Life cycle assessment of metallic vs. wooden structured solar dryers: Insights into the environmental sustainability

Solar drying has emerged as a viable alternative drying method to fossil fuel–based methods, extending the shelf life of agricultural products, reducing post-harvest loss, ensuring food security, improving the livelihood of the people, and minimizing environmental impacts. While the thermal efficiency of solar dryers has been studied by many researchers, their environmental sustainability remains mostly understudied. This study attempted to fill this gap by comparing an indirect metallic structured solar dryer (ISDM) and a wooden structured dryer (ISDW), both equipped with thermal energy storage (TES) materials. The study employed the cradle-to-grave method of life cycle assessment, whereby the midpoint and endpoint characterization values were calculated using the ReCiPe 2016 (H) model. Primary data for the assessment of the dryers was collected from the owners and manufacturers of the two types of solar dryers, supplemented by some secondary data from the ecoinvent database. The life cycle of ISDM shows endpoint single-score impact values of 2.15, 19.6, and 414.26 pt on resources, ecosystem, and human health, respectively. ISDW shows endpoint single-score impact values of 1.99, 17.49 and 289.32, respectively, for the same factors. These findings suggest that ISDW has a lower environmental impact than ISDM; hence, it is recommended for small-scale farmers in developing countries like Tanzania. The findings further demonstrate that not all solar dryers have equal sustainability benefits and that not all solar drying technologies have the same environmental impact. This calls for further investigation into proper material selection and end-of-life management strategies in order to reduce environmental impacts. Policymakers should prioritize the development and implementation of policies that promote the widespread adoption of environmentally sustainable solar dryers (such as the ISDW model) by providing support to small-scale farmers through incentives and investments in research and development. Furthermore, national renewable energy strategies should incorporate end-of-life (EoL) management strategies to mitigate resource depletion and promote circular economy practices in the design and disposal of solar drying components and materials. Future research should focus on identifying alternative, low-impact materials for solar dryer construction and adopting a holistic sustainability assessment approach that integrates environmental, economic, and social dimensions in the assessment. In addition, further LCA studies should explore viable EoL options for solar dryer materials such as recycling, safe disposal (land filling), repair or refurbishment, and new manufacturing. These measures will contribute to extending the shelf life of crops, particularly perishables, reducing post-harvest losses, enhancing food security, and promoting environmental sustainability. Ultimately, such efforts will contribute to the realization of Sustainable Development Goals (SDGs) 2, 13, and 15, which emphasize zero hunger, climate action, and sustainable ecosystems, respectively.