After years of tinkering, inventor Dean Kamen is ready to show off what he says is the world's first hybrid electric car with a Stirling engine.
"I'm a car manufacturer! It's so exciting," he said last week, showing off his state registration for his new car, listed as a 2008 DEKA Revolt.
The prototype, uses a recycled version of the Ford Think, an electric car that was discontinued in 2000. The two-seat hatchback can go about 60 miles on a single charge of its lithium battery with almost zero emissions.
In the trunk is a Stirling engine that powers the features that normally would drain power from the battery, including the defroster and heater, leaving the batter primarily for propulsion.
"You're running a pure electric, which is enormously cheaper to operate and enormously more environmentally friendly," Kamen said.
If the battery runs low, the Stirling also can recharge it, so drivers wouldn't get stranded.
The engines are named for Robert Stirling, a minister in Scotland who first applied for a patent on his "economiser" engine in 1816. They use external heat to drive internal pistons, creating clean, quiet power for almost unlimited applications and have been used on occasion to power submarines, coal mine pumps and generators. But engineers have yet to figure out a way to manufacture them economically for mass use.
Kamen started applying for and receiving Stirling-related patents in 2002, sparking speculation that he was working on a way to incorporate the engines into his much-hyped Segway scooters. He said he is in "conversation" with a group of Norwegian investors about producing the car and hopes it will be in production within two years.
He doesn't know how much it would cost, but the goal is to make it affordable for average consumers, unlike the Segway, which Kamen had said would revolutionize short-distance travel. At about $5,000, the self-balancing vehicles have appealed mostly to police, mall security crews and airport personnel.
Kamen said he is not optimistic that struggling American carmakers will embrace Stirling engine technology. Most big companies seem to misconstrue Darwin's ideas about which species survive, he said.
"I think what Darwin was really saying was: It's not the fittest, not the smartest, not the strongest; it's the ones that can adapt to change. And big industries that have long histories, particularly successful long histories and a lot of ingrained infrastructure become the least adaptable to change."
But he sees the car as "a step along the way to be able to build, in high volume, high-quality, low-cost electric generation for a couple billion people."
"If we can demonstrate the utility of the Stirling engine by putting it in a car ... it will leave me with an engine that I can use to supply electricity to the world."