ERE3.4 | Underground Thermal Energy Storage; applications, concepts, impact and processes.
EDI
Underground Thermal Energy Storage; applications, concepts, impact and processes.
Convener: Martin Bloemendal | Co-conveners: Kathrin Menberg, Claire BossennecECSECS, Stijn BeerninkECSECS, Peter Bayer
Orals
| Fri, 28 Apr, 08:30–10:00 (CEST)
 
Room -2.16
Posters on site
| Attendance Fri, 28 Apr, 10:45–12:30 (CEST)
 
Hall X4
Orals |
Fri, 08:30
Fri, 10:45
Thermal Energy Storage (TES) is a key component for an efficient energy supply and for achieving a low-carbon energy balance. TES allows a flexibility of storage volume and storage time, and represents a cross-sector technology as it is coupling heat, cooling energy, and electricity. This session is dedicated to Underground Thermal Energy Storage (UTES) technologies, their performance and engineering, and new insights into related heat transport processes in the subsurface. In particular, the focus is on Aquifer Thermal Energy Storage (ATES), Borehole Thermal Energy Storage (BTES) and related ground based variants such as pit storage and artificial water-gravel storage basins. The aim of this session is to overcome technical obstacles concerning the design and sustainable operation of TES. We want to improve our understanding of any UTES-related thermal, hydraulic and environmental effects. In a broader context, we invite contributions that show how to enhance social acceptance of UTES and how to integrate various renewable energy sources (e.g., geothermal, solar, waste heat) in UTES technologies. Furthermore, the session aims to provide an overview of the current and future research in the field, covering any temporal or spatial scale. Both in research and in practice, accurate characterization of subsurface flow and heat transport based on observations of induced or natural variations of the thermal regime are essential. We invite contributions that deliver new insight into advances in experimental design, reports from new field observations, as well as demonstration of sequential or coupled modelling concepts. The seasonal and long-term development of thermal and mechanical conditions in aquifers, and heat transfer across aquifer boundaries are focus points. This also includes the role of groundwater in the context of UTES and geothermal energy use for predicting the long-term performance of geothermal systems (storage and production of heat), and integration in urban planning. There are many ongoing research projects studying heat as a natural or anthropogenic tracer, and which try to improve thermal response testing in aquifers. Such techniques are of great potential for characterizing aquifers, flow conditions, and crucial transport processes, such as mechanical dispersion. Understanding the interaction of hydraulic, thermal and mechanical processes is a major challenge in modern hydrogeology and in particular relevant for many UTES variants.

Orals: Fri, 28 Apr | Room -2.16

Chairpersons: Peter Bayer, Claire Bossennec
08:30–08:40
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EGU23-8903
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ECS
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On-site presentation
Vasileios Christelis, Andrés González Quirós, Corinna Abesser, David Boon, Edward Hough, and Michael Spence

Aquifer Thermal Energy Storage (ATES) systems use reversible abstraction and injection in combination with warm and cold wells to provide efficient heating and cooling solutions at scales up to ~0.5 MW per installation. It has been shown that these systems are able to improve the efficiency of thermal installations, but rely on an appropriate design, especially when several ATES systems share the same aquifer. In this work, we combine groundwater flow and heat transport numerical models with optimization frameworks to investigate the optimal distribution of wells for avoiding system interferences and improving recovery efficiency. To that end, we employ hypothetical modelling scenarios based on geological properties of the Sherwood Sandstone bedrock aquifer as one of the main potential targets for the development of ATES systems in the UK. Some of the available information is acquired from activities at the UK Geoenergy Observatory (UKGEOS) in Cheshire, which is under construction and will be equipped with a range of technologies and monitoring sensors for research, training, and on-site experiments. The Observatory will be open to industry and the research community to evaluate technological options for shallow geothermal use and energy storage and to gain a detailed hydraulic and thermal characterization of the Sherwood Sandstone. As practical application, we present an approach for the optimal design of the installation of multiple doublets that consider various spatial features as decision variables. The benchmark solution is provided by a simulation-optimization framework that uses a direct coupling of the groundwater flow and heat transport numerical model with an evolutionary algorithm. This approach is typically hampered by increased computational cost due to the time-intensive numerical simulations and the thousands of objective function evaluations required until convergence of the evolutionary algorithm is achieved. Therefore, we also investigate a lower computational resource strategy by applying surrogate-assisted optimization methods which are either embedded in the operations of the evolutionary algorithm or utilize an adaptive-recursive framework. The performance of the surrogate-based optimization method is assessed via several independent optimization trials and for different computational budgets. The ability of the surrogate-based optimization frameworks to approximate a near global solution is compared against the benchmark solution.

