Enhancing Efficiency of Corncob-Fired Power Generation with Carbon Capture and Storage

Abstract

Bioenergy from biomass wastes with carbon capture and storage (CCS) is an important way to compensate for hard-to-abate emissions and collaborate with decarbonizing the energy industry. This work evaluates a corncob-fired power generation with CCS regarding overall energy efficiency in two process alternatives: (a) post-combustion CO2 capture by an aqueous blend of methyl-diethanolamine and piperazine; and (b) oxy-combustion coupled to state-of-art air separation unit. The alternatives are simulated in Aspen HYSYS and compared with a conventional plant to evaluate the energy penalty of capturing CO2. The lean solvent composition is optimized for the lowest regeneration heat demand (2.92 GJ/tCO2). Post-combustion capture designed for 90% CO2 abatement presents an efficiency penalty of 7.96%LHV. In contrast, Oxy-combustion has zero CO2 emissions and outperforms Post-combustion with a lower penalty of 6.77%LHV, given a chance to have oxygen supplied at an energy cost of 139 kWh/tO2. To render Post-combustion the most efficient route, it would be necessary to have its reboiler heat ratio reduced to 2.30 GJ/tCO2.