Performance assessment and optimization of a biomass-based solid oxide fuel cell and micro gas turbine system integrated with an organic Rankine cycle

Rice straw is a potential energy source for power generation. Here, a biomass-based combined heat and power plant integrating a downdraft gasifier, a solid oxide fuel cell, a micro gas turbine and an organic Rankine cycle is investigated. Energy, exergy, and economic analyses and multi-objective optimization of the proposed system are performed. A parametric analysis is carried out to understand the effects on system performance and cost of varying key parameters: current density, fuel utilization factor, operating pressure, pinch point temperature, recuperator effectiveness and compressors isentropic efficiency. The results show that current density plays the most important role in achieving a tradeoff between system exergy efficiency and cost rate. Also, it is observed that the highest exergy destruction occurs in the gasifier, so improving the performance of this component can considerably reduce the system irreversibility. At the optimum point, the system generates 329 kW of electricity and 56 kW of heating with an exergy efficiency of 35.1% and a cost rate of 10.2 $/h. The capability of this system for using Iran rice straw produced in one year is evaluated as a case study, and it is shown that the proposed system can generate 6660 GWh electrical energy and 1140 GWh thermal energy. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.