Impurities in a geothermal steam cause substantial technical and economic challenges in the utilization of geothermal energy, because they impact the most expensive component of a geothermal power plant the steam turbine. The moisture content of steam, expressed as steam quality, directly relates to steam purity in most cases. On-line sensors are needed to monitor steam quality and purity for the optimization of plant efficiency and control of upset conditions that can damage this expensive hardware. This project will develop advanced on-line steam quality and purity sensors using laser absorption spectroscopy and laser scattering spectroscopy. These instruments will be robust process sensors that are substantially less expensive, easier to maintain, and more accurate than currently available mechanical and manual methods for steam quality and purity measurement. In Phase I, a laser absorption spectrophotometer and laser scattering spectrophotometer will be designed and built to measure fundamental optical properties (absorption and scattering of infrared light) of steam and liquid water in the laboratory at high pressure and temperature. These data will be used to optimize and calibrate the instruments for on-line tests at geothermal power plants, where the technique will be validated against conventional reference methods.
Commercial Applications and Other Benefits as described by the awardee: These sensors should provide a high benefit-to-cost ratio for geothermal facilities and would help optimize and maintain up to 8000 MW of geothermal power generation worldwide. These sensors also should be applicable in the steam cycles of many conventional power plants and industrial processes. For a small geothermal plant alone, a 1% loss in efficiency can result in revenue losses of $175,000 to $400,000 per year for a 50 MW plant, depending on the power sale price
