Carbon Fiber Cars: BMW's Electric Automobile Revolution
BMW is hoping to revolutionize the electric car industry. Whereas most manufacturers rely on traditional -- and heavy-- steel car bodies, the German company hopes that carbon fiber components could lead electric cars into the future.
Cars may have conquered the world, but they didn't do it overnight. Decades after its invention in 1886, the passenger car was still too expensive and too impractical to be anything more than a rare sight on the streets. Gas stations didn't even exist in those days.
Mitsubishi has released its first electric car series under the rather uninspiring model designation i-MiEV. It's a simply furnished compact car with an oval body and lithium-ion batteries under the floor panel. With one charge of the battery, the vehicle can travel 100 kilometers (62 miles) in summer or 60 kilometers (37 miles) in winter. It costs 34,390 ($45,240).
Nissan's electric car, the Leaf -- set to hit the German market next year -- faces the same cost-benefit plight. Even so, European automobile journalists saw fit to name the Leaf their "Car of the Year."
It doesn't take extensive market research to see that something doesn't add up here. What customer is willing to pay the price of a luxury sedan for a spartan vehicle whose operating radius barely extends beyond the range of commuter trains?
Too Weak and Too Heavy
All car manufacturers face the same problem -- even the most modern rechargeable batteries are too expensive, too weak and too heavy to power conventional cars, which are already excessively heavy even without the batteries.
"Integrating electric power into existing vehicle concepts is the wrong way, a dead end," declares Rainer Kurek, head of the Munich-based MVI Group, which develops car bodies and other components for the automotive industry. In his recently published book, Kurek urges vehicle manufacturers to take a completely new approach. "The current hype surrounding electric vehicles," the engineer writes, "is obscuring the fact that today's auto bodies have become far too heavy over the course of the last decades."
A first-series Volkswagen Golf from 1974 weighs 750 kilograms (1,653 pounds). A Golf from today's production series weighs around half a ton more. It's also an entire vehicle class larger than its predecessor, contains a standard eight airbags and can drive into a wall at 64 kilometers per hour (40 miles per hour) without its occupants being seriously injured. Such an accident in the original Golf would have meant certain death.
Technological progress has long meant an inevitable increase in weight. The aluminum auto bodies used in Audi's luxury cars, for example, just barely manage to make up for the weight added by the all-wheel drive system that the brand has made its trademark. Hardly a technical revolution.
Now, though, BMW is attempting to break the cycle. Three years from now, the Munich-based company plans to offer an electric vehicle of a completely different construction type. The project, known as Megacity Vehicle (MCV), won't contain steel or aluminum bodywork. Instead, it will have a light alloy frame in the car floor and a body made of carbon fiber-reinforced polymer (CFRP).
An Economic Riddle
CFRP is a dull black material which has a chemical structure similar to that of diamonds. It is sturdier than steel and weighs less than half as much. The MCV body will be 250 to 300 kilograms (550 to 660 pounds) lighter than that of a conventional electric car of the same size, compensating fully for the additional weight of the batteries.
BMW is alone in pursuing the concept -- the boldest idea currently under development in the automobile world, and one which is an economic riddle for the competition. CFRP materials have been available for nearly 50 years and are used in the aviation and aerospace industries, in car racing and, most recently, in rotor blades for wind turbines. Still, the idea of mass-producing cars from the material would appear to make little sense.
CFRP, after all, is 50 times as expensive as steel. A car body component made of steel sheet costs about 4 in its final form; the same part made from CFRP costs at least 200. To achieve the desired lightweight construction, BMW will need to use very large quantities of the material -- 150 to 200 kilograms (330 to 440 pounds) per vehicle.
BMW, of course, has no intention of manufacturing a compact with a body that alone costs 40,000. Company engineers have set a goal of a tenfold reduction in production costs for CFRP. That would spell a true revolution in industrial engineering.
BMW's partner in this venture is SGL Carbon. Based in Wiesbaden, SGL was once owned by the Hoechst chemicals company and is currently Europe's sole manufacturer of carbon fiber materials. The company's profits have traditionally come mainly from other carbon products, such as graphite. But the company hopes to be able to transform carbon-fibers from a niche material into a profitable business. CEO Robert Koehler calls it a "megatrend in materials substitution."
The joint venture of SGL and BMW produces these carbon fibers, 10 times thinner than a human hair, in the northwestern United States. The manufacturing process consumes an enormous amount of electricity, but hydroelectric power is cheap in the mountainous state of Washington.
Four knitting machines, each as large as a train car, take up most of a 7,500-square-meter (80,700-square-foot) factory floor. But instead of producing material for T-shirts and jeans, the outsized machines produce carbon fiber fabric, at speeds no other manufacturer has even approached.
- Part 1: BMW's Electric Automobile Revolution
- Part 2: Will Technology Be Enough?
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