1. National research program on the effects of Underground Thermal Energy Storage (UTES) - use of the subsoil in a sustainable way - Benno Drijver – IF 24 september 2010

2. Content 1) UTES –Why UTES? –What is UTES? –Application in the Netherlands 2) Research program –Organization –Approach –First results 3) Conclusion

3. 1) UTES – Why UTES? Fossil fuels are finite Security of energy supply (reduce dependence on fossil fuels) Reduce global warming  Urgent need to reduce the use of fossil fuels  Trias Energetica: I.Reduce energy demand (energy-saving) II.Use renewable sources instead of fossil fuels III.Use the most efficient techniques to produce/use energy  UTES saves energy (and energy costs)

4. 1) UTES – What is UTES?  TES = thermal energy storageUTES = using the underground for TES TES using ice has been used for hundreds of years

5. 1) UTES UTES – What is UTES? What is UTES? Aquifer TES (ATES): Open loop systems Groundwater is extracted from and infiltrated in the aquifer Borehole TES (BTES): Closed loop systems

6. 1) UTES – What is UTES? ATES – Types Doublet Monowell Recirculation

7. 1) UTES – Application in the Netherlands ATES permits in the Netherlands: 1990, 2000, 2009

8. 1) UTES – Application in the Netherlands Growth of ATES and BTES in the Netherlands Applications of ATES in the Netherlands

9. 2) Research program – Why a research program? Government wishes to stimulate UTES (less stringent regulations, faster permit procedures, etc.) Growth has to take place in a sustainable way  Research on the remaining concerns - Impact on groundwater chemistry and microbiology - Interference between UTES systems - Claim on subsurface space - Perforation of protecting clay layers - Potential leakage of fluids from BTES-systems  Investigating opportunities: combination concepts UTES/Remediation and UTES/other concepts in the watercycle

10. 2) Research program – Organization Research parties Specialist in (bio)remediation Combination UTES – remediation Research institute on the subsurface Geohydrology, geochemistry, remediation Consultant specialized in UTES > 20 years of experience Fundamental research UTES, remediation, microbiology

11. 2) Research program – Organization Made possible by our participants –Foundation for Knowledge Development and Disseminiation on Soil (SKB) –National government (ministries of Economic Affairs and of Housing, Spatial Planning and Environment) –All 12 provinces –Municipalities (Almelo, Amersfoort, Apeldoorn, Den Bosch, Deventer, Haarlem, Hengelo, Tilburg, Utrecht, Zwolle) –Water boards (Groot-Salland, Regge en Dinkel) –Drinking water companies/organizations (Brabant Water, Vitens, VEWIN) –Agency NL, Arcadis, Essent (Energy company), Port of Rotterdam, Dutch association for UTES (NVOE), Dutch horticultural association (PT), Dutch Railways Foundation for Soil Remediation (SBNS), Rendo

12. 2) Research program – Approach Literature review  Direct impact ATES: (hydrological, thermal)  Indirect impact ATES (compaction, chemistry, microbiology)  BTES (anti-freeze liquids)  Combination concepts (UTES – remediation/other concepts)

13. 2) Research program – Approach Field measurements at 9 UTES-projects  Different types of UTES systems: BTES, different ATES types, high temp., contaminated sites  Relatively old projects (long term impact)  Availability of a reference well  Existing data set  Different geochemical (redox) conditions  Temperature difference > 2 °C  Geographical distribution 1x 3 x 1x 1x 2x

14. 2) Research program – Approach Field measurements at 9 UTES-projects  Clean sites: 3 monitoring wells (warm zone, cold zone, reference well)  Contaminated sites: 5 monitoring wells Parameters: Physical -hydraulic head, temperature, EC, pH Chemical -main and trace elements, redox parameters, pollutants, nutrients, substrates Microbiological -numbers, diversity, species, functional groups, pathogens, remediating species

15. 2) Research program – Approach Laboratory experiments Step 1: Batch experiments to investigate mobilisation of organic matter from aquifer sediment. Static and dynamic (shaken) tests at 10, 20, 30, 50 ºC. Step 2: Batch experiments on bioremediation at different temperatures (with and without stimulation) to investigatie the influence of temperature on remediation kinetics. Step 3: Column experiments to investigate the influence of flow velocity on bioremediation kinetics.

16. 2) Research program – First results Geochemistry – Results from literature review Conclusions  impact of temperature on main elements seems insignificant below 25 ºC  > 40 ºC precipitation of carbonates can occur  > 45 ºC fulvic acids are mobilized from organic matter in aquifer sediments Little research was found on:  The impact on trace elements  The impact of (vertical) mixing

17. 2) Research program – First results Microbiology – Results from literature review Conclusions  Microbiologic growth is limited by the amount of assimilible organic carbon => Limited temperature increases seldom lead to microbial growth  Organic matter mobilized at high temperatures might stimulate microbial growth  Temperature changes can cause shifts in the composition of the microbiologic population to species that are adapted to these temperatures  Pathogens are not expected to grow in aquifers used for UTES Little research was found on:  The impact on functional groups (e.g. denitrifiers, sulfate reducers)  The impact on microbial diversity

18. 2) Research program – First results Laboratory experiments Step 1 (Static and dynamic (shaken) batch experiments at 10, 20, 30, 50 ºC) is finished Conclusions: -Temperatures up to 30 ºC do not influence COD; -Increasing temperature to 50 ºC leads to elevated COD levels; This indicates mobilisation of organic matter between 30 and 50 ºC

19. 2) Research program – First results Interference Projected interference risk: growth to 2250 ATES systems The Hague Amersfoort Amsterdam

20. 2) Research program – First results Interference: Factors influencing interference Calculated temperatures after 20 years of ATES: Energy balance Large energy imbalance

21. 2) Research program – First results Interference: Factors influencing interference Hydrological impact ATES (well configuration)  Extraction without re-injection (I)  Extraction with re-injection (ATES – A,B,C) BC A A I

22. 3) Conclusion Questions that lawmakers have to deal with are: - To what extent should other groundwater users (e.g. drinking water companies) be protected against UTES? - Should high temperature storage be allowed and under which conditions? - Which monitoring prescriptions should be demanded in permits? - What requirements should be made to reduce the risk of leakage of fluids from BTES systems and limit the consequences? - Is legislation necessary to minimize interference? (how bad is interference?) Goal of the research program (2009- end of 2011): - Provide scientific information on the effects of UTES - This information must help lawmakers to develop new legislation

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