Bamboo solar dryer solves the post-harvest problems  

Grace Aguti and Peter Onyango grew up in Gulu District, with their families suffering from food shortages and wastage due to lack of ways to store food harvested from the farm. 

This led the two MasterCard Foundation scholars at Earth University in Costa Rica to create a combination food dehydrator and greenhouse made from bamboo. 

Innovation 
Their innovation, which they called Pura Vida, is a prefabricated bamboo greenhouse and dryer system that they describe as an adaptable, climate-change-friendly food security system that allows families to grow food during the dry season and to dry produce during the wet season. 

“We both grew up in rural areas seeing our parents struggle through every wet and dry season of the year. During the dry season, there is not enough to eat, and in the wet season, a good part of the harvest is lost to rotting,” Onyango says.

Dryer 
Pura Vida is an arch-shaped structure constructed from bamboo sticks, insect screens, and polyethylene plastic, an idea that was inspired by the da Vinci bridge model designed for the sultan of the Ottoman Empire in the early 1500s. 

The ground where the dryer will be constructed is levelled and the dryer varies in size depending on the user’s needs. The arched shape is formed when the bamboo pieces are firmly fixed at one end and curved to the other end, with other bamboo pieces laid horizontally to fasten the structure.

“We chose bamboo because it is an environmental wonder-plant that can be harvested in just two years. The design, also called the da Vinci bridge model, is easy to construct and does not need special skills or equipment to build,” says Onyango.

Process 
The bamboo is treated using borax and boric acid before use in order to deter borers, termites, and fungi and ensure a product life of around 35 to 50 years. To provide partial shade during the growing season, passion fruits are planted to cover the top and filter out a portion of the sunlight so as to reduce the temperature inside the bamboo greenhouse. 

“Our system has varying sizes based on the needs of the farmers, for example our prototype for a demonstration centre will measure 11.8 m x 7.6 m with a total area of 89.68m2 and the estimated construction time is two days from ready bamboo.”  

A 10 m2 tray can dry 25 to 40 kilogrammes of fresh produce over a period of three to four days. The solar dryer has a high drying rate and a shorter drying time than outside sun drying. The trays are made of wire mesh in a bamboo framework, allowing 99 percent of the food dried inside to be retrieved. 

The venture will provide food security by providing controlled conditions for growing and drying all year round, transforming bamboo into a family and community asset for household income, environmental conservation, food security, and employment.

“According to a report by the Food and Agriculture Organisation (FAO) and the Ministry of Trade, Industry and Cooperatives, 75 percent of basic food in Uganda comes from cereals and pulses; about 13 to 18 percent of grains alone are lost in post-harvest due to poor drying and high moisture content at the time of storage. The bamboo greenhouse/solar dryer system will save 99 percent of farmers’ food from moisture and rotting,” Aguti says.

Mission 
The venture’s targets is to commission five model farmers in different communities in the first two years and then develop a business design that will target both small- and large- scale farmers.

The five participants in the pilot project will receive the structures free of charge.  After the two years, the venture will offer consultation, sale of the prefabricated system, sale of crops from the demonstration farms, grants, commercial and business model design, and help NGOs and government who need business training.

Pura Vida won the 2019 Resolution Social Venture Challenge, a competition that rewards compelling leadership and promising social ventures led by the youth.