10 Dezember 2010

Modern cars, made from wheat straw and carrots

What are cars made from these days? Would you believe, vegetables?

This is not new. Bio-composite materials have been around since the 1920s, when Henry Ford built prototype car components, including dashboards, door panels and passenger compartment parts, out of hemp-derived plastics. But as the car-making industry works to become more sustainable, veggie-based bio-composites are taking on newfound importance across the industry. After all, compared to traditional materials, they’re light, strong, durable and competitively priced.

The parts are not made from raw vegetables; instead, their fibres and chemicals are broken down at microscopic levels and reformed into usable compounds. Scientists say bio-composites are kilo-for-kilo stronger than steel, and are lighter and cheaper to produce than traditional petroleum-based plastics. They stand to create new, value-added markets for agricultural materials that often have been discarded as worthless or undesirable – such as wheat straw – and for a range of common vegetable crops.

“A car made from grass may not sound sturdy,” says Lawrence T. Drzal of Michigan State University’s Composite Materials and Structures Center, “but plant-based cars are the wave of the future.” Bio-fibres like kenaf, hemp, grass, corn straw, flax, jute, henequen, pineapple leaf and sisal offer light weight and strength and thereby help extend fuel mileage, says Drzal.

Up to 11 million vehicles in North America reach the end of their life cycle each year, he says. A network of salvage and shredder facilities process about 96 per cent of these old cars, but about 25 per cent of the vehicles by weight, including plastics, fibres, foams, glass and rubber, remains as waste, none of which break down easily in the environment.

“A car made mostly of heated, treated and molded bio-fibre would simply be buried at the end of its lifetime,” Drzal says, and would be consumed naturally by bacteria.

Working with academic researchers at the University of Windsor and one of its suppliers, the Ford Motor Company is the first automaker to develop and use environmentally friendly, wheat straw-reinforced plastic in a vehicle.

Ford is using 20 per cent wheat straw bio-filler in the third-row storage bins of its 2010 Flex, with plans to extend the material’s use further throughout its lineup.

“This application alone reduces petroleum usage by some 20,000 pounds (9,000 kg) per year, reduces carbon dioxide emissions by 30,000 pounds per year and represents a smart, sustainable usage for wheat straw, the waste byproduct of wheat,” says Ford engineering manager Patrick Berryman, who develops interior trim in Dearborn, Mich. Potential long-term savings could be staggering, he adds.

An interior storage bin might seem like a small start, says Dr. Ellen Lee, technical expert with Ford’s Plastics Research, but “we see a great deal of potential for other applications since wheat straw has good mechanical properties, meets performance and durability specifications and can further reduce our carbon footprint, all without compromise to the customer.”

Already under consideration by Ford are centre console bins and trays, interior air registers, door trim panel components and armrest liners. She says traditional components made of steel, plastic and glass will increasingly be replaced with plant-based products.

A “hemp-infused” bio-composite bodied electric car concept, called the Kestrel, was recently unveiled in Calgary by Motive Industries Inc. The company says that its manufacturing techniques will allow the vehicle to be made profitably at smaller initial volumes than traditional vehicles.

Motive president Nathan Armstrong says a major advantage to using advanced composites versus metal is increased impact absorption, rust resistance and reduced weight. Where a steel-stamped vehicle will absorb impact by crumpling under pressure, “a composite vehicle will absorb the energy, then return to its original shape.” That observation, he said, was recently verified by British automaker Lotus, which found similar results with its Evora sports car.

The tiny Kestrel with its extreme cab forward design, seats four, weighs about 450 kg and with a lithium-ion battery driving an electric motor, will achieve a top speed of 135 km/h. But perhaps the most radical example of a bio-composite vehicle is a Formula Three-style racing car developed at the University of Warwick in England. The ‘ecoF3’ single-seat racer is made from vegetables and runs on chocolate-derived biofuels. Its steering wheel is made from carrots and other root vegetables while the seat is made from soybean oil, recycled polyester and plant-based lubricants; the bodywork is crafted from potatoes and the side pods are made from recycled bottles.

Plant-based oils and greases provide all necessary lubrication, and the biodiesel-powered engine can operate on chocolate extracts or vegetable oil. Team WorldFirst project leader, James Meredith, says the car does contain traditional materials: no glass, but plenty of steel and aluminum in and around the engine, gearbox and suspension, plus plenty of virgin carbon fibre used in the tub and wings. The car hasn’t been crashed but all the unconventional parts have stood up well to use around various tracks, he says.

At this time, says Meredith, bio-composites can’t match the strength properties of carbon fiber, “but we are hopeful they will in the future.”

Source: Wheels.ca, 2010-12-10.

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