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Hydraulisk och termisk grundvattenmodellering av ett geoenergilager i Stockholmsåsen
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
2014 (Swedish)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesisAlternative title
Hydraulic and thermal groundwater modelling of a geothermal energy system in the Stockholmesker (English)
Abstract [en]

Geothermal energy can be extracted from an aquifer, where the groundwater is used as heat

exchange medium while heat and cold are stored in the surrounding material in the aquifer

and to some extent in the groundwater. Application of aquifer storage for the use of

geothermal energy is mainly used in large scale facilities and is limited to sites with suitable

aquifers in the form of ridges, sandstone and limestone aquifers.

Löwenströmska hospital in the municipality of Upplands Väsby, north of Stockholm, is

located nearby the northern part of the Stockholm esker. This means that it can be profitable

and environmentally beneficial for the hospital to examine the possibilities of aquifer storage

in the esker material next to its property.

The purpose of this master thesis has been to investigate if geothermal energy storage with a

seasonal storage of heat and cold can be applied within Löwenströmska hospital’s property

area using groundwater modeling. A hydraulic groundwater model was constructed in

MODFLOW based on a simplified conceptual model of the groundwater system. The

hydraulic groundwater model was calibrated and validated against observed groundwater

levels before and after a pumping test. The hydraulic groundwater model was then used to

implement a fictitious geothermal energy storage with MT3DMS. MT3DMS is a modular

function used with MODFLOW, which can be modified to simulate heat transport.

The result shows that the geothermal energy storage can store seasonal heating and cooling of

about 4 GWh, which covers 85 % of the hospital’s heating demand with an assumed SP-factor

of 4, and the entire cooling demand. To cover 50 % of the peak heating power it was

calculated that a flow of 63 l/s was needed, and according to the model this is possible. The

geothermal energy storage does not need to be completely in energy balance, since the aquifer

is recharged with its natural groundwater. The location of the wells influences which flows

that are needed to create energy balance. A too close placement of the wells leads to a thermal

breakthrough. The hydraulic conductivity of the esker material affects the amount of energy

that can be stored. A higher hydraulic conductivity provides greater energy losses and a lower

hydraulic conductivity favors the energy storage but gives a greater influence area.

A number of assumptions have been made in the model construction of the hydrogeological

model and further investigation of the geological and hydrogeological conditions are desirable

to improve the model.

Place, publisher, year, edition, pages
2014. , 54 p.
UPTEC W, ISSN 1401-5765 ; 14041
Keyword [sv]
Akviferlager, MODFLOW, MT3DMS, geoenergilager, hydraulisk grundvattenmodellering, termisk grundvattenmodellering
National Category
Other Engineering and Technologies not elsewhere specified
URN: urn:nbn:se:uu:diva-234325OAI: oai:DiVA.org:uu-234325DiVA: diva2:756168
External cooperation
Sweco Environment
Educational program
Master Programme in Environmental and Water Engineering
Available from: 2014-11-24 Created: 2014-10-16 Last updated: 2014-11-24Bibliographically approved

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