The grindability, the air carrier ability and the combustion characteristics in woody biomass co-firing with coal were investigated by a coal combustion test facility (combustion rate: 100kg/h). The almost of woody biomass after grinding became fiber form. The size was larger than pulverized coal particles. When the length of fiber was extremely long, the carrier air pipe was blocked with biomass fiber. At two-stage combustion ratio of 30%, NO_x concentration in co-firing of woody biomass was lower than that in coal combustion. In case of co-firing for bark, the unburned carbon concentration in fly ash increased in comparison with coal combustion.
