This research identifies the relationship between characteristics of project and governing structure for hot spring power generation in hot spring areas. The main findings are as follows. (1) Governing structure for hot spring power generation in hot spring areas has big differences in both the number of stakeholders and their role involving management of hot spring power generation. (2) Local resident’s acceptance level for hot spring power generation in the hot spring areas where local residents have the central role of managing hot spring power generation is higher than that in the hot spring areas where nonlocal persons have the central role of this. (3) Hot spring areas implementing hot spring power generation differ in the objective and the influence according to the characteristics of hot spring areas. Based on these findings, we propose a list of considerations in order to review the establishment and management of project for hot spring power generation.

抄録全体を表示

The purpose of this research is to identify characteristics of the process of establishing the project for a demonstration experiment about hot spring energy generation in Obama Hot Spring Area, Unzen City, Nagasaki Prefecture, Japan. The main findings are as follows. (1)The development of the alternative energy program in Unzen City, based on involvement by a stakeholder taking the initiative role, contributed greatly to the giving assurance for the legitimacy of carrying out the project. (2)The establishment of a consultative body on the project, which consists of multiple stakeholders, contributed greatly to developing an atmosphere conducive to carrying out the project. (3)The transmission of information about the project by stakeholders, who have a high expertise and reliability, contributed greatly to increasing the feasibility of the project. (4)Utilization of unused hot spring water and lands owned by public sectors contributed greatly to avoiding the non-public sector’s risk of carrying out the project. Based on these findings, we propose a list of considerations for reviewing the establishment of the project for a demonstration experiment about hot spring energy generation.

抄録全体を表示

The continuous monitoring of onsen (hot springs) is important for assessing the quality and sustainability of the onsen, and for evaluating the effects of geothermal energy developments on the onsen’s water supply. Due to the complexity of the data, automated monitoring once a week or less is insufficient to detect changes in the quality of the onsen due to natural variability or scaling in a pipeline, and other factors such as the weather and maintenance operations. In this study, the effects of scaling and other site-specific factors on the performance of the monitoring sensors were revealed by field experiments at the Obama and Kakkonda sites. The sensors considered in the experiment measured the flowrate, temperature, electric conductivity (EC) and fluid pressure. The sampling rate of each sensor was 1 measurement per second. The analysis of scale samples using X-Ray diffraction and energy dispersive X-ray spectroscopy revealed that the main components of the scales were aragonite at the Obama site and amorphous silica at the Kakkonda site. At both sites, the scaling reduced the accuracy of the observations of EC, although its effect was negligible for the other variables being monitored. The daily averages derived from the 1/sec observations were almost the same as those derived from the 1/hour observations. However, there were differences in the results for the daily observations when measured at noon and midnight. Site-specific maintenance operations correlated with pressure change, and fluid temperature decreased with increased precipitation. These results suggested that the onsen monitoring device can be constructed with the sensors used in this study, except for EC. In addition, a sampling rate of one measurement per hour, along with information about regional phenomena, are needed for the accurate evaluation of the onsen quality.

抄録全体を表示

 The microstructure of scale adhered to the inner wall of elbow steel pipe, in which the gushing hot spring water was flowed for 3.5 months at a geothermal plant in Obama-cho, Unzen-shi, Nagasaki, Japan, was analyzed. The adhesion substance consisted of four layers, that were amorphous magnesium silicate, aragonite, amorphous magnesium silicate and corrosion product of iron on the carbon steel from top to bottom. The corrosion product fully covered the steel surface. The magnesium silicate with the thickness of 1-2 mm was initially generated as adhesion substance on the corrosion product. The layer thickness of aragonite, orthorhombic calcium carbonate (λ-CaCO₃), was 15-70 mm. The elements of calcium carbonate such as carbon, oxygen and calcium were solved in the magnesium silicate, and the calcium carbonate with massive and/or stratiform was precipitated there. The chemical contents in the magnesium silicate layers on both the top side and the bottom one were the almost the same. Therefore, the precipitation of aragonite and its growth in the magnesium silicate may form the aragonite layer which showed a columnar structure along the heat flux direction.

抄録全体を表示