Applying EGS (Artificial Water Recharge) to a Geothermal Reservoir in Japan

Abstract

The power generation output of many Japanese geothermal power plants has been declining over time. One of the reasons is the imbalance between their production and the natural recharge of meteoric water. To mitigate or improve the decline, JOGMEC, an independent administrative agency in Japan, has focused on artificial recharge technology, which is classified as a type of enhanced/engineered geothermal system (EGS).
In 2013, JOGMEC set out a project to apply the technology to Japan’s geothermal power plants. The purpose of this project is to establish appropriate recharge methods for their long term stable production, including techniques for predicting and evaluating the effects of the EGS (artificial water recharge). To establish methods and verify the effectiveness of the project, recharge tests were carried out in 2017 and 2019 through to early 2020 at the Yanaizu-Nishiyama geothermal power plant in Fukushima prefecture, of which production has been gradually declining. Although some positive effects of the EGS have been confirmed, continued recharge and further verification are required to establish the appropriate methods and prove their effectiveness.