Characterization and cooking performance of charcoal briquettes made solely from matooke peelings

Abstract

Charcoal briquettes are an inexpensive alternative cooking fuel to wood charcoal and firewood, that can be made from loose biomass. Matooke is one of the most consumed foods in Uganda and the Great Lakes Region. It contributes the bulk of the organic household waste in regions where matooke is a staple food. This study was undertaken to; determine the yields of char and binder obtained from fresh matooke peels, produce charcoal briquettes using matooke peels as binder and char, characterize, and determine the cooking performance of the charcoal briquettes made. Matooke peelings were collected, sun dried and processed to make both binder and char feed material. Briquette samples of 1000 grams of char blended with matooke peels binder solution of; 0%, 2.5%, 5%, 7.5%, and 10% dry weight ratio were made. The samples obtained were sun dried, characterized and their cooking performances tested. 1000 grams of fresh matooke peels yielded 226 grams of flour and 91.5 grams of char, charcoal briquette samples made yielded between 72 grams to 1358 grams. Matooke peel starch binder increased briquette samples physical strength with lowest drop test weight loss of 5.1% and showed improved moisture penetration resistance with longest water dissolving time of 12.71 seconds. Test sample briquettes also shown the highest Higher Heating Values of 20.9MJ/kg. Test samples showed fixed carbon (31.69 to 38.31%), moisture content (7.18 to 7.69%) and volatile matter (32.29 to 35.73%) and ash content (21.3 to 27%), thermal efficiency (33 to 41%), burning rate (5.23 to 6.92 grams/min), specific fuel consumption rate (41.9 to 51.83 grams/litre) and indoor emission rates of carbon monoxide CO (4.15 to 5.76 grams/min), particulate matter PM 2.5 (66 to 114.1 grams/min). The study in general found that fresh matooke peels yield for binder is higher compared to the yield for char. The matooke peel char and binder produced charcoal briquettes of good physical strength, high energy content, similar thermal cooking performance to common charcoal briquettes but with drawbacks of high-water solubility, high ash content, and high emissions rate. This study therefore concluded that due to the extremely high emissions above the WHO stipulated guidelines (CO 0.59 grams/min and PM2.5 0.8 grams/min) for indoor emission rates, the matooke peels charcoal briquettes produced in this study do not qualify as a good cooking fuel.