Assessment of the quality of briquettes produced from shea cake and shells in Northern Ghana

Abstract

Shea cake and shea nut shells are major yet underutilized residues from the shea butter industry in northern Ghana, representing a locally abundant biomass resource that could be upgraded into cleaner solid fuels. This study aimed to systematically assess the physicochemical, mechanical, and combustion quality of briquettes produced from shea cake and shells. The research was conducted in the Tamale Metropolis and Sagnarigu Municipality. Composite samples were prepared from residues collected across 10 processing centres (≈330 kg shells and 270 kg cake), and briquettes were produced using a full factorial design (2 × 3 with three replicates; 18 products) varying feedstock type (cake only, shell only, and shell+cake) and binder system (paper, clay, and paper+clay) at 10%, 20%, and 30% binder levels. Materials were sun-dried, milled to 2.5 mm, compressed at 1500 psi into cylindrical briquettes, and air-dried for three weeks. Paper-bound briquettes exhibited very high to high flammability, with the highest HHV (notably 90% shell and 10% paper at 19.5 MJ/kg), and the lowest ash content (3.5–4.0%), supporting efficient domestic cooking. In contrast, clay-rich briquettes achieved greater compaction and the longest burn times (up to 60 min) but reduced HHV and increased ash, favouring sustained heating applications. This indicates that optimised, standardised production can enable shea-waste briquetting as a practical circular-economy pathway to expand renewable household and small-scale industrial energy options in shea-producing communities.