In this study, a process model was developed to determine the net energy ratios and life cycle greenhouse gas emissions of three energy storage systems: adiabatic and conventional compressed air energy storage and pumped hydroelectric energy storage, with estimated capacities of 118, 81, and 60 MW, respectively. The net energy ratios were calculated as ratios of net energy outputs to the total net energy inputs. The greenhouse gas emissions associated with construction, operation, decommissioning life cycle stages of the energy storage systems were evaluated. The net energy ratios for the adiabatic and conventional compressed air energy storage and pumped hydroelectric energy storage are 0.702, 0.542, and 0.778, respectively. The respective life cycle greenhouse gas emissions in g CO2 eq./kWh are 231.2, 368.2, and 211.1. The emissions are highly dominated by the operational stage in all the energy storage systems. It was also observed that energy consumption in the form of electricity is the key driver, while the contributions due to the use of material are minimal. Sensitivity and uncertainty analysis was also performed. The results help in understanding the comparative net energy ratios and emission footprints of various energy storage systems in order to make an informed decision. (C) 2018 Elsevier Ltd. All rights reserved.