Abstract
It is desirable to reduce the moisture content of woody biomass in order to use it for energy production. This study investigated the natural-drying process of Sugi (Cryptomeria japonica) branches as logging residues during their storage in a clear-cut field for producing fuelwood. Three natural-drying experiments were carried out; i) drying branches in summer, ii) drying in late autumn, iii) drying branches piled with a water-proof sheet cover. In the first experiment, the initial moisture content of the fresh branches was 146% on a dry-weight basis (d.b.). The final average moisture content of the branch residues had decreased to 40%d.b. after 66 days’ drying. Another drying experiment in late autumn showed that the average moisture content of the branches decreased from 120%d.b. to 51%d.b. during a 35-day drying period. Furthermore, we evaluated the effect of a water-proof sheet on the top of the branch piles. The average moisture content of branch piles with the sheet cover decreased from 115%d.b. to 35%d.b. during 35 days’ drying in late autumn. The sheet cover protected the branch piles from wetting down and was effective in decreasing the moisture content of the branches. Natural-drying of logging residues in the field would be an efficient low-cost drying method for woody biomass.
