Near-autarkic heating and cooling of buildings using a triple well aquifer thermal energy storage concept

Abstract

The energy transition relies on electrification and due to the increased use of heat pumps this is especially true for the heating and cooling of buildings, causing congestion on the electricity grid. The Aquifer Thermal Energy Storage (ATES) Triplet can decrease the reliance of low-emission heating and cooling on electricity by utilizing on-site energy generation, two heating and cooling supply wells and one well to prevent thermal pollution of the other wells. With this setup the system provides heating and cooling without the use of a heat pump, only by circulating groundwater for the energy supply and asynchronous energy generation. A simulation study is conducted to identify when the ATES Triplet is a more viable option than a standard ATES doublet. Five building energy variables are systematically assessed with a subsurface thermohydraulic dynamics model, i.e. heating demand, cooling demand, injection temperature levels, cutoff temperature levels, and return temperature levels. These scenarios are evaluated based on the calculated electricity requirements, pumping volume, and on-site energy generation requirements. The results show that the Triplet outperforms an average low-temperature ATES doublet in most of the considered cases, especially cases with low sub-surface losses, a high heating ΔT, a low cutoff temperature and a low return temperature after heating. This requires building HVAC (Heating, Ventilation and Air Conditioning) systems to accept as wide a range of supply temperature as possible. Systems with a low heating demand (< 1 TJ) in combination with a high required temperature for heating (> 80 °C) are unfavourable.