Unplugged, and ready to roll

If the phrase "electric cars", makes you think of childhood Scalextric, shame on you. With growing environmental concern over vehicle pollution in our gridlocked cities, dwindling deposits of easily-recoverable petroleum, and toughening legislative attitudes towards car emissions, large sums are currently being invested to try and find an alternative to the internal combustion engine. Its abbreviation may be "ICE" but it is no longer cool.

The effort to make electric vehicles (EVs) the white knights of the 21st century roads has been spurred by American legislation, most notably California's deadline of 2003 for 10 per cent of vehicles in the state to be zero-emission - and that's going to be an estimated 100,000 electric cars, since only EVs will meet the strict rules on emissions. New York and Mass-achusetts are other states with zero emission mandates. The European climate, too, is changing, though there has not yet been much legal bite to go with the worthy discussions of the benefits of cutting pollution levels in Europe's cities, which are frequently higher than US black spots such as Los Angeles. Some countries, however - notably Switzerland and France - are pursuing active policies of encouraging people to switch to EVs in the form of both subsidies to car buyers and tax benefits to owners.

Electric cars, then, are definitely part of the future of motoring, and the major car manufacturers are well advanced in their efforts to produce economically-viable EVs. BMW, Toyota, Volkswagen, Peugeot, General Motors, Citroen, Renault, Mercedes, Volvo and Fiat already boast various electric prototypes and hefty bills for research - BMW alone spent more than pounds 330m developing sodium-sulphur batteries for its El prototype, while Volkswagen spent a similar sum in partnership with battery giants Varta for a nickel-potassium hydroxide effort that combined electric power with liquid fuel to create a hybrid-electric vehicle (HEV).

Generating the electricity to power EVs is all about chemistry. Though the basic principle of the various batteries is the same - cells with two electrodes are immersed in a conducting medium that allows internally stored chemical energy to be converted into current - many different combinations of substances can create the necessary flow of electrons between the two electrodes. The aim is to find the pairing that achieves an optimum blend of factors for the ideal EV battery. These involve specific energy (energy stored per kilogram of battery); energy density (energy per unit of volume); specific power (how fast the energy can be released); charging time; life time; and cost per kilowatt-hour of the energy in the battery. Other considerations include ease of recycling, reliability and the ability to work in temperatures ranging from summer heat to winter cold.

The particular beauty of petrol is its high energy content - a normal tankful contains around 100 times more energy than an equal mass of lead-acid batteries, for example. But batteries based on other combinations are beginning to turn in performance figures in trials that look set to help swing the pendulum towards EVs.

In particular, the success of a zinc-air battery developed by the Jerusalem-based company Electric Fuels has finally persuaded one major European fleet owner, Germany's postal operator Deutsche Post, to take the lead in converting to the electric cause. Trials over the past two years, using Mercedes 410E delivery vehicles powered by the Israeli battery, have seen the new technology pass every test demanded of it with flying colours.

Tests involved 40 vans, and a typical task had them carry a full load the 425km between Bremen and Bonn without refuelling. Not only did the adapted Mercedes vans manage the journey - which is three times the range of most rival batteries - but they also coped perfectly with driving conditions that ranged from steep hills to congested town traffic, while managing top speeds of 120kph (around 70mph). Test drives across the Alps also proved the adapted vehicles capable of coping with temperatures well below freezing. Adding icing to the cake is the fact that the batteries are more powerful than rivals and much lighter (a sixth of the weight of an equally powerful lead-acid battery), while offering all the benefits of zero emission and easy recycling. The final flourish is ease of refuelling - when exhausted, all you do is swap the used zinc-anode cassettes for a fresh set, a process that takes around five minutes.

Against critics who carp about the higher cost per kilometre - at present, a zinc-air van comes in at DM1.40 per km compared to around DM0.45 for a diesel version - Deutsche Post point out that the comparison is unfair, since the figure for the electric Merc is based on individually-adapted vans (single-piece production) as opposed to mass-produced diesel versions. With Deutsche Post planning to replace up to 15,000 vehicles in its fleet with electric versions, the costs per van will drop considerably, while diesel costs are projected to rise. On cost terms, the gap will narrow significantly. Combined with the environmental benefits, Deutsche Post has given the go ahead to the phasing in of the new vehicles. Other German companies, such as Deutsche Telekom, have said they will now also consider making the switch.

