1:45 PM - 3:15 PM
[O08-P65] Research on Binary Geothermal Power Generation
Keywords:geothermal power generation, geology, global environment
1. Background and Objectives
We have learned that geothermal power generation, which utilizes geothermal resources unique to the region, has great advantages, but that its penetration rate in Japan is low compared to the amount of resources available. Therefore, we decided to conduct a survey on the current status of geothermal power generation in Japan.
2.Methods
・We collected information on geothermal power generation by visiting geothermal power plants and reading references.
・We also built a geothermal power generation model to deepen our understanding of geothermal power generation.
3. Results
In order to deepen the understanding of geothermal power generation, the participants conducted surveys based on literature and field trips, and built a geothermal power generation model.
Through field visits, we learned that, in many cases, it is difficult to maintain a stable supply of hot water for a long period of time in the current mainstream system due to corrosion or clogging of impurities in the pipes that collect the hot water and steam necessary for power generation from the ground. The cost of drilling new production wells each time this occurs has been found to be a contributing factor to the high maintenance costs of geothermal power generation facilities.
Binary power generation, on the other hand, can generate power even at relatively low temperatures. Therefore, it is considered to have lower maintenance costs than mainstream methods in that it does not require the drilling of new production wells. Furthermore, they can be downsized and have the advantage of being relatively easy to install.
However, as a disadvantage, some of the binary power plants we visited had all equipment that was made in foreign countries, and the maintenance frequency was high, and parts for the equipment were imported from overseas, which contributed to the high overall maintenance costs of the facilities.
In order to gain a better understanding of geothermal power generation, a simple geothermal power generation model using a dry steam method was built and an experiment was conducted to reproduce geothermal power generation.
In the experiment, the energy conversion efficiency was less than 0.01%.
Using thermography to investigate the cause of this power generation efficiency, it could be inferred that heat was escaping from the steam outlet area and from the joint between the pressure cooker and the vinyl pipe. As a way to improve the power generation efficiency, it is necessary to use insulating materials to keep heat from escaping and to change the shape of the propeller.
In addition to the experiment, the geothermal power generation model was also used in presentations and classes.
4. Considerations and future issues
The utilization of geothermal resources can be further accelerated if the problems of cost and frequency of maintenance of binary power generation are solved. Therefore, we are currently focusing our research on binary power generation, with the goal of producing a binary power generation model. Since the structure of binary power generation requires the use of a substance with a low boiling point as the medium, we are considering using CFC substitutes as the medium, sealing the room where the turbine rotates, and interlocking the turbine with an external generator using magnets. In addition, in order to develop a detailed concept of binary power generation using non-contact magnets, they are visiting Prospire, a company that sells magnets in Osaki City.
The team aims to complete a model of binary power generation, compare it with a model of dry steam power generation that has already been completed, and use it to explain geothermal power generation to elementary and junior high school students in on-site classes.
References
Teikoku Shoin, "Junior High School Social Studies Map" edited by Teikoku Shoin, October 2022, etc.
We have learned that geothermal power generation, which utilizes geothermal resources unique to the region, has great advantages, but that its penetration rate in Japan is low compared to the amount of resources available. Therefore, we decided to conduct a survey on the current status of geothermal power generation in Japan.
2.Methods
・We collected information on geothermal power generation by visiting geothermal power plants and reading references.
・We also built a geothermal power generation model to deepen our understanding of geothermal power generation.
3. Results
In order to deepen the understanding of geothermal power generation, the participants conducted surveys based on literature and field trips, and built a geothermal power generation model.
Through field visits, we learned that, in many cases, it is difficult to maintain a stable supply of hot water for a long period of time in the current mainstream system due to corrosion or clogging of impurities in the pipes that collect the hot water and steam necessary for power generation from the ground. The cost of drilling new production wells each time this occurs has been found to be a contributing factor to the high maintenance costs of geothermal power generation facilities.
Binary power generation, on the other hand, can generate power even at relatively low temperatures. Therefore, it is considered to have lower maintenance costs than mainstream methods in that it does not require the drilling of new production wells. Furthermore, they can be downsized and have the advantage of being relatively easy to install.
However, as a disadvantage, some of the binary power plants we visited had all equipment that was made in foreign countries, and the maintenance frequency was high, and parts for the equipment were imported from overseas, which contributed to the high overall maintenance costs of the facilities.
In order to gain a better understanding of geothermal power generation, a simple geothermal power generation model using a dry steam method was built and an experiment was conducted to reproduce geothermal power generation.
In the experiment, the energy conversion efficiency was less than 0.01%.
Using thermography to investigate the cause of this power generation efficiency, it could be inferred that heat was escaping from the steam outlet area and from the joint between the pressure cooker and the vinyl pipe. As a way to improve the power generation efficiency, it is necessary to use insulating materials to keep heat from escaping and to change the shape of the propeller.
In addition to the experiment, the geothermal power generation model was also used in presentations and classes.
4. Considerations and future issues
The utilization of geothermal resources can be further accelerated if the problems of cost and frequency of maintenance of binary power generation are solved. Therefore, we are currently focusing our research on binary power generation, with the goal of producing a binary power generation model. Since the structure of binary power generation requires the use of a substance with a low boiling point as the medium, we are considering using CFC substitutes as the medium, sealing the room where the turbine rotates, and interlocking the turbine with an external generator using magnets. In addition, in order to develop a detailed concept of binary power generation using non-contact magnets, they are visiting Prospire, a company that sells magnets in Osaki City.
The team aims to complete a model of binary power generation, compare it with a model of dry steam power generation that has already been completed, and use it to explain geothermal power generation to elementary and junior high school students in on-site classes.
References
Teikoku Shoin, "Junior High School Social Studies Map" edited by Teikoku Shoin, October 2022, etc.