First Generation Graz Cycle Power Plant for Near-term Deployment

Carbon Capture and Storage (CCS) is a recognized technology pathway to curb the increasing emissions of carbon dioxide (CO2) from the power generation sector. But most available technologies are still on the study or laboratory-scale level, so that considerable R&D efforts are needed to achieve commercialization level. The Graz Cycle originally presented in 1995 by Jericha [1] is an oxyfuel technology and promises highest efficiency using state-of-the-art turbine materials and improved thermodynamic developments in a comparatively complex interaction of rotating machinery, condensers and heat exchanger components. But although detailed conceptual design for all main components has been presented, there is still a large step towards a Graz Cycle pilot demonstration plant. In order to facilitate construction of a demonstration plant we consider the performance of a near-term Graz Cycle process design based on modest cycle data and available turbomachinery components using a simplified flow scheme. The work is supported by on-going development work for a first generation oxyfuel turbine that has already been undertaken by Clean Energy Systems, Inc. [2]. Their further work on a second generation oxyfuel turbine received $30 million funding support from the U.S. Department of Energy in September 2010 [3]. Two near-term Graz Cycle plants are presented based on basic and advanced operating conditions of the proposed commercially available turbine. Besides the turbine the additional equipment for a first-generation cycle is discussed. The predicted optimum net efficiency is 23.2 % (HHV). A near-term zero-emission power plant can only be commercially attractive if it will be deployed in a niche market. Therefore an economic analysis commensurate with an early pre-FEED conceptual study is carried out for the U.S. Gulf Coast where revenue from multiple product streams that could include power, steam, CO2 and water, as well as argon and (potentially) nitrogen from the ASU is provided. The economic analysis suggests that a capital investment of $94 million can secure construction of a 13.2 MWe zero emission oxyfuel power plant and yield a 14.5% (unlevered) return on capital invested.