Charcoal production and agricultural activities are main drivers of deforestation in Sub-Saharan Africa. They both generate a lot of residues, such as charcoal fines and biogenic residues from crops such as corn cobs and cassava peel. Deforestation could be reduced, if these residues could be utilized as fuel, particularly in rural areas. Low-pressure briquetting is a suitable approach for rural areas to valorize residues and obtain a uniform fuel quality. When charcoal is briquetted under low pressure, a water-binder mixture needs to be added. To determine the optimal briquetting parameters, the binder content, water temperature and briquette diameter were varied. The quality of the briquettes was evaluated by determining and assessing their compressive strength and density using Response Surface Methodology. The investigation shows that (i) regional residues are partly suitable as a fuel regarding their chemical composition, (ii) the quality of briquettes improves with increasing binder content and decreasing diameter, while an effect of the water temperature was only observed in two cases (iii) it is feasible to produce high-quality briquettes using regional agricultural residues. Based on these results, a low-pressure briquetting process suitable for rural areas could be developed for briquetting agricultural residues. • Low-pressure densification of residual charcoal and biochar from residual biomasses • Finding optimal binder content, water temperature and briquette size with RSM • Char grinding is a crucial pretreatment for low-pressure densification • Binder content of <15w-% is sufficient for low pressure briquetting • Shredded cassava peel can be utilized as binder in low-pressure char densification
Nikolaus et al. (Fri,) studied this question.