As oxy-fuel power generation is currently on the pre-demonstration stage of development many studies dealing with optimization and simulation aspects are still in progress. This paper is focused on the development of a simulation model of the integrated oxy-fuel system and cumulative energy analysis of an oxy-unit operation in separated national economy. The analyzed oxy-fuel system consists of a steam boiler, steam cycle, air separation unit, as well as a CO2 purification and compression island. The built model is based on physical relations. It has been developed as a set of modules modelling isolated devices (e.g. combustion chamber or flue gas dehumidifier). Interconnections between these devices can be easily changed, which permits to analyse different oxy-fuel structures and operating parameters. The simulation model has been partially verified on the basis of literature data. Results of oxy fuel energy analysis have been presented for one selected structure and compared with an air combustion power unit, assuming the same steam cycle parameters. For both cases indices of cumulative primary energy consumption have been calculated. The obtained results show that the increase of oxy-fuel primary energy consumption (compared with air-based combustion) can be significantly reduced if by-produced nitrogen will be used for external applications. (C) 2009 Elsevier Ltd. All rights reserved.