Design Concept for Large Output Graz Cycle Gas Turbines

The introduction of closed cycle gas turbines with their capability of retaining combustion generated $CO2$ can offer a valuable contribution to the Kyoto goal and to future power generation. Therefore research and development work at the Graz University of Technology since the 1990s has led 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 $CO2$ by condensation. The efforts for the oxygen supply in an air separation plant are partly compensated by cycle efficiencies far higher than for modern combined cycle plants. Upon the basis of the previous work, the authors present the design concept for a large power plant of 400 MW net power output making use of the latest developments in gas turbine technology. The Graz Cycle configuration is changed, insofar as condensation and separation of combustion generated $CO2$ takes place at the 1 bar range in order to avoid the problems of condensation of water out of a mixture of steam and incondensable gases at very low pressure. A final economic analysis shows promising $CO2$ mitigation costs in the range of $20–30/ton $CO2$ avoided. The authors believe that they present here a partial solution regarding thermal power production for the most urgent problem of saving our climate.