Assessing the quantitative potential of seasonal aquifer thermal energy storage and recovery in the Brussels-Capital Region using combined 3D- groundwater flow, heat and reactive transport modelling

Abstract

In an evolving energy system it is important that urbanized areas contribute to their own energy demands. The availability of renewable energy sources often does not coincide with demand and production. An attractive manner to store energy is to facilitate urban aquifers for seasonal aquifer thermal energy storage and recovery (ATES). ATES can improve environmental quality in urban areas and decrease primary energy consumption In this study, we investigate the potential of ATES for the Brussels Sand Formation, a phreatic aquifer up to 70 m thick located in the Brussels-Capital Region, Belgium. Distributed groundwater flow and heat transport models are applied on representative pilot sites to quantify the potential of ATES. The process of well clogging by iron hydroxide precipitation, which can be an important problem in ATES operation is addressed with reactive transport models. Distributed models can provide feasibility maps, which help to establish guidelines for future subsurface planning in an urban area. Different model scenarios show that only for low hydraulic conductivities of 4.2e-6 ms-1 that the hydraulic and thermal output is insufficient for ATES systems. For a high hydraulic conductivity scenario (1.4e-4 ms-1) the potential output of ATES is satisfactory, as long as the groundwater flow velocity does not exceed 5e-4ms-1. The reactive transport model shows that to avoid well clogging, groundwater should be pumped only from above or below the aquifers redox boundary.