2. UBeG GbR - Dr. E. Mands & Sauer Umwelt - Baugrund - Geothermie - Geotechnik Zum Boden 6, D-35580 Wetzlar, Tel.: 06441 212910 Email: e.Mands@UbeG.dee.Mands@UbeG.de Exploration of thermal underground conditions Geothermal Response Test and design of Borehole Heat Exchangers Systems

3. Geology of Hessen 1,6 – 2 W/mK 2-2,5 W/mK 1,8 – 2,6 W/mK Granites 2,5 – 3,5 W/mK

4. Heat conductivity

5. Thermal Conductivity

6. Determination of Thermal Conductivity Borehole thermal Resistance undisturbed underground temperature Geothermal-Response-Tests

7. First generation of Mobile Geothermal Test in Germany 1999 First comercial test in Germany Commercial Geothermal Test in Germany

8. Second generation of Mobile Geothermal Test computer-controlled Hardware

9. 3. Generation of Mobile Geothermal Test (compact) with small catapillar Max. Heat load 9kW, steppless regulation Computer-Controlled Hardware

10. Automatic evaluation:- Datenfiles can be read directly into the soft ware - Controle of result by stepwise evaluation Software GeRT-CAL

11. A constant increase and irregular behaviour of the stepwise evaluation curve shows an influence of groundwater Testdauer: without groundwater influence Groundwater influence Stepwise evaluation

12. Information from the Temperature log: Determination of undisturbed underground temperature Determination of Geothermal Gradient Gives information about irrregular thermal conductivity Shows the influence of Groundwater Temperature-profile Undisturbed (before Test) 1h after end of test Directly after end of test

13. Example GeRT Berlin 11/2006

14. Example GeRT Camburg 10/2006

15. Experience with Geothermal Tests

16. Benefit of Gethermal-Response-Test

17. Undersized Cost for a Geothermal Response Test +- 3400€

18. Oversized I Cost for a Geothermal Response Test +- 3400€

19. Design of BHE - System Input information from HVAC - Engineers

20. Input Underground

21. EED Calculation

22. Type of BHE Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k Double U-BHE Single U-BHE

23. Comparison and recommendation Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k Double U-BHE 165m Total BHE length Single U-BHE 195m Total BHE length A Double U- BHE has 10-15% more efficiency than a single U-BHE

24. Depth of BHE Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k 1 x 165m2 x 82,5m

25. Comparison and recommendation Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k Single BHE (deep) 165m Total BHE length Two BHE (shallow) 184m Total BHE length For purly heating purposes a single deep BHE is more efficient than two shallow BHE

26. Borehole diameter Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k 152mm diameter180mm diameter

27. Comparison and recommendation Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k Diameter 152mm 165m Total BHE length Diamter 180mm 178 m Total BHE length Kleiner Bohrlochdurchmesser wirkt sich günstig auf die Entzugsleistung aus

28. Grouting-material Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k Bentonit-Zement Verpressung Thermisch verbessertes Material

29. Grouting Material

30. Comparison and recommendation Example: 10 KW Heating 2100 Full load hours Heat conductivity of underground 2,5 W/m/k Cement – Bentonite Grouting 165m Total BHE length Thermal Grout e.g. STÜWATHERM 128 m Total BHE length Thermal Grout has 15% more efficiency

31. Sumary The design of BHE – Systems is in Germany under the regulation of VDI 4640 Geological investigations are always necessary (interpretion of geological maps) The design can be done by diagrams, tables, and calculations. Project with more than 30KW heating load should be calculated Furthermore Geothermal Response Tests should be performed from 30KW and more Thermal enhanced grouting material should be used for all BHE drillings (STÜWA – THERM)