How to cite: Christelis, V., González Quirós, A., Abesser, C., Boon, D., Hough, E., and Spence, M.: Integration of at-scale field observations and application of surrogate modelling strategies for optimal design of ATES systems in the Sherwood Sandstone aquifer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8903, https://doi.org/10.5194/egusphere-egu23-8903, 2023.

08:40–08:50
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EGU23-11413
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ECS
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On-site presentation
Alireza Arab, Leonie Gabler, Martin Binder, Christian Engelmann, Christine Viehweger, and Traugott Scheytt

Aquifer thermal energy storage (ATES) is one of the main types of geo-storage concepts aimed at an efficient energy supply and for achieving a low-carbon energy balance. In ATES, thermal energy is stored underground for later use; for instance, by intentionally injecting warm water - heated up by excess heat energy of industry and commerce - into the aquifer, and recovering it later for heating purposes, e.g., during the winter period. However, a significant number of ATES projects suffer from operational and maintenance issues or failures. Mineral precipitation (scaling) and flocculation, or microbial growth are major risks for ATES. By reducing the permeability in reservoirs, these processes threaten medium- to long-term operational reliability.  

The BMBF-funded research project ‘UnClog-ATES’ comprehensively investigates clogging and scaling in two typical reservoirs for ATES systems (siliciclastic sediments and carbonate-bearing sediments) which are widely distributed and exhibit different reactivity with respect to temperature and hydrochemical changes. Laboratory-scale flow-through column experiments as well as batch reactor experiments will be performed to simulate transport under representative ATES conditions (pressure, temperature, hydraulics, and chemical composition). Additionally, countermeasures (e.g., scaling inhibitors, acids, or CO2) will be investigated to maximize the potential of ATES in the future. Finally, based on numerical reactive solute transport models, a catalog of criteria for users and decision-makers will be created to facilitate an initial site assessment in order to minimize the operational risk of ATES at this level.

How to cite: Arab, A., Gabler, L., Binder, M., Engelmann, C., Viehweger, C., and Scheytt, T.: Analyzing clogging and scaling processes in carbonate and siliciclastic ATES systems based on column and batch experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11413, https://doi.org/10.5194/egusphere-egu23-11413, 2023.

08:50–09:00
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EGU23-16904
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On-site presentation
Raoof Gholami

Over the past decade, there have been numerous attempts to use low-grade waste heat (30 oC and 100 oC) for a variety of different applications, especially district heating systems. However, the initial investment in waste heat recovery systems is usually high and the temperature is too low to meet the needs of the different end users. One possible solution is to integrate seasonal thermal energy storage with data centers or other industries that deals with waste heat. This is especially possible when considering borehole thermal energy storage (BTES), as it is highly adaptable, expandable and economical. However, almost all research and technical applications of BTES systems have focused on solar energy storage, with the exception of the projects in Emmaboda (Sweden) and Chifeng (China), where BTES systems have been used to store waste heat. In this paper, the results of a series of measurements on a BTES in Norway are presented and numerical simulations are performed to evaluate the long-term performance of the BTES once it is connected to a continuous supply of waste heat from a data center. The results obtained show how important a long-term prediction of the system performance is for planning and optimization. It was found that the storage temperature and heat recovery of the BTES are lower than expected when the quantity and quality of waste heat is overestimated. It seems that the borehole has the capacity to store  heat at a temperature of more than 75 C, but it may reduce its functionality over time and shorten its lifespan from 30 to 10 years.

How to cite: Gholami, R.: Thermal Energy Storage Integration with Waste Heat: What are the Challenges?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16904, https://doi.org/10.5194/egusphere-egu23-16904, 2023.

09:00–09:10
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EGU23-12390
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ECS
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On-site presentation
Kai Stricker, Robert Egert, Peter Fokker, Phil J. Vardon, Jan Diederik van Wees, Eva Schill, and Thomas Kohl

In central Europe, the majority of the CO2 emissions in the energy sector are related to the provision of building and process heat. Due to seasonal fluctuations in demand, especially to provide heat for residential and industrial buildings, local storage of excess heat in summer for utilization in winter is becoming increasingly important. With the current state of technology and foreseeable developments, sufficient amounts of heat can only be stored underground, taking advantage of the large available storage volumes. In contrast to typical near-surface aquifer thermal energy storage (ATES), the utilization of deep reservoirs enables the storage of much larger thermal energies due to potentially significantly higher injection temperatures (e.g. > 80 °C).

Previous studies demonstrated the high potential of deep reservoirs for high-temperature (HT) ATES, in particular for former hydrocarbon reservoirs in the Upper Rhine Graben. However, these studies focused on thermo-hydraulic processes, only rarely considering the impact of coupled mechanical processes. Using the case study of the DeepStor project, a demonstrator for HT-ATES under development in the north of Karlsruhe (Germany), the present study investigates the influence of coupled thermo-hydraulic-mechanical (THM) processes during the operation of HT-ATES systems.

