Some hydrodynamic aspects of compressed-air energy storage in aquifers

Abstract In a compressed-air energy storage in an aquifer (CAESA) project, compressed air is injected into an anticlinal aquifer to form a compressed-air reservoir at a desired pressure. Once a compressed-air reservoir has been established, air is withdrawn for energy production during periods of peak demand for electric power, and reinjected during off-peak periods. In this way, excess energy produced during off-peak hours is stored for use during periods of peak demand. In order to plan a CAESA project, information is required, among other parameters, on the pressure fluctuations in the production-injection well as a function of the rate of production-injection and other pertinent reservoir parameters. During the preliminary phases of planning, it is important to obtain estimates of this information, quickly and at low cost. A simplified model is proposed here for this purpose. The model is based on the assumption that the air and the water domains are separated by an abrupt interface. Two simplified geometries are investigated: a one-dimensional vertical column with air injection and pumping at the top, and a partially penetrating well in the center of a cylindrical domain. For each case, the mathematical model was established and solved numerically. Several examples are given to demonstrate the application of the proposed model.