Predictability of initial hydrogeochemical effects induced by short-term infiltration of ∼75 °C hot water into a shallow glaciogenic aquifer. (1st December 2021)

• Record Type: Journal Article
• Authors: Lüders, Klas; Hornbruch, Götz; Zarrabi, Nilufar; Heldt, Stefan; Dahmke, Andreas; Köber, Ralf
• Is Part Of: Water research. Number 13(2021)
• Publication Date: 2021-12-01
• Subjects: Underground thermal energy storage -- Groundwater quality -- Hot water infiltration field test -- Batch test based prognosis -- Hydrogeochemical predictability; Water supply -- Periodicals; Water-supply engineering -- Periodicals; Water -- Pollution -- Research -- Periodicals; 361.6105
• DOI: 10.1016/j.wroa.2021.100121
• Languages: English
• ISSNs: 2589-9147

Abstract

Highlights: Batch tests predicted (de)sorption-based concentration changes. Good prediction of maximum concentrations of environmentally relevant components. The less the hot water cooled, the better the predictive power of batch tests. The initial hydrochemical state was approached downstream from the infiltration. Abstract: Despite their potential in heating supply systems, thus far high-temperature aquifer thermal energy storages (HT-ATES) currently lack widespread application. Reducing the potential risks by improving the predictability of hydrogeochemical processes accelerated or initiated at elevated temperatures might promote the development of this technology. Therefore, we report the results of a short-term hot water infiltration field test with subsurface temperatures above 70 °C, along with associated laboratory batch tests at 10, 40 and 70 °C for 28 sediment samples to determine their usability for geochemical prediction. Most groundwater components had lower maximal concentrations and smaller concentration ranges in field samples compared to the batch tests. This indicates that the strongest geochemical effects observed in laboratory tests with sufficient site-specific sediment samples will likely be attenuated at the field scale. A comparison of field measurements with predicted concentration ranges, based on temperature induced relative concentration changes from the batch tests, revealed that the predictive power was greatest, where the hot infiltrated water had cooled least and the strongest geochemical effects occurred. The batch test-based predictions showed the best accordance with field data for components, with significant temperature-induced concentration changes related to ion exchange and (de)sorption processes. However, accurate prediction of concentration changes based on other processes, e.g. mineral dissolution, and downstream reversals in concentrations, requires further investigation. The here presented procedure enables the prediction of maximal expectable temperature-dependant concentration changes for most environmentally relevant ancillary groundwater components, e.g. As, with limited effort.