Simulation of a Lignite-Based Polygeneration System Coproducing Electricity and Tar with Carbon Capture

Lignite-based polygeneration systems for coproducing tar and electricity with and without carbon capture and storage (CCS) were proposed and simulated. Predried lignite was pyrolyzed into coal gas, tar, and char. Coal gas was fired in a gas turbine after the cleanup process, while char was combusted in circulating fluidized-bed (CFB) boilers. The polygeneration plant without CCS turned out to be more efficient than the conventional CFB power plant, suggesting that the former is a promising and efficient option to utilize lignite resources. Moreover, the performance and emissions of polygeneration plants with and without CCS were compared. It was shown that the more CO2 is captured, the larger energy penalty it will cost. Therefore, a trade-off should be made between low emissions and high efficiency.