This paper focuses on the economics of integrating thermal energy storage into natural gas combined cycle power plants for improved operational and economic performance of the utility grid. Costs and fuel consumption are modeled based on a Florida electric utility’s hour-by-hour load data under two scenarios: 1) no storage, and 2) thermal storage attached to intermediate load, NGCC plants, displacing energy production from older, less efficient NGCT peaking units. Due to the nature of the power grid, several of the older units feature abnormally high fuel costs and abnormally low thermal efficiencies. By shifting load from the most expensive peaking units to more cost-effective combined cycles with a 204 MWhth storage system costing about $4 million, savings of more than $1 million per year can be realized while also reducing CO2 emissions by about 5000 metric tons per year. These savings represent an internal rate of returns of up to 23% over a 30-year lifetime, depending on the initial cost of the storage system.

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