Thermo-economic analysis of using an organic Rankine cycle for heat recovery from both the cell stack and reformer in a PEMFC for power generation

• Published in: International journal of hydrogen energy 2019-02, Vol.44 (7), p.3876-3890
• Main Authors: Lee, Jae Yoon, Lee, Jae Hong, Kim, Tong Seop
• Format: Article
• Language: English
• Subjects: Organic Rankine cycle; Polymer electrolyte membrane fuel cell; Steam reformer; Thermo-economics; Waste heat recovery
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2018.12.071

Distributed power generation is gaining attention as a solution for the transmission loss and site selection in centralized power generation. Polymer-electrolyte membrane fuel cells (PEMFCs) are suitable as a distributed power source for residential areas because of their high efficiency and low environmental impact. This study proposes a combined power generation system for recovering waste heat from both the cell stack and the reformer of a PEMFC by applying an organic Rankine cycle (ORC). The best working fluid with the highest ORC power output (i.e., the highest combined system efficiency) was identified through a parametric study of different working fluids. An economic analysis was also performed for different working fluids, waste heat sources, and types of system operation. The results show that the installation cost of the ORC can be recovered within the fuel cell's lifetime in all design cases. Greater cumulative profit can be generated by maintaining the same power output as the stand-alone PEMFC system for greater efficiency than when increasing the power output to sell surplus power. The results demonstrate that the optimal heat recovery from the PEMFC system is both thermodynamically and economically beneficial. •A combined PEMFC/ORC system is proposed, and a thermo-economic analysis is presented.•The ORC recovers heat from the fuel cell stack and reformer.•Design options were investigated for different heat sources and types of operation.•The combined system provided both thermodynamic and economic benefits.•The best option is to use both heat sources while maintaining the net power output.