Optimization of compressed air storage´s volume for a stand-alone wind-diesel hybrid system

Hybrid wind-diesel-compressed air generator with pneumatic hybridization of diesel generator (DG) represents an innovative concept to overcome most of the technical, economic and social barriers that faces the deployment of wind energy in isolated sites. Adding compressed air energy storage (CAES) to the hybrid system increases the wind energy penetration rate in the overall production and further improves fuel savings. The CAES has numerous advantages for wind-diesel systems due to its high power density and reliability. The pneumatic hybridization of the Diesel engine consists to introduce the CAES through the admission valve. The combustion efficiency and the fuel consumption are improved by optimizing air/fuel ratio thanks to the CAES assistance. With limited tank volume, the pressure becomes an influent factor. As the pressure increase inside the tank, more power is required to introduce the same quantity of air. The goal of this study is to find the optimum tank volume, associated with the minimum mass of the tank and the maximum time of feeding DG with CAES.