RESOURCES | technical resources

Department of Energy SBIR Geothermal Asset Integrity Phase I Report

This report summarizes the work done by OLI and its partners under DOE Award Number: DE-SC0022494. Localized corrosion of corrosion-resistant alloys (CRAs) is a major factor limiting the performance of downhole and surface components in geothermal energy systems, thus significantly affecting the generation of low-cost electricity. To optimize materials selection and provide operational guidance for geothermal systems, a predictive physics-based model is necessary.

For this purpose, we have constructed a preliminary mechanistic model that incorporates two key modules: (1) a comprehensive thermophysical model for predicting the phase and chemical behavior of chemical species, both ionic and neutral, in multicomponent, solid-liquid-vapor aqueous systems, and (2) an electrochemical model for simulating the phenomena at the metal/solution interface that are responsible for corrosion.

Based on an extensive review and critical evaluation of experimental data, the model has been developed for representative CRAs, including stainless steels (304, 316 and s13Cr), nickel-base alloys (625, 29), and titanium alloys (CP Ti, Gr 7, and Gr 12). The localized corrosion model has been validated against experimental data over broad ranges of temperatures and concentrations of chloride ions, dissolved O2, and acid gases. Finally, the model predictions have been compared with selected plant corrosion data, showing statistically significant agreement with the reported data.