Thermodynamic and economic investigation of an improved Graz Cycle power plant for C[O.sub.2] capture

Introduction of closed-cycle gas turbines with their capability of retaining combustion generated C[O.sub.2] can offer a valuable contribution to the Kyoto goal and to future power generation. Therefore, research and development at Graz University of Technology since the 1990s has lead to the Graz Cycle, a zero emission power cycle of highest efficiency. It burns fossil fuels with pure oxygen, which enables the cost-effective separation of the combustion C[O.sub.2] by condensation. The efforts for the oxygen supply in an air separation plant are partly compensated by cycle efficiencies far higher than 60%. In this work a further development, the S-Graz Cycle, which works with a cycle fluid of high steam content, is presented. Thermodynamic investigations show efficiencies up to 70% and a net efficiency of 60%, including the oxygen supply. For a 100 MW prototype plant the layout of the main turbomachinery is performed to show the feasibility of all components. Finally, an economic analysis of a S-Graz Cycle power plant is performed showing very low C[O.sub.2] mitigation costs in the range of $10/ton C[O.sub.2] captured, making this zero emission power plant a promising technology in the case of a future C[O.sub.2] tax. [DOI: 10.1115/1.1850944]