A modular Process Simulator, CAMEL®, developed by the University of Roma 1, has been applied to analyse a series of “zero emissions” high efficiency cycles. This paper compares three different cycles integrated with CO2 separation technologies based on chemical or physical absorption upstream of the combustion process: pure hydrogen is burnt in presence of pure oxygen to produce superheated steam. All solutions are based on nonconventional plant configurations: two of them are H2/O2 cycles and the third one is the so called ZECOTECH® cycle. The main features of all three configurations are presented and their thermodynamic cycles are simulated in order to perform an exergy analysis.