Due to the depletion of fossil fuels and their adverse effects on the environment, there is a need of hour to shift towards the renewable energy resources. However, the most promising renewable resources such as wind power and solar power are intermittent in nature. Thus, a sustainable shift requires economical and efficient energy storage systems. Use of batteries is the widely accepted storage systems for such resources and significant research work has been carried out in last few decades to improve the cycle life of batteries but they are still unsuitable for large scale systems and disposal of discarded batteries is also a major environmental concern. In view of this, researchers found compressed gas energy storage (CGES) system as one of the potential alternatives to store renewable energy at large spatial and temporal scales. The current study provides a comparison between air and carbon dioxide (CO2) based CGES systems from a thermodynamic standpoint. In an effort of improving efficiency of system, it is proposed to supply additional heat via renewable resource to CO2 based system before the expansion of gas in the turbine. The performance comparison of six different systems has been carried out using first and second law efficiencies. Copyright © 2019 ASME