Socioeconomic and environmental benefits of substituting firewood with charcoal briquettes produced from biomass residues in the Forestry Belt in Chile

Abstract

An assessment of the potential economic, environmental, and health benefits of substituting firewood with charcoal briquettes as heating fuel in cities located in the Forestry Belt in Chile is conducted. Experimental results obtained by the authors allowed to determine production yields and energy packing of charcoal briquettes obtained from Eucalyptus globulus and radiata pine residues. Given the large annual harvested surface of these two species, large quantities of residual biomass are left available at very low cost. The technology proposed to produce these charcoal briquettes is based in the process of pyrolysis in retort kilns. These give better results than traditional methods used until now in Chile to produce charcoal, but a higher technology level is required. Retort kilns rendered yield ratios of 0.247 and 0.286 [kg of charcoal/kg feedstock] for eucalyptus and radiata pine respectively. Charcoal briquettes gave a LHV (lower heating value) of 7836 kcal/kg and 7975 kcal/kg for eucalyptus and pine forest residues feedstock respectively, about twice that of dry firewood. Our economics analysis renders a cost of 0.1059 USD/kWh, which is competitive against firewood and other fuel options. In terms of health and environmental impact it is estimated that using charcoal briquettes from eucalyptus and pine harvested residues would reduce PM2.5 (particle matter <2.5 μg) air pollution, the most critical source of contamination in this geographic region, around 7.96 %, saving annually an estimated 9376 tons from being delivered into the atmosphere. An estimated 8.3 % of the annual firewood consumption (966,656 m3/year of which 2/3 is native) would be saved, so that 2041 ha of native deforestation would be avoided.