Peter Dearman didn't come up with the idea of running a vehicle on liquid air; the concept goes back more than 100 years. But in 2001, he actually built one that worked. Dearman took that old idea and set to work fixing the problems that kept it off the market all that time.
Still, the underlying principle was sound. Most engines rely on heat differentials. In the case of, say, a gasoline-powered car, the fuel is mixed with air, crammed into a piston chamber, and set alight, causing it to jump more than 1,000 degrees in temperature. The gas rapidly expands, propelling the piston and, in turn, the wheels. Take the same process, slide it way down the Fahrenheit scale, and you've got a liquid air engine. The nitrogen fuel starts out at 320 degrees below zero. When it enters the (much warmer) piston chamber, it boils off into gas. The change in temperature is smaller than with gasoline, so the pistons move with a little less oomph—but it's enough to get the wheels going. The real problem comes later: All that frigid fuel coursing through the engine quickly freezes it, effectively wiping out the heat differential. The air stops expanding, and the car runs out of puff.
The roadblock was clear, Dearman told me recently. He'd been pondering how to get around it since he was a teen. In a car that runs on heat, you need something to keep it cool—a radiator. In a car that runs on cold, you need the opposite. “I had an idea in my head for how to make it work, but I knew I wasn't going to get anywhere until I had some research to go on,” he said.
Dearman not only came up with a way to dissipate the cold, but also harness it in a way that would make the vehicle efficient enough to justify its development, all while being eco-friendly. Read the story of Peter Dearman's liquid air engine at Wired.
(Image credit: Jan Siemen)