Engineering process model for high-temperature electrolysis system performance evaluation

To evaluate the potential hydrogen production performance of large-scale High-Temperature Electrolysis (HTE) operations, the Idaho National Laboratory has developed an engineering process model for a 300 Mw HTE H₂ production facility using the commercial systems-analysis code HYSYS. Using this code, a detailed process flowsheet has been defined that includes all the components that would be present in an actual plant, e.g., pumps, compressors, heat exchangers, turbines, and the electrolyzer. A custom one-dimensional electrolyzer model was developed for incorporation into the overall HYSYS process flowsheet. This electrolyzer model allows for determination of operating voltage, gas outlet temperatures, and electrolyzer efficiency for any specified inlet gas flow rates, current density, cell active area, and external heat loss or gain. The one-dimensional electrolyzer model was validated by comparison with results obtained from a fully three-dimensional computational fluid dynamics model developed using FLUENT. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).