Influence of aquifer heterogeneity on the design and modelling of Aquifer Thermal Energy Storage (ATES) systems

A modelling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in aquifer thermal energy storage (ATES) systems. An existing ATES system installed within a heterogeneous aquifer system in Agassiz, British Columbia, Canada was used as a case study. Two 3D heat transport models of the study site were developed and calibrated using the heat transport code FEFLOW, including: a "simple" model domain with uniform hydraulic and thermal properties (no layering); and, a "complex" aquifer domain with variable hydraulic and thermal properties assigned to discrete layers to represent aquifer heterogeneity. Comparison of simulation results indicated heat transport in higher permeability layers was significant. Effects of heterogeneity on thermal energy storage and recoverability were not observed. Heat transport in the aquifer was determined to be more sensitive to properties and boundary conditions which influence convective heat transport.