Increasing Shelf-Life and Reducing Postharvest Loss of Nutrient-Rich Foods: An Assessment of the Potential for Solar Chimney Dryers in Rural Bangladesh

Abstract

Postharvest food losses represent a significant challenge worldwide. Enhanced solar drying technologies are a promising way to reduce losses of perishable foods, thereby enhancing accessibility and potentially increasing dietary diversity. This paper assesses the field-level performance of one chimney dryer design used for drying vegetables, fruits, and fish in rural Bangladesh. A mixed-methods research design was used for this study, including qualitative data analysis based on focus group discussions (FGD) and key informants' interviews (KII), coupled with detailed real-world quantitative assessments of the benefit–cost ratio (BCR), net present value (NPV), and internal rate of return (IRR) associated with the technologies tested. The chimneys were introduced in three locations of southwestern Bangladesh and used by 35 smallholder households. The IRR was found to be relatively high, resulting in profitability within 2 years of operation, depending on the food items selected for moisture removal through the chimney dryers. Two of the three dryers had a BCR > 1, and all three showed positive NPV values. However, none of the chimneys were used at full capacity. These findings suggest that such dryers are both technologically and economically viable, by accelerating drying times, improving food quality and market value, and reducing food losses in the process. The potential exists for enhancing local diets with dried nutrient-rich foods. Promotion of solar chimney dryer technologies could represent an important value-chain investment benefiting adopting households and food purchasers. The economic case would be stronger still if such technologies were used at full capacity for the drying of high-value perishable foods having high demand in local markets.