Investigation of an Ammonia-Fuelled SOFC-mGT Hybrid System: Performances Analysis and Comparison With Natural Gas-Based System

Description

Among power generation systems, Hybrid Systems (HS) are very attractive due to the opportunity to reach higher power outputs and efficiencies by coupling different technologies. Among Solid Oxide Fuel Cell plants, one of the most studied innovative HS is the SOFC-Micro-Gas Turbine (mGT) integrated system: in the pressurized configuration, the Fuel Cell (FC) is in the place of the mGT combustion chamber, and an afterburner is used to complete the fuel combustion upstream the expander. Several system configurations, designs, and control system challenges have been studied in the last decades, and prototypes have been already developed around the world with satisfactory results in terms of system efficiency. However, these systems have been deeply studied feeding the FC with Natural Gas (NG) and Biogas, not completely allowing to reach zero carbon emissions. The growing global demand for carbon-free energy production is increasing, highlighting the importance of alternative fuels in the power generation sector: among them, thanks to its chemical and physical properties, ammonia is gaining more and more interest. In the present work, the authors want to investigate an innovative Ammonia-to-Power (A2P) system based on a SOFC-mGT HS, focusing on the main thermodynamic parameters, the system's features, and critical aspects, from a technical and environmental point of view. To perform this analysis, a MATLAB/Simulink model has been developed, starting from a fully validated model of the HS fueled by NG and considering the FC operating with an anodic ejector recirculation. In the new plant configuration, the SOFC pre-reformer has been substituted by an ammonia cracker, permitting to investigate the effects of the anode gas recirculation and properly design the whole system. In particular, the operating parameters, such as anodic recirculation factor, fuel utilization, performance, gas turbine size, and features are presented and discussed. Finally, a comparison between hybrid systems and mGT fed by methane, biogas, and ammonia is carried out. Copyright © 2024 by ASME.

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