He is a jovial but serious driver, a man who has been inventing in his garage for the last four decades. He said he has come up with hundreds of ideas, but only seen about half a dozen to fruition.
"The car and all that was really an accident," he said, pouring the purest form of liquid air -- liquid nitrogen -- into the beer keg. He was "thinking about geology and realizing that resources were finite and realizing that someone had to come up with an alternative to using fossil fuels."
'We're Taking Energy that Otherwise Would Be Wasted'
In Slough, on the outskirts of London, a tall, white cylinder sits in the middle of a power plant that's about as large as a hockey rink. The words "liquid air" are printed on the front, a tangle of white pipes leading off of it. This is Highview Power Storage -- and it's proof that Dearman's invention will reach far beyond one car.
Dearman originally set out to create efficient power storage, and that's exactly what Highview does -- with Dearman's invention. The plant stores energy created by renewable power sources when supply is high and demand is low -- say, when wind blows through wind farms at night, and local houses aren't using electricity.
Often, storing that "wrong-time" energy can be expensive and environmentally unfriendly, requiring pricey battery farms that use scarce materials. But Highview takes the "wrong time" energy and converts it into liquid air.
The plant then expands the liquid air using the same process as occurs in the car, exporting electricity back onto the grid without any effect on the environment.
"We're taking energy that otherwise would be wasted," said Stuart Nelmes, the engineer team leader at Highview. "The ins and outs are just electricity, and zero emissions."
In the United States, more than $100 billion is earmarked for investment in energy storage in the next 10 years. For Highview, the tower provides energy to a few hundred homes. But soon, Nelmes said, it could provide electricity for 3,000 to 5,000 homes.
"As we integrate the renewables into our system, as that percentage gets larger and larger, then the demand for storage devices such as these will ever increase," he told ABC News. "These systems basically enable renewable power to work. And that can only mean cheaper, cleaner fuel in the future."
'Until the Next One'
In his garage -- which looks as if it's never been cleaned in 40 years -- Dearman shows off a newer version of his engine.
Soon, his homemade invention will be put inside a very professional package.The engineering company Ricardo, which helps design engines for, among others, McLaren race cars, is creating a state-of-the-art version this year.
By next year, Dearman hopes there will be a complete car built around his engine. It will be a large improvement on his Vauxhall Nova.
"I've done sort of the basic work, and they're going to refine it and bring it onto the next stage for us," he said, pouring liquid nitrogen into a small engine on his garage floor, recreating the process that occurs in the car.
After that, Ricardo is looking into combining the air powered engine with a bus diesel engine, creating a gas-air hybrid.
"That would make the liquid air side much more efficient and it would reduce the emissions from the bus," Dearman said. "And we'd be harvesting the heat from the engine and using that to give us a higher temperature of the heat exchange fluid -- and that would make this engine even more efficient."
He showed off one of his other recent inventions -- a resuscitator currently used by British paramedics.
Asked why he has spent 40 years inventing technology that he hopes will help save the planet, Dearman offered a shrug that suggested, "Why not?"
"Everyone assumes someone else can do it, don't they? But that somebody else is someone," he said. "You can't rely on other people to do things because, you know, it might never get done."
Asked if this is the invention he is most proud of, he said, "Yeah, at the moment."
And then he paused and smiled.
"Until the next one," he said.