The reference feedstock for the downdraft gasifier is woodchips (Simone et al. 2011). Some other fuels
can be actually used if they comply with the fuel specifications reported in Table 1. Many lignocellulosic
biomasses (of different origin) can meet such specifications. The crucial specifications concern the
moisture content and particle size distribution, which may require a conditioning step of the biomass. The
size distribution is indeed a remarkable limitation for agricultural and food residues, since many of them
have a small size or even a dusty consistency. Also the shape of many biomass fuels is crucial for
operational conditions in the gasifier, although defined specifications are not given on that point.