Biochar mass yield, moisture content and volatile solids decreased by increasing the carbonization
temperature and the residence time.
• The values of the newly originated BDI ranged between 27% and 77% and reflected the changes
in carbonization severity.
• The maximum biochar HV (21.9 MJ kg−1
), volumetric HV (2.36 GJ m−3
) and fixed carbon
content (44.9%) were achieved at the carbonization temperature of 400 °C and residence
time of 3 h.
• Activation energy values and the pre-exponential factors of biochar degradation, in a
nitrogen environment, decreased as the severity of the carbonization process increased.
• Carbonized switchgrass, through loss of water and volatile matter, increasingly approaches the
composition of lignite coals, thus it may serve as a valuable solid biofuel. Energies 2014, 7 564
Acknowledgments
Authors of this paper would like to express gratitude to the