Torrefaction is a process in which biomass is heated to 250-350°C in a low-oxygen environment. This changes the elements of the biomass, resulting in a refined product with new characteristics. During this process, abut 30% of the mass convert to torrefaction gases, but these gases contain merely 10% of the original biomass’ energy, resulting in an increase of energy density by a factor 1,3. This gives significant cost savings during the value chain, for both transport and handling.
Torrefaction and pelletizing of biomass can provide an important piece in the puzzle of phasing out fossil fuels in favor of renewable alternatives. It shares many of the advantages with fossil coal in terms of energy density, hydrophobicity and burner feeding. It also lacks the challenges of many other renewable alternatives, such as irregular availability.
Black pellets will outcompete its white counterpart with superior properties by delivering more energy per volume and mass unit. Further, the torrefaction process gives;
- A hydrophobic product which can be stored outdoors
- Decreases biological degradation in the product
- A more homogenous product, resulting in a wider range of feed stocks
- A product easier to grind and feed in coal plants
Torrefied biomass can also be used for co-firing with coal, in CHP plants and for industrial applications such as steel and cement production. Torrefied material is also better than non pre-treated biomass for production of liquid biofuels in gasification processes.