Charcoal Production from Macadamia Shells Using Super Sun Retort and Kon-Tiki Kiln

Crop residues in Thailand are abundant but underutilized, creating a need for better valorization methods, such as charcoal production. This research aims to utilize agricultural waste by studying the production of high-quality charcoal briquettes from macadamia shells using a Super Sun retort, utilizing heat generated from the Kon-Tiki kiln. This method adds value to surplus agricultural residues and can help reduce air pollution caused by the open-field burning of biomass. In each experimental run. 53-79 kg of firewood and 25 kg of macadamia shells were used. Data on pyrolysis temperature and charcoal yield were collected over a carbonization period of approximately 7 - 8.5 h. The resulting charcoal was then processed into charcoal briquettes. The quality of the charcoal briquettes was tested according to the Thai community production standard (TCPS 238/2004). The results showed that the Super Sun retort produced charcoal at high temperatures (>600 °C), while the temperature above the Kon-Tiki kiln reached 745 °C. The macadamia shells were completely converted into charcoal, with the highest charcoal yield reaching 32%. The charcoal briquettes from macadamia shells had a high calorific value of 7,257 cal/g and a low moisture content of 2.62%. both of which were better than the requirements of the standard. These findings indicate that the macadamia shell charcoal produced in this study has strong potential for use in high-quality charcoal briquette production. The results also suggest that the combination of the Super Sun retort and Kon-Tiki kiln could offer a sustainable and cost-effective solution for charcoal production in developing countries.