Torrefaction is a thermal treatment process that involves heating biomass (such as wood, agricultural residues, or energy crops) in the absence of oxygen at a temperature between 200 and 300°C, to produce a dry, stable, and energy-dense material called torrefied biomass or bio-coal.
During the torrefaction process, the biomass undergoes physical and chemical changes that remove moisture, volatile organic compounds (VOCs), and hemicelluloses, which leads to an increase in its energy density, and improved grindability and hydrophobicity. Torrefied biomass can be used as a renewable fuel for heat and power generation, or as a feedstock for the production of bio-based chemicals and materials.
Compared to raw biomass, torrefied biomass has several advantages, including higher energy density, lower moisture content, improved storage and handling properties, and reduced emissions of greenhouse gases and pollutants during combustion.