Techno-economic assessment on wellbore heat loss of the high-temperature aquifer thermal energy storage system in the area of Burgwede, Germany

High-temperature aquifer thermal energy storage offers a promising solution for balancing fluctuating energy supply and demand. While previous studies have primarily focused on heat and mass transfer within reservoir, wellbore heat loss has received comparatively limited attention. In this study, a coupled wellbore-reservoir model is developed and validated with a real district case to quantify the impacts of wellbore heat loss on overall system performance. Sensitivity analyses and a comprehensive techno-economic assessment are conducted to identify the dominant factors influencing heat loss. The results indicate that continuous heating losses occur in both the reservoir and the wellbore throughout system operation. At a low flow rate of 10 l/s, nearly 90% of the total energy loss originates from the wellbore. At a higher flow rate of 40 l/s, the contribution of wellbore heat loss decreases but still increases over time, rising from ca. 60% in the 1st year to ca. 70% as the operation proceeds. Furthermore, variations in flow rate and injection strategy primarily affect the system levelized cost of heat through changes in the total recovered energy, whereas improvements in wellbore insulation performance mainly reduce costs by decreasing heat loss within the wellbore.