Uganda: Solar Cold Storage for Fruits and Vegetables

 Solar Cold Storage

Perishable food especially fresh fruits and vegetables usually get wasted as soon as they are harvested because they are cut off from their source of water and nutrition.

They lose weight, texture, flavour and nutritional value. Cooling significantly slows down the rate of deterioration, thus increasing storage life of the produce.

Against this backdrop, two scientists--Hadija Nantambi Ssekyondwa, a graduate of Technology and Industrial Development from Makerere University, and Sylvia Namazzi, a plant breeder and an expert in seed systems--developed a cold storage facility.

It is an integrated solar powered walk-in cold room that can help in off-grid storage and preservation to address post-harvest losses in fruits, vegetables and other perishable food like meat.

Ms Ssekyondwa, who graduated last year, analysed the challenge of lack of storage for perishable produce, and ventured into developing solar-powered cold room with the aim of farmers adopting it.

It operates with power generated from a solar panel mounted on the roof, which is stored with high capacity batteries. This feeds an inverter, which in turn feeds the refrigeration unit. The capacity of the solar panel depends on the size of the storage house.

The structure of what the developers term "eco cold room" has plastic (PET) bottles, which act as an insulation. This is after constructing the structure using bricks and cement.

There are two cavity walls with the PET bottles in between. The bottles as an insulator help to suck the dry air between the walls once the room is cold.

The condenser and evaporator are connected to sockets and the cooling system is connected to a thermostat, which enables automatic switch off in case the room attains the required cold temperature.

Nantambi contends that tropical fruits and vegetables require maximum temperatures range from 10 to 13 degrees Celsius.

Whereas a 20 cubic metre cold room would require Shs25m as total cost, a modest cold room which uses hydro electric power costs about Shs120m to construct. Nantambi's design is to make it less costly for the farming community.

Farmers may not afford such a facility as an individual but they can form associations and solicit funds for group storage facilities.

"Our innovation is a novel technology coupled with a unique business model of collective marketing approach," she explains.

Given Uganda's solar potential and the necessity of storage facilities to minimise transport distances, off-grid solar-powered cold storage is an opportunity to improve agricultural production and incomes leading to reduced produce waste and improve food security.

How it is being done

Explaining how the innovation came about, Hadija Nantambi Ssekyondwa noted that when one buys fruits and vegetables in markets, the quality is low due to challenges of storage facility.

"Farmers bring their vegetables and fail to sell them the same day. They either cover it with paper boxes or simply leave them open. To curb this challenge, I thought of developing cold room storage which will not require electricity from the main grid."

Ms Ssekyondwa and her colleague Sylvia Namazzi have set up 20 cubic metre cold room in Bulindo, Kiira Town Council in Wakiso District where they operate Eco Life Foods. It deals in agricultural produce mainly fruits and vegetables.

"We are already storing these fruits and vegetables on seasonal basis especially peak times during the rainy season," she says.