On a hot Thursday in May 1938, more than 50 years after the world’s first mechanically cooled warehouse opened its doors in Boston, Minnesota transportation company boss Harry Werner enjoyed a round of golf with four friends. When he got back to the clubhouse, however, Werner’s good mood was promptly ruined by a phone call: One of his trucks had broken down on the way to Chicago, and its cargo of 35,000 pounds of raw chicken, worth at least $80,000 in today’s money, had started to fester.

Like all perishable foods at the time, the chicken had been packed in ice to keep it cool on its long journey between slaughterhouse and refrigerated warehouse or consumer. As the ice melted in the sun, the temperature in the truck would rise, making spoilage common. Produce was shipped in a similar fashion: A railcar full of Imperial Valley cantaloupes destined for New York City was packed in an extraordinary 10,500 pounds of ice—and re-iced with another 7,500 pounds several times during its 11-day journey. Even then, a season never went by without at least one shipment being lost entirely, while all experienced considerable shrink due to rot.

Transportation was the weakest link in the cold chain, the series of refrigerated spaces that, starting in the late 19th century, helped turn the regional, seasonal American food system into a national, and eventually international, supply chain. Refrigerated warehouses may have made perishable food all but immortal, but without refrigerated trucks, it was more or less immobile.

Fred McKinley Jones, a high-school dropout turned self-taught engineer, changed all of that when he invented the world’s first mobile refrigeration unit—and, with it, redesigned the American food system. However, the emissions from a growing global fleet of refrigerated trucks are inadvertently redesigning the world’s atmosphere as well. Today, the tomatoes on sale at a New York City grocery store all year round likely traveled hundreds of miles from Florida in a refrigerated truck much like the one Jones invented. In the days of shipping produce on ice, that tomato would have come from New Jersey—and would have been available for just a few precious weeks each year. While some would like to go back to that local, seasonal supply, tomatoes in January aren’t going anywhere—but they may soon take their long ride from farm to table in a far more environmentally friendly manner.

The transportation chain that moves our perishable food from its origins to our plates is a complex series of shipping and holding facilities that preserve fruit, vegetables, and meat for days and even weeks longer than before Jones’ invention. The bright red tomatoes you buy in the dead of winter give the impression that they were picked just before you purchased them. In fact, they were likely picked weeks before, while still green, and then chilled, shipped, stored, and eventually gassed with ethylene, which speeds up the ripening process that the coldscape had until then deliberately slowed, creating what ultimately amounts to the simulacrum of a perfectly ripe tomato that you encounter at the store. The intricate system, of which Jones’ mobile refrigeration unit is a linchpin, excels at meeting our endless expectation of fresh food in our local stores all year round. It works, but it comes at a cost.

A worker uses a tablet while loading a refrigeration truck. (Photo: Monty Rakusen/Getty Images)

Freight transportation emissions already account for just under 6 percent of global greenhouse gas emissions. And that number is set to rise as the global truck fleet is projected to expand by a minimum of fivefold (some experts anticipate as much as ninefold) in the coming decade. On top of that, the hydrofluorocarbon chemicals that Jones' transport refrigeration units use in their cooling cycle are known as “supergreenhouse gases” because they are thousands of times more warming than CO2. Can another self-taught dropout figure out how to keep our food cold on the road without overheating the planet?

Back in the 1930s, the consensus was that it was impossible to make a mechanical cooling unit that was small and sturdy enough to fit on a truck and that could run on diesel engine power alone. But as Al Fineberg, president of the United States Air Conditioning Company and one of Harry Werner’s golf partners that day, apologetically explained this, another buddy, Joe Numero, who had built a business manufacturing sound system for movie theaters, teased Fineberg by betting that his engineers could figure out how to do it.

Numero’s bravado was based on the extraordinary inventiveness of one employee: an entirely self-taught engineer named Fred McKinley Jones. The first African American to receive the National Medal of Technology, Jones was an orphan who had left school after sixth grade. One year after Werner’s fateful golf game, Jones registered a patent for the world’s first mobile mechanical refrigeration unit. The final link in the cold chain was complete.

A Thermo King refrigeration unit. (Photo:

Larry Hirshowitz)

After the Defense Department seized on Jones’ technology to supply troops with everything from blood plasma to ice-cold Coke during World War II, Thermo King trucks, as they came to be known, took off. In the 1950s and ’60s, refrigerated trucking took center stage in the American foodscape, weaving together a new retail landscape of warehouse distribution centers and supermarkets with increasingly enormous and remote farms, feedlots, and processing facilities. This expanded foodshed and its economies of scale brought down the price of meat, making it an everyday staple on the American dinner table, and created what food writer Joanna Blythman describes as “permanent global summertime”—a seasonless cornucopia of produce on supermarket shelves.

