Techno-economic Analysis of Integrated Gasification Fuel Cell Power Plants Capturing Co2

This work analyzes the efficiency and economic performance of different configurations of a coal-fed Integrated Gasification Fuel Cell (IGFC) plant with CO2 capture. Our analysis evaluates novel configurations, providing a detailed economic assessment for each case. The plants studied here are based on a pressurized Solid Oxide Fuel Cell (SOFC) based power cycle integrated with a Shell coal gasifier. The design variations focus on syngas cleaning and pre-processing upstream of the SOFC power island. In particular, we have designed, simulated and optimized three main system configurations; two with a partial methanation process upstream of the SOFC (‘TREMP’ and ‘HICOM’ cases, respectively) and one without (‘DIRECT’ case). Depending on the specific plant layout, carbon capture is accomplished either before or after the SOFC power island, or both. The best performance, both thermodynamic and economic, was achieved by the ‘HICOM’ case, whose coal-to-electricity conversion efficiency is 50.1% (lower heating value basis). In addition to outperforming the other IGFC configurations analysed, compared to a conventional IGCC-CCS plant, the ‘HICOM’ case produced almost 30% reduction in the levelizedcost-of-electricity (LCOE) delivered by the power plant. INTRODUCTION SOFC-based power cycles have the potential to significantly increase the fuel-to-electricity conversion rates of new generation power plants; furthermore, when CCS is employed, the penalty efficiency paid is significantly reduced compared to conventional power cycles. For NG-based systems without CO2 capture, as far back as a decade ago both Singhal [1] and Hassmann [2] mentioned ideal conversion LHV efficiencies as high as 70% using a SiemensWestinghouse hybrid cycle for plants larger than 2-3 MW; Haussmann refers to a pressurized system with a more ‘sophisticated’ turbine cycle, replacing the micro-turbine, to achieve such high efficiency. More recently, a 2011 DOENETL report [4] on NG SOFC plants capturing CO2 calculated a LHV efficiency of 70.3% for a pressurized plant with external reforming of methane. According to a NETL review of conventional fossil energy power plants [3], the penalty due to CCS is almost 8% (LHV basis) in NG-fed combined cycles and ~8-11% for IGCC plants (depending on the specific gasifier employed). For NG pressurized hybrid SOFC cycles, Franzoni et al. [4] calculated an efficiency loss less than 3% using postSOFC CO2 capture. Similarly, Park et al. [5] calculated a LHV efficiency of 67.4% for a NG hybrid SOFC plant venting CO2, which reduced to a value of 65.0% when CO2 was captured after the SOFC reactors. With post-SOFC capture, the anode exhaust is oxy-combusted yielding a stream containing only steam and CO2, from which the latter is separated after steam condensation and water knock-out. Concerning coal IGFC plants, Grol et al. [6] calculated the efficiency of a pressurized SOFC integrated with a low temperature catalytic gasifier (producing a syngas with a relatively high methane content, ~ 18%) with/without post-SOFC CCS, obtaining LHV efficiencies of 62.4% and 59.2% in the vented and CCS cases, respectively. In another recent report, DOE-NETL [7] calculated a LHV efficiency of 51.6% for a pressurized IGFCCCS plant that employs an enhanced gasifier able to produce a syngas with up to 11% vol. of methane.