1 CO 2 - Retention Capapility of CH 4 / O 2 - Fired Graz Cycle

The Graz Cycle, a hydrogen oxygen fired double loop high temperature steam cycle, combining gas turbine philosophy with steam plant praxis, can be adapted for combustion of methane with oxygen. The resulting combustion products carbon dioxide and hydrogen oxide, i.e. high temperature steam, are mixed with cooling steam and expanded to lowest pressure and temperature. By condensing the steam, separation of carbon dioxide in the condenser can be effected, which is then recompressed in an isothermal compresser and is presented at system boundaries at ambient temperature and ambient pressure for storage or further reintegration into a solar hydrogen fuel cycle. The paper presents the cycle, its thermodynamic and flow conditions, and design deliberations concerning the major components especially the methane oxygen combustion chamber and the high temperature turbine. Methods of cooling the very high temperature blades are studied, the general dimensions of turbomachinery for a typical pilot plant are given. The development of such a pilot plant would allow the application for carbon dioxide (CO2) retention by deep sea storage or by use in chemical industry. Such a pilot plant could demonstrate the feasibility of CO2 retention, a means of CO2 emission reduction, an environmental goal to which many governments have devoted themselves. In the farther future, after the establishment of a world wide solar energy system creating artificial fuels like liquid methane to be transported in the same way as liquid natural gas (LNG) today, such a plant would work as the means of effective reuse of these artificial fuels. CO2 would be transported back to the solar sites as an essential component in the production of the artificial fuels created there, thus closing the fuel cycle.