Development of charcoal briquettes using Sehalahala (Seriphium plumosum and Felicia filifolia)

Abstract

Introduction: Production of charcoal briquettes using invasive shrubs found on Lesotho’s rangelands can provide alternative sustainable biomass energy for household heating and cooking applications in rural Lesotho. Objectives: To develop briquettes using the two species of Sehalahala (Seriphium plumosum and Felicia filifolia) and evaluate the performance properties of charcoal briquettes made from the two shrubs. Methods: Sehalahala feedstock was harvested and dried for five days to reduce the moisture content. Dried materials were cut and carbonised using a 200L steel drum. Wheat and clay binders were added at 5% (w/w) with charcoal powder and mixed together. Puck shaped briquettes were developed using a car jack driven briquetting machine. Four treatments (2 species and 2 binders) were developed and compared with a briquette purchased from the local supermarket for benchmarking. Proximate analysis was conducted using ASTM standards. Caloric value (MJ/Kg) was calculated using an empirical formula. Ultimate analysis was undertaken using a LECO CHNS 628 Determinator. Results: The mean percentage value of the four manufactured briquettes for the respective parameters evaluated were found to be as follows: moisture content (6.83 ± 2.72) m %,volatile matter content (30.53 ± 5.93) m %, ash content (3.77 ± 1.10) m %, fixed carbon (58.88 ± 6.51) m %, and higher heating value (25.66 ± 1.28) MJ/kg. In addition, the results indicated that the clay binder yields higher calorific value compared to the boild wheat flour suspention mix. Results of the ultimate analysis showed total carbon (35.14 ± 4.13) %, total nitrogen (1.01 ± 0.20) %, hydrogen (2.13± 0.26)% and sulphur (0.34 ± 0.08) %. Conclusion: Based on the results, it can be concluded that Sehalahala is suitable for production of bio-char briquettes. The newly produced briquettes have a higher energy content, less indoor air pollution and burns longer than traditional biomass (cow dung, agro-residues, shrubs, wood, etc) used in rural Lesotho for cooking and laughing applications. However, the results also indicate an opportunity for optimising production methods in order to achieve better results for mass production.