The Oxy-Fuel, Supercritical CO2 Allam Cycle: New Cycle Developments to Produce Even Lower-Cost Electricity From Fossil Fuels Without Atmospheric Emissions

Abstract

The Allam Cycle is a new, high-pressure, oxy-fuel, supercritical CO2 cycle that generates low-cost electricity from fossil fuels while producing near-zero air emissions; all CO2 generated by the system is produced as a high-pressure, pipeline-ready by-product for use in enhanced oil recovery, industrial processes, or sequestration. The base cycle was developed by 8 Rivers Capital and is being commercialized by NET Power, LLC in partnership with Toshiba Corporation, Exelon Corporation, and CB&I. The four parties are currently developing a natural gas-fired power plant to demonstrate this system. Target net efficiencies for the natural gas and coal versions of this cycle, based on current process modeling, are 59% and 52% (LHV) respectively, both with full carbon capture and no other air emissions. Detailed designs indicate that NET Power plants, with full carbon capture, will produce lower-cost electricity than state-of-the-art fossil fuel plants without CCS. 8 Rivers Capital continues to develop on top of the Allam Cycle platform. Building upon the original single turbine design, 8 Rivers has developed a two-turbine design that combines the benefits of the original, high-pressure Allam Cycle with a low-pressure reheat cycle. This new design can enable Allam Cycle-based plants to greatly increase power output with only a moderate increases in capital cost, substantially lowering the overall plant $/kW cost. Such a configuration would enable Allam Cycle plants to produce even lower-cost electricity than the single turbine Allam Cycle design currently being commercialized by NET Power, CB&I, Toshiba and Exelon. This paper outlines the design considerations utilized for the base Allam Cycle development and then details this new cycle design and its potential benefits.