Subscribe to RSS
Subscribe to our Newsletter

Join us for:

Unsubscribe
Manage Your Subscription

  David Marlow

Green Machines: First Person: Green Without Envy

Amory B. Lovins

April 1, 2007

Lighter weight formerly meant costly metals, like aluminum and magnesium. Now, ultralight steels can double a car’s efficiency without extra cost or decreased safety. With clever design, even conventional steels can yield surprising results. A German start-up firm’s 2+2-seat 990- to 1,034-pound diesel roadster www.loremo.com combines 99-to-137 mph top speeds with a fuel economy of 87-to-157 mpg, and is slated to sell in 2009 for just $14,250 to $18,000.

Loremo roadster. (Click image to enlarge)

Next, hybrid drive and carbon composites can put those designs’ modest acceleration—respec­tive­ly nine and 20 seconds for zero-to-60 mph—back into sports-car territory. For example, Opel’s 2002 Eco-Speedster concept car is a 1,450-pound, 0.20-drag-coefficient, two-seat carbon-fiber diesel-hybrid roadster getting 155 mph and 94 mpg—though not at the same instant.

Carbon-fiber-reinforced composites can be as strong and stiff as steel, yet one-third as dense, cutting total curb mass by 50 percent to 60 percent while improving stiffness and hence handling. (The lightest two-seater body-in-black I know, in the Swiss Omekron concept car, weighs just 34 kg.) While halving fuel use, advanced composites can also boost safety, because they can absorb up to 12 times as much crash energy per kg as steel, and do so more smoothly, using the crush stroke up to twice as effectively. Tom Friedman’s 2006 film Addicted to Oil shows sledgehammer blows bouncing off a 2-mm-thick hemispherical helmet shell: Its ultrastrong carbon fibers are embedded in a special thermoplastic that’s tougher, but lighter, than titanium.

Advanced composites can make cars big (comfortable and protective) but not heavy (hostile and inefficient), saving both oil and lives. And now they can save money, too. A new manufacturing process automatically and rapidly lays up a flat “tailored blank” of thermoplastic with optimally oriented layers of continuous carbon-fiber reinforcement, then thermoforms them to final shape by stamping them on a hot die. This can make a carbon-fiber car producible at the same cost as a steel one, because the costlier materials are offset by simpler automaking and a propulsion system that is two to three times smaller. Composite bodies can also offer enhanced stylistic and operational flexibility.

Opel’s Eco-Speedster concept car is a 1,450-pound, two-seat carbon-fiber diesel-hybrid roadster that can reach 155 mph and get 94 mpg. (Click image to enlarge)

For example, a mid-size sport-utility vehicle designed in 2000, equipped with the 2004 Prius hybrid-electric powertrain (with half a million on the road today), could comfortably carry five adults and up to two cubic meters of cargo, haul a half-ton up a 44 percent grade, accelerate from zero-to-60 mph in 7.2 seconds, and use less than one-third the normal amount of gasoline, while getting about 67 mpg. Industry-standard simulations say you could run it into a wall at 35 mph without damaging the passenger compartment, or run it head-on into a steel SUV twice its weight at a combined speed of 60 mph, yet still be protected from serious injury. And with an aerospace-inspired structure so stiff it almost rings like a bell—first bending and torsional modes 93 and 62 Hz—it would also handle impressively.

If produced at a rate of 50,000 cars per year, its retail price would be about $2,511 higher than today’s equivalent steel SUV, but only because it’s hybrid-electric, not because it’s ultralight. Savings in gasoline would repay this investment in two years at U.S. fuel prices, or one year at current E.U. or Japanese fuel prices. Manufacturing such cars would use far less space and two-fifths less capital than today’s leanest plant, thanks to up to 80 times less tooling, and elimination of the body shop and paint shop—the two hardest and costliest steps in automaking.

Such light-but-strong materials and novel manufacturing techniques are likely to be accelerated by the Pentagon’s need to lighten its sluggish, vulnerable platforms. But just as military R&D created microchips, the Internet, and GPS, so it can shift automaking to ultralight materials, leading the world to wean itself off oil so we needn’t fight over it.

Page:  1  |  2  |  3
Print ArticleEmail ArticleAdd to DiggAdd to Del.icio.us