«Near Surface Geothermal Resources in the Territory of the Alpine Space» Pilot Study Switzerland, Davos

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1 Departement Umweltwissenschaften «Near Surface Geothermal Resources in the Territory of the Alpine Space» Pilot Study Switzerland, Davos Peter Huggenberger Stefan Scheidler Birte Anders Projectpartners: ANU Graubünden, Community Davos, Geotest Davos, ARE, BFE

2 Greta - INTERREG VB project Alpine areas rising energy consumption reduction of CO 2 emissions from heating (mainly from residential and tourism) Opportunity to utilize Near-Surface Geothermal Energy (NSGE) not yet properly highlighted Country-specific regulations and practices To demonstrate the potential of Geothermal Energy in the Alpine Space Integration into future plans at different administrative levels. The outputs of the project will serve to promote and guide the implementation of shallow geothermal energy into policy instruments, e.g., the energy plans of municipalities.

3 Project area GRETA - pilot project Davos Quelle Alpenrelief: Quelle Schematische Geologische Karte:

4 Energy for conference and sports facilities, hotels etc.

5 Objectives Pilot Study Davos The objective of the pilot study is to work out the use potential and productivity of shallow geothermal energy from an alpine aquifer, the Arosa Dolomite, an aquifer of regional spatial extent, embedded in a sequence of tectonic units in the eastern alpine system. The energy should be used for energy supply part of conference and sports facilities as well as hotel complexes. Geologically, the Arosa Dolomite unit includes mainly rocks of the Triassic Hauptdolomit- Formation. It is sandwiched between austroalpine and penninic tectonic units. A major challenge of our approach lies in integrating complex geological geometries from a 3D geological model (GOCAD) of the study area into the numerical groundwater flow model (COMSOL). Modelling pumping tests, understanding the dynamic character of capture zones of pumping wells, testing how different boundary conditions and hydraulic property distribution and evaluating the influence calculated flow regimes.

6 Previous work and activity of Greta BFE project 2012 Exploration drilling: 400 m Hydraulics Artesian conditions, 2.6 bar 1200 L/Min Aquifer Dolomites (Arosa Dolomite) Water inflow m Temp. 14 C Pumping Test 1240 L/Min (max 1740 L/Min) GW uptake m bar, GW, decline 15 m, 31 m Goal GW uptake 2000 L/Min GW decline 40 m GW observation wells m 2016 GRETA 3D GW model Increase in renweable heat production Connection to conference center (WEF) Waste heat (june-july) From 1200 to 1600 MWh Increase of heat supply from 12 to 13 h/day to 20 h/day = phase with max cold production Geotest AG Davos

7 From Geology to hydrogeological understanding 3D Geological Model Tektonics Stratigraphy? Fazies? Kinematics? Fracture distributions Hydrogeological Model Hydrogeological properties (K-value, porosity, (singleund multipoint statistics) defined geographic position Continuum Hydraulic Model Parametrisation of geol. Properties Definition boundary conditions discretisation (Mesh) Process equations (Darcy and conservation of mass Calibration

8 Davos Project Area: Geology Presentation is vertical exageration Tectonic zones: from WMS service geology, Canton Graubünden Geothermal drilling Davos

9 Geological Profile target formation Geothermal drilling Davos Change of hydraulic conductivity (info from drilling) Projection distance of the bore in the profile plane around 10 m Daten Geothermiebohrung Davos: Regli et al. 2013

10 Schafläger Zug Quartär Implementation geological units in hydraulic groundwater model Weissfluh Gotschna Schuppe B Rothorn Schuppe Silvretta Decke A BB Set-up of hydraulic model: Geometries from the geological model were adopted in the hydraulic model AA Prättigau Flysch A Quartär AA B A Prättigau Flysch BB B BB AA

11 Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez [mm/a] Boundary Conditions GW recharge Flux from Precipitation GWNB correspond to 900mm/a resp. 1200mm/a Calculation of influence of recharge precipitation possible 0 Grundwasserneubildung Quaternary: GW levels as «head» boundaries Quaternary-AD: Exchange across boundary Arosa Dolomite- Quaternary as semipermeable Boundary («Conductance») layer with defined hydraulic properties

12 Information derived from modeling tools Step pumping test: comparison measured modeled data Water budget during pumping test Calculation of water fluxes accross formation boundaries (water budget Arosa Dolomite) Influence of seasonal GW recharge Temperature development during pumping test Flow lines and capture zones Arosa Dolomite (Flowlines with and without puming) Influence of additional pumping locations Re-injection

13 1628 l/min 1206 l/min 256 l/min 919 l/min 628 l/min Step Pumping Test Pumping at EKB Locality Geotest AG,

14 18. Apr 20. Apr 22. Apr 24. Apr 26. Apr 28. Apr 30. Apr 02. Mai 04. Mai 06. Mai 08. Mai 10. Mai 12. Mai 14. Mai 16. Mai 18. Mai 20. Mai Kote [m ü.m.] H2O über Sonde [m] Pumping test (measured data) EKB fast response levels to pumping Overall decrease of GWT : 36.5m Hertistrasse Scalettastrasse Mattastrasse fast response levels GW to PT but slightly delayed compared to the reaction EKB At the highest pumprate plateau is not reached Decrease gwt 1548 Hertistrasse: 7.5m 1547 Scalettastrasse: 5.1m 1546 Mattastrasse: 4.5m Geotest AG,

15 Calculated reaction at 6 localities Kleine «Spitzen» und kurzfristige «Anreicherung» sind numerische Artefakte Mattastrasse: Absenkung gesamt 1.0m EKB Absenkung 50m Hertistrasse: Absenkung gesamt 1.3m Für Piezometer 28A sind die Artefakte ebenfalls noch vorhanden, jedoch schwächer ausgeprägt Scalettastrasse: Absenkung gesamt nur 0.6m

16 Calculation water fluxes

17 Flowlines with and without pumping B A A B Red: without pumping Green: with (high) pumping

18 Future pumping locations Geotest AG, Comparison EKB / S3 / Schulstrasse / puming all together Puming according Pumping Test GW recharge constant 900mm/a

19 Conclusions Model tool allows to calculate the head distributionin the Arosa Dolomite depending on groundwater discharge to simulate response of pumping tests to calcualte flow budgets from different boundaries to visualize the non-stationary capture zones of wells to calculate the changing contribution of the Quaternary deposits to use szenario techniques Future How much energy can produced (Scenarios) Coupling of flow and thermal aspects