Our strengths
Idemitsu Kosan’s geothermal business
Following the first oil crisis in 1973, we considered it important to diversify our energy sources, and started to focus on geothermal Resources as a new energy source and to conduct geothermal Resources surveys from that time on. In Oita Prefecture, we started a steam supply business to the Takigami Power Plant of Kyushu Electric Power Co., Inc. in 1996, and in 2017, we started independent operation of the Takigami Binary Power Plant.
Geothermal energy is a type of renewable energy. Through our geothermal business, which can stably produce energy domestically without emitting greenhouse gases, we will contribute to the realization of carbon neutrality society.
Supply of steam for power generation to Takigami Power Plant
We provide a stable supply of steam for power generation to Kyushu Electric Power Co., Inc.'s Takigami Power Plant.
Takigami power plant distant view
| Name | Idemitsu Oita Geothermal Co., Ltd. Takigami Complex |
|---|---|
| Location | Kokonoe Town, Kusu District, Oita Prefecture |
| Main business | Steam supply business to Takigami Power Plant (Kyushu Electric Power Co., Inc.) |
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【reference】 Kyushu Electric Power Takigami Power Plant |
Address: 2862-12 Nogami, Kokonoe-cho, Kusu-gun, Oita Prefecture Power generation capacity (rated output) 27,500 kW Annual power generation scale: 197 million kWh |
At the Takigami Power Plant, we select an appropriate power generation output commensurate with the amount of sustainable underground Resources. As a result, we have been able to maintain and continue to maintain a particularly high level of capacity utilization rate among geothermal power plants, which are characterized by a stable and high capacity utilization rate*. This takes into account the non-operation status during periodic inspections that occur once every two years, and can be said to be a highly efficient power plant.
*Capacity utilization factor: The ratio of the output actually generated to the maximum output that can be generated by the equipment.
Operation of Takigami Binary Power Plant
Binary power generation is a power generation method that enables power generation using low-temperature steam and hot water, which cannot be used with conventional geothermal power generation. The word "binary" is used in the name because it uses two fluids: water as a heat source and a low-boiling point medium.
Heat exchange between hot water and a low boiling point medium produces high pressure medium steam for power generation. After passing through the turbine, the low-boiling medium is cooled in a water-cooled condenser and then flows back into the heat exchanger where it is heated.
The Takigami Binary Power Plant was awarded the highest award in the 2017 New Energy Awards sponsored by the New Energy Foundation for increasing the thermal efficiency of the Takigami geothermal system by 15% through power generation using reduced hot water and cooling water from steam power generation. We received the Minister of Economy, Trade and Industry Award.
Panoramic view of Takigami Binary Power Plant
The Binary 1 power generation facility is located on the east side of the No. 1 production base (left side of the photo).
| Name | Takigami Binary Power Plant |
|---|---|
| Location | 3330-152 Nogami, Kokonoe-cho, Kusu-gun, Oita Prefecture (within the production base No. 1) |
| Solar power generation capacity | 5,050kW (rated output) |
| Annual power generation scale | 31 million kWh |
| Main business | Geothermal power generation business (using renewable energy feed-in tariff system) |
| Start of commercial operation | March 2017 |
1. Regular geothermal power generation
1. Regular geothermal power generation
In normal geothermal power generation, only steam is used for power generation, and hot water is returned underground.
2. What is binary power generation?
2. What is binary power generation?
Binary power generation is a system that extracts thermal energy by exchanging heat between hot water that has been returned underground and a low-boiling point medium, making it possible to generate electricity.
3. Mechanism of binary power generation
3. Mechanism of binary power generation
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The medium is vaporized from liquid to gas by exchanging heat between hot water and a low-boiling point medium in stages through the heater, evaporator, and preheater.
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The expansion of the volume of the medium due to vaporization and temperature rise is used to rotate a turbine and generate electricity.
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After the turbine has turned, the steam medium is cooled and turned back into liquid. From the cooling tower, warm water vapor is cooled by contact with the outside air and comes out as steam.