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ATES research ATES research Presentation Transcript

  • Aquifer thermal energy storageResearch of the impacts of ATES on groundwater quality
  • Aquifer thermal energy storage
  • Development of ATES in Holland
  • Research questions and projects- What are the risks of ATES systems on groundwaterquality (chemical, microbiological and physical)?- Where can we allow what type of ATES systems?Two research projects:- Matthijs Bonte: hydrochemical impacts (BTO)- Philip Visser: physical impacts (TTiW)
  • Approach and methods- Monitoring ATES systems at 3 sites (mostly 7-17°C)- Laboratory experiments (5-60°C)- Numerical modelling (Modflow/Mt3D,Phreeqc)
  • Sampling and field locations
  • Field ATES system – Eindhoven:Monitoring program 2005-2012 (Brabant Water)Key question: what effects are visible at field scale? Drinking water ATES site Pumping station
  • Field data – EindhovenDepth profiles of ambient groundwater quality -ATES system is realized in Sterksel aquifer -Vertical redox zonation: removal of NO3, SO4; followed by appearance of CH4
  • Field data Eindhoven:Water quality patterns in ATES wells Ambient concentration range
  • Modflow-MT3DModelling of water quality pertubations Hydrogeology Simulated sulfate concentration
  • Laboratory investigations Aim: - Detailed analyses of Hydrochemical changes -Investigate more extreme T - Investigate reaction kinetics at different temperatures
  • Types of lab experiments-Test 1: Continuous flow test with 1 day residence time at 5,11,25 and 60ºCin three sediment samples from the Sterksel formation focus equilibrium reaction (sorption, mineral interaction)-Test 2: Incubation test with increasing residence time (1-35d) focus kinetically restricted (redox) reactions-Text 3: Temperature ramping test with 5d residence (T = 5 to 80ºC) focus kinetically restricted (redox) reactions
  • Collection of soil cores -Percussion drilling -Ackerman coring -Working water sparged with N2 -Transport in N2 filled cooling box
  • Sampling of influent water
  • Installation in lab
  • Results of 1 day leaching test: comparingconcentration at 5, 25 and 60ºC with 11ºCLeaching behavior Geochemical Temperature level 5ºC 25ºC 60ºC Organic matterSubstances significantly Substance present in As DOC, P Silicatesthermally sediment K, Si Trace elementsinfluenced (p<0.01) in all three As, Mo, Vexperiments, Substance not present in Be sediment above detection limit Not analysed F, Li
  • Results of 1 day leaching test: comparingconcentration at 5, 25 and 60ºC with 11ºCLeaching behavior Geochemical Temperature level 5ºC 25ºC 60ºC Organic matterSubstances significantly Substance present in As DOC, P Silicatesthermally sediment K, Si Trace elementsinfluenced (p<0.01) in all three As, Mo, Vexperiments, Substance not present in Be sediment above detection limit Not analysed F, LiLeaching behavior not Substance present in Alkalinity, SO4, Na, Mg, Sr, Ca, Fe, Mn, Al, Ba, Co, Cr,significantly sediment Cu, Eu, Ho, Ni, Pb, Sb, Sc, U, Yb, Zninfluenced by temperature in allthree experiments Substance not present in Ag, Bi, Cd sediment Not analysed Br, Cl, B, In, TlSubstance below detection Substance present in Ga, La, Thlimit in reference and testing sedimenttemperature Substance not present in Bi, Se sediment
  • Most relevant for drinking water: Arsenic (but also in B, Mo, P) Arsenic concentration as function of temperature 0.1 Mechanism (oxy)anion desorption 0.09 from Fe-oxides due to 0.08 - primarily temperature increaseDissolved As (mg/l) 0.07 0.06 0.05 - DOC and P release (competition 0.04 for sorption sites) 0.03 0.02 Exp A Exp B, Fe=3.2mg/l 0.01 Exp B, Fe=0.8mg/l 0 Exp C 0 10 20 30 40 50 60 70 Norm WLB T(degC)
  • Arsenic sorption: described with Freundlich sorption and van ‘t Hoff equationSorption isotherm (Freundlich curve)Q = KFC 1/ n
  • Sorption temperature dependence: Van ‘t Hoff relation Van ‘t Hoff plot ∆H ∆Sln K d = + RT RΔH points to Exothermicsorption(decreasing with T↑)Literature range ~-25 to -110kJ/mol
  • Field evidence of As and B leaching? Heuvelgallerie Eindhoven (multiple RIVM PB437-2 MWs) 0.04 13.5 30 13.1 0.035 25 12.7 20[As] mg/l T(ºC) 0.03 12.3 15 B (ug/l) 0.142x y = 0.4323e 0.025 2 11.9 R = 0.5273 10 0.02 11.5 5 Aug-10 Nov-10 Feb-11 May-11 Sep-11 Dec-11 Mar-12 Jul-12 0 As Temp with data logger Manual T-readings 0 5 10 15 20 25 Temp (degC)
