The present study focused on the combustion of four types of briquettes made from paper and cardboard waste produced in Ouagadougou (Burkina Faso). Rotary and tubular kilns were used to study the combustion. The combustion mean temperatures, nitrogen, phosphorus and potassium (NPK) content in the ash and heavy metals content in the ash and the flue gas were analyzed. The combustion steady phase mean temperatures ranged from 950 °C to 750 °C were obtained according to briquettes type. The temperature favored the transfer of the heavy metal in the flue gas comparatively to the ash mainly for Hg, Cd and Pb. The Pb, Hg and Mn content in flue gas and the ash are higher than their content in the parent wood used for paper production due to the additive during the manufacturing process. The results showed a high content of heavy metal in flue gas produced by combustion of briquette made with office paper and in the ash for the briquette made of corrugated cardboard. Furthermore, the low heavy metal contain in the ash allow their use for soil amendment. However, ash contained a low proportion of NPK (less than 2%) which does not allow their usage as fertilizer alone.

For decentralized power generation in West Africa, gas from a small biomass gasification unit can be used as the main fuel in a dual-fuel engine with diesel as the pilot fuel. To study the combustion in this type of engine (Lister Petter), experiments were conducted with a surrogate gas composed of liquefied petroleum gas and nitrogen (LPGN2), the energy context of which is similar to that of syngas. The tests were conducted at different loads and for different diesel substitution rates. The combustion analysis showed that the LPGN2 mixture had an overall behaviour similar to neat diesel, while the pressure peaks were lower in dual-fuel mode. The results also indicated a longer ignition delay and a pronounced diffusive combustion phase leading to a lower indicated mean effective pressure with gas. The fuel efficiencies remained low in both mono- and dual-fuel operation. The relative instability of the combustion in dual-fuel mode gave rise to an increase in the coefficient of variation (COV_IMEP). Compared to neat diesel, the engine running at low loads in dual-fuel mode showed higher emission levels of CO, a slight reduction of 2.5% of CO₂ and a substantial decrease of 73% for nitrogen oxides.