The inevitable depletion of fossil resources and increasing atmospheric greenhouse gas concentrations demonstrate the need for renewable energy conversion technologies for a sustainable economy. Inter-mittencies and variability in availability of renewable energy sources are the challenges for uninterrupted energy supply, which can be overcome by large scale energy storage facilities. Pumped hydroelectric energy storage is an efficient but a very low energy density energy storage method that dominates the current energy storage market with similar to 96% share. We first present a recently developed potential solution for large scale efficient and dense energy storage: closed loop carbon storage cycles and a specific example dimethyl ether storage cycle. We then discuss the relevant US energy storage regulations, policy initiatives, their status, and potential modifications that will contribute to the invention and implementation of novel energy storage systems. (C) 2015 Elsevier Ltd. All rights reserved.