Biochar higher heating value estimative using thermogravimetric analysis

The higher heating value (HHV) is an important parameter to indicate the energetic potential of biomass from different sources. Bomb calorimeter is the standard to obtain this data; however, in the absence of this equipment, estimative through proximate analysis aided with multiple regression formulas is an acceptable alternative. Still, this is a time-consuming technique and highly dependable of operator skills. In this context, thermogravimetric analysis has been used to obtain proximate analysis results with higher precision and demanding a small amount of samples. Here, a simple and effective method to estimate HHV from data obtained by thermogravimetric analysis using different sources of biomass is presented. The proposed method showed to be more accurate to estimate HHV than proximate analysis laboratory procedure. Greater correlation was observed between the HHV values obtained from calorimeter-thermogravimetry than the ones obtained from calorimeter-proximate analysis. Multiple regression analysis indicated that fixed carbon and ashes have an inverse influence over HHV, while the former is responsible for high calorific value and the latter affects energy release. Finally, the proposed method showed to be fast and accurate to estimate HHV of biochar samples and should be easily adaptable to other studies that require fast assessment of calorific value from biochar.