Advanced Geothermal System Commercial Demonstration at The Geysers, in Northern California

This report summarizes the results of a California Energy Commission-funded project that tested GreenFire Energy Inc.’s Advanced Geothermal System (AGS) in an existing legacy geothermal well within the southern portion of The Geysers geothermal field, a steam-rich geothermal field in Northern California. The goal was to demonstrate that existing wells can be upgraded using a pipe-in-pipe closed-loop system, and to evaluate its performance under real reservoir conditions.

Over a 90-day test period, the system was operated at various flow rates using water as the working fluid. The system was tested in both forward (water flows down the central insulated pipe and up the outer annulus) and reverse (water flows down the outer annulus and up the central insulated pipe) flow configurations, with reverse flow showing better thermal performance. A 30-day test at 330 gallons per minute yielded stable production (outlet) temperatures of about 311 degrees Fahrenheit (155 degrees Celsius) and sustained heat extraction rates of 7.4 megawatts of thermal power. At peak flow of about 400 gallons per minute, the system achieved around 9 megawatts of thermal power, which is equivalent to an estimated gross power production of around 1.1 megawatts of electric power when paired with a standard Organic Rankine Cycle power system.

The results in this report confirm that AGSs are both technically and economically viable for repurposing idle or underperforming geothermal wells. Based on extrapolated performance data and preliminary economic modeling, a full-scale 100 megawatts of electric power AGS project at The Geysers could be deployed within the next 4 to 5 years, with an estimated levelized cost of electricity of between $90 and $95 per megawatt-hour over a 20-year horizon. These estimates are subject to further technical, geologic, and commercial validation as described in the economic feasibility section of this report. California holds over 200 megawatts of electric power of additional potential in idle wells that could be tapped quickly using this technology, offering a scalable, low-impact pathway to expand the state’s clean energy capacity.