Photograph by Michele Tantussi, Bloomberg/Getty Images

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A visitor inspects a carbon fiber chassis on display at the BMW auto plant in Leipzig, Germany. BMW plans to incorporate the lightweight, super-strong material into its new electric Megacity vehicle.

Photograph by Michele Tantussi, Bloomberg/Getty Images

Cheap Renewable Power Key to BMW’s Electric Megacity

Lightweight, high-strength carbon fiber has long been seen as the secret—but an expensive one—for more efficient cars; BMW details a strategy for slashing the cost.

This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

Carbon fiber has long been seen as a potentially powerful weapon in automakers' arsenal for designing more efficient vehicles. But the lightweight, super-strong material does not come cheap—at least, not yet. BMW plans to use carbon fiber for its upcoming Megacity electric vehicle, and at the Los Angeles Auto Show the company detailed its strategy for slashing production costs for the material.

Richard Steinberg, BMW's manager of electric vehicle operations and strategy for North America, said on Wednesday that the automaker plans to use hydropower for the energy-intensive manufacturing of carbon fiber.

With plans initially to invest $100 million, a joint venture between BMW and Germany’s SGL Group began building a new plant this summer in Washington—a state that has become a hot spot for energy-guzzling data centers due to the abundance of cheap hydropower generated there. Thanks to the giant Grand Coulee Dam and other hydroelectric stations on the Columbia River, Washington State has the lowest electricity rates in the United States—about four cents per kilowatt-hour for industrial customers, or 40 percent below the national average.

BMW is also reportedly planning to reuse scrap in the carbon-fiber production process to further cut costs, and Steinberg noted that BMW hopes to achieve economies of scale by ramping up carbon-fiber production. How big and how soon remain open questions for the carbon-fiber plant under construction in Moses Lake. Earlier this month, Washington Governor Chris Gregoire said discussions had begun about whether to double the size of the facility.

Less Weight Lowers Battery Cost

Lightweight materials are particularly appealing for plug-in vehicles, which carry hefty lithium-ion battery packs. According to David Hwang, an advanced materials analyst with Lux Research, fuel consumption generally drops by about 2 percent with every 3 percent reduction in weight. "In an EV, that directly translates to 2 percent fewer batteries for the same range," he explained. "Given how large a portion of the final cost of the vehicle comes from the batteries, the reduction is pretty significant in terms of the payback period for the car." As Steinberg put it, "it changes the equation" for carbon fiber when battery costs come into the picture.

Minimizing weight is at the heart of General Motors-backed startup Bright Automotive's scheme for carving out a slice of the work-van market with a plug-in hybrid model called the IDEA. As Bright's corporate strategy chief Michael Brylawski explained to National Geographic recently, the company has opted for a 13-kilowatt-hour pack, rather than a larger 16-kilowatt-hour pack, even though the larger pack could potentially qualify the IDEA for a higher federal tax credit.

The larger battery, he said, “would have a cascading effect,” forcing the company to beef up the entire vehicle to handle the increased battery size and weight. The result would be a vehicle that, despite the government subsidy, would cost more to own—due to fuel costs—than the version with a smaller battery pack and more streamlined design.

BMW Seeks “Electric Mobility”

For the Megacity, BMW plans to employ a carbon-fiber body and "aluminum sandwich platform," to minimize weight, Steinberg said. Unlike the Mini E (a two-seat electric version of BMW’s Mini) and ActiveE (an electric four-seater based on the BMW Series 1 Coupe) the Megacity is specifically designed to run on electricity. The efforts to minimize weight, said Steinberg, will help the car achieve as much as 100 miles (160 kilometers) of electric range, with less battery capacity than a heavier car would require to travel that distance.

The Megacity fits into BMW's three-phase approach to "electric mobility," which includes ongoing field trials of the electric Mini E and U.S. trials of the electric ActiveE to begin in summer 2011. Technology (in particular the electric drivetrain) used in the ActiveE, noted Steinberg, will be very similar to that in the Megacity, due out in 2013.

By using composite materials (including carbon and glass fibers), said Hwang, automakers could conceivably cut vehicle weight by as much as 15 percent, "so the effect that this has on the economics of EVs isn't trivial." Plus, these advanced materials can reduce some tooling and assembly costs because, as Hwang put it, "you can make much more fancy shapes with composites than you can with steel." The materials themselves remain considerably more expensive than steel, but on the whole, said Hwang, composites "are definitely starting to make their way from exotic sports cars into cars for ordinary consumers."

(Related from National Geographic Channel, "Man Made: Chevy's New Electric Car")