In particular, we investigate the impact of seasonal HT-ATES with biannual injection/production cycles on the stress distribution in the subsurface and subsequently caused displacements in the reservoir and the surface as well as the shear capacity at faults. This study further aims at improving the understanding of poro- and thermoelastic processes related to HT-ATES. Whereas the thermoelastic component dominates the vertical displacements at the top of the reservoir, the uplift at the surface is primarily controlled by the poroelastic component. Furthermore, an assessment of potential risks such as surface uplift or shear capacity at faults is performed. Our results show that surface uplift is primarily controlled by the reservoir depth, Young’s modulus, and the injection/production flow rate.

How to cite: Stricker, K., Egert, R., Fokker, P., Vardon, P. J., van Wees, J. D., Schill, E., and Kohl, T.: Risk assessment of high-temperature heat storage (HT-ATES) at the DeepStor demonstrator site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12390, https://doi.org/10.5194/egusphere-egu23-12390, 2023.

09:10–09:20
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EGU23-14087
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ECS
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On-site presentation
Stefan Heldt and Sebastian Bauer

The seasonal storage of heat has the potential to reduce greenhouse gas emissions, since it accounts for the seasonal disbalance between heat production and demand in renewable-based energy-systems. High temperature aquifer thermal energy storage (HT-ATES) is a heat storage technology utilising the subsurface and therefore provides high storage capacity with limited above-ground usage, which is especially required in urban areas. Since the temperature difference between the ambient groundwater and the injected water (> 50 °C) results in density differences, convective buoyancy flow can be induced by HT-ATES. This process leads to an uneven heat distribution over the aquifer thickness, reduced storage efficiency and increased thermal impacts. The occurrence and intensity of buoyancy flow is site-specific, since it depends on operational parameters, such as injection temperature, as well as geological parameters, such as aquifer thickness and especially vertical and horizontal permeability.

The geological site considered for HT-ATES storage is located in Hamburg, Germany, using the Miocene Lower Braunkohlensande (brown coal sands) as storage aquifer. This sedimentological formation was deposited in a coastal transition regime between terrestrial and shallow-marine settings and consists mainly of sands. Peat swamps and lagoons formed brown coal, silt and clay layers, which have the potential to hinder convection due to their low permeability, depending on their lateral extent in relation to the size of the induced heat plume by HT-ATES. Lithological classifications of 25 wells provide the data basis for the geological analysis.

The aim of this study is to evaluate the influence of thin low permeability layers on induced buoyancy flow and thus HT-ATES performance, as measured by heat recovery. To this end, a site-specific numerical HT-ATES model is created, which simulates the coupled thermo-hydraulic processes. Different scenarios with varied vertical permeability as well as the number and lateral extent of low-permeability layers show the effect on density-driven buoyancy flow and HT-ATES efficiency. Increasing the vertical permeability by a factor of 10 results in an efficiency decrease from 78 % to 57 % in the 10th storage cycle. The findings serve as a process understanding basis for complex heterogeneous facies models of the HT-ATES site, which will be based on the geostatistical evaluation of site data.

How to cite: Heldt, S. and Bauer, S.: Evaluating the impact of anisotropy and low-permeability layers on high temperature aquifer thermal energy storage performance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14087, https://doi.org/10.5194/egusphere-egu23-14087, 2023.

09:20–09:30
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EGU23-14917
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ECS
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On-site presentation
Jessica Chicco and Giuseppe Mandrone

The current energy crisis since February 2022, have led governments to put in place short and long-term measures aimed at shielding consumers from the direct impact of the rising energy prices across Europe, and to counteract the continuous economic volatility. The pressure is high for finding solutions to reduce energy imports, and fight against climate change impacts. The numerous debates on climate change such as the COP27 are pushing for a greater acceleration in decarbonising the energy sector. Low carbon sources such as geothermal energy can substantially decrease energy consumptions and costs, especially if included into decarbonized heating and cooling grids (Chicco et al., 2022). The use of geothermal energy for thermal energy production and storage in district heating and cooling (DHC) grids may also be a key element in overcoming short-term energy peaks overcoming of the gap between energy supply and demand, which is still a challenge for the energy transition.  In this framework, underground thermal energy Storage (UTES) systems can be a key element for efficient operation of heating and cooling grids. Here, we present a study aimed at evaluating the performance of one of the most promising underground thermal energy storage systems, which uses boreholes to store heat or cold (BTES). Aimed at testifying the replicability of the used methodology, we replicated the same workflow already presented in Chicco and Mandrone (2022) but on a different area in northern Italy, with similar hydrogeological and thermo-physical characteristics. Based on real field data, the study focused on numerical simulations aimed at understanding how these technologies can be used as backup systems, or when the energy demand overcomes that supplied by conventional heating systems. Obtained results proved again how the integration of these technologies in DHC contexts can contribute to greater energy and economic savings, showing that BTES are very flexible to meet both the base and peak load requests for several users.

