Better Hybrid Cars

Source: Sciencentral.com
[May 07, 2006]

Driving on (Almost) Empty

Andy Frank loves to drive, but he's not bothered by high gas prices. He says they're fueling interest in hybrid vehicles with all the power and size of the cars and SUVs we love, but with a simple difference — a plug.

"If the car companies were to make plug-in hybrids we could begin reducing foreign oil immediately, because each car would reduce the gasoline consumption by up to 90 percent on an annual basis," says Frank, a professor of Mechanical Engineering at the University of California, Davis.


Those steep gas prices have led to a lot of talk of hybrid cars in recent years. But "hybrid" can mean a number of different things. Most simply defined, a hybrid is any kind of vehicle that combines two or more sources of power. So diesel-electric vehicles like the city buses in San Francisco or like most locomotives are examples of hybrids.

Most hybrid cars on the road today are gasoline-electric versions. A purely electric car would produce no fuel exhaust, but could only go 50-100 miles between charging. That's why tempering the benefits of electricity with the convenience of gas makes for a good combo. But Frank's plug-in variety allows for even more electricity to be used in the equation than in currently available hybrids.

Frank's team at UC Davis converts commercially available hybrids into plug-ins by modifying what's under the hood. "A plug-in hybrid is like a regular hybrid except we use a much smaller gasoline engine, much bigger electric motor, and many more [rechargable] batteries," says Frank.

He wrote in Scientific American magazine that at current gasoline and electricity prices, his plug-ins are easier on the wallet. "Current cars would cost you about ten to twelve cents per mile to drive that car using gasoline. However in one of these plug-in hybrids you're using electricity for the first 60 miles, then it's about three to four cents a mile," says Frank.

And he adds that really industrious drivers could even make money by selling energy back to the power company. "We could charge the batteries in this car at night at very low rates and feed it back to the grid during the middle of the day at a higher rate and we could actually make money," he explains. Frank says the idea is especially attractive if the cars charge at night, when there is unused electrical production capacity available.

There is also the environmental benefit of a hybrid. Even though electricity still has to come from somewhere, it's often produced in a much cleaner way than the energy we get from burning gas in individual cars. "The electricity for this car could easily come from renewable sources such as solar and wind," Frank adds.

He argues that companies already making hybrids could produce plug-ins with little retooling. With lighter, more-affordable batteries due to come out soon, the technology should become even more affordable. And he hopes to convince auto-makers it's an idea that would also charge up consumers.

Frank's article on his work was published in the April 2006 issue of Scientific American and was funded by General Motors, the U.S. Department of Energy, the National Science Foundation and many others (for a complete list).