The Impact of varying thermal and hydraulic properties on HT-ATES systems
A Study Based on Sediments of the Maassluis Formation with a focus on thermal properties
Master Thesis
(2025)
Author(s)
L.N. Barlet (TU Delft - Civil Engineering & Geosciences)
Contributor(s)
JM Bloemendal – Graduation committee member (TU Delft - Water Systems Engineering)
Philip J. Vardon – Graduation committee member (TU Delft - Geo-engineering)
S.T.W. Beernink – Mentor (TU Delft - Geo-engineering)
Faculty
Civil Engineering & Geosciences
To reference this document use:
https://resolver.tudelft.nl/uuid:1384cfaf-8fb0-4051-808c-f92875f85de7
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Publication Year
2025
Language
English
Graduation Date
13-06-2025
Awarding Institution
Delft University of Technology
Programme
['Applied Earth Sciences']
Faculty
Civil Engineering & Geosciences
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Abstract
To address the gap of constant heat supply by geothermal doublets and the varying demand throughout a year, High Temperature Aquifer Thermal Energy Storage (HT-ATES) systems have attracted a growing amount of research interest as a way of storing the excess heat produced in summer for later use during the winter months.
The performance of seasonal heat storage systems in confined shallow aquifers depends on several (hydro)geological and design parameters.
The storage aquifer and sealing aquitard characteristics are subject to uncertainty and spatial heterogeneity. The present study examines the variability of hydrological and, in particular, thermal properties in cores taken from boreholes of the Maassluis formation in four different locations in the Western Netherlands. Because the uncertainty of thermal properties is rarely implemented in (HT-)ATES models, it is the main focus of this research.
In a laboratory study, the hydraulic conductivity and thermal properties of the cores and smaller-scale core plugs are measured to create a database of those parameters for the Maassluis formation, which is a promising heat storage target.
The samples are classified according to their grain size and evaluated with respect to their spatial variability. Results yield thermal conductivities ranging from 1.35W/mK to 2.37W/mK for clay samples and from 2.05W/mK to 2.94W/mK for sands.
These thermal conductivities are subsequently utilized to populate a numerical model of a potential HT-ATES system at the TU-Delft campus, using the SEAWAT code. The present study aims to assess the impact of the expected range of thermal conductivity in the aquifer and sealing layers on two key aspects: firstly, the recovery efficiency over the lifetime of the system, and secondly, the thermal impact on the subsurface.
Simulation outcomes demonstrate that recovery efficiency differences are marginal for varied thermal conductivities. In contrast, the vertical hydraulic conductivity of the aquifer exerts a significant influence, resulting in absolute recovery efficiency differences of up to 7% in the modeled scenarios.
Varied thermal conductivity of the sealing layer modeled can have a noticeable thermal impact on the subsurface around the system, while the horizontal spread of heat into the aquifer is predominantly influenced by buoyancy flow, caused primarily by larger vertical hydraulic conductivities.
The overall impact of the uncertainty of thermal sediment properties on system performance is minor when compared to other uncertainties However, the effect of thermal plume spread could be significant, depending on the surrounding environment.