Torrefaction – Fuel of the Future or Technical and Economical Mistake?

Torrefaction – the thermal upgrading of solid biomass – is supposed to become a key technology for opening up huge resources of unused biomass and enabling an easier use of biomass in coal fired power plants. Several R&D groups all over Europe and North America have been engaged in this topic for the last few years – now the development reached the level of starting first industrial productions in 2010/2011. The torrefaction process involves heating biomass to a temperature between 240 – 320 °C in the absence of oxygen. This heating drives off the moisture and part of the volatile organic components in form of torrefaction gases (gas with low net calorific value). Most of the energy of the biomass is retained in the torrefied product. The result is a friable material with an energy density and physical characteristics closer to coal. The torrefied biomass can subsequently be densified into, for example, pellets or briquettes for easier and cheaper handling, shipping and storage.