Analysis of a precipitating solvent absorption process for reducing CO2 emissions from black coal fired power generation

Abstract

Carbon capture and storage (CCS) is a technology that has the potential to provide deep cuts in CO2 emissions from coal-fired power generation. This paper describes retrofitting the CO2CRC's low cost “UNO MK 3” precipitating potassium carbonate (K2CO3) process to a 335MW (net) black coal-fired subcritical power station, typical of those in Australia.The use of heat integration to reduce the net energy penalty of retrofitting CO2 capture is also studied and the modifications required to the steam cycle for these cases are outlined. Retrofitting the UNO MK 3 process has a smaller energy penalty compared with amine-based processes. Heat integration strategies can reduce this energy penalty by an additional 20%.To further reduce the impact of CO2 capture on the net output of the power station, the option of partial capture of CO2 is also described here. In the partial capture case, the CO2 emissions intensity of the coal-fired power station is equivalent to that of a natural gas combined cycle (NGCC) power station.A detailed cost analysis of various cases of CO2 capture with and without heat integration is also performed. The results suggest that compared to standard amine-based solvent technologies, the UNO MK 3 process can provide up to 50% cost savings in the cost of CO2 avoided. The levelised cost of electricity also reduces by up to 35% using UNO MK 3 compared to commercial amine-based solvent technologies.