Introducing wood log boilers in spa facilities: Impacts of small scale heat utilizations of woody biomass on regions of Japan

In recent years, wood log boilers have been introduced to hot water bathing facilities or spas in Japan, particularly in mountainous areas. Producing wood logs is relatively easy, on the other hand, input of wood logs into the boilers has to be done manually, and it is pointed out that wood log boilers are not efficient if they are used as facilities generating over 100 kW. In this context, the cases discussed in academic papers are limited to small scale ones. In this paper, the analysis of two cases of boilers generating over 100 kW are examined to verify potentials of the large scale facilities with wood logs. It reveals that (1) operating costs are reduced compared with the system using kerosene, and substitution rates are over 70% (2) manual input of wood logs was a certain load on the boiler users; (3) impacts on the managements, such as rise of labor costs caused by the manual input of wood log, were not seen and (4) wood log systems can potentially reduce the loads on the facilities depending on heat supply systems.