GASIFICATION COMBINED-CYCLE - CARBON-DIOXIDE RECOVERY, TRANSPORT, AND DISPOSAL

Initiatives to limit carbon dioxide (CO2) emissions have drawn considerable interest to integrated gasification combined-cycle (IGCC) power generation. With its higher efficiency, this process can reduce CO2 production. It is also amenable to CO2 capture, because CO2 can be removed before combustion and the associated dilution with atmospheric nitrogen. This paper presents a process-design baseline that encompasses the IGCC system, CO2 transport by pipeline, and land-based sequestering of CO2 in geological reservoirs. The intent of this study is to provide the CO2 budget, or an ''equivalent CO2'' budget, associated with each of the individual energy-cycle steps. Design capital and operating costs for the process are included in the full study but are not reported in the present paper. The value used for the ''equivalent CO2'' budget will be 1 kg CO2/kWhe. The base case is a 470-MW (at the busbar) IGCC system using an air-blown Kellogg Rust Westinghouse (KRW) agglomerating fluidized bed gasifier, U.S. Illinois #6 bituminous coal feed, and in-bed sulfur removal. Mining, feed preparation, and conversion result in a net electric power production of 461 MW, with a 0.830 kg/kWh(e) CO2 release rate. In the CO2 recovery case, the gasifier output is taken through water-gas shift and then to Selexol, a glycol-based absorber-stripper process that recovers CO2 before it enters the combustion turbine. This process results in 350 MW at the busbar. A 500-km pipeline takes the recovered CO2 to geological sequestering. The net electric power production in the recovery case is 320 MW, with a 0.234 kg/kWh(e) CO2 release rate.