EXERGOECONOMIC ANALYSIS OF AN ADVANCED ZERO EMISSION PLANT

Exergy-based methods are reliable means for the comparison and the evaluation of the operation of energy conversion systems. In this paper, the Advanced Zero Emission Plant, a plant that performs combustion in a nitrogen-free environment (oxy-fuel combustion) is presented, compared to a reference plant (without CO2 capture) and evaluated based on an exergoeconomic analysis. A variation of the oxy-fuel plant with a lower CO2 capture percentage (85%) is also presented in order to (1) evaluate the influence of CO2 capture on a plant's overall performance and cost, and (2) enable the comparison with other conventional methods, such as post-combustion with chemical absorption that also performs CO2 capture with lower effectiveness. When compared to the reference case, the oxy-fuel plants achieve a minimal decrease in exergetic efficiency, essentially due to their more efficient combustion processes. Cost calculations reveal that the membrane used for the oxygen production in the oxy-fuel plants is their main expenditure. Nonetheless, the cost of electricity and the cost of CO2 avoided for these plants are calculated to be competitive with chemical absorption.