An investigation and multi-criteria optimization of an innovative compressed air energy storage system is presented. The study focuses on a constant-pressure air tank (CP-CAES) system that improves energy storage efficiency, reduces exergy destruction, and enhances system performance. The system stores excess grid power as compressed air and heat during off-peak times and uses it to generate electricity during peak demand. The system's total electrical efficiency is 65.63%, round-trip efficiency is 68.28%, and exergy round-trip efficiency is 66.01%. The system's levelized cost of electricity is 190.4 $/MWh, with a payback period of approximately 5.11 years and an ultimate profit of around $40 million. The CP-CAES system integrates principles of compressed air energy storage (CAES) and pumped hydro energy storage (PHES). It uses a high-temperature energy storage (HTES) unit to preheat compressed air before it enters the air turbine, improving system performance and reducing the need for a continuous combustion chamber. A waste heat recovery (WHR) unit, consisting of an organic Rankine cycle (ORC) with a reheater, internal heat exchanger (IHX), and thermoelectric generator (TEG), recovers waste heat from the compression process, enhancing system functionality and reducing thermal pollution. The system is analyzed from energy, exergy, economic, and exergoeconomic perspectives. A multi-criteria optimization using artificial neural networks (ANN) and genetic algorithms is applied to determine the optimal working conditions. The results show that the system's performance is significantly improved compared to conventional storage methods. The study also highlights the importance of considering both thermodynamic and economic factors in the optimization process. The findings demonstrate the potential of the CP-CAES system as a viable solution for grid-scale energy storage, with high efficiency, low environmental impact, and cost-effectiveness.An investigation and multi-criteria optimization of an innovative compressed air energy storage system is presented. The study focuses on a constant-pressure air tank (CP-CAES) system that improves energy storage efficiency, reduces exergy destruction, and enhances system performance. The system stores excess grid power as compressed air and heat during off-peak times and uses it to generate electricity during peak demand. The system's total electrical efficiency is 65.63%, round-trip efficiency is 68.28%, and exergy round-trip efficiency is 66.01%. The system's levelized cost of electricity is 190.4 $/MWh, with a payback period of approximately 5.11 years and an ultimate profit of around $40 million. The CP-CAES system integrates principles of compressed air energy storage (CAES) and pumped hydro energy storage (PHES). It uses a high-temperature energy storage (HTES) unit to preheat compressed air before it enters the air turbine, improving system performance and reducing the need for a continuous combustion chamber. A waste heat recovery (WHR) unit, consisting of an organic Rankine cycle (ORC) with a reheater, internal heat exchanger (IHX), and thermoelectric generator (TEG), recovers waste heat from the compression process, enhancing system functionality and reducing thermal pollution. The system is analyzed from energy, exergy, economic, and exergoeconomic perspectives. A multi-criteria optimization using artificial neural networks (ANN) and genetic algorithms is applied to determine the optimal working conditions. The results show that the system's performance is significantly improved compared to conventional storage methods. The study also highlights the importance of considering both thermodynamic and economic factors in the optimization process. The findings demonstrate the potential of the CP-CAES system as a viable solution for grid-scale energy storage, with high efficiency, low environmental impact, and cost-effectiveness.