NOURISH
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Silicon Valley, if you’re listening, here’s
how you can help:_
Lab-grown Thanksgiving dinner for 12,
complete with the wishbone._
Waterless dishwashers._
Biodegradable cling wrap._
A smart pantry that serves up recipes
for soon-to-expire ingredients.matter of years. Modern cynics suspect he
was engaged in a Theranos-style fraud, in
part because no one could figure out how
he’d done it. For years, a working liquid-air
engine seemed about as fanciful as a per-
petual motion machine.
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 pis-
ton 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) pis-
ton chamber, it boils off into gas. The change
in temperature is smaller than with gaso-
line, 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.
The breakthrough came in 1999. Dear-
man was watching an episode of the BBC’s
dearly departed flagship science program,
Tomorrow’s World, in which the pre-
senter visited the University of Washing-
ton to report on a rather clunky-looking
converted mail truck. It had trouble with
hills, and its top speed was 22 mph, but it
ran on liquid nitrogen (a profligate 5 gal-
lons per mile). Invented by Abe Hertzberg,
an eccentric professor who had previously
come up with a laser-powered airplane,
the truck boasted one major innovation.Before the freezing-cold fuel reached the
engine, it ran through a heat exchanger, a
series of concentric tubes that circulated
outside air around the fuel line. John Wil-
liams, who worked on the truck as a grad-
uate student, explained that the exchanger
ensured “the whole thing didn’t turn into a
giant ball of ice.” But it didn’t tackle the fun-
damental problem—that the liquid nitrogen
still rapidly cooled the engine, throttling its
own expansion into a gas. “Our project was
a proof of concept,” Williams explained. “We
were reconciled to a certain degree of ter-
ribleness.”
From his sofa in the historic market town
of Bishop’s Stortford, Dearman immedi-
ately saw both the logic of Hertzberg’s
design and a way of improving on it. The
answer to making sure the nitrogen con-
tinued expanding? Antifreeze. “It’s obvious,
but it’s only obvious once you’ve seen it,”
Dearman said. He went out into his garage,
grabbed a blue plastic jug from the shelf,
and started playing around with his lawnBACK IN 2001, A MIDDLE-AGED MAN
made a video of his car and sent it around
to a few friends. So far, so predictable—
but this video featured a dilapidated Vaux-
hall Nova whizzing around a junk-strewn
yard in a cloud of fog. At the wheel was
Peter Dearman, a rumpled-looking auto-
didact who had spent the better part of four
decades imagining a way to build engineer-
ing’s ultimate vaporware: a motor powered
only by air.
Born in 1951 on an egg farm north of Lon-
don, Dearman would seem an unlikely can-
didate to have solved the problem. He left
school at age 15 and worked in the family
business for a while, then took a job at a local
sheet-metal factory. He spent his evenings
as many Englishmen do—out in the garage
or the garden shed, tinkering. But Dearman’s
aptitude and ambition set him apart from
other hobbyists. Over the years he filed pat-
ents for an improved adjustable wrench, a
solar hot-water system, and a portable
resuscitator that is still used in ambulances
today. His most impressive achievement,
however, was the Nova, whose engine he
cobbled together from string, a used beer
keg, a red plastic trash bin, and a coffee can’s
worth of liquid nitrogen.
The idea behind Dearman’s project dated
back to at least 1899, when a Danish inven-
tor named Hans Knudsen claimed to have
designed an automobile that could run on
“clear, bluish” fuel—liquefied air, to be sold
at a penny a gallon. Rather than spewing
out a toxic mix of pollutants and green-
house gases, it would leave a harmless
trail of condensation in its wake, wafting
by at the stately speed of 12 mph. Knudsen
received admiring media coverage at the
time, but his company went belly-up in a
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