It had an equally huge impact on the geography of food production: Without refrigerated trucks, it makes no sense to grow 30 percent of America’s supply of frozen french fries in Idaho, which hosts just 0.5 percent of its population, or to slaughter 7,200 cows a day in a town with a population less than a third of that. With reliable, chilled transportation, food production can be pushed far away from the people who eat it, to places where the farming can be done most efficiently—with the result that California now grows half of the fruits and vegetables eaten in the United States.

Whether you think this kind of industrialization is a net positive or not, as the story of Werner’s chickens makes clear, refrigerated trucking also prevents a great deal of food waste. In China, where the cold chain is still developing, produce is often still transported packed in ice and hay—and farmers expect to lose at least a quarter of each load to rot. Globally, one-third of the world’s food production goes to waste. Researchers estimate that if developing countries had the same level of refrigerated transport and warehousing as the United States does, between a quarter and half that food could be saved.

But Jones’ engine comes with a hefty price tag in terms of emissions, air pollution, and noise. “We actually spent at least six months not being able to believe that diesel refrigeration units were as inefficient as all the figures we could find said they were,” admitted Michael Ayres. Ayres is managing director of the Dearman Group, a company founded to commercialize another mobile refrigeration unit invented by a self-taught high-school dropout. “Part of getting conventional transport refrigeration units at the right price point and slim enough that you can fit them on the vehicle means that you have to make quite significant compromises in terms of efficiency,” Ayres explained, noting that, on average, cold trucks use 25 percent more fuel than their room-temperature equivalent, with the refrigeration unit also responsible for releasing more than 29 times the polluting particulate matter of the truck’s main engine.

Peter Dearman, the company’s founder, left school at 15 to work on his family’s poultry farm. He is “the classic British garden-shed inventor,” explained Toby Peters, the Dearman Group’s chief executive—but Dearman’s three decades of tinkering have resulted in an entirely reinvented refrigerated unit whose only emission is cold air, and which is set to go into commercial trials next month.

Onions in a temperature-controlled loading dock. (Photo: Larry Hirshowitz)

The actual unit is both very clever and remarkably simple. The way it works is so similar to a conventional engine that the company built the first prototype using the motor from a Yamaha quad bike as the base—but instead of relying on high-pressure diesel to push the piston that powers the refrigeration unit, the Dearman engine runs off a tank of liquid nitrogen. At -320 degrees Farenheit, the liquid nitrogen circulates through the truck trailer, cooling its contents by absorbing heat. It expands as it warms, generating enough pressure to push the piston and generate power. Finally, its job done, it is vented to the air, which is already 78 percent nitrogen and can easily absorb a little more.

A handful of companies, including Thermo King, have been looking into cryogenic temperature control systems, as liquid nitrogen refrigeration units are called. A recent survey by California’s Air Resources Board found that, compared with the diesel-powered refrigerated trucks currently delivering America’s meat, dairy, and produce, cryogenic systems cool down more rapidly, are much quieter, contain no polluting refrigerant chemicals, and, most important, generate absolutely no greenhouse gas emissions or asthma-triggering particulates while in use. But the Dearman engine goes one better: Because it also takes advantage of the used, warmed nitrogen to power an engine, it extracts 50 percent more cooling from the same amount of liquid air than a cryogenic engine does. That additional efficiency is just the frosting on the cake in environmental terms, but it makes all the difference economically, making the Dearman engine cheaper to run than its diesel competition in most circumstances. That, combined with its minimal infrastructural requirements and impressive range, also makes it much likelier to achieve widespread adoption than rival clean-cold technologies such as hydrogen fuel cells or electric-powered refrigerated trucks.

In a food system where the ingredients for an average meal travel 1,500 miles to reach your plate, this kind of improved efficiency could have a huge effect on the environmental footprint of perishable food transportation.

Very little in life is free, of course, and cooling nitrogen into a liquid takes energy—but even after those carbon emissions are included in the equation, the Dearman engine results in a 40 percent saving over diesel. And, as Ayres pointed out, because liquid nitrogen production plants draw their power from the grid, if the developed world actually meets its climate change commitments and replaces fossil fuel electricity with renewably generated power, that figure will go up to 90 percent by 2030.

Meanwhile, as China, then India, and then the rest of the world catches up to American levels of cooling, there will be 15.5 million refrigerated trucks on the road within a decade. If they all run on Jones’ engine, a great deal of food waste will likely be prevented—but the cost, in greenhouse gas emissions and air pollution, may well be high enough to outweigh the benefits.

Perhaps it’s time to make another bet: Just as a self-taught engineer transformed the world with the invention of the first mobile refrigeration unit, let’s wager the next generation of garage tinkerer can reinvent that technology in order to help save the planet.