Extensive research efforts have been applied to obtain more efficient and less cost-intensive absorption-based processes and solvent systems for CO2 capture during the last 15–20 years. High concentrated aqueous solutions of piperazine (PZ) have been suggested as a good replacement for the current bench-mark solvent mono-ethanolamine (MEA). So far, the research on concentrated PZ solutions has mainly focused on the development and evaluation of various configurations for the post-combustion CO2 capture process. The present paper studies the integration of a configuration based on high-pressure flash regeneration with the upstream power plant. The main focus is on the overall energy performance, but a qualitative analysis of the effect of flexible operation is added as this is important for the optimization of the total plant. A power plant integrated with the optimal PZ-based capture plant is found to have a net electric efficiency of 37.4%, which is 7.2% less than the reference power plant without CO2 capture. The efficiency penalty when using an MEA-based capture plant including lean-vapour compression is 9.1%.