Pyrolysis and torrefaction of waste wood chips and cone-like flowers derived from black alder (Alnus glutinosa L. Gaertn.) for sustainable solid fuel production

Abstract

The aim of this study was to investigate black alder (Alnus glutinosa L. Gaertn.) waste wood chip biochar in torrefaction and pyrolysis over a wide range of temperatures (250, 300, 400, 500, 600 and 800 °C) and residence times of 1 h. The resultant biochar was investigated in detail. The carbon-rich materials obtained were compared with biochar derived from black alder cone-like flowers, which are woody by product in black alder cultivation. The obtained results displayed rather high heating values for both examined materials. The higher heating values were as high as 27.9 and 29.7 MJ kg−1 for biochar obtained at 600 and 800 °C from cone-like flowers and wood chips, respectively. Black-alder-originated biochar displayed a relatively high energy densification ratio; thus, such bioresources might be promising in terms of the production of sustainable solid smokeless fuels.