Techno-economic Evaluation of Flexible CCS Concepts in a CHP System

In the framework of the Finnish national CCSP R&D program, the possible positive effects of enhanced CO2 capture flexibility to a combined heat and power (CHP) system's net profitability was examined using optimization modelling, technology review and market scenario assessment. A system model was used to (i) compare economic performance of CO2 capture against fuel switch options under high emission allowance prices and (ii) quantify added value of flexible CO2 capture compared to conventional CO2 capture in the case CHP system. The supply side of the studied CHP system consists of coal- (PC and IGCC) and gas-fired (NGCC) CHP plants, a multi-fuel CHP plant with a circulating fluidized bed (CFB) boiler and an oil-fired district heating plant. The cash flow of the system is maximized assuming the optimal use of flexible pre- post- and oxy-combustion as CO2 capture concepts. Fuel-switch to bio-based renewable fuels is included as an alternative emission reduction technology. The market and fiscal environments reflect the current and anticipated situations in Finland. The flexible CO2 capture concepts assumed for the CHP plants include: (i) solvent storage in post-combustion capture (in PC, CFB & NGCC plants); (ii) hydrogen-rich gas storage in pre-combustion capture (in IGCC plants); and (iii) liquid oxygen storage in pre-combustion capture (in IGCC plants) and in oxy-combustion (in PC and CFB plants)