The Evaluation of the Oxycombustion for Power Cycles GHEORGHE DUMITRASCU Engineering Thermodynamics, Thermal Machines, and Refrigeration Department "Gh. Asachi" Technical University of Iasi, Blvd. D. Mangeron, 59–61, 700050-Iasi, ROMANIA Abstract: The sustainable energy systems require zero emissions into environment. The main emission’s component is CO2 that contributes mainly to the global warming. The goal of zero emissions follows two ways: reduction of carbon intensity factor, e.g. Clear Sky initiative in USA, and the capture of CO2, respectively the European move towards. On a global scale, the growth of population will lead to expansion of needs that will cause an increasing impact on environment by exhausting consume of resources, and raw materials, accompanied by a much more use of energy and these will ruin intensively the environment by harmful emissions. The CO2 capture from fossil fuelled power plants is technically feasible, but it nevertheless remains to find viable solutions for actual retrofitted or new large-scale power generation systems, workable economically and environmentally. The paper seeks to evaluate the cycles based on atmospheric/pressurised oxy-combustion in recycled/rich CO2 medium, that have the benefit to use the high efficient combined cycle technology. The oxy-combustion has the advantage to supply a very rich in CO2 exhaust flue gases stream, allowing consequently a more effectual CO2 capture&sequestration. Power plant processes based on pressurised oxy-combustion, producing enriched CO 2 flue gas ready for disposal, are neither demonstrated on a pilot scale nor have the necessary components tested out in semi-technical or pilot plants. Investigations by the IEA GHG programme have estimated cost, efficiency and emission data for various types of power stations, including both current and future technology providing representative base cases for studies of CO 2 capture and storage. According to this study, power plant process options with CO 2 capture are: -conventional power plants with chemical CO 2 scrubbing of the atmospheric flue gas; -integrated oxygen/steam-blown gasification of fossil fuel and combined cycle (IGCC) plants with CO shift and separation of CO 2 and H 2 before combustion; -combustion/gasification of fossil fuel (especially coal) in an atmosphere of pure oxygen and recycled CO 2 . The probability of further technical research and developments in each of the main types of plant has also been examined. This paper evaluates the oxy-combustion processes in recycled/rich CO2 medium. Keywords: oxy-combustion based power cycle evaluation, first laws efficiencies 1 Introduction In the field of the design of new co–generation energy plants and of optimization of existing ones, there has been a substantial effort dedicated to the repowering techniques, new fuels, renewable and recovered energy, new suitable working fluids, second law optimization, modelling, and simulation, study of technical solutions to diminish the non – desired operating influences. The co–generation systems that combine a gas turbine engine to a steam engine are very sensitive to the intake state parameters of the ambient air. The convenient operation mode must assure a constant power output at constant rpm. This paper performs an evaluation of the oxy- combustion process in recycled/rich CO2 streams. At present, it is almost impossible to decide which technologies of CO 2 capture & sequestration are applicable to large power plants for the future. Taking all known facts into account, it appears to be a promising solution to use pure oxygen instead of air, either to produce H 2 by gasification or for a direct combustion process. The arrangement of power generation systems might be foreseeable for the next future, and it is obvious that there still stay behind a larger contribution of fossil fuels. Noticeably, to meet the demands for a cut in CO 2 emissions, on one hand it becomes necessary to raise the overall efficiency of power generation processes and on the other hand to settle proper procedures for CO 2 capture. Besides coal and natural gas, oil plays a minor role for power generation in the countries of the EU, therefore in diminishing the CO 2 the researches should focus on coal and natural gas. Table 1 shows an overview of process principles for fossil fuelled power generation with low CO 2 emissions. The table includes combustion (1a) as well as gasification processes (1b) at atmospheric or higher pressure, subject of CASTOR and ENCAP EC-Projects. The targets are: -to identify the "best scheme" for high efficiency oxycombustion-based power plants for CO 2 capture; -to develop and pre-design prototypes of critical components and to test them; -to analyse the feasibility 5th WSEAS Int. Conf. on ENVIRONMENT, ECOSYSTEMS and DEVELOPMENT, Tenerife, Spain, December 14-16, 2007 135