Performance and economic evaluation of a locally fabricated biochar kiln for sustainable production from agricultural residues in Ghana

Biochar has gained attention due to its potential to improve soil carbon storage and mitigate climate change. However, to encourage widespread adoption, biochar production must be cost-efficient and easily accessible, particularly from farm residues. The present study evaluates the performance of a self-energy-recirculating, locally fabricated biochar kiln using five feedstocks: maize cob, rice husk, coconut shell, and flamboyant pods. The specialised kiln can char all organic-based feedstocks, regardless of the particle size. The focus was on energy use efficiency, biochar yield, and the quality of the produced biochar. The study used a slow pyrolysis ranging from 300 ˚C to 600 ˚C. Results showed that biochar quality varied across feedstocks, with coconut shells and rice husks requiring more energy but yielding higher amounts of biochar than flamboyant pods, maize cob, and maize stover. Economic analysis indicated that coconut shells and maize cob were the most profitable feedstocks, with profit margins of 57.05% and 76.96% and internal rates of return of 3.75 and 1.84, respectively. This suggests that while some feedstocks are more energy-intensive, they offer higher financial returns. Further studies on the environmental benefits of these biochars, both short-term and long-term, are necessary. The findings of this study provide a basis for the development of kilns suited to local conditions, promoting the economical production of biochar from agricultural residues.