Eficiência energética e emissões de GEE do processo de combustão de biomassa florestal

Abstract

The environmental impact of economic activities has been increasingly monitored, with the aim of minimizing GHG emissions to the atmosphere as much as possible. In the agricultural sector, tobacco, in addition to its economic importance for small rural producers in southern Brazil, has a strong environmental appeal throughout its production process. Part of this appeal is due to the drying of tobacco, Virginia variety, which uses forest biomass as a source of energy for the thermal generation necessary for the process. The objective of this research was to evaluate the energy efficiency and the emissions of polluting gases from the combustion process using different forest biomass in different curing units (UC) of tobacco, as well as to verify the possible obtainment of carbon credits in the analyzed scenarios. The method included the analysis of energy efficiency and firewood consumption of Eucalyptus saligna and Eucalyptus dunnii firewood in three technologically distinct UCs, from the most technological to the least technological, namely: continuous load UC, forced air UC and conventional UC. Furthermore, the biomass of pine pellets in adapted conventional UC was analyzed. The GHG emissions (CO2, CO, CxHy and NOx) from the combustion process were also quantified. The base scenario was the use of E. saligna firewood in conventional UCs. According to the results, the lowest consumption of firewood per kg of tobacco was obtained in the continuous load UC, with values of 2,38 and 1,98 kg/kg for the use of firewood from E. dunnii and E. saligna, respectively. The worst performance was observed in conventional PAs, reaching an increase of 50,75% in biomass consumption. The use of pellets resulted in consumption of 1.44 kg/kg, being the most efficient result. Regarding GHG emissions, the use of pellets in conventional UC was where the lowest emissions occurred (0,0022 tCO2e) per kg of tobacco, followed by continuous load UC (0,0068 tCO2e) and conventional (0,0129 tCO2e), both using E.dunnii. The worst result of the emission factors was obtained with the use of the UC Forced air. Finally, it was possible to obtain carbon credits taking into account three of the seven emission scenarios analyzed, namely: Use of pellets in adapted conventional UCs and use of E.dunnii firewood in continuous and conventional load PAs. The financial return is viable and thus, there is the possibility of promoting low carbon activities in tobacco drying.