Chicco, J.M.; Antonijevic, D.; Bloemendal, M.; Cecinato, F.; Goetzl, G.; Hajto, M.; Hartog, N.; Mandrone, G.; Vacha, D.; Vardon, P.J. Improving the Efficiency of District Heating and Cooling Using a Geothermal Technology: Underground Thermal Energy Storage (UTES). In New Metropolitan Perspectives; Calabrò, F., Della Spina, L., Piñeira Mantiñán, M.J., Eds.; NMP 2022; Lecture Notes in Networks and Systems; Springer: Cham, Switzerland, 2022, 482, 1699–1710. https://doi.org/10.1007/978-3-031-06825-6_164

Chicco, J.M.; Mandrone, G. Modelling the Energy Production of a Borehole Thermal Energy Storage (BTES) System. Energies 202215, 9587. https://doi.org/10.3390/en15249587

How to cite: Chicco, J. and Mandrone, G.: Borehole thermal energy storage (BTES) as backup systems in district heating and cooling contexts: results from numerical simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14917, https://doi.org/10.5194/egusphere-egu23-14917, 2023.

09:30–09:40
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EGU23-9471
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Highlight
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On-site presentation
Philipp Blum, Kathrin Menberg, Paul Fleuchaus, Simon Schüppler, Ruben Stemmle, Florian Barth, and Peter Bayer

Decarbonising the heating and cooling sector is crucial for reducing our global CO2 emissions. One promising option for environmental friendly energy supply in buildings is the use of shallow geothermal energy (SGE) (< 400 m depth) such as ground source heat pump (GSHP), groundwater heat pump (GWHP) and tunnel geothermal systems. In addition, renewable energy sources such as wind and solar are typically intermittent in nature, which is why they are characterized by an abundant but limited instantaneous availability. Peak time shaving and shifting by thermal energy storage are therefore considered as a key to the transition of the heating and cooling sector from fossil-based to zero-carbon. To balance these temporal variations in the availability and demand, Underground Thermal Energy Storage (UTES) systems could be used. In particular, Aquifer Thermal Energy Storage (ATES) systems are characterized by high storage capacities and low storage costs and is, therefore, drawing growing attention worldwide. However, only little is known about global application and distribution of ATES systems. Hence, this talk will provide an overview of the present and future potential of ATES systems including the chances and risks associated with such systems, which can play an important part in achieving our ambiguous climate targets.

How to cite: Blum, P., Menberg, K., Fleuchaus, P., Schüppler, S., Stemmle, R., Barth, F., and Bayer, P.: Chances and risks of aquifer thermal energy storage (ATES) systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9471, https://doi.org/10.5194/egusphere-egu23-9471, 2023.

09:40–09:50
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EGU23-15738
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ECS
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Highlight
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On-site presentation
Matthijs S. van Esch, Martin Bloemendal, Niels Hartog, and Philip J. Vardon

Low temperature Aquifer Thermal Energy Storage (ATES) is increasingly used for space heating and cooling. Though these systems emit 3-4 times less CO2 compared to gas heating, they still require a substantial amount of electricity, mostly because of the heat pump (~60%). Storing higher temperatures (HT) to be used for direct heating can be a solution to circumvent the use of a heat pump, however the return temperature after heating is not usually cold enough to use directly for cooling. The first HT ATES systems that are implemented have either no cooling, or alternative means for cooling. With better insulated buildings, that require both heating and cooling, as well as an increased pressure on the electricity grid, an autarkic system is needed that can supply both heating and cooling. The ATES Triplet system aims to do just that.

Similar to and HT ATES system, the ATES Triplet stores hot water at supply temperature needed for space heating in a hot well. Unlike the HT-ATES system, it also aims to store water at the supply temperature for cooling in a cold well. This heat and cold can be harvested by solar collectors and dry coolers (or other green heat/cold sources locally available). After the water extracted from the wells is used to heat/cool the building, the solar collectors and dry coolers can be used to store water at the right temperatures. However, the availability of these sources can be insufficient to reach the required temperatures. A third well is added that functions as a buffer. Water used for heating or cooling can be stored here until there is enough heating/cooling capacity available from the solar collectors and dry coolers to upgrade the water to the required temperature, and store in the hot or cold well. Furthermore, the solar collectors and dry coolers can also be used for direct space heating and cooling, making the entire system and autarkic heating and cooling system.

Initial simulations show a substantial reduction to operational CO2 emissions compared to conventional heating systems. Though a higher initial investment is required, systems also show an increased economic performance over conventional ATES systems and gas heating. Further research will investigate the effect of subsurface conditions, system layout and other operational conditions on the economic and environmental performance of the system.

