Additional cooking fuel supply and reduced global warming potential from recycling charcoal dust into charcoal briquette in Kenya

Rising demand for energy is one of the major challenges facing the world today and charcoal is a principal fuel in Kenya. Faced with energy poverty many poor households turn to briquette making. This study assessed the additional cooking fuel obtained from recycling charcoal dust into charcoal briquettes. It applied Life Cycle Assessment (LCA) to assess the global warming potential (GWP) from use of charcoal and production of briquettes from charcoal dust and cooking a traditional meal for a standard household of five people. Native vegetation of Acacia drepanolobium and a low efficiency kiln were considered the common practice, while an Acacia mearnsii plantation and a high efficiency kiln was used as an alternative scenario. Charcoal and kerosene were considered as reference fuels. Recovering charcoal dust for charcoal briquettes supplied an additional 16% cooking fuel. Wood carbonization and cooking caused the highest GWP, so there is a need for technologies to improve the efficiency at these two stages of charcoal briquettes and charcoal supply chain. Supplying energy and cooking a traditional meal in a combined system using charcoal and recovering charcoal dust for charcoal briquettes and charcoal alone accounted for 5.3–4.12 and 6.4–4.94 kg CO2 eq. per meal, respectively, assuming trees were not replanted. These amounts declined three times when the carbon dioxide from the carbonization and cooking stages was assumed to be taken up by growing biomass. This requires replanting of trees cut down for charcoal if the neutral impact of biomass energy on GWP is to be maintained.