Electric dreams

The G-Wiz: Electric cars

Electric cars are genuinely green machines, but we don’t love them yet, says Paul Horrell

Ever thought about buying an electric car? In many ways, they are an environmental dream: they are silent, don’t produce any CO2 emissions locally – in fact, they don’t even have an exhaust pipe. And if you power an electric car from renewable energy, it produces zero emissions – so why aren’t we all driving around in them?

One explanation is that they’ve not had much time to catch on – until global warming became so topical, there was little interest in cutting CO2 emissions. But, arguably, a bigger reason is convenience. We expect our cars to handle more than the daily commute, shop or school-run – we also want to make longer journeys.

Low battery

An electric car can usually do about 100 miles before its batteries need recharging and that process takes many hours – typically overnight. A 300-mile journey, which would need three lengthy stops, would be impossible. One possible way to avoid this is to drive an electric vehicle day-to-day and hire a conventional car for long journeys.

But there are other complications – namely the battery. Conventional lead-acid batteries (as used in milk floats) are so heavy and bulky that they severely compromise the car. Meanwhile, new batteries, such as nickel-metal-hydride and lithium-ion, demand high-tech electronic management to keep them in peak condition over many charge cycles.

A car is also a very harsh environment for batteries. If you left your mobile phone outside at sub-zero temperatures rather than in your warm pocket, its battery life would be hopeless. Cars have to stay outdoors in frost and snow. Research is improving the batteries, but the challenges are huge.

All of this means that what you might call mature electric cars remain tantalisingly out of reach.

Green driving

Two of the most popular electric models are the G-Wiz and the Mega City. These are good choices in cities because they’re compact, environmentally friendly and exempt from road tax and schemes such as the London congestion charge.

But these cars can’t yet boast the safety and comfort standards of conventional cars. You certainly wouldn’t want to go down a rural road or fast dual carriageway in them.

And there’s a more mundane reason why most of us city-dwellers can’t have an electric car yet: we don’t have an off-street parking space, so it’s impossible to recharge them at home. But if electric cars become more popular, it’s likely that car parks and bays will be introduced with charging points.

Coming soon...

However, better cars are coming – I’ve driven prototypes of three convincing examples.

One is an electric version of the Smart. It is just entering the test phase with certain fleets, including Islington (London) and Coventry councils. If the trials are successful, a version will be made available for sale or lease to the public. It’s surprisingly smooth and nippy, with no sacrifice in the safety and the style that Smarts are known for.

Another likely contender is the four-seat electric version of the Mitsubishi i minicar – again, it’s on fleet test, but this time in Japan. If that goes well, UK sales are likely in a couple of years. This model has four seats and again can cruise at motorway speed – and like the Smart, its range will be 80 miles or so.

In the US, a very high-profile start-up company Tesla Motors is working on an electric sports car. Sports cars are a good place to try new propulsion because they are light, which means they need less electric energy to drive them. Also, users don’t normally go long distances in them. But Tesla insist they are using the Roadster as a test bed and that they will build a saloon car in a few years.

Petrol vs electric

Tesla Motors produced a well-verified comparison of various car types: an electric sports car in development in America (Tesla Roadster), a hybrid (Toyota Prius), a small diesel (VW Jetta) and a small petrol (Honda Civic).

It also included a natural gas powered Civic and the Honda FCX, a prototype fuel-cell machine. The Tesla electric car proved to be twice as efficient as its nearest rival. It's worth noting that the figures use US gallons, not imperial, and the VW and Hondas aren’t exactly the ones sold here, but the comparison still stands.

The very fact that they are so efficient is why a full charge for all these electric cars costs just a few pence.

So what does all this mean for the future of electric cars? The G-Wiz and other current models are important groundbreaking cars and the companies behind them should be applauded for their efforts. For now it seems that they’re still too limited to cross over into the mainstream, but don’t think the electric dream is over. Better models are on the way - just watch this space…

The science bit

If electric cars really take off, there will be a surge in demand for electricity. Luckily, people will typically recharge overnight when the energy network is least stretched.

And, yes, much of this electricity will come from fossil fuel, but a well-engineered electric car still has the potential to reduce CO2. Here’s why: most combustion engines (petrol or diesel) struggle to be more than 30 per cent efficient at turning the energy in the fuel into propulsion. The rest disappears as heat – out of the radiator, exhaust and brakes.

Hybrids increase that efficiency by preventing the engine running when it’s doing no useful work and by reusing waste from the brakes. Taking the energy comparison one step further, some 10-20 per cent of fuel’s energy is lost in the drilling, refining and distribution processes, before it even reaches your car.

On the other hand, an electric car turns a far higher proportion of the energy in the batteries into actual motion. And crucially, power stations are more efficient than conventional cars at getting the energy out of fossil fuel.