How to cite: van Esch, M. S., Bloemendal, M., Hartog, N., and Vardon, P. J.: The reduction of heating and cooling CO2 emissions with the ATES triplet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15738, https://doi.org/10.5194/egusphere-egu23-15738, 2023.

09:50–10:00
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EGU23-8618
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ECS
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On-site presentation
Haegyeong Lee, Andy Wilkins, Philipp Blum, Peter Bayer, and Gabriel Rau

Accurate prediction of heat transport in porous media is important for understanding geoscience processes and properties and to design applications, for example geothermal energy systems. While heat transport is generally modelled assuming of local thermal equilibrium (LTE), i.e., instantaneous heat transfer between the fluid and solid phases, previous studies have demonstrated presence of local thermal non-equilibrium (LTNE), i.e., delayed heat transfer, in natural porous materials. However, factors that influence the rate of heat transfer between the phases and their significance for inherently heterogeneous natural systems remain unknown and untested. We develop an open-source fully coupled, finite-element application to numerically simulate heat transfer between the fluid and solid phases. This is based on the Multiphysics Object-Oriented Simulation Environment (MOOSE) and allows massively parallel modelling of heat transport including customized transfer rates. We verify our model using an analytical solution considering LTNE and illustrate several applications. The model can be used to investigate processes that affect heat transport such as heat transfer mechanisms and their dependence on different hydrogeological conditions.

How to cite: Lee, H., Wilkins, A., Blum, P., Bayer, P., and Rau, G.: Fully coupled heat transport modelling in porous media considering transfer between phases, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8618, https://doi.org/10.5194/egusphere-egu23-8618, 2023.

Posters on site: Fri, 28 Apr, 10:45–12:30 | Hall X4

Chairpersons: Peter Bayer, Claire Bossennec
X4.129
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EGU23-1030
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ECS
Ruben Stemmle, Haegyeong Lee, Philipp Blume, and Kathrin Menberg

Aquifer thermal energy storage (ATES) is a promising technology for sustainable and climate-friendly space heating and cooling which can contribute to the energy transition, as it causes significantly less greenhouse gas (GHG) emissions than conventional space heating and cooling technologies. Using 3D thermo-hydraulic numerical models, this study quantifies the technical potential of shallow low-temperature ATES in the city of Freiburg, Germany. The numerical models consider various ATES configurations and different hydrogeological subsurface characteristics relevant for the study area. Based on the modeling results, spatially resolved ATES power densities for heating and cooling are determined and compared to the space heating and cooling energy demand. High ambient groundwater flow velocities of up to 13 m d-1 cause relatively high storage energy losses resulting in maximum ATES power densities of 3.2 W m-2. Yet, these still reveal substantial heating and cooling energy supply rates achievable by ATES systems. While heating energy supply rates of larger than 60 % are determined for about 50 % of all residential buildings in the study area, the cooling energy demand could be supplied entirely by ATES systems for 92 % of the buildings. Also, ATES heating alone could allow for greenhouse gas emission savings of up to about 70,000 tCO2eq a‑1, equivalent to 40 % of the current greenhouse gas (GHG) emissions from space and water heating in the study areas’ residential building stock. The proposed modeling approach in this study can also be applied in other regions with similar hydrogeological conditions to obtain estimations of local ATES supply rates and support city-scale energy planning.

How to cite: Stemmle, R., Lee, H., Blume, P., and Menberg, K.: Residential heating and cooling with Aquifer Thermal Energy Storage (ATES) on city scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1030, https://doi.org/10.5194/egusphere-egu23-1030, 2023.

X4.130
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EGU23-6500
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ECS
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Clara Fraile, Emmanuel Gaucher, and Thomas Kohl

In Central Europe, the thermal energy required for heating and cooling represents a major CO2 emitter in the energy sector. Seasonal underground heat storage offers the option to store a large amount of excess heat in summer for usage in winter and, with that, decrease the need for conventional sources of energy. Today, high-temperature aquifer thermal energy storage (HT-ATES) systems are attracting large interest for securing a heat demand in a sustainable manner.

In HT-ATES systems, hot water is injected into a reservoir over the summer months while exchanged cold water is injected over the winter season. These changing temperatures and pressures will affect the geomechanical and thermo-hydraulic properties of the reservoir and the surrounding layers. Monitoring the changes in the reservoir properties is key to run a heat storage system safely and efficiently. We try to determine if active seismic imaging could be a suitable method to characterize the time-space evolution of the reservoir.

