Thermodynamic analysis of hybrid adiabatic compressed air energy storage system and biomass gasification storage (A-CAES + BMGS) power system

A thermodynamic analysis of a power system consisting of adiabatic compressed air energy storage and biomass gasification energy storage power system in a hybrid mode for simultaneous production of electricity and warm water for use domestically is presented in this paper. The hybrid system is designed to meet peak load power demand of 1.3 MW from a blend of 1 MW adiabatic compressed air energy storage system powered by electricity and 0.3 MW rated dual fuel (syngas + diesel) powered engine. The syngas fuel used in the dual fuel engine is supplied by a downdraft biomass gasification system whose wood feed is supplied by a hot air dryer system operated by waste thermal energy recuperated from the system. The performance of the overall system is assessed with total system efficiency, electrical efficiency, effective electrical and exergy efficiency as metrics. In addition, the performance of the sub-components of the system is appraised using exergy destruction and exergy efficiency. The overall energy and exergy efficiency of the system is found to be approximately 38% and 29%, respectively. The electrical and effective electrical efficiency, are 30 and 34%, respectively. The exergy efficiency of the sub-system components are 61.38, 21.47, 5.76, 89.17 and 86.12% for the biomass gasifier, dual fuel engine, hot air dryer, air compressor and air expander, respectively. It is found that the destroyed exergy in the components of the hybrid system is the uppermost in the biomass gasifier, then the DFE and the AE in that order. The minimum destroyed exergy occurs in the hot air dryer. The system has a primary energy savings ratio 10 which means it cannot be deployed as a CHP system under the EU criteria.