Minimization of CO2 capture energy penalty in second generation oxy-fuel power plants

Abstract Oxy-combustion is one of the most promising technologies to reduce CO 2 emissions from coal-fired power plants. Nevertheless, as CO 2 capture system there is an important energy penalty and efficiency of the overall power plant substantially decreases. It is well accepted that the application of first generation post-combustion and oxy-fuel combustion technologies reduce the power plant efficiency in 10–12 efficiency points. Air separation unit (ASU) and compression and purification unit (CPU) are the main energy consumers in the oxy-fuel process. Moreover, the oxidant flow, which is a mixture of O 2 and recirculated flue gases (RFG), requires a high heating demand in order to preheat it before the boiler inlet. This paper presents a methodology for the minimization of the energy penalty in oxy-fuel power plants that also includes ASU and CPU optimized designs with lower energy consumption, a boiler working with a high oxygen concentration (up to 40% v ) in oxidant and waste energy integrated with a new designed steam cycle. Results show an important increase in power plant net efficiency (36.42%, LHV basis) regarding oxy-fuel reference power plant (32.91%). As a consequence, energy penalty can be reduced from original 10.5 points to 7.3 points.