Thermodynamic, economic and environmental investigations of a novel solar heat enhancing compressed air energy storage hybrid system and its energy release strategies

Abstract

In this paper, a novel solar heat enhancing compressed air energy storage hybrid system is proposed, which mainly consist of three subsections: wind power sub-system, compressed air energy storage sub-system, and solar heat enhancing sub-system. The hybrid system driven by the excess electricity of wind power sub-system storages compressed air in an air storage tank and reserves compression heat with thermal storage medium from cylinder liner heat exchangers and inter-stage heat exchangers, and improves the thermal storage medium to a higher temperature by solar heat enhancing sub-system for a greater power output of the system. Three energy release strategies of the systems are proposed. And the thermodynamic performance of three release strategies is compared. The results show that Strategy 2 has a largest energy storage efficiency and energy storage density, which is 56.52%, 19.8 MJ/m3, respectively. In addition, energy, economic and environmental analyses are conducted. The payback period of system is 3.5 years. Compared with systems which are not combined with solar energy, the energy conversion efficiency of the system designed in this paper enhances by 25%, and the carbon emission reduces approximately by 42%. The payback period of system is also reduced. The influence of important parameters on system performance is explored using parametric analysis. The system can achieve a maximum energy storage efficiency when wind speed is 11 m/s. Meanwhile, energy storage efficiency and energy storage density all improve with the increase in environment pressure and solar irradiance, whereas these characteristics show divergent trends as the ambient temperature changes.