Eco-Technoeconomic Analyses of Natural Gas-Powered SOFC/GT Hybrid Plants Accounting for Long-Term Degradation Effects Via Pseudo-Steady-State Model Simulations

Abstract

In this study, four solid oxide fuel cell (SOFC) power plants, with natural gas (NG) as the fuel source, that account for long-term degradation were designed and simulated. The four candidate SOFC plants included a standalone SOFC plant, a standalone SOFC plant with a steam bottoming cycle, an SOFC/ (gas turbine) GT hybrid plant, and an SOFC/GT hybrid plant with a steam bottoming cycle. To capture dynamic behaviors caused by long-term SOFC degradation, this study employed a pseudo-stead-state approach that integrated real-time dynamic 1D SOFC models (degradation calculation embedded) with steady-state balance-of-plant models. Model simulations and eco-techno-economic analyses were performed over a 30-year plant lifetime using matlab simulink R2017a, aspen plus V12.1, and python 3.7.4. The results revealed that, while the standalone SOFC plant with a steam bottoming cycle provided the highest overall plant efficiency (65.0% LHV), it also had high SOFC replacement costs due to fast degradation. Instead, the SOFC/GT hybrid plant with a steam bottoming cycle was determined to be the best option, as it had the lowest levelized cost of electricity ($US 35.1/MWh) and the lowest cost of CO2 avoided (−$US100/ton CO2e).