Introduction

Post combustion CO2 capture technology is one of the potential technologies which will most likely to be applied at large scale CO2 capture facilities in power plants. One of the main concerns for the solvent based CO2 post combustion capture (PCC) technology for power plant is the relatively large energy penalty. The energy required to regenerate the solvent and run the PCC process in a coal fired power plant is currently considered to be equivalent to a reduction in the thermal efficiency of about 20% (from roughly 44 -35% LHV) when around 90% CO2 is captured1. A reduction in energy penalty for solvent based CO2 post combustion capture process can be achieved by improving solvent properties, better integration with power plant as well as by improving process design.

Key Messages

• Post combustion capture process improvements that are already well established such as intercooling in the absorber and improved heat integration with power plant, combined with improved solvents typical of those that are expected to become available by 2020, should substantially reduce the efficiency penalty on power plant.

• Current stage of process design improvements and improvements in solvent properties leads to reducing efficiency penalty from 9.8% to 6.11% for super critical pulverised coal (SCPC) fired power plant with amine based solvent CO2 capture process base case.

• In natural gas combined cycle (NGCC) power plant with improved solvent properties CO2 Capture process base case, reductions in efficiency penalty from 7.8% to 5.93% are achieved by flue gas recirculation, process design improvements.

• The overhead condenser (OHC) process modification was found to be having the lowest efficiency penalty of 5.84% for SCPC case, due to the reduction in steam extraction penalty, and for NGCC case was found to be 5.28%.

• The heat integrated stripper + OHC heat integration process modification was found to have the second lowest efficiency penalty for SCPC and NGCC case.

• The process modifications such as improved split flow process, OHC heat integration, vapour recompression + split flow and heat integrated stripper + OHC heat integration showed reduced CoE (cost of electricity) and lower CO2 avoidance cost for both SCPC and NGCC case.

• Overall it can be noticed from this study that once all current improvements have been implemented in the solvent based post combustion capture process, different process modifications for SCPC and NGCC only bring slight improvements in the power plant efficiency penalty.

• The performance and cost of different post combustion capture process modifications depend on the type of solvent used. Therefore, for new solvents further evaluation for all process modifications will be required.