Towards retrofitting integrated gasification combined cycle (IGCC) power plants with solid oxide fuel cells (SOFC) and CO2 capture - A thermodynamic case study

This article presents a detailed thermodynamic case study based on the Willem-Alexander Centrale (WAC) power plant in the Netherlands towards retrofitting SOFCs in existing IGCC power plants with a focus on near future implementation. Two systems with high percentage (up to 70%) biomass co-gasification (based on previously validated steady state models) are discussed: (I) a SOFC retrofitted IGCC system with partial oxy-fuel combustion CO2 capture (II) a redesigned highly efficient integrated gasification fuel cell (IGFC) system with full oxy-fuel CO2 capture. It is concluded that existing IGCC power plants could be operated without major plant modifications and relatively high electrical efficiencies of more than 40% (LHV) by retrofitting SOFCs and partial oxy-combustion CO2 capture. In order to apply full scale CO2 capture, major process modification and redesign needs to be carried out, particularly in the gas turbine unit and heat recovery steam generator (HRSG). A detailed exergy analysis has also been presented for both the systems indicating significant efficiency improvement with the utilization of SOFCs. Additional discussions have also been presented on carbon deposition in SOFCs and biomass CO2 neutrality. It is suggested that scaling up of the SOFC stack module be carried out gradually, synchronous with latest technology development. The thermodynamic analysis and results presented in this article are also helpful to further evaluate design challenges in retrofitted IGCC power plant systems for near future implementation, gas turbine part load behaviour, to devise appropriate engineering solutions and for techno-economic evaluations.