Drying Methods of Unutilized Cedar Logs for Use as a Source of Heating Fuel

Abstract

Abstract-There are many small, artificial cedar forested areas in Japan, although these areas are often destroyed through neglect. The promotion of forest maintenance is desired, and using unutilized woody biomass as heating fuel is one way to do so. In this study, drying methods of cedar (Cryptomeria japonica) logs to be used as heating fuel were examined. Log samples with different patterns of scratches and holes were subjected to a drying test. The experimental results show that logs with scratches or holes dried more rapidly than normal logs. Logs with four scratches dried more rapidly than those with two scratches. Logs with larger holes dried more rapidly than those with small holes, and those with three holes dried more rapidly than those with one hole. The drying time to reach the fiber saturation point was reduced from 5 months to 3 months using this simple method. Index Terms-Unused woody biomass, cedar log, drying, heat utilization. I. INTRODUCTIONUnlogged forests have been linked to an increasing number of landslides, which are a serious problem for rural areas. One of the most effective ways to solve this problem is to use woody biomass as a carbon-neutral energy resource [1]. With regard to the use of woody biomass in rural areas, we proposed burning woody biomass as fuel for heaters because the preparation process for logs is simple in comparison with that for other biomass fuels, such as pellets or chips. The target moisture content after drying is lower than 20% for heating fuel [2]. Because drying is essential to prepare the biomass fuel, conserving energy during drying can significantly decrease the overall operating costs [3]. Therefore, in terms of energy savings, a natural drying process, sun drying, is better than forced-drying methods for energy production in rural areas.According to the results of previous drying experiments, heating and wind are important factors for cedar drying [4]. Short (0.5-m) logs dried more rapidly than long (4-m) logs, and cedar log samples (0.5-m logs) reached the fiber saturation point (FSP) after 4-5 months of drying on the study site, which had good ventilation and plenty of sunlight [4]. When the cedar logs dried, the water in the wood moved to the Manuscript