Torrefied biomass and its handling aspects: A state-of-the-art review

To enhance the transportation ability of biomass and improve its material properties such as energy density and hydrophobicity, biomass is modified by torrefaction. This process, counting as a mild pyrolysis, takes place between 200 C and 300 C. The densified torrefied product is usable as a biofuel for heat and energy production. Over the past years, research on the torrefaction process itself has been intensified and has led to a further understanding of the main chemical mechanisms and their effects. However, the logistics and handling aspects for the supply chain have hardly been covered yet in research. Similar to the use of wood pellets, factors such as dust generation and the risk of dust explosions could pose a serious issue for transport and storage of densified torrefied products and should therefore be examined. The aim of this paper is to present the state of the art on torrefied biomass and biomass logistics as a basis for the research into the handling characteristics of the supply chain. Firstly, densification and torrefaction are introduced. Following, an overview on literature of the handling aspects of torrefied material is presented. Conclusions will be given on the approach to identify key factors for further research on the handling of torrefied biomass.