With view on designing future geophysical assessment and monitoring systems, we perform thermo-hydro-mechanical (THM) modelling, using MOOSE and TIGER applications, with characteristics based on the DeepStor demonstrator under development in the north of Karlsruhe (Germany), at KIT, to determine the changes in the poroelastic properties of the underground. The first three layers model includes different mechanical properties with one borehole. The simulation of hot water injection over a period of time allows to quantify its effect on the underground material properties. Besides the DeepStor demonstrator expected operational frame, we test additional injection schemes with varying underground properties to simulate the different ranges of porosity changes and look at their effects on the elastic properties.

The changes in the parameters from the THM model are linked to seismic sensitive variables, such as velocities and impedances, using empirical equations. Hence, we can quantify the effects of injection on such variables and determine if it would be possible to detect them with active seismic surveys.

How to cite: Fraile, C., Gaucher, E., and Kohl, T.: THM modelling of seismic velocities changes at DeepStor heat storage demonstrator, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6500, https://doi.org/10.5194/egusphere-egu23-6500, 2023.

X4.131
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EGU23-6706
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ECS
Maximilian Dörnbrack, Dr. Chaofan Chen, Dr. Haibing Shao, and Prof. Dr. Holger Weiß

In the scientific park of Leipzig an Aquifer Thermal Energy Storage (ATES) system is planned in combination with the remediation of groundwater contaminated with chlorinated volatile organic compounds.

During the operation of the ATES system a two-well system is used. The cold groundwater is extracted from one well, and reinjected after heating up through the other well into the aquifer as storage. Later this pumping mode will be reversed and the heated-up groundwater will be extracted as a heating source.

In the most of ATES system, hot water is injected into aquifers at temperature lower than 25°C, while the planned system will inject at temperature of up to 80°C. This leads to a more significant influence on the chemical composition of the groundwater than with lower temperature ATES systems. Additionally laboratory tests from a previous project also show a drastic change in the microbiological biome at 45 and 60°C.

To facilitate the understanding of such impacts, a simplified 2D numerical model has been constructed, simulating both hydraulic and heat transport process in the aquifer. The model is currently being used as a planning tool to predict the propagation of the thermal plume, as well as designing the pumping rate of the circulation system. The model results already show a larger thermal-affected zone due to the high-temperature injection compared to low temperature ATES system.

Future application of the model is to investigate the impact of thermal signal on the mobilization of the contaminants, and also its contribution to the natural attenuation through change in the microbiological biome and activity, which determines the degradation rate in most cases. The overall goal of the project is to develop a fully coupled THC model that will be used to simulate the thermal, hydraulic and chemical processes associated with the thermal usage of a contaminated aquifer in urban areas.

How to cite: Dörnbrack, M., Chen, Dr. C., Shao, Dr. H., and Weiß, P. Dr. H.: Modelling the combination of aquifer thermal energy storage with remediation of contaminated groundwater, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6706, https://doi.org/10.5194/egusphere-egu23-6706, 2023.

X4.132
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EGU23-6913
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ECS
Claire Bossennec, Ingo Sass, Lukas Seib, Matthias Landau, and Tien Hung Pham

Heat storage in crystalline basement rocks is a promising technology because it can provide a reliable source of heat and help to increase the efficiency of energy systems, and reduce greenhouse gas emissions. BTES systems work by circulating water in multiple borehole heat exchangers (BHE). However, BTES systems can be expensive to install, as they are sub-surface installations which require the drilling of medium-deep boreholes into often complex, sometimes fractured, heterogeneous lithologies.  Therefore, the geological uncertainties must be integrated from the early planning stage on.

This contribution focuses on the insights gained in the SKEWS (Seasonal Crystalline Borehole Thermal Energy Storage) project (research project SKEWS, project administrator Jülich, funding code 03EE4030A) and how these will be developed and rolled out in the Horizon Europe PUSH-IT project into follow-up sites at the European scale. The SKEWS project implements the world’s first demo site for Medium-Deep Borehole thermal energy storage in crystalline rocks, with three 750 m deep boreholes separated from an 8.6 m distance, drilled at campus Lichtwiese from the Technical University of Darmstadt, Germany.

From the drilling campaign carried out in the summer and autumn 2022, new insights have been gained into the implementation of BTES in such an urban environment. These insights go from the drilling technologies and verticality to the installation of the BHE. This knowledge and know-how will then be developed during the test phase and with the integration and surface connection of the BHE field with a section of the district heating grid.

Borehole heat exchanger installation, with insights on the experience gained on the optimal design, drilling, and completion, will be detailed. The planning and first results of the reservoir test phase and monitoring through optic fibre will be presented, as well as perspectives on targeted digital twin geological static and dynamic modelling of the reservoir and the district heating grid in a co-simulation workflow.

Such outputs will allow quantitative estimation of the technical and economic potential of the MD-BTES systems in existing or future district heating grids.