General Motors, meanwhile, have taken a lead in the passenger car market, by putting their lead-acid powered EV1 Saturn on sale in the United States. Though performance figures place it neck and neck with conventional rivals in terms of 0-60mph acceleration, the car is tempered by some negative factors. Recharging from home by plugging the car into the mains takes about 3 hours, though GM have emphasised that consumers in the car's trials preferred this way of refuelling to having to visit a petrol station, particularly late at night or in bad weather. A limited driving range of between 70 and 90 miles per charge is also a drawback, though again GM point out that its affluent target market would be more likely to use the car for urban commuting rather than cruising down the interstate. Federal and state financial incentives for EV users help sugar the pill.

In Europe, too, authorities are acting to encourage the use of EVs. In France, for example, purchasers of Peugeot's electric version of its 106 - Europe's first fully commercial passenger EV - are offered a cash grant of 5,000FF from France's electricity authority (Peugeot collect 10,000FF per car) to help boost the initially low volume of sales often experienced by new technology products. So far, there have been around 1,000 takers at the 150,000FF price for the car and its nickel-cadmium battery pack, which comes with an eight-year battery life before needing to be recycled. Performance figures - 50 mile range per charge, 56mph top speed and 0-31mph in 8.1 seconds - put the Peugeot 106 firmly in the town traffic class. Full recharging from a home 13 amp socket is six hours, though a one-hour zap will give you 13 miles of travel. Cost, however, is impressively low, with the six hours full charge time coming in at just under 40 pence.

The weighing up of cost and pollution benefits against price and performance is a common factor with the first clutch of EVs to hit the forecourts. Toyota's electric RAV4 4x4 (currently only available on Jersey for hire) comes with a price tag of pounds 50,000, but spokesman James Thomas points out that it is just a first toe in the commercial water for the company. "The RAV is a bit of a gimmick," he admits, "but we have to start somewhere." Toyota's main thrust into the emerging low-emission market will actually be a hybrid EV scheduled to go on sale in Japan at the end of 1997 at a price comparable to conventional models.

The rush to get a foothold in the emerging EV market has, however, led many of the leading manufacturers to opt for established battery technologies - such as lead-acid and nickel-cadmium - that are perhaps not really the best bets in the longer term. According to Tony Bosworth, head of Friends of the Earth's transport campaign, "only zinc-air seems certain to reach the long-term goals for specific energy requirements" for EVs that can truly match or better conventional vehicles, as the Deutsche Post tests with Mercedes seem to show. Of the other existing technologies, nickel- hydride is also promising, and is the battery chosen by Honda for an EV that goes on sale in California later this year, which is capable of 125 miles per charge. This car, moreover, will be an all-new design rather than an adaptation of an existing vehicle, something many proponents of EVs say will be necessary to get the best out of electric power. Honda's Japanese rivals Nissan are, meanwhile, embracing lithium ion batteries in a jump into new technology that will bear fruit when the Prairie Joy goes on sale in Japan later this year. The benefits of pure EVs to the lungs are undeniable, but many experts believe that it will be hybrid EVs (HEVs) that will actually make a real mark on the market, at least initially.

HEVs aim to combine the power-density benefits of liquid fuel with the zero-emission character of electric power. In an HEV, battery range is less important due to the presence of a conventional engine - the battery is there to deliver high pulses of power for things like acceleration and also to capture energy when the car is breaking (which the con- ventional engine cannot do). A number of companies are developing HEVs, with much of the work going on under America's PNGV programme (Partnership for the Next Generation of Vehicle) which has brought the US government together with manufacturers. The aim of PNGV is a mid- size sedan capable of 80 miles per gallon which, thanks to its EV component, is also a green machine - the type of car experts such as Mike Ristic of London's Imperial College believe will provide "an acceptable compromise between the emissions and the general acceptability of the vehicle".

As in many things in life, you pays your money and takes your choice. Should EVs ever sweep the world, they may pose one unexpected hazard: so quiet are they that pedestrians may not hear them coming. Will the "audible pedestrian warning signal" fitted by GM to its pioneering EV1 become a bane of urban motoring similar to present-day car alarms? Look, listen, breathe - then make your choice. !