Solar powers novel dryer for preserving crops

Purdue College of Engineering
Purdue Engineering Review
4 min readJun 10, 2024
Elementary school students in Kenya learn to use the Dehytray™, a solar crop dryer developed and commercialized by Klein Ileleji, a Purdue professor of agricultural and biological engineering. (Photo provided)

Humankind has been drying food to preserve it since prehistoric times. Food dehydration removes the moisture from food to inhibit the growth of bacteria and mold in order to increase its shelf life. Food typically is dehydrated by using heated air in an electric or gas-fired oven; drying in a solar dryer, which concentrates the heat; employing a desiccant; leaving a product to dry in the open air; or sun drying in the open air.

The use of heated air is the most common method in developed countries and can be quite expensive. Globally, the majority of farmers today use open-air sun drying to preserve the crops they grow. Sun drying is fairly inexpensive (zero energy input) and carbon neutral. However, it has a daunting limitation in a food-insecure world: It can only work effectively during the daytime when sunshine is plentiful and it doesn’t rain.

Technologies for drying horticultural produce (specialty crops) at a scale for small and midsize farmers are some of the least developed in the industry. We’re creating such technology for a multipurpose solar dryer. As its name suggests, a multipurpose solar dryer can dry several types of crops, and is designed for high-moisture horticultural produce, including fruits, vegetables, spices and medicinal plants.

It works by capturing solar energy in the form of heated air and transferring the heated air to a drying chamber where the crops are presented. Rather than using open-air sun drying, which can result in foods being contaminated with things like dust, insects, birds and livestock, the heated chamber provides a more hygienic drying environment.

The innovation originated when I worked with USAID’s Feed the Future Innovation Lab for Food Processing and Post-Harvest Handling. The goal was to develop a solar dryer for maize (corn) suitable for smallholder farmers in Senegal and Kenya. Rather than design a crop dryer to focus on just drying maize, I pivoted to designing a multipurpose crop dryer. As we interacted with farmers and stakeholders in the region about the crop dryer for maize, they said they would like a dryer that also could dry vegetables, fruits, root crops, and so forth.

USAID encourages technologies developed in the lab to be transferred to farmers in the field via commercialization. In keeping with that aim, I worked with the Purdue Office of Technology Commercialization (OTC) to patent two different solar dryers and launch a company, JUA Technologies International, Inc. (JTI), to sell them.

The smaller, portable dryer is manufactured and sold by JTI under the tradename Dehytray™; the larger unit is still under R&D by JTI. Our goal is to make both dryers hygienic and efficient drying platforms to meet the needs of home, small and midsize farms and businesses, which are key to local food growers and urban agriculturalists.

Klein Ileleji trains a women’s cooperative in Qubodiyon District, Tajikistan, on solar drying using the Dehytray, in an effort supported by the USAID Feed the Future Horticulture Innovation Lab. (Photo provided)

In emerging countries, growers can experience postharvest losses of as much as 50% of vitally important produce. Multipurpose solar dryers can not only increase growers’ food security but also enable the growers to raise revenue by more successfully processing their harvests.

Solar is critical. With access to affordable electricity still in short supply, and out of reach for some 2 billion people, the use of electric dehydrators is out of the question. The use of fossil fuel (such as natural gas and fuel oil) is simply out of reach for most rural dwellers in developing countries. Due to climate change, the current global trend is to pursue energy sources such as renewables that decarbonize society, which makes solar energy a viable option.

Solar energy, on the other hand, is abundant, but it unfortunately has not been harnessed effectively for drying crops. While an enormous amount of research literature on solar drying has been generated, very few designs have been commercialized at scale. In fact, it is easier to buy a Tesla car than a solar dryer.

Solar dryers capable of drying fruits and vegetables that are high in crucial micronutrients are essential to meet global food demand and will have a net positive impact on the environment. JTI is working to make its solar dehydrators accessible to anyone around the world who needs them.

Klein E. Ileleji, PhD

Professor and Extension Engineer

School of Agricultural and Biological Engineering

College of Engineering

Purdue University

Co-founder and CEO, JUA Technologies International, Inc. (JTI)