AIST FREA

産総研トップへ

Geothermal Energy Team

Technologies for Effective and Sustainable Use of Geothermal Resources

Over View

Japan has many volcanoes and a vast amount of geothermal energy that can contribute to stable power without being affected by the weather conditions. Geothermal energy has the potential to provide the base load power.


Research Target

The team is conducting research and development for the sustainable use of geothermal energy on a suitable scale and in a proper style according to underground conditions and social situations with the following catchphrase: “Proper use of geothermal energy.” In the short term, the team aims to make a direct contribution to sustainable power generation and to increase its amount by developing a monitoring system for the coexistence of geothermal power generation with hot springs and advanced monitoring of changes in the reservoirs.
In the long term, the team will make geothermal energy available on a large scale as a base load power source by developing an innovative power generation technology through the use of supercritical geothermal resources originating from the subduction zone and the development of a method for using geothermal energy in society.

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Need for studying and developing geothermal energy
Need for studying and developing geothermal energy

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FREA’s Geothermal Energy Research Roadmap
FREA’s Geothermal Energy Research Roadmap

Research Outline

 

The team is conducting various projects commissioned by the national government, private companies, and others to establish the proper utilization of geothermal energy in Japan. The team also conducts basic studies in geosciences to improve the scientific understanding of geothermal systems. Since the area underground is invisible and the properties of geothermal resources largely depend on the specific area, it is very important to acquire actual data in the field for conducting geothermal studies. The team therefore conducts field experiments, monitoring, equipment testing, etc. at many field sites mainly in the Tohoku region.
The team mainly aims to accomplish the following goals:

  • Understanding and visualizing the phenomena that occur in the reservoir by developing a sensing system for monitoring geothermal energy using microelectromechanical systems (MEMS), optical fibers, etc., and by developing advanced analysis technologies such as transient multicomponent signal processing and integrated interpretation.
  • Compiling huge amounts of geothermal resource information possessed by AIST into an advanced database, presenting optimal development methods, and achieving coexistence with hot springs by developing a geothermal energy simulator.
  • Developing an optimal reservoir creation and control technology using hydraulic stimulation and fluid injection, through laboratory tests and numerical simulations. This allows us to derive a universal development and utilization method.
  • Exploring the possibility of developing supercritical geothermal resources originating from the subduction zone and making it available for large-scale base load power generation by around 2050.
Concept of a supercritical geothermal system Distribution of old calderas (Oyagi, 2003)

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Concept of a supercritical geothermal system
Distribution of old calderas (Oyagi, 2003)
The team has proposed the possibility of generating several tens to several hundreds of GW of power by exploiting a supercritical geothermal resource originating from the subduction zone. The team is drawing up a research plan to make this geothermal resource available as a base load power source by around 2050. The results of seismic and other analyses suggest the existence of magma-originated volcanic complexes containing about 1% of the supercritical fluid beneath the old volcano and caldera (4‒5 km). There are more than 50 old volcanos and calderas in the Tohoku region.

In order to prevent a decrease in steam production and to recover production, water-recharge injection tests have been conducted at the Yanaizu-Nishiyama Geothermal Power Plant in Fukushima Prefecture since FY2015. In this area, the Geothermal Energy Team installed a precision microearthquake remote monitoring network using a three-component downhole accelerometer for a geothermal well and other equipment, and operations were commenced. This enables real-time monitoring of microearthquake activity and advanced integrated analysis in FREA, and our plan is to contribute to production recovery through appropriate water injection.

Yanaizu-Nishiyama Geothermal Power Plant (Photo courtesy of Tohoku Electric Power Co., Inc.)
Yanaizu-Nishiyama Geothermal Power Plant
(Photo courtesy of Tohoku Electric Power Co., Inc.)
Installation status of three component seismometers
Installation status of three component seismometers

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Microearthquake data integration and visualization system (monitoring the behavior of the injected water)
Microearthquake data integration and visualization system
(monitoring the behavior of the injected water)

Main Research Facilities

Examination device for hot spring system Experimental facility for shear slip of a fracture Experimental facility for the development of borehole tools for high-temperature and high-pressure geothermal wells
Examination device for hot spring system Experimental facility for shear slip of a fracture Experimental facility for the development of borehole tools for high-temperature and high-pressure geothermal wells
The device simulates a hot spring pipeline in the laboratory for evaluating hot spring monitoring sensors and conducting experiments on hot spring This facility enables the simulation of various mechanical phenomena in geothermal reservoirs under high temperature and pressure. This facility is capable of simulating 350°C, 60 MPa borehole conditions.

Activities and Achievements

1. Development of simulator for water injection to a geothermal well

In some cases, the capacity of a geothermal reservoir is improved by injecting water into the reservoir through a geothermal well. The Geothermal Energy Team collaborated with US and European researchers and developed a simulator for investigating the response to a crack for water injection. As a result of conducting a demonstration test on a well with reduced capacity in a geothermal field of the Tohoku region, the team boos ted capacity as predicted by the simulation and succeeded in increasing the power generation (to about 1.1 MW).

2. Development of a remote and continuous system for monitoring a hot spring’s quality

The team began developing a system for measuring a hot spring’s qualities including the temperature, flow rate, electric conductivity , etc., producing a prototype to scientifically explain the relationship between geo thermal power generation and hot springs. This system enables stand-alone measurements and continuously transfers the obtained data to a server through the Internet. The performance evaluations by laboratory experiments and field demonstration tests for practical application will continue to the end of FY2017.

Simulation of a subsurface crack
Simulation of a subsurface crack
Results of a water injection test
Results of a water injection test

Team Member

Title Name
Leader Hiroshi Asanuma
Chief Senior Researcher Yasuaki Murata
Senior Researcher Norio Yanagisawa
Researcher Hanae Saishu
Researcher Takuya Ishibashi
Researcher Kyousuke Okamoto
Researcher Norihiro Watanabe
Researcher Youta Suzuki