Economic Viability of Flexible Carbon Capture for Natural Gas Power Plants

J.C. Quinn, B.J. Limb, E. Markey, S. Garland, R. Vercellino, M.D. Pisciotta, P. Psarras, J. Wilcox, D.R. Herber, T. Bandhauer
Colorado State University,
United States

Keywords: natural gas power plant, carbon capture, thermal energy storage


Over the last decade, 121 coal-fired power plants have been decommissioned or converted to natural gas-fired plants due to stricter emissions standards, economic constraints, and social pressures to reduce carbon emissions. Additionally, low-carbon nuclear plants are not being deployed because of safety concerns, policy changes, and rising equipment costs. As environmental policies continue to be implemented, natural gas power plants are expected to serve as a bridge fuel to replace coal and nuclear loads, as well as meeting peak demands when renewable energy is not available. To meet the Paris Agreement climate goals, carbon capture and sequestration (CCS) will be required on every natural gas power plant. Major drawbacks to utilizing CCS systems include the large parasitic heat load placed on the power plant and a reduction in the plant’s operating flexibility. To overcome these issues, this research evaluates the economic feasibility of incorporating a variety of thermal energy storage (TES) systems with natural gas combined cycle (NGCC) power plants using CCS. Combining a NGCC power plant with TES and CCS allows for flexible power output while meeting strict environmental constraints. TES systems can be made up of both hot and cold thermal units and can provide many benefits to the NGCC+CCS system. First, hot thermal storage can be used to supply heat to the CCS unit during times of peak power demand which increases the overall power output to the grid. Second, cold thermal storage can be used to chill the power plant’s inlet air which increases efficiency and power output. Third, TES units will charge during times of low electricity demand and discharge during peak demand which increases overall power plant profitability. Lastly, the charging and discharging of the thermal storage system allows the power plant to have a more flexible power output range than comparable NGCC+CCS systems. The modeling work developed to evaluate these technologies incorporates real-world electricity pricing data, lifetime economic costing, and 14 unique thermal storage configurations that range from Brayton cycle heat pumps to Vapor Compression heat pumps. Initial feasibility results show promising economic benefits for incorporating TES with NGCC+CCS systems. Adding TES can decrease the levelized cost of electricity for NGCC power plants to