Enabling Low-Cost CO2 Capture via Heat Integration

Hollow fiber sorbents in rapid thermal swing mode, packed bed solid sorbents in thermal swing mode, hollow fiber membranes, monoethanolamine-based liquid amines, and chilled ammonia CO2 sorption systems are compared on an energetic basis for CO2 capture from coal-fired power plants. The systems are compared on an intrinsic heat and auxiliary basis both with and without plantwide heat integration efforts. Without heat integration, every technology considered was shown to be highly parasitic, consuming between 1.0 and 4.0 GJ/(ton of CO2 captured) (effectively between 40 and 100% parasitic, depending on plant efficiencies). When heat integration strategies are considered, such as utilizing feedwater preheating heat flows (without disrupting plant operation) and utilizing heats generated during CO2 compression, the overall parasitic nature of the technologies decreases dramatically. Namely, chilled ammonia and zeolite MFI-based fiber sorbents consume approximately 0.07 and 0.13 GJ/(ton of CO2 captured), respectively. The overall energetic analysis strongly suggests that CO2 capture systems must be highly integrated with the plant systems for successful widespread deployment as retrofits to large power plants.