Electricity-free Fridge Could Change Millions of Lives

An illustration of the EV-8, which can vastly extend the life of perishables. Evaptainer/Maximillian Stock Ltd./Getty

A lightweight, portable cooler could help keep food fresh for the millions of people who have unreliable electricity or don't have access to electricity at all. Evaptainers' EV-8 uses evaporative cooling to keep the temperature inside it 27 to 36 degrees Fahrenheit (15 to 20 degrees Celsius) lower than the temperature outside.

The EV-8 could work, not just for people without refrigerators in their homes, but for displaced migrants living in refugee camps, and for victims of natural disasters that have destroyed local infrastructures.

"On average, it doubles or triples the shelf life of the foods," says Quang Truong, who conceived of the idea and cofounded Boston-based Evaptainers with Spencer Taylor.

In Morocco, where Evaptainers has tested several prototypes of the device, tomatoes last a week, as opposed to two or three days. Onions that usually last five days could last 10 days to two weeks. The country is the perfect location for the device, since it works best in hot, dry climates.

"Some of the most vulnerable populations in the world live in those environments," says Taylor.

These locations — including India, African nations north and south of the Congolese jungle belt, the entire continent of Australia, and the states in the American Southwest — have an average relative humidity less than 65 percent. "The drier the air, the greater the rate of evaporation," says Taylor.

When Taylor and Truong crunched the numbers, they estimated they could potentially help 652 million people.

Why It's So Cool

Anyone who's ever stepped out of a pool on a hot, summer day knows the cooling effects of evaporation. The physics are straightforward. Heat excites molecules, causing them to escape the liquid's surface as gas molecules. As they do, they take some of the heat with them, cooling what they've left behind.

Evaporative cooling techniques have been around for centuries. Stone frescoes from Egypt that date to 2500 B.C.E. depict slaves fanning a stoneware jar to cool its contents. Leonardo da Vinci also experimented with evaporative techniques, and so did Benjamin Franklin. But then electricity came along, as did the refrigerator and evaporative cooling seemed to fade into history.

Then, in the late 1990s, a Nigerian man named Mohammed Bah Abba revived the ancient technology of the clay pot-in-pot system. Still in use today, the zeer pot consists of two clay pots, one smaller than the other. The smaller one is placed inside the larger one and the space between them filled with sand. By wetting the porous matrix of sand with water and then placing a cool, wet cloth over the top as a lid, evaporation goes into effect, and any perishables stored inside stay fresh longer.

It was a great innovation but was not widely adopted outside of Nigeria.

"The zeer pots have a life span of about one or two years because they either break or the pores get clogged up," says Truong.

They're also difficult to mass-produce, notes Taylor, and if the user adds too much or too little water to a pot, it doesn't work efficiently.

But the basic concept was sound, and one day it dawned upon Truong that it could be improved. He was taking a class for budding entrepreneurs at the Massachusetts Institute of Technology and was instructed to come up with a good or service that would change the lives of a billion people.

He thought of the times he spent traveling through countries like Vietnam, Haiti, India and Liberia, and how the smell of rotting food frequently dominated his experiences. After doing some research, he found that, according to estimates from the Food and Agriculture Organization of the United Nations, about 45 percent of fruits and vegetables in Africa spoil before they reach the market. Truong thought he could modernize the zeer pot concept into something larger and more lightweight.

That was back in 2012. After refining several prototypes and winning a couple of innovation competitions along the way, Truong and Taylor think they're nearly ready for the market, where they hope to sell the EV-8 for about $30 to $35.

Getting to Know the EV-8

The EV-8 has a rigid, top and bottom with collapsible sides made from a lightweight membrane Evaptainers developed called PhaseTek. In the collapsed state, the rigid top and bottom fit together to make the device compact for shipping. To expand the box, the user flips up the fiberglass stays at each corner. In that state, it measures 53 centimeters (21 inches) long x 41 centimeters (16 inches) wide x 28 centimeters (11 inches) tall, with a volume of 60 liters (16 gallons). You can get a better idea of how big that is by watching the company's explainer video.

To cool the inside, the user fills an opening in the lid with 1 liter (1 quart) of water. The water soaks into the four membrane walls and over the course of the day, the water evaporates, cooling the inside. The user need only fill the reservoir once per day, a considerable water savings over the zeer pot, which needs to be filled with 1 liter of water about every six to eight hours.

In May 2017, the EV-8 won its latest award, the People's Choice Award at FoodBytes San Francisco. This summer, the company is launching its final pilot in Morocco before taking the EV-8 to a fully commercial product.

"Everyone on the team is really passionate about the project," says Truong. "Everyone really believes in the current version that we have, and that it will work for a lot of people."