A new reinforced concrete foundation system is being proposed to store renewable energy through the compressed air energy storage technology. For this application, the concrete is required to resist considerable tensile strength and to have low air permeability, which is not observed in normal concrete. Therefore, this paper is proposing to use reactive powder concrete for the suggested foundation system. Reactive powder concrete (RPC) is obtained by introducing either micro-cementitious materials like silica fume or fine powders like crushed quartz into the concrete mixture from where coarse aggregates had been removed. RPC has low water content and dense particle packing which lead to high strength and low air permeability characteristics. This paper conducts preliminary experimental investigations on the strength and air permeability of the RPC. Two important mix design parameters are studied including water-to-binder ratio ad silica fume content. Preliminary correlations between mix design parameters and strength/air permeability are developed. From the preliminary test results, it is concluded that the reactive powder concrete has potential to meet the high strength and low air permeability requirements, and is suitable for the proposed energy storage foundation system.