ENGINEERING FOR CHANGE
LOW-ENERGY REFRIGERATION
Cooling chambers keep food fresh in low-resource areas, all with just a swamp cooler and stacked crates.
Written by Rob Goodier
FOUNDED AS A SPINOUT from MIT D-Lab, the CoolVeg Foundation is a non-profit focused on technologies that utilize evaporative cooling for the preservation of fruits and vegetables in hot and dry climates.
The solution combines a swamp cooler and stacked crates, with the option of adding solar panels. Coolers keep costs down with off-the-shelf parts, and they have a customizable footprint and functions. One custom version even blows the cool exhaust from the chamber over the front of the store that it serves, creating a cool breeze to attract customers escaping the heat.
Eric Verploegen founded CoolVeg in 2023 after moving on from MIT D-Lab. His work expands on another simple-but-effective innovation: clay pot evaporative coolers. Clay pot coolers are two nested terracotta pots with wet sand in between. As the water evaporates, it draws heat from the inner chamber, cooling the contents and extending the shelf life of produce inside. CoolVeg offers clay pot cooler training programs, and Verploegen has been an advocate for the technology long before the launch of CoolVeg.
CoolVeg’s solution keeps produce fresh with just a swamp cooler, stacked crates, and optional solar panels. Photo: CoolVeg
Now CoolVeg is designing and building bigger, more complex evaporative coolers for farms, stores, and transportation, supporting the entire cold chain. The largest coolers are modified shipping containers, and the mobile coolers are built on trailers for hauling by truck. CoolVeg’s portable coolers are intended for use in stationary applications on farms or at retail markets. ‘Portable’ refers to their maneuverability. Five or six people can lift a portable cooler off a truck and carry it into place before setup.
All three systems are built around swamp—or evaporative—coolers. They blow air over wet pads that lower the temperature as the water evaporates. One of CoolVeg’s innovations is the careful design of airflow pathways throughout the chamber, maximizing the cooling rate and energy efficiency.
CoolVeg’s three systems are in different design stages. The team is preparing to test the commercializability of the portable system in Kenya, India, and Nigeria this year, Verploegen said.
A diagram shows how air flows through the CoolVeg coolers. Photo: CoolVeg
“The current prototypes are performing well and they’re easy to construct, and the price points are more aligned with the market,” he added.
The portable systems can cool 1,100 pounds (500 kg) of produce by 18 °F (10 °C) in six hours using less than 200 Watts of electricity. At the moment, the portable prototypes cost $1,300 in India and $1,700 in Nigeria for on-grid systems. Off-grid systems that include solar panels, batteries, and inverters cost up to $2,200 in India and $2,700 in Nigeria. The costs are 60 percent less than traditional cold rooms of similar size, according to CoolVeg’s research.
The work is supported by the Efficiency for Access Research and Development Fund, which backs innovations that improve energy access and livelihoods. And CoolVeg collaborates with partners, including Artisana in India and ColdHubs in Nigeria.
With over-the-counter materials and smart designs, these coolers can give farmers and grocers a practical way to keep food fresh, reduce post-harvest loss, and earn more income.
Rob Goodier is news editor at Engineering for Change, a community working to prepare the international technical workforce to improve life for people and the planet. ASME is a founding partner of E4C.
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