Evaluating the economic viability of NGCC-SWITCC: Natural Gas Combined Cycle System With Integrated Thermal storage and Carbon Capture

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. 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 to meet peak demands when renewable energy and expensive battery storage is not available. To meet the Paris Agreement climate goals, carbon capture and sequestration (CCS) will be required on every natural gas power plant. However, major drawbacks to utilizing CCS systems include the large parasitic heat load placed on the power plant and a reduction in plant’s operating flexibility. To overcome these issues, the team has developed the Natural Gas Combined Cycle System With Integrated Thermal storage and Carbon Capture (NGCC-SWITCC) concept, which incorporates thermal energy storage (TES) with natural gas combined cycle (NGCC) power plants that use CCS. This research evaluates the economic viability of the NGCC-SWITCC system in future electric grids with a high penetration of variable renewable energy systems.The TES component can be made up of dual hot and cold thermal units and can provide many benefits for the NGCC-SWITCC approach. 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 inlet air which increases efficiency and power output. Third, TES units can 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 models developed for this work consist of three interconnected technology, optimization, and techno-economic models. These models work synergistically to optimize the system size and operation for maximum net present value (NPV) using lifetime economic costing and future electricity price signals generated by the National Renewable Energy Laboratory (NREL) ReEDS model and the Princeton University GenX model. In total, 4 unique thermal storage configurations were evaluated. The National Energy Technology Laboratory (NETL) Case B31B using Shell CANSOLV® CCS was assumed to be the base power plant in this study. To understand the feasibility of next generation CCS technologies, ION Clean Energy’s ICE-31 solvent was also evaluated with the NETL Case B31A NGCC base power plant (B31A+ION CCS).