Raw Materials, Selection, Preparation and Characterization

Among the different energy sources, biomass wastes hold most promise for the near future. Biomass is considered a neutral carbon fuel because the carbon dioxide released during its use is an integral part of the carbon cycle. Increasing the share of biomass in the energy supply contributes to diminishing the environmental impact of CO₂ and to meeting the targets established in the Kyoto Protocol. The use of biomass waste material as a fuel, however, has certain drawbacks related with its high-moisture content, low-energy density and the problem of reducing the size of the biomass, especially in the pulverized range of entrained flow gasifiers. Currently, there is increasing interest in developing new processes for the pre-treatment of biomass wastes, through the modification of their properties prior to gasification, so as to make them more attractive for their subsequent use. Pelletization is a proven technology for improving biomass properties, whereas torrefaction is considered a plausible alternative for decreasing the moisture content, increasing the energy density and greatly facilitating the handleability and grindability properties of the torrefied material.