Research paper: Torrified wood fuel
Moving torrefaction towards market introduction - Technical improvements and economic-environmental assessment along the overall torrefaction supply chain through the SECTOR project
D Thran, J Witt, K Schaubach, J Kiel, M Carbo, J Maier, C Ndibe, J Koppejan, E Alakangas, S Majer, F Schipfer
The large-scale implementation of bioenergy demands solid biofuels which can be transported, stored and used efficiently. Torrefaction as a form of pyrolysis converts biomass into biofuels with according improved properties such as energy density, grindability and hydrophobicity. Several initiatives advanced this development. The first pilot-scale and demonstration plants displayed the maturity and potential of the technology.
The European research project SECTOR intended to shorten the time-to-market. Within the project 158 Mg of biomass were torrefied through different technologies (rotary drum, toroidal reactor, moving bed). Their production led to process optimization of combined torrefaction-densification steps for various feedstocks through analysing changes in structure and composition. The torrefied pellets and briquettes were subjected to logistic tests (handling and storage) as well as to tests in small- and largescale end-uses. This led to further improvement of the torrefied product meeting logistics/end-use requirements, e.g. durability, grindability, hydrophobicity, biodegradation and energy density. Durability exceeds now 95%.
With these test results also international standards of advanced solid biofuels were initiated (ISO standards) as a prerequisite for global trade of torrefied material. Accompanying economic and environmental assessment identified a broad range of scenarios in which torrefied biomass perform better in these areas than traditional solid biofuels (e.g. white pellets), depending e.g. on feedstock, plant size, transport distances, integration of torrefaction in existing industries and end use. The implementation of industrial plants is the next step for the technology development. Different end user markets within and outside Europe can open opportunities here.