A car made from grass may not sound sturdy, but scientists say plant-based cars are the wave of the future.
Researchers in Australia and England are working on developing materials from plants like hemp and elephant grass to replace plastic and metal-based car components. Scientists say the materials are biodegradable and can increase fuel efficiency since they weigh about 30 percent less than currently used materials.
"The lighter the car, the less fuel you need to propel it," explains Alan Crosky of the School of Material Science and Engineering in the University of New South Whales in Australia.
Use, Then Bury
Crosky and his partners have been developing tough material from hemp, the reedy, less controversial cousin of the marijuana plant. "Hemp fibers have higher strength to weight ratios than steel and can also be considerably cheaper to manufacture," he says.
The hemp used in car construction contains only traces of the narcotic tetrahydrocannabinol, which lends marijuana its psychedelic effect.
Crosky explains building cars — even their outer shells — from plants like hemp could reduce the number of rusting car bodies and rotting car parts on old lots. The plant fibers are cleaned, heated, in some cases blended with small amounts of biodegradable plastics and molded into hardened paneling and filling.
Each year in the United States, 10 million to 11 million vehicles putter out and reach the end of their useful lives. While a network of salvage and shredder facilities process about 96 percent of these old cars, about 25 percent of the vehicles by weight, including plastics, fibers, foams, glass and rubber, remains as waste.
A car made mostly of heated, treated and molded hemp, says Crosky, could simply be buried at its life end and then consumed naturally by bacteria.
Europe Leading the Way
The idea has already taken firm root in countries like Germany and Britain, where manufacturers are required to pay tax for the disposal of old vehicles. As environmental issues become more pertinent, researchers believe natural fibers are likely to become a major component of cars around the world.
"Manufacturers pay a lot of money here to landfill something," says Mark Johnson, an engineer at the University of Warwick Manufacturing Group in England. "If it's made from degradable parts, you don't have to pay."
Johnson and his team have been creating parts from elephant grass, a bamboo-like plant that, he says, requires less processing than hemp to harden and mold into car components.
German car companies including Mercedes (Daimler/Chrysler), BMW and Audi Volkswagen have been leading the way in incorporating plant fibers in their models. Since the introduction of jute-based door panels in the Mercedes E class five years ago, German car companies have more than tripled their use of natural fibers to about 15,500 tons in 1999.
The next trend could be in building the shells of cars from plants. Crosky says he and his team are now looking at building exterior car panels from hemp.
In the United States, automobile companies have approached the idea more gingerly.
"We use natural fibers only when it makes sense technologically," says Phil Colley, a spokeman for the Ford Motor Co.