Torrefaction/biochar production by microwave and conventional slow pyrolysis - comparison of energy properties

Mark J. Gronnow*, Vitaliy L. Budarin, Ondřej Mašek, Kyle N. Crombie, Peter A. Brownsort, Peter S. Shuttleworth, Peter R. Hurst, James H. Clark

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The energy efficiency of torrefaction/pyrolysis of biomass to fuel/biochar was studied using conventional (slow) and microwave (low temperature) pyrolysis. Conventional pyrolysis is approximately three times as energy efficient as microwave pyrolysis, in terms of the energy required to process a unit of feedstock. However, this is more than compensated for by the higher energy content of the condensable and gaseous coproducts from microwave pyrolysis, as these can be utilized to generate the electricity required to drive the process. It is proposed that the most efficient method of torrefaction/biochar production is a combination of conventional heating with 'catalytic' amount of microwave irradiation.

Original languageEnglish
Pages (from-to)144-152
Number of pages9
JournalGlobal Change Biology
Issue number2
Early online date1 Nov 2012
Publication statusPublished - Mar 2013


  • Biochar
  • Bioenergy
  • Calorific value
  • Microwave
  • Pyrolysis
  • Torrefaction

Cite this