Waste heat from a flame-assisted fuel cell for power generation using organic Rankine cycle: Thermoeconomic investigation with CO2 emission considerations

The increasing concerns about pollutant emissions from the electricity generation sector have urged the deployment of novel and efficient technologies. In this regard, fuel cells are predicted to be essential in upcoming clean electricity generation systems. In particular, Flame-assisted Fuel Cells (FFCs) are among the new technologies and are envisaged to operate with various fuels; however, their relatively low electrical efficiency is a major drawback. The present research aims at the efficiency improvement of a methane-fueled FFC by recovering its waste heat for additional electricity generation using an Organic Rankine Cycle (ORC). To do so, a combined FFC-ORC framework is developed, and its thermodynamic performance as well as economic and environmental emission characteristics, are modeled. By implementation of parametric analysis, impacts on the performance of design/operating variables were examined. A tri-criteria optimization is also accomplished based on exergy efficiency, electricity cost, and CO2 emission for the combined FFC-ORC and the standalone FFC. The results indicate better performance of the developed FFC-ORC over the standalone FFC in terms of efficiency and CO2 emissions, respectively by 8.5-percentage points and 35.2%, under optimized cooperating conditions. However, the electricity cost shows an increment of 9.68% due to the additional expenditures associated with the ORC.