A new sustainable refrigeration technology that can extend the shelf life of perishables in developing nations with dry climates was born at the Massachusetts Institute of Technology in a class that challenged its students to create something that would help improve the lives of 1 billion people.
But the concept, which involves no electricity, was born 4500 years ago, when people in dry climates used evaporative cooling for food preservation in a technique that involved nesting two terra-cotta pots — filling the space in between with sand, and adding water.
Rudimentary evaporative cooling devices that include the stoneware above have proven to be effective for agricultural use, tripling or quadrupling the shelf-life of most produce. Evaptainers took these techniques and upgraded them for modern and commercial use.
The company’s products — modular and completely mobile refrigeration units that preserve produce along the supply chain — utilize the phenomenon of evaporative cooling, rather than more energy-intensive vapor compression refrigeration. This enables low-cost, electricity-free cooling. Using state-of-the art materials and improved design, they created more effective, more durable, easier to use, mass-producible units. The concepts have patents pending and there are currently no other similar devices on the market.
Evaptainer’s EV-8 is a collapsible, light-weight, fully portable refrigeration unit that can keep perishables like fruits, vegetables and dairy products fresh in the hot summer months. EV-8 requires no electricity to operate and is 100% eco-friendly with absolutely no greenhouse gas emissions. It can also improve the shelf stability of medical supplies such as insulin.
According to the 2016 World Energy Outlook, 16% of the world’s population has no access to electricity, which means they also have no access to refrigeration. Without refrigeration 45% of produce goes to waste. The United Nations’ Food and Agriculture Organization estimates that as much as $310 billion worth of food spoils in developing countries every year due in part to heat and lack of refrigeration.
One of Evaptainer’s small farm users in Morocco is typical of a family without refrigeration. The farmer’s story (see video below) shows clearly how it can impact quality of life. To shop for food the farmer must plan for a full day away, walk to the nearest taxi stop on the rural road and wait for a car to come to take him to the larger town. He pays for the ride, goes from stall to stall, buys as much as possible so he doesn’t have to come back frequently, pays for his lunch and pays extra for storage. He cannot work during this time. As a result, these trips cost 60-90% of his income. This expense does not even include the cost of spoiled food. During the hot summer his food only lasts 2 to 3 days so he must repeat the trip two or three times per week.
With an Evaptainer costing 30 dollars, the unit pays for itself in a few months’ time. It requires only one liter of water every two days and provides refrigeration than can significantly extend the shelf life of the produce. The farmer says it saves him money and gives him more time to work.
Evaptainers makes use of a technology they call PhaseTek. The cooling is activated when a user fills the internal reservoir with any source of water such as a tap, well, river, or lake. The walls of the device then begin to draw out heat from the interior of the device through evaporative cooling. The EV-8 can cool its internal storage space by 15-20 degrees Celsius from ambient conditions.
How does evaporative cooling work?
Evaporative cooling is something you may have experienced — for example, when you leave the water after swimming, a wind blows and suddenly you feel a bit chilled. This is due to an effect called latent heat of vaporization, where water consumes available heat in order to change phases, or in this case, evaporate.
For a detailed discussion of the science behind evaporative cooling, take a look at the Evaptainers video about the phenomenon, below or check out their “deep dive” paper on the website. One of the drawbacks of the technology at this time is that it functions less well in humid climates. Nonetheless the company hopes to supply refrigeration to the millions of people without electricity in arid climates.