In order to reduce the emission of greenhouse gases, much attention has been focused on energy utilization of biomass in recent years. The promotion of the utilization of domestic woody biomass contributes not only to the improvement of energy selfsufficiency, but also to the environmental protection of forests and undeveloped woodlands near populated areas or satoyamas in Japan. Typical woody biomass derived from Japanese forests and satoyamas are Japanese Cedar and Konara. When woody biomass

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... s utilized as biomass fuel, it is important to examine the energy consumptions for pretreatments such as comminution and reforming. In this study, using Konara, Japanese Cedar, and Balsa, the effects of tree species, comminution methods, and semicarbonization of the woody biomass on comminution energy are investigated. The results obtained in this study are as follows. (1) In the case that water content is less than a fiber saturation point, the comminution energy for three species is expressed as a function of water content. In the case that water content exceeds a fiber saturation point, comminution energy for three species is expressed as a function of density. The comminution energy can be estimated by using the present empirical equations within ±50% accuracy. (2) Regarding the comminution property of semi-carbonized woody biomass, for the wood region, the empirical equations of work index depend on the comminution methods regardless of tree species and sieve of screen. For the semi-carbonized and carbonized regions, the empirical equation of work index is presented regardless of tree species, comminution methods, and sieve of screen. The comminution energy can be estimated by using the present empirical equations within ±60% accuracy.