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In the present paper, an energy storage concept based on the integration of a Compressed Air Energy Storage system into a Gas Steam Combined Cycle plants is investigated. The integration of CAES results in a noticeable power augmentation in respect to normal GSCC plant operations. Being such a power increase obtained without using additional fuel, the storage system can be compared to PHS, BES and A-CAES. Two CAES integrated into medium size GSCC plants arranged with Aero Derivative and Heavy Duty Gas Turbines have been investigated. A techno economic analysis aimed at assessing plant performance and investment costs has been performed. Despite the relatively high investment costs and the storage efficiency lesser than those featuring alternative storage approaches, the proposed system may be considered of interest due to the long life duration and the established technologies available for the key plant components

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Abstract:In the present paper, the performance of an energy storage concept based on the integration of a compressed air energy storage (CAES) system into a gas-steam combined cycle (GSCC) plant is investigated. CAES systems featured by different design specifications have been coupled with a commercially available small size GSCC plant. Storage efficiencies up to 65% have been evaluated for CAES design power output ranging from 5 to 10 MW. A techno-economic analysis aimed at assessing plant performance and investment costs has been performed. Despite the relatively high investment costs and the storage efficiency being less than those featuring alternative storage approaches, the proposed system may be considered of interest due to the long-life duration and the established technologies available for the key plant components.

Two small size second-generation compressed air energy storage (CAES) systems have been investigated. Both plants are based on a 4600 kW Mercury recuperated gas turbine (GT) and on an artificial air storage system. In CAES air injection (CAES AI) plant, the stored compressed air is mixed with the air flow exiting the GT compressor and fed after a recuperative heating to the GT combustion chamber. A topping air expander is included in the CAES air injection/expander (CAES AI/E) plant scheme. Preliminary evaluations have been carried out to assess the maximum achievable GT power augmentation taking safety of operations and plant life duration into consideration. Plant performance has been evaluated during the overall operational cycle (charging, storage and discharging phases). CAES AI plant allows a 30% maximum extra power delivery (some 1500 kW) in respect to the nominal design GT power. The introduction of the topping air expander in CAES AI/E plant allows an additional power production of some 300 kW. Both plants have shown storage efficiency improvements by reducing the discharge period duration. Satisfactory values around 70% have been found in the best operating conditions