Influence of diameter and quality of beech logs on the potential energy of sawmill residues

The influence of log diameter and log quality were studied relative to the potential heat energy produced from wood residue. Research was conducted on beech sawmill logs (30 cm to 49 cm in diameter and 4 m in length) of different qualities. Logs with greater diameters and of better quality increased the amount of products and decreased the amount of residue. A decrease in the diameter and quality of beech logs increased the total energy capacity, ranging between 840 kWh/m3 (highest quality logs, 40 cm to 49 cm in diameter) and 1,350 kWh/m3 (lower quality logs, 30 cm to 34 cm in diameter). Drying the lumber produced from logs of small diameters used less than 10% of the potential heating energy. However, logs of 40 cm to 49 cm in diameter increased this usage to 33%. When burner losses and drying energy losses were calculated, there was approximately 430 kWh/m3 to 960 kWh/m3 of leftover energy. This could be used for various purposes or it could be sold. The amount of obtained energy was influenced more by log diameter than by the log quality.