Reducing greenhouse gas emissions from households and industry by the use of charcoal from sawmill residues in Tanzania

Like many countries in sub-Saharan Africa, Tanzania faces considerable challenges in meeting the future energy demands of its rapidly growing urban population without depleting its forests. Nonindustrial charcoal production generates large emissions of greenhouse gases (GHG) in the form of CO2 from forest degradation and methane from oxidation in traditional kilns. On a global scale, the GHG emissions from cement production are of considerable magnitude and are increasing rapidly. In this study, the impact of converting sawmill residues into charcoal briquettes and charcoal powder in Tanzania was assessed, using a cradle-to-grave approach. Furthermore, the net effects on GHG of substituting more GHG-intensive fuels with these charcoal products were evaluated. Replacing coal in cement manufacturing with this sawmill charcoal powder may reduce GHG emissions by 455-495 kg of CO2eq MWh−1, corresponding to an 83-91% decrease. The net GHG emission reduction when replacing charcoal from miombo woodlands with these sawmill charcoal briquettes is 78-557 kg of CO2eq MWh−1, or 42-84%, depending on whether the substituted charcoal can be considered carbon neutral or not. These replacements may considerably reduce the GHG emissions from the cement industry and in charcoal-dependent households in Tanzania. Due to the significant problems related to energy supply and forest deterioration in sub-Saharan countries, as well as the global growth of GHG emissions from the cement industry, this study might of relevance also outside Tanzania.