How to cite: Bossennec, C., Sass, I., Seib, L., Landau, M., and Pham, T. H.: MD-BTES construction and integration into a district heating grid: Insights and targets of SKEWS and PUSH-IT projects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6913, https://doi.org/10.5194/egusphere-egu23-6913, 2023.

X4.133
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EGU23-11492
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ECS
Geraldine Regnier, Hayley T. Firth, and Matthew D. Jackson

Aquifer Thermal Energy Storage (ATES) has the potential to provide large scale, seasonal, low carbon heating and cooling to the built environment. Currently, heating of buildings represents 23% of the UK’s greenhouse gas emissions. ATES could therefore be a key technology for the UK to meet its net zero targets, particularly as cooling demand is set to increase in a warming climate.

The potential for ATES developments in the UK is significant: it has a seasonal climate, and many major cities are underlain by suitable storage aquifers such as the Chalk beneath London, and the Permo-Triassic sandstone aquifers beneath Manchester and Liverpool. Despite this large potential, the uptake of ATES in the UK is limited, with only 11 installations over the past 16 years. 10 of these installations target the Chalk aquifer and 9 are located in London. In this study, we report the current status of ATES installations in the UK. A case study of an operational ATES system in the fractured Chalk aquifer in London is presented. Monitoring data over a 7 year period are used to quantify the performance of the system, with key metrics such as energy balance and thermal recovery being reported.

We also report challenges to uptake of ATES in the UK. Poor performance due to a lack of understanding of the technology is observed. Inadequate monitoring of the systems (temperature, flowrate) as well as large imbalances between heating and cooling loads are identified as key issues with some current ATES systems in the UK. The complexity of the UK aquifers is also identified as a potential challenge, as geological heterogeneity has been shown to lower system efficiency and increase the risk of well interference. Finally, a lack of awareness of ATES technology is also identified as a key barrier to uptake, so it is not considered as an option to provide heating and cooling to buildings by key stakeholders such as local and national planners and policy makers.  We report ongoing work to overcome these challenges.

How to cite: Regnier, G., Firth, H. T., and Jackson, M. D.: Aquifer Thermal Energy Storage in the UK: current status and challenges to uptake, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11492, https://doi.org/10.5194/egusphere-egu23-11492, 2023.

X4.134
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EGU23-2795
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ECS
Christoph Bott, Mathias Ehrenwirth, Christoph Trinkl, Tobias Schrag, and Peter Bayer

Heat storages have become an increasingly important component of innovative energy systems on a  district-level, characterized by a high share of renewable energy and/or a high degree of autarky. Large-scale thermal energy storages are required to compensate for the seasonal mismatch between demand and supply; they form a central junction in the distribution network of a district, linking the various sources and sinks.

Established geothermal heat storage systems (Aquifer/borehole thermal energy storages) already show a high market availability. Based on a large number of customized implementations, substantial expertise and best practice is available in this sector. Additionally, closed systems based on artificial basins (Tank, pit, water-gravel thermal energy storages) were developed for site-independent implementation;  they can be distinguished by different components, materials and construction methods. However, they still lack market maturity, with two key aspects as critical barriers: firstly, building complexity of such facilities is high, resulting in high investment costs. Secondly, planning processes are still subject to a significant degree of uncertainty. Consequently, such sophisticated and expensive projects are often contrasted with a high financial and technological risk.

In order to tackle both of these key issues, we present two solutions within our study. We introduce an interesting alternative based on recycling. As high investment costs result mainly from excavations and expenses for structural components, we suggest the re-use of existing infrastructures and artificial basin installations. In our presentation, we estimate the potential of these technical conversions. From a conceptual perspective, we demonstrate the variety of possible types of infrastructures and analyze their suitability for being re-used as storage based on different requirements, e.g., accessibility, integrability, competing interests and legal constraints. From this, we derive an overall assessment with regard to the suitability of sites and highlight advantages and weaknesses of the various types of infrastructures.

Still, any implementation can only be successful if the structure used shows sufficient performance. This is in high contrast to the usually considerable deviations from common design conventions for closed seasonal thermal energy storages, e.g., geometrically with respect to the surface/volume ratio. Here, the possible maximum storage capacity, charging/discharging power and efficiency of a re-used infrastructure after its conversion needs to be analyzed from a technical perspective. To address this suitability aspect, we use a recently developed simulation tool “STORE”, which allows versatile modelling and evaluation of storage design scenarios on a component level using a 2.5‑D approach. In our presentation, we employ “STORE” to a case study and examine a potential re-use of a former water-treatment basin. After applying common boundary conditions of an energy system and setting different design scenarios, we focus on performance indicators and reveal the best technical solution for this specific case study and discuss transferability of the results.

Finally, we use our study to demonstrate, under which conditions the conversion and re-use of artificial infrastructures can be a promising approach: By reducing investment costs of large-scale, closed thermal energy storage systems, it can pave their way to full market availability.

