Modeling and performance evaluation of fractured thermal energy storage (FTES)

Abstract

Fractured thermal energy storage (FTES) is an open-loop type system that uses hydraulically propagated horizontal fracture planes for storage and extraction of heat in low-permeability hard rock formations. Groundwater circulation through the fracture system is accomplished by pumping and injection via a set of vertical peripheral wells symmetrically positioned around a central well. In this paper, a numerical approach for modeling of FTES systems based on the finite element method is presented. The modeling approach that is established can be used to investigate various storage design configurations and operation conditions. To demonstrate the application of the approach, an illustrative long-term simulation using a 3D model of a FTES system is performed, and the thermal performance of the modeled storage is evaluated in terms of energy and exergy efficiency indicators.