined vehicles of the time were far too heavy and cumbersome. Beginning with the 1880s, following some real steps forward in electrical engineering and electrochemistry, quite a few vehicles with an electric engine ranging 3-3.5 hp, with an average speed of 10-15 kmph and an operational time of six hours were developed in several countries.

A rather good design was produced in Russia in 1899 by I. Romanov, an electrical mechanic who exhibited his elec­tromobile in Petersburg. This 720 kg electrically driven ve­hicle could reach a speed of 35 kmph and had a range of about 50 km. Heavy duty electrical buses for municipal transport were developed in Paris, London and elsewhere.

The development of a light-weight internal combustion engine sent the idea of the electromobile almost into obliv­ion, where it stayed for almost 80 years. But now the idea has made a big comeback—electric transport vehicles are becoming increasingly popular alongside the electrically driven loaders and lifters that are widely used in industry. The electromobile has a lot of advantages—non-toxic, non-explosive, practically noiseless and easy to control. But the electromobiles that are around now have disadvantages that actually cancel out the good points.

Power Sources. The basic hitch with today's electromo­bile is its limited range and excessive weight, coupled with the short life and high cost of the power source. The problem lies with the lead-acid accumulator now being produced and used, so researchers and designers are concentrating on im­proving the kind of electric cells we have, and on more ef­fective power sources.

The big job is to increase power capacity per unit of mass. In a lead-acid accumulator this figure is approximately 22 watt/hour per kg of mass, with top models being perhaps 33 watt/hour per kg of mass. The power capacity of gaso­line will reach about 11,000 watt/hour per kg of mass. So the conventional car with a 40-60 kg fuel tank can cover 400-600 km at a speed of 80-100 kmph, while an electromo­bile with a 15 kW engine (20 hp) and a battery of lead ac­cumulators weighing 300-400 kg can cover (without recharg­ing) 60-80 km at a speed of 40-60 km per hour. The electro-mobile would need a battery of 1,200-1,500 kg for a 400 km run, and that, needless to say, would be absolutely impracticable, since all its power would be expended just to move its own weight.

There are designs that will help overcome the problem of the time lost in recharging the accumulators, things like replacing the used-out battery in 10-15 min. Another drawback of lead accumulators is that they are quite expensive; one other drawback is that they have a short life relative to the number of rechargings. So it ends up that the cost of the accumulator in many of the electro-mobiles we now have is approximately half the cost of the entire vehicle, and its service life is 300-500 rechargings, equivalent to just 12-18 months of normal operation.

All kinds of other accumulator cells have been developed, with the best, in the weight sense at least, being the sodium sulphur battery, whose power capacity is five times greater than that of a lead battery. The problem is that its service life is one-tenth as long.

Despite the difficulties, there is more and more research being done on the electromobile.

The forecast that the first electro-mobiles would be one or two passenger vehicles, turned out to be wrong because of the inadequate battery power capacity. It is estimated by some that there are approximately 100,000-110,000 electro-mobiles now being used around the world; most are vans, although light passenger electro-mobiles have been recently exhibited in several countries.

One way to get around the problem of the battery power inadequacy is the hybrid vehicle—a small internal combustion engine coupled with an accumulator power source. The in­ternal combustion engine is used only outside residential areas to recharge the battery or as a simultaneous source of power. The range of this kind of vehicle is a lot greater. A recent model with a combined power plant used on the RAF van gets 80 km per hour and can cover up to 300 km without recharging.

But being realistic, the electromobile seems gradually to become the dominant mode of municipal transport (both passenger and goods) alongside conventional mass transit systems based on the tram, the trolleybus and the underground. But it is still a long way to go, and a lot of research and development will be needed before this actually happens.