Until now, the main focus of electric car designers has been finding places to store the heavy and bulky batteries. But suppose the car’s body was itself the battery? That’s the intriguing premise of a project jointly undertaken by the Imperial College of London and Volvo, which is already planning on fielding a small fleet of electric C30 sedans.

No, they’re not smoking anything funny. The Imperial College researchers are working with a polymer resin and carbon fiber blend to make special body panels (such as the spare wheel housing) that could store enough energy to restart a hybrid car’s engine, or add a minor amount of range to an electric car. Here's a closer look:

There’s nothing new about polymer resins, or carbon fiber, either. The latter is well-known to offer both high-strength and lightness, but it’s also expensive and difficult to form. The new work focuses on figuring out how to prepare this new material for affordable mass production, and getting it to store energy as batteries do. An early priority is working on the nanoscale (really, really tiny particles) with carbon fiber to increase its surface area and thus its energy-storing ability.

Emile Greenhalgh, the aeronautics engineer at Imperial College London who’s coordinating the three-year project (in part funded through a $4.5 million grant from the European Union) told me, “Our lightweight carbon-fiber panels can carry a mechanical load and store energy simultaneously, and we’re working toward achieving a 15 percent weight savings in a Volvo hybrid test car.” It may be another year before researchers actually begin testing one of their energy-storing body parts in a vehicle.

How’s this Buck Rogers contraption work? Beats me. No, sorry, I really do know: The program turns the body panels (which could ultimately include hoods, roofs and doors) into structural ultracapacitors, which are like batteries in that they store energy, but unlike them in that they have to discharge it quickly. It's great for short jolts, like a hybrid accelerating. 

A number of automakers are working on ultracaps to supplement batteries in hybrid or electric vehicle applications. No, you won’t get shocked — the carbon fiber carrying the charge will be sandwiched and insulated with other composite materials. And because the voltages aren’t high, there’s not much danger if the panels are broken up in an accident.

Volvo has long been intrigued by this concept. A company researcher, Per-Ivar Sellergren, first proposed a related method of energizing body panels in 1989. Volvo’s role in the EU-funded project is providing advice on how the new technology might be incorporated into future vehicles, and offering pros and cons on cost and user-friendliness, Sellergren told me.

If the work goes well, the energy panels could find their way into future Volvos, such as the plug-in hybrid the company plans for 2012. Sellergren said that the panels could entirely replace battery packs, but that’s still a long way down the road.

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

Not a car with batteries, but a car that is a battery
It's true, say top researchers--you can "energize" body parts on a car and get them to store enough energy to restart a hybrid car or give a battery EV a bit of