Torrefaction and Pyrolysis
Using biomass that has been pre-processed, for example, through “pyrolysis” and “torrefaction” is environmentally beneficial and easier to process. Both of these new techniques process biomass by heating it with little or no oxygen.
This technology has a number of advantages over wood pellets, which are widely used at the moment. How it works: The wood pellets are roasted. This changes the structure of the biomass fibers and creates carbonised biomass. In that process the weight of the biomass is reduced by extracting moisture. By compressing the roasted biomass into pellets the volume is reduced as well. This produces a compact biofuel with a high energy content, sometimes called “bio-coal”.
With pyrolysis, an oil-like product is created, which can serve as liquid fuel when using special burners. As a result, alternative biomass streams can be utilised for power.
All kind of biomass materials such as straw, bagasse, roadside grass clippings and other agricultural waste can be used for pyrolysis. Until recently this was less suitable because these materials produce a high content of undesirable components in the ashes in the power station.
Pyrolysis eliminates those components in the ashes by separating them early in the process.