US researchers develop freezer system to bring free fruits, vegetables to Africa

When people go hungry, they oftentimes suffer, but fresh produce is extremely scarce in some parts of Africa — with up to 70 percent of some populations lacking access to adequate food. In southern Nigeria, until recently, people living in the rural villages had to rely on local foods that could not stand the harsh climate.

But thanks to a system called ColdHubs, residents of the region can have fresh produce from various farms delivered to their homes every week. The system, developed by a team at the University of California, Riverside, is an adaptation of the ColdSeparator method that has been used for decades in Russia. The ColdSeparator is a refrigerator that when a plant is located on its roots, directly below the ground, the ambient temperatures are zero degrees Celsius.

There is a water-filled lid on the freezer compartment which has “fresh air mass flowing in around the wall of the cavern so the air is denser and more dense,” said Dr. Sabino Machá, a PhD student on the ColdHub team, in a press release. “This causes all these things to evaporate and condense, and only the gases leave the cavity.”

The room is pressurized to maintain the air pressure and temperature around zero degrees, but the humidity cannot rise above five percent. When crops are placed inside the system for a three-week storage, the greenhouse surrounding it will act as a water reservoir, which will eventually fill up and create a state of condensation which contains the same gases as in the chamber.

“This whole mode of production is designed to resemble a garden,” Machá said. “Where everybody has the experience of gardening, not only will we produce more food because we have more people involved, but we will have less carbon emissions because the harvest will be more efficient.”

Machá is the winner of the 2018 Distinguished Student Lecture Award by the Institution of Naval Affairs in Science, Technology, and Engineering, and says his work with ColdHubs is a form of peaceful change.

“We are all solving for the same problem, and in that way we are reducing our own carbon footprint,” Machá said. “Even a country that is the largest emitter in the world is using the same system as us. It’s a global problem.”

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