Carbon recycled CO2 geothermal power generation technology

Carbon recycled CO2 geothermal power generation technology Conceptual diagram of CO2 geothermal power generation (source: Taisei Corp.)
Alexander Richter 11 Oct 2021

A collaboration between Japanese firms Taisei and GERD will work on innovative geothermal power generation technology utilising CO2 as part of a JOGMEC research project.

Japanese companies Taisei Corporation and Geothermal Engineering Research & Development Co Ltd (GERD) have jointly been selected by the Japan Oil, Gas and Metals National Corporation (JOGMEC) to participate in the publicly advertised Carbon Recycling CO2 Geothermal Power Generation Technology Project. The project is scheduled to run for five years, from 2021 to 2025, as was announced in a press release already in August 2021.

Located in the Pacific Rim orogenic belt, Japan is one of the world’s leading countries in terms of geothermal resources, and boasts the world’s third largest geothermal resource (23.47 GW). Geothermal power generation is a renewable energy source that uses the vast geothermal resources of Japan to generate electricity by extracting “hot water (including steam)” heated underground and rotating a turbine.

However, geothermal power generation requires a considerable amount of time from research to commercialization, and even when borehole surveys confirm that the geological formation is sufficiently hot, the lack of hot water makes it unsuitable for power generation and prevents commercialization. As a result, the share of geothermal power generation to total power generation in Japan is only 0.3%. Therefore, in order to accelerate geothermal power generation projects through the effective utilization of geothermal resources in the future, the development of new geothermal power generation technologies to replace hydrothermal technologies is required.

Therefore, Taisei and GERD have started to develop an innovative geothermal power generation technology that does not rely on hydrothermal resources. With the technology, CO2 is injected into the geothermally heated strata and circulated as a heat transfer medium to extract heat from the geothermal resources.

The project will enable geothermal power generation by injecting CO2 into geothermal reservoirs, which are not suitable for geothermal power generation using conventional technology due to the lack of hot water, and recovering the hot CO2. According to previous studies, the physical properties of CO2 at high temperatures and pressures are considered to be advantageous for the highly efficient extraction of heat from geothermal resources. A part of the injected CO2 is fixed as carbonate minerals in the geothermal reservoir, which is expected to contribute to carbon neutrality.

The technologies to be developed for this project are as follows:

  1. Overall system design for CO2 geothermal power generation
  2. Technology for the creation of artificial geothermal reservoirs using CO2 as a fracturing fluid
  3. Technology for understanding CO2 fluid behaviour in geothermal reservoirs

The article was shared by Yushifumi Imamura, Head of Business Development for NZ Trade and Enteprise in Tokyo, Japan in a LinkedIn post.

Source: Official Press release/ Taisei