Performance evaluation and economic analysis of integrated solid oxide electrolyzer cell and proton exchange membrane fuel cell for power generation

Abstract

In order to generate clean electricity from thermal energy, a hybrid electrochemical system is conceptually developed by coupling the proton exchange membrane fuel cell (PEMFC) and solid oxide electrolyzer cell (SOEC). For evaluating the proposed hybrid system, firstly, the two subsystems are modeled numerically and then they are merged into an integrated SOEC-PEMFC system. Moreover, the SOEC-PEMFC is analytically modeled for further evaluation. The effects of important operational parameters are examined. The outcomes show that when the SOEC operating temperature increases from 823 to 1273 K, the efficiency increases from 18.7% to 38% and the net output power improves about 36% while cost per unit of power of hybrid system decreases about 80%. Furthermore, by increasing the PEMFC operating temperature from 323 to 348 K, the system net output power and efficiency increase about 16.7% and 10%, respectively, whilst the cost per unit of electricity decreases about 19%. In addition by increasing operating pressure of system, the net output power and efficiency are also improved. The proposed system has maximum output power density of 3.9 kW.m-2 and maximum efficiency of 38%. In addition, the SOEC-PEMFC system is compared with the previously studied proton exchange membrane electrolyzer cell-proton exchange membrane fuel cell (PEMEC-PEMFC) system. In comparison with the previous PEMEC-PEMFC system, the present system's cost per unit of power and efficiency are about 16% and 17% higher, respectively; while the output power density is about double that of the PEMEC-PEMFC system. Generally, because hydrogen-powered systems offer reliable operation from an economic and energetic perspective, the SOEC-PEMFC system represents a promising technological solution to the clean energy demands.