  • Result batch experiment: clear impact on sulfate reduction rate and organic carbon mobilization 8 10 7 9 6 8DOC (mg/l) SO4 (mg/l) 7 5 degC 5 6 12 degC 4 5 25degC 3 4 60degC 3 Influent 2 2 1 1 0 0 0 10 20 30 0 10 20 30 Residence time (day) Residence time (day)
  • Temperature dependence of sulfate reductiondescribed with Arrhenius equationArrhenius equation: Arrhenius plot SO4 reduction 4 3 Exp A 2 Exp B Ln k (nmol/l/d) 1 Exp C 0 Linear (Exp B) -1 Linear (Exp A) -2 Linear (Exp C)Ea = 38-50 kJ/mol -3Q10 = 1.7 - 2 -4 2.9 3.1 3.3 3.5 3.7 3.9 1000/T(1/K)
  • Results temperature ramping revealsa ‘double peak’ pointing to 2 microbiological pop. 7Effluent sulfate concentration (mg/l) 6 after 5 day residence time 5 4 3 2 1 0 0 10 20 30 40 50 60 70 80 90 T(°C) Topt 1 Topt 2
  • Linear increase in dissolved organic carbon but not in methane 4.0 60 CH4 3.5 50 3.0 40DOC (mg/l) DOC CH4 (ug/l) 2.5 30 2.0 20 1.5 1.0 Influent DOC 10 0.5 0 Influent CH4 0.0 -10 0 20 40 60 80 100 T(°C) -Biological methane production, no methane producers at 70ºC? -DOC shows no correlation with SO4 reduction rate (DOC is often considered intermediate in Sulf.Red.)
  • Field evidence of DOC and CH4 increase?(Heuvelgallerie ATES 30ºC) 4.0 1000 3.5 800 3.0 DOC (mg/l) DOC- Lab 600 CH4 (ug/l) DOC- 2.5 Field CH4-field 2.0 400 1.5 200 1.0 CH4- LAB 0 0.5 0.0 -200 0 20 40 60 80 100 T(°C)
  • Mapping microbiological community:TRFLP fingerprinting, distinctly different at 60ºCCluster analysis DNA fragments Temperature
  • PHREEQC modelling of 1-day residence timecolumn experimentsKey question:-Can the inferred chemical processes explain the observedquality trendsProcesses included:-Cation exchange-Equilibrium with carbonate solid solution-Kinetic dissolution of k-feldspar-Surface complexation of trace elements to goethiteModel optimised with PEST (Marquardt-Levenberg method)
  • Modelling results: pH, Ca, Mg, Sr and alkalinity:89% CaCO3, 10%(CaMg)CO3, 1%SrCO3
  • Modelling results: Si and KExplained by incongruent K-feldspar dissolution Decreasing rate with time due to precipitation of secondary minerals
  • Modelling results: As, B, P, DOC, MoExpansion of PHREEQC / Dzombek & Moreldatabase with ΔH values for surface complexation
  • Conclusions PHREEQC modellingTest results can be simulated with combination of cation exchange,carbonate & K-feldspar dissolution and surface complexationConstraint of the model is for some parameters quite poor, especiallysurface complexation, e.g.: ΔHAs = -38.5 ±13.3 kJ/mol (van ‘t Hoff plot: -42±2kJ/mol) ΔHMo= -36.3 ± 32.2 kJ/mol ΔHB = -14.9 ± 14.1kJ/mol (van ‘t Hoff plot: -22±4kJ/mol)Due to high correlation between ΔH values (R2>0.8) Surface complexation describes competition between species, differentparameters are closely linked
  • Conclusions: effects of ATES on water qualityField data:-Mixing of vertical stratifiedwater qualities dominateseffects measured in field-ATES induced mixingpotentially increasesvulnerability of phreaticpumping stations
  • Conclusions: effects of ATES on water qualityField data: Laboratory data:-Mixing of vertical stratified -Sorption of heavy metals is stronglywater qualities dominates temperature dependent (but probablyeffects measured in field reversible)-ATES induced mixing -Sulfate reduction rate breakdownpotentially increases in aquifers appears to followvulnerability of phreatic Arrhenius (Q10 1.7-2) but morepumping stations temperature detail shows 2 maxima: ~40 and 70ºC
  • General conclusions-ATES not in capture zone / protection zone’s of vulnerablepumping stations
  • General conclusions-ATES not in capture zone / protection zone’s of vulnerablepumping stations-In other area’s, impacts are probably acceptable and reversible
  • General conclusions-ATES not in capture zone / protection zone’s of vulnerablepumping stations-In other area’s, impacts are probable acceptable and reversible-At much higher temperatures (>25ºC), ATESimpacts reactive (buffering) capacity of aquifer (SOM degradation)
  • General conclusions-ATES not in capture zone / protection zone’s of vulnerablepumping stations-In other area’s, impacts are probable acceptable and reversible-At much higher temperatures (>25ºC), ATES drasticallyimpacts reactive (buffering) capacity of aquifer-High T ATES is still an option, but only in aquifers whereirreversible impacts are acceptable (high salinity aquifers, highvertical anisotropy)
  • Questions?