PUT the pedal to the metal in the XH-150—a souped-up Saturn Vue—and watch the instruments. Sure enough, the speedometer shoots up in a satisfactory way. But an adjacent dial shows something else: the amount of charge in the car's capacitors is decreasing. Ease off the accelerator and as the speedo winds down the capacitors charge up again.
Such a capacitor gauge could become a common sight on the dashboards of the future. A capacitor can discharge and recharge far faster than a battery, making it ideal both for generating bursts of speed and for soaking up the energy collected by regenerative braking. AFS Trinity, a company based in Washington state, has turned that insight into a piece of equipment that it has fitted into an otherwise standard production model as an experiment. The result—the XH-150—was unveiled at this year's Detroit motor show.
In fact the XH-150 is a three-way hybrid, employing a petrol engine and conventional lithium-ion batteries as well as its special capacitors. An overnight charge gives it an all-electric range of 40 miles (60km), after which the petrol engine needs to come into play. AFS Trinity says the vehicle is capable of more than 80mph and returns the equivalent of 150 miles per gallon (more than 60km/litre) in normal use. Edward Furia, the firm's chief executive, reckons the extra kit would add around $8,700 to the price of a petrol-only vehicle were it put into mass production.
This, however, may be only the start. Eventually, the so-called ultracapacitors on which the XH-150 is based may supplant rather than merely supplement a car's batteries. And if that happens, a lot of other batteries may be for the chop, too. For it is possible that the long and expensive search for a better battery to power the brave, new, emission-free electrical world has been following the wrong trail.
