The combined operation of postcombustion CO2 capture and a power plant is a complex process with significant mutual interactions. Although the application of CO2 capture imposes an efficiency, penalty on the power plant, it also provides the opportunity to operate the power plant in a more flexible way. To analyze this process, a detailed model of a postcombustion capture plant is developed and validated with measurement data. Afterward, the model is coupled to the model of a hard coal-fired power plant to study the effects of a joint operation. In a case study scenario, the steam extraction of the carbon capture plant is reduced by 50% to increase the power generation of the power plant. The results indicate that it is possible to provide primary frequency control by using this mode of operation.