Improved Silica Removal for Enhanced Geothermal Plant Performance

The purpose of this project was to develop and demonstrate the capability of geothermal mesofluidic enhanced particle separator (GMEPS) technology for removing silica precipitate in geothermal plants in the Salton Sea Geothermal Field. Silica management in geothermal plants is a costly process that limits the flexibility of geothermal plant operations. GMEPS technology would reduce the costs of operating geothermal plants and provide more flexibility than conventional silica management technologies to use geothermal power in areas with loadfollowing grid operation. A project team consisting of Hell’s Kitchen Geothermal (a subsidiary of Controlled Thermal Resources), Pacific Northwest National Laboratory, and Barr Engineering collaborated to demonstrate GMEPS technology as an effective and less costly method of silica removal in geothermal plants. Project goals included demonstrating silica removal from flowing geothermal brine at laboratory and pilot scales, gathering scaling factors to assist in design of larger scale demonstration or commercial plants, and developing a techno-economic analysis to show economic and operational advantages of using GMEPS over traditional silica removal technologies. Laboratory and pilot scale testing results have shown that GMEPS devices effectively remove silica from geothermal brine, can run at a maximum flow rate 10.6 times greater than the device’s minimum flow rate (10.6x dynamic range), can separate and concentrate silica particles by size, can operate at brine flow rates of 10 gallons per minute, can operate uninterrupted for 30 hours, and have been estimated to be less costly to install and operate compared to traditional silica removal methods.