There are two alternatives to the internal combustion engine as the power source for the car your great-grandchildren will buy. They both make use of electricity.
But you can dismiss the first option, which is to feed electricity into the car from an external source. We already have vehicles propelled by this method. They go by the names of “locomotive” and “tram”. Since your great-grandchildren will inherit some of your free-spirited genes, however, they’ll probably demand more freedom of movement.
So how about beaming electrical power into a free-ranging car?
This scenario belongs in the realms of more improbable science fiction. Even if it could work, the costs would be prohibitive and you’d probably end up with a lot of microwaved drivers literally stewing in the middle of a traffic jam.
The second option places the source of electrical power inside the car. Here, too, you can dismiss some of the recent suggestions.
A small nuclear generator, a scaled-down version of the reactor in a nuclear submarine? Like beamed microwaves, the economics wouldn’t be acceptable even if the technology could be developed. You’d also need to overcome consumer resistance to a vehicle with the marketing slogan of “Chernobyl on Wheels”.
As for the much-vaunted use of solar cells, they’re just not powerful enough. So that leaves batteries. Not the familiar, heavy-as-lead type of battery you usually forget to check when you stop at a service station. The current buzz is hydrogen fuel cells.
In principle a hydrogen fuel cell works like any other battery cell. Electrodes in the cell produce an exchange of protons and electrons between two chemicals to produce electric current and a third chemical. The difference is that hydrogen fuel cells do this more efficiently and cleanly than other types of cells.
Early hydrogen fuel cells used either liquid hydrogen or a volatile, corrosive liquid compound of hydrogen as one of the fuel chemicals. The other used to be oxygen or an oxidising compound. This was potentially hazardous. The spectacular fireball in the Space Shuttle disaster resulted from the rapid and uncontrolled combining of oxygen and potassium hydroxide, the same chemicals used in prototype hydrogen fuel cells.
For the electric car of the future, the most promising hydrogen fuel cell development replaces liquid compounds of hydrogen with metallic hydrides that are highly stable. You can hit the metallic hydride with a sledgehammer or attack it with a blowtorch and it won’t explode or catch fire. This in itself is not extraordinary. We’re familiar with another hydrogen compound that remains inert if you hit it or try to ignite it — water. What is special about the metallic hydride, though, is that it releases its hydrogen so efficiently inside the fuel cell. The only waste products are water and laughing gas — nitrous oxide. The nitrous oxide doesn’t float up to the stratosphere and kill the ozone layer. It combines with water vapour at lower altitudes and forms nice, friendly nitric acid.
Hydrogen fuel cells hold the promise of becoming the acceptable alternative to internal combustion engines. Their proponents tout their benefits, while their opponents point out the shortcomings.
- Pro: Hydrogen fuel cells will Save The Whale, metaphorically speaking. They don’t emit nasty hydrocarbons that screw up the environment.
Anti: Currently it requires the consumption of huge amounts of energy in coal-burning and nuclear power plants to produce hydrogen compounds or extract pure hydrogen. We’re replacing one source of pollution with another.
- Pro: Using hydrogen will conserve our dwindling resources of fossil fuels.
Anti: Not if you’re using those same fossil fuels to produce the hydrogen.
- Pro: Hydrogen-powered vehicles will be light and efficient.
Anti: At what cost? Yes, the price should come down when they go into mass production, but right now any cost estimate of a hydrogen car or its fuel falls in the “experimental” bracket. A really competitive hydrogen car might cost as much to own and run as Schumacher’s F1 Ferrari.
- Pro: Exchanging a set of hydrogen fuel cells will take no more than five minutes. They’ll swap your tired cells for fresh ones and take the old cells away to replenish their fuel.
Anti: The best current hydrogen car uses about 1,5kg of hydrogen, which is a very low-density element and needs lots of storage space, per 100km. Its range is about 400km. That means a lot more stops to refuel. And who’s going to set up the international network of hydrogen cell refuelling stations?
- Pro: Current technology might allow us to fit four hydrogen-powered engines, one a wheel, each delivering about 20kW. In total that would give the same power and more take-off torque than the average petrol engine.
Anti: The best near-production car, Chrysler’s Necar 4, can just top 140kph. It takes off quickly, but doesn’t continuously accelerate rapidly the way a Shelby Cobra does when the torque kicks in. Who really wants a car that performs about as well as a big 1954 Austin?