New battery technologies and electric "refuelling" options offer some hope of getting around this problem.
Lead acid batteries the type used for years to power the starter, lights and accessories in gas-powered cars are just too heavy to be suitable for electric cars designed for long-distance travel, says Michael Bergeron, vice-president of engineering at Zenn Motor Co., a Toronto maker of low-speed electric cars for city use.
Zenn uses lead-acid batteries in its Low Speed Vehicle, which is available in Quebec where it may be driven on roads with speed limits of 50 kilometres per hour or less (so far no other Canadian province has approved its sale), and through about 25 retailers in several U.S. states, but Bergeron says lead-acid batteries needed to support highway speeds and distances would weigh too much.
That's why Zenn has a 3.8 per cent stake in EEStor Inc., a secretive Cedar Park, Tex., company trying to develop battery alternatives using ultracapacitors. Traditional capacitors can store small amounts of energy one of their uses is maintaining power in battery-powered devices while batteries are changed but not enough to compete with batteries. Ultracapacitors store much more energy, and can be recharged more times than batteries before wearing out.
Zenn hopes to use ultracapacitors from EEStor in a future product called the CityZenn that would have a 400-kilometre range and a 125-kilometre-per-hour top speed.
But while EEStor says it has made some progress, prompting Zenn recently to announce plans to increase its stake in the company to between 6.2 and 10.5 per cent, it doesn't have a commercial product yet, and no public independent tests have verified its claims about its technology.
An alternative technology getting attention today is the lithium ion battery, a technology increasingly common in cellphones and computers.
Tesla Motors Inc. of San Carlos, Calif., chose lithium ion for its Roadster, a $109,000 electric sports car that can run about 400 kilometres on a charge and has a top speed of a sizzling 200 kilometres per hour.
Lithium ion technology has the best combination of density and cycle time, says Michael van der Sande, Tesla's senior vice-president of sales, service and marketing. This means it delivers the most power for its weight and is reasonably quick to charge.
A selection of all-electric cars:
Up to 400 km on a full charge.
Top speed of 185 km/h.
Battery uses ferrous ion.
For sale in China in late 2009.
Citroën C1 ev'ie
Up to 112 km on six-hour charge.
Top speed of 95 km/h.
Adapted by new U.K. company Electric Car Corp.
Not for sale; Only for use in trial by 500 members of public.
Mistubishi I MiEV
160 km on single charge.
Top speed of 130 km/h.
To be released in Japan in mid 2009.
Nissan Electric Car
Up to 100 km on single charge.
Top speed of 122 km/h.
Release set for 2010 in the U.S.
Up to 390 km per charge.
Top speed of 200 km/h.
Costs $109,000 U.S.
For a list of upcoming electric and hybrid vehicles, visit the Electric Drive Transportation Association's website.
Skeptics argue that a problem with this technology is the limited global supply of lithium with which to make the batteries (a U.S. Geological Survey report in 2006 put the known world reserves at about 11 million tonnes). So electric cars powered by lithium ion batteries risk trading one non-renewable resource, oil, for another.
Van der Sande shrugs off these worries, saying that a lithium ion battery actually uses very little lithium. "We don't expect any shortage," he says.
A lithium ion battery can be recharged about 500 times before wearing out, van der Sande adds.
How often batteries need replacing will affect not only the cost of owning an electric car the cost of the battery today is roughly the same as the cost of the rest of the car, says Dave Pascoe, vice-president of e-car systems at Toronto auto parts maker Magna International Inc. but also its environmental friendliness and convenience.
The cost of batteries is a major problem, though it can be reduced eventually, Pascoe says. He said he expects a 20 per cent reduction is possible within five years, but he adds that it will probably take about an 80 per cent reduction in battery costs to make electric cars attractive to mainstream consumers.
Better Place has another idea.
Instead of making batteries that last for long distances, the Palo Alto, Calif., company wants to separate ownership of batteries from ownership of electric cars and provide different options for electric-car drivers to fill up with volts.
"We provide kilometres the same way that Rogers would provide minutes to your cellphone," says the head of global development for Better Place, Sean Harrington.
Better Place customers will be able to recharge their car batteries by plugging them in at home or at a network of public charging spots in parking garages and other locations. That approach to juicing up a car's batteries will work much of the time for instance, for commuters who need an overnight charge capable of taking them 50 to 100 kilometres each day. But for longer trips, Better Place has developed a battery-switching system that can pull the depleted battery out of an electric car and replace it with a fully charged one in about a minute.
To make this marketable, Better Place, rather than the car owner, will own the batteries. When you buy an electric car, Harrington says, you'll sign up for a plan that allows a certain amount of driving per month possibly with some averaging allowed between months much as a cellphone plan gives you a maximum number of minutes. There will be no initial fee or added charges, he says.
Harrington also says Better Place will be able to manage the way its customer recharge their vehicles, thus using electricity more efficiently and reducing the impact of electric cars on the power grid.
This brings up another concern about electric cars. Supposing they do become commonplace, how would thousands of people plugging in their cars affect the demand for electricity?
Ontario Power Generation is seeking to answer that question. The government agency responsible for power generation in the province will soon complete the first phase of its research on how power generation and distribution will need to change if electric cars go mainstream.
The first goal is to identify gaps in the infrastructure, says Cara Clairman, vice-president of sustainable development for Ontario Power Generation. The second phase will be to study those gaps further and look for ways to close them. The agency is working with a number of university researchers and plans its first conference on the topic in Toronto in November.
Even supposing batteries eventually supplant the internal combustion engine, one big question remains: Will the environment actually benefit?
Electricity must be generated before it can be used. In the United States, 70 per cent of electricity is generated from coal and fossil fuels, notes Kamiel Gabriel, associate provost of research and graduate programs at the University of Ontario Institute of Technology in Oshawa, Ont., and Ontario's incoming assistant deputy minister of research and innovation.
Canada is better positioned than most countries in this respect: More than half of the country's electricity comes from renewable sources such as hydroelectricity, wind, solar and geothermal energy. This means electric cars will have more impact on greenhouse gas emissions in Canada than elsewhere. Conscious of this issue, Better Place is also committing to obtain all its power from renewable sources.
For now, electric cars are limited to short trips or buyers with deep pockets. Whether they can move into the mainstream depends on solving the problems of battery technology and building an infrastructure to support them.