“The little engine that could,” as Kamen calls the Stirling, was invented in 1816 by Scottish clergyman Robert Stirling. He found that alternately heating and cooling gases in a closed system could create power to do work, such as drive a piston. But steam engines soon became far superior in producing power for large applications, such as railway locomotives. Later, the diesel and gasoline internal combustion engines proved superior for mid-sized jobs, such as cars and trucks. And in the 20th century, the jet engine combined tremendous thrust and relatively light weight to rule the skies.
So the Stirling was mostly forgotten, even though its simple concept is “elegant, it’s brilliant,” Kamen says. But its time to shine might be now. All-electric cars still suffer from wimpy batteries that limit driving range and refuel slowly. “The energy you can carry around in a liter of gasoline is 100 times higher than you can carry in the same size and weight of a battery,” Kamen says. “And that’s going to be true for a long time.”
Today’s hybrid cars add a gasoline engine to both power the vehicle and recharge the battery. But the sooner cars can be weaned from fossil fuels, the better for US security and the environment.
Why not use a Stirling to charge the hybrid car’s batteries, Kamen asks. The Stirling’s waste heat could warm the car’s interior on cold days, saving even more battery power.
Outside the offices of DEKA Research & Development Corp., Kamen’s company located in a former mill along the banks of the Merrimack River in Manchester, N.H., Kamen shows off his prototype. The exterior and chassis are from a Think electric car, developed and abandoned by Ford years ago. It was shipped in a crate from a Norwegian company trying to revive the brand. Its pebbled plastic body is a little larger than the Smart ultracompact now on US roads.