Electric vehicles were among the first cars developed at the beginning of this century and they may yet predominate in the next one.
Although car manufacturers have had alternative vehicle programmes since the 1960s, EVs have taken a back seat to the internal combustion engine. But with today’s technology driven by energy, environment and economy, electric vehicles look set to move to the fore.
However, this may not be in their most familiar form, the battery-powered car. Batteries have advanced from the basic lead-acid, which is still the cheapest technology, working out at about 3p/mile, to the more expensive nickel metal hydride and lithium-ion which store at least twice as much energy as lead acid.
But despite developments such as fast charging, battery powered vehicles still suffer from limited range and performance.
More promising is a hybrid of internal combustion and electric power. The Toyota Prius, launched in Japan last year, uses an electric motor to start and when driving at low speeds. But for motorway driving the petrol engine and electric motor are engineered to work in the most fuel-efficient combination. Compared with other family saloons, says Toyota, the Prius has double the fuel economy (28km/l about 78mpg) and its exhaust emissions are only a tenth of the legal limit in Japan.
But many industry experts agree that the rapidly approaching availability of hydrogen fuel cell technology will give electric cars a big boost and could ultimately put the internal combustion engine out of operation in the 21st century.
‘Fuel cells will give you an electric vehicle with the same range as a gasoline internal combustion engine but with zero emissions,’ says Neil Otto, president of Ballard Automotive, which is developing fuel cell technology in an alliance formed last December with Ford of the US and Daimler-Benz of Germany. The aim is to commercialise the technology by 2004, the year in which General Motors is also planning to bring its rival fuel cell vehicle to the market.
Ford and Daimler-Benz have invested $1bn in the project, which has the support of oil giants Shell and Mobil. The oil firms are working on a processor to convert petrol or diesel to hydrogen. This would eliminate the need for a new infrastructure to support electric vehicles a key block to their commercialisation.
Fuel cell technology was first developed to supply electricity on spacecraft. It works by combining hydrogen and oxygen electrochemically to form water, in a process which is essentially the reverse of electrolysis, giving off heat and electricity which powers the car.
The cells do not have the limited range of batteries. ‘A fuel cell is an energy conversion device so, unlike a battery, it can continue to supply electricity as long as you put fuel in it,’ says Ron Sims, a specialist in energy storage and fuel cells at Ford’s US Research Laboratory.
Hydrogen can be supplied as the pure gas but it can also be obtained from fuels such as methanol, which could be supplied from existing filling station networks. Daimler-Benz and manufacturers such as Toyota have developed on-board fuel processing systems, or ‘reformers’, which produce hydrogen from liquid fuels. However, an environmental drawback with this technology is that carbon dioxide is a by-product.
‘If you fuel the cell with hydrogen the only by-products are electricity and water,’ says Sims. However, while the production of hydrogen is not entirely emission-free, fuel cells offer the prospect of zero emissions, Sims adds: ‘With the possibility of producing hydrogen by electrolysing water using electricity generated from renewable energy sources such as wind, solar or wave power, you have a truly zero-emission vehicle.’
Major difficulties will have to be overcome to make fuel cell cars a commercial reality. Storing hydrogen on board tends to be difficult due to its volume and the need for a pressurised cylinder. Then there is the size of the fuel cell. Because of the size of the stack, manufacturers have concentrated on putting them into larger vehicles. There are a number of fuel-cell powered buses and British company Zevco, the Zero-Emission Vehicle Company, this year launched a hydrogen fuel cell taxi.
Daimler-Benz’s first prototype, Necar, was a Mercedes van in which the fuel cell took up the entire load carrying area. The company has now developed a fuel-cell version of the Mercedes A-class, Necar 3, in which the fuel cell stack sits in the sandwich platform beneath the passenger cell. Nonetheless, the methanol reformer still takes up the rear seat and the luggage compartment.
There are big challenges to be overcome in making the technology affordable. Even with volume production, Sims estimates a cost of $300/kW nearly 10 times the present cost of an internal combustion engine at $35 40/kW.
In the short term, Sims envisages that fuel cell vehicles with on-board reformers will be first on the market ‘to get customers used to fuel cells’. In time, a hydrogen supply infrastructure could be put in place. He also expects more compromise and collaboration between the various technologies. For example, the high costs of fuel cells could be reduced initially by supplementing the technology with battery power, as in the Zevco taxi.
The Ford/Daimler-Benz/Ballard alliance is not alone in the race to commercialise fuel cells. General Motors is working with oil firms Arco and Exxon to develop an on-board fuel processor. And more and more manufacturers are incorporating them into their new vehicle plans.
‘It’s going to a long, hard, steady challenging time for us,’ says Sims, ‘but we’re going to do our best to make it happen in the next decade.’