Assessment of Potential Small hydropower Generation: A Case Study in Otsuchi, Iwate Prefecture, Japan

Abstract

Developing renewable energy is crucial not only to reduce greenhouse gas emissions, but also to vitalize local economies by generating new jobs related to their operation and management. Small hydropower (SHP), a baseload renewable energy, has substantial potential in Japan due to its high rainfall and steep geography. However, the SHP sector in Japan is underdeveloped. In this study, the potential power generation by SHP was estimated for the town of Otsuchi, Iwate Prefecture, Japan. The town is famous for its riverine ecosystem, which includes important salmon fisheries and the endangered fish species, three-spined stickleback. Therefore, any future SHP must be installed with careful considerations not to damage the local riverine ecosystem. The total annual potential power generation by SHP in Otsuchi was estimated to be around 2 GWh under the assumption of balancing energy–food and energy–ecosystem nexi to minimize influences on the riverine ecosystem. The potential power generation could meet approximately 4% of the current demand for the entire town and reduce carbon dioxide emissions equivalent to those of around 200 people. The potential power generation is estimated to double by the 2040s because of the greater expected precipitation and changes in land-use patterns in the future; however, such changes are expected to differ among sites in the town. Therefore, attention is necessary when selecting installation locations for new SHP facilities based on estimated potential power generation and anticipated social changes, such as population.