How to cite: Bott, C., Ehrenwirth, M., Trinkl, C., Schrag, T., and Bayer, P.: Simulation of Re-Used Basin Structures for Long-Term, Large-Scale Sensible Thermal Energy Storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2795, https://doi.org/10.5194/egusphere-egu23-2795, 2023.

X4.135
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EGU23-7241
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ECS
Matthias Landau, Lukas Seib, Claire Bossennec, Heiko Handke, Jürgen Muhl, Jürgen Stumpf, Uwe Schindler, and Ingo Sass

As a result of the current energy crisis triggered by war and increasing shortage of resources, renewable energy sources are becoming increasingly important. The storage of heat from fluctuating energy sources is an essential component for independent and base-load capable energy supply. A promising technology are medium-deep geothermal storage systems, which store excess heat in the crystalline subsurface and offer significant advantages over near-surface geothermal storage systems. At the Lichtwiese campus of the Technical University of Darmstadt, the world's first medium-deep research geothermal storage system was constructed in the crystalline bedrock with three 750 m deep boreholes with a distance of approx. 8.6 m (research project SKEWS, project administrator Jülich, funding code 03EE4030A). The outer casing of the coaxial system has a diameter of 7", on which an attached glass fiber cable records temperature and strain measurements. Research operations began in the spring of 2023, which consists of an initial enhanced Geothermal Response Test (eGRT) followed by five heating and cooling phases.

The experience and knowledge acquired are intended to demonstrate the basic construction and operational feasibility of such storage systems, as well as to be used as a basis for the planning, dimensioning, construction and costing of future projects.

With the current project status, it has already been possible to evaluate the processes of the drilling phase and their effects on the drilling operation. The encountering of deviating geological and hydrogeological conditions to the prognosis from the planning phase required, among other things, the change of the drilling technique from water hammer to rotary drilling with a clay-fresh-water fluid and accordingly also affected the verticality of the drillings. Based on the detailed drilling data recorded and the geological conditions explored, the drilling phase of the storage system could be evaluated in terms of its material usage, drilling accuracy, costs and energy consumption.

How to cite: Landau, M., Seib, L., Bossennec, C., Handke, H., Muhl, J., Stumpf, J., Schindler, U., and Sass, I.: Drilling engineering experience gained from MD-BTES construction phase of SKEWS demo-site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7241, https://doi.org/10.5194/egusphere-egu23-7241, 2023.

X4.136
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EGU23-15943
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ECS
The effects of density and viscosity changes on well flow distribution in HT-ATES well screens
(withdrawn)
Stijn Beernink, Jan van Lopik, Niels Hartog, Philip J. Vardon, and Martin Bloemendal
X4.137
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EGU23-7656
Evaluation of High-temperature Borehole Thermal Energy Storage (HT-BTES)
(withdrawn)
Mohsen Assadi and Abdelazim Abbas Ahmed
X4.138
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EGU23-11517
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ECS
Max Ohagen, Hung Pham, Claire Bossennec, and Ingo Sass

District heating grids (DHG) face the problem of seasonal variability and peak demands, e.g., there is a high demand for heat in winter and a low demand in summer. Operators of district heating networks and energy suppliers are therefore seeking solutions to store heat and access it at peak times, thus reducing the use of carbon-emitting heat sources. Aquifers are well suited for heat storage because of high storage capacity relative to the surface occupancy and reasonably high recovery efficiency, if geological suitable. In this study, the potential of Aquifer Thermal Energy Storages (ATES) contribution in decreasing seasonal peak heat loads is investigated by numerical modelling. Each part of the overall system (surface and subsurface) is modelled in their corresponding simulation environment. They are numerically coupled with a novel approach, allowing for highest accuracy in both subsystems. The District Heating Grid is modelled in the object-oriented modelling language Modelica including the Open-Source library MoSDH. Using the Functional Mock-Up Interface (FMI) the Modelica models are exported to executable Functional Mock-Up Units (FMU). The groundwater flow and heat transport processes are modelled in the finite-element software FEFLOW. By developing a C++ Plug-In for FEFLOW the FMU is imported and dynamically co-simulated. This approach allows for easier adjustments in both subsystems and more coupling options to existing models and softwares.  Through numerical analysis different hydrological and geological scenarios of the ATES and different operational cycles are investigated to determine the long-term efficiency and capacity of the storage. This modelling approach can be used to develop strategies for the operation of the ATES as well as to evaluate in advance whether geological conditions are suitable for the particular network situation.

How to cite: Ohagen, M., Pham, H., Bossennec, C., and Sass, I.: Co-Simulation of Seasonal Aquifer Thermal Energy Storage and District Heating Grid using the Functional Mock-Up Interface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11517, https://doi.org/10.5194/egusphere-egu23-11517, 2023.