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GreenFire to start testing of closed-loop geothermal demonstration project in Coso, California

Coso well, California (source: GreenFire Energy)
Carlo Cariaga 18 Apr 2019

After finishing the construction of the world's first closed-loop geothermal system, GreenFire Energy is now prepared to start testing of their ECO2G technology.

GreenFire Energy Inc. announced the completion of construction and the beginning of testing of the world’s first field-scale demonstration of a closed-loop geothermal power system. The project uses an inactive well in the Coso, California, geothermal field. Acceptance testing of key components is in process and active flow testing will begin in early May. A final report of testing results will be made available to the California Energy Commission and project participants later this year.

“This project will be a major milestone in the development of closed-loop geothermal power generation,” said Joseph Scherer, chief executive officer of GreenFire Energy.  “We have been working with the California Energy Commission, our project partners, and the Coso Operating Company for over two years to demonstrate how closed-loop geothermal technology can overcome the difficult issues that have limited geothermal power generation, both in existing and new geothermal projects.” GreenFire has branded its closed-loop geothermal technology as ECO2G™.

GreenFire will demonstrate and test two approaches to closed-loop geothermal:

  • The use of GreenFire’s technology to retrofit nonperforming or underperforming hydrothermal wells to become more productive. GreenFire will allow geothermal steam and brine from the geothermal resource to be produced, while simultaneously circulating water and then supercritical CO2 (sCO2) as working fluids in a downbore heat exchanger.
  • The use of the technology in hot dry rock formations for large greenfield projects. GreenFire will circulate both water and then sCO2 in the downbore heat exchanger under static resource conditions. The conceptual simplicity of closed-loop systems in such formations is inherently appealing because a sealed downhole heat exchanger obviates the need to deal with the full subsurface complexity. Drilling risk is reduced because intersecting natural fractures with flowing water is not essential and the problems associated with maintaining water circulation through rock are avoided. Further, a closed-loop system in hot dry rock reduces the problems of corrosion, non-condensable gases, chemical reactions, and particulates.

GreenFire’s Brian Higgins, chief technology officer, said, “The physical aspect of the project is conceptually straightforward. GreenFire will insert a tube-in-tube heat exchanger into the well to a depth of 1000 feet. Testing will compare the performance of water with sCO2 as working fluids in a closed-loop system. Test results will be compared to our proprietary models which were developed in conjunction with research with in house as a result of four years of research with the U.S. Department of Energy, national laboratories, and a variety of expert consulting firms.”

Chris Ellis, vice president and general manager of Coso Operating Company, is closely involved in the project and has provided key support. “This technology has multiple applications for geothermal power generation. On a stand-alone basis, or as a retrofit into existing infrastructure, GreenFire’s design allows for the generation of electricity from wells/resources that are not economically viable utilizing a traditional approach. In our case, we hope to recover use of stranded assets (wells) that either do not produce at commercial levels (but contain high heat), and wells that produce, but cannot be utilized due to high gas content. We are excited about the prospect that closed-loop geothermal could enable substantial additional capacity at our site.”

The Coso demonstration project was made possible by a major grant from the California Energy Commission. Additional funding was obtained from the Shell GameChanger program and from the Electric Power Research Institute (EPRI), and its member, Electric Power Development Company, Ltd. (J-POWER Company), a major Japanese utility that operates its own geothermal fields. Coso Operating Company has been instrumental in providing an appropriate site and extraordinary support for the project.

Source: GreenFire Energy