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| Titel |
The effect of soil heterogeneity on ATES performance |
| VerfasserIn |
W. Sommer, H. Rijnaarts, Tim Grotenhuis, P. van Gaans |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067398
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| Zusammenfassung |
| Due to an increasing demand for sustainable energy, application of Aquifer Thermal Energy
Storage (ATES) is growing rapidly. Large-scale application of ATES is limited by the space
that is available in the subsurface. Especially in urban areas, suboptimal performance is
expected due to thermal interference between individual wells of a single system, or
interference with other ATES systems or groundwater abstractions. To avoid thermal
interference there are guidelines on well spacing. However, these guidelines, and also design
calculations, are based on the assumption of a homogeneous subsurface, while studies
report a standard deviation in logpermeability of 1 to 2 for unconsolidated aquifers
(Gelhar, 1993). Such heterogeneity may create preferential pathways, reducing ATES
performance due to increased advective heat loss or interference between ATES
wells.
The role of hydraulic heterogeneity of the subsurface related to ATES performance has
received little attention in literature. Previous research shows that even small amounts of
heterogeneity can result in considerable uncertainty in the distribution of thermal energy in
the subsurface and an increased radius of influence (Ferguson, 2007). This is supported by
subsurface temperature measurements around ATES wells, which suggest heterogeneity gives
rise to preferential pathways and short-circuiting between ATES wells (Bridger and Allen,
2010).
Using 3-dimensional stochastic heat transport modeling, we quantified the influence of
heterogeneity on the performance of a doublet well energy storage system. The following key
parameters are varied to study their influence on thermal recovery and thermal balance:
1) regional flow velocity, 2) distance between wells and 3) characteristics of the
heterogeneity.
Results show that heterogeneity at the scale of a doublet ATES system introduces an
uncertainty up to 18% in expected thermal recovery. The uncertainty increases with
decreasing distance between ATES wells. The uncertainty in the thermal balance ratio related
to heterogeneity is limited (smaller than 3%). If thermal interference should be avoided, wells
in heterogeneous aquifers should be placed further apart than in homogeneous aquifers,
leading to larger volume claim in the subsurface. By relating the number of ATES systems in
an area to their expected performance, these results can be used to optimize regional
application of ATES.
Bridger, D. W. and D. M. Allen (2010). "Heat transport simulations in a heterogeneous
aquifer used for aquifer thermal energy storage (ATES)." Canadian Geotechnical Journal
47(1): 96-115.
Ferguson, G. (2007). "Heterogeneity and thermal modeling of ground water." Ground
Water 45(4): 485-490.
Gelhar, L. W. (1993). Stochastic Subsurface Hydrology, Prentice Hall. |
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