Hydrochemistry and energy storage in aquifers - NHV.nu

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AQUIFER THERMAL ENERGY STORAGE: THE IMPORTANCE OF GEOCHEMICAL REACTIONS E.A. Jenne ABSTRACT Aquifer Thermal Energy Storage (ATES) is a technology that uses waste heat to raise the temperature of groundwater until needed for heating during a season of greater demand. Geochemical problems encountered in ATES systems and the underlying geochemical processes are the subject of this paper. Geochemical problems arise from the formation of precipitates that reduce the efficiency of heat exchangers and clog the pores of aquifers, reducing their permeability and maximum injection rates. Precipitates result from oversaturation of the water with solid phases because of changing temperature, changing partial pressures of oxygen and/or carbon dioxide, and/or displacement of Ca from cation exchange sites. Precipitates are generally composed of CaC03(s) or Fe and Mn oxyhydroxides. As storage temperatures in excess of 100°C are used, the likelihood increases that silicate scale will form during heat extraction. The infiltration of surface water through river and lake sediments commonly results in an increase in dissolved Fe and Mn because first oxygen then Mn(1V) and Fe(II1) oxides serve as the electron acceptors for the products of microbial respiration. Thus, near-surface aquifers often contain significant levels of dissolved Fe and Mn that precipitate when exposed to oxygen. The water of ATES systems frequently calculates to be oversaturated with pure calcite as a result of the formation of solid solutions of calcite with Mg, Fe and Mn. The capability to model carbonate solid solutions empirically and theoretically has been
developed within Annex VI (Environmental and Chemical Aspects of Thermal Energy Storage in Aquifers and Research and Development of Water Treatement) of the International Energy Agency (Programme of Research and Development on Energy Conservation Through Energy Storage). However, the presence of crystal growth inhibitors (e.g., dissolved organic carbon, phosphate) may decrease precipitation rates of CaC03(s) and thereby cause oversaturation. The formation of precipitates in ATES systems can be avoided by appropriate selection of the storage aquifer, use of municipal water as initial source water, andlor continuous water treatment. Air andlor microbial oxidation can be used to lower dissolved Fe and Mn concentrations. Calcium andlor carbonate concentrations can be reduced by acidification, precipitation induced by increased pH, or by cation exchange. Any of these treatments can avoid clogging of the well and aquifer; however, certain treatments may cause local degradation of water quality. This work was supported by the U.S. Department of Energy under Contract DE-AC06- 76RLO 1830. 1 INTRODUCTION A high degree of dependence on foreign sources of petroleum is of major economic and political concern to many countries. One expression of this concern is multi-national research, such as that carried out under Annex VI of the International Energy Agency, into alternative energy forms. Seasonal energy storage, e.g., aquifer thermal energy storage (ATES), is a technology that uses waste heat or electricity during low-cost periods (e.g., spring, fall) to heat water, which is stored in a groundwater aquifer until needed for heating during a season of greater demand. Economic benefits can accrue from using alternative energy forms during periods of peak demand by the avoidance, or at least the delay, of capital outlay for electric power plants. Geochemical problems encountered in ATES systems and the underlying geochemical processes are the subject of this paper. However, because certain mineralogic, geologic,
Page 1 and 2: 4 'Hydrochemistry and energy storag
Page 4 and 5: CONTENTS AUTHORS INTRODUCTION J.W.
Page 6 and 7: 4 Corrosion 5 Some conclusions Refe
Page 8 and 9: AUTHORS 0. Andersson VIAK AB P.O. B
Page 10 and 11: INTRODUCTION J.W. Lyklema This volu
Page 12 and 13: THE INTERNATIONAL ENERGY AGENCY AND
Page 14 and 15: 3 THE IEA The International Energy
Page 16 and 17: In addition to projects in the doma
Page 18 and 19: THE RELATION BETWEEN AQUIFER THERNl
Page 20 and 21: 3 VIABILITY ATES systems contribute
Page 22 and 23: Figure 4 Temperature fluctuations o
Page 24 and 25: 10°C between two cycles. We have t
Page 26: groundwater quality so seriously th
Page 31 and 32: carbonate phase, the use of a high-
Page 33 and 34: generally contain sufficient organi
Page 35 and 36: precipitation from solutions at nea
Page 37 and 38: of the water for storage. These tre
Page 39 and 40: the higher ATES temperatures. There
Page 41 and 42: One of our research objectives is t
Page 43 and 44: COUDRAIN-RIBSTEIN, A. and GOBLET, P
Page 45 and 46: SPOSITO, G, and LeVESQUE, C.S. ; 19
Page 47 and 48: saturation with respect to calcite
Page 49 and 50: system would influence the hydroche
Page 51 and 52: columns were heated from 11°C to 9
Page 53 and 54: (Table 2), clearly shows that the i
Page 55 and 56: Plate 1: CaC03 grain from first cen
Page 57 and 58: decrease in ca2+ activity, to reach
Page 59 and 60: y thermodynamic equilibrium calcula
Page 61 and 62: HOLM, T.R., EISENREICH, S.J., ROSEN
Page 63 and 64: INTRODUCTION The use of aquifers fo
Page 65 and 66: As can be seen "cloggingn has been
Page 67 and 68: specific capacity of the well and c
Page 69 and 70: the water being injected. The reaso
Page 71 and 72: Figure 5 Simplified stability diagr
Page 73 and 74: 3.4 Clogging by organic slime Clogg
Page 75 and 76: 4 CORROSION 4.1 Forms of corrosion
Page 77 and 78:
When halogens are known to be prese
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available on the market. SOME CONCL
Page 82 and 83:
BIOGEOCHEMICAL ASPECTS OF AQUIFER T
Page 84 and 85:
In accordance with Figure 1 mangane
Page 86 and 87:
at a neutral pH is kinetically dete
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of such biocides used against desul
Page 90 and 91:
HYDROGEOCHEMICAL TRANSPORT MODELLIN
Page 92 and 93:
The complexity of the models with a
Page 94 and 95:
The comparison shows that inclusion
Page 96 and 97:
the component O2 (Oxygen) has been
Page 98 and 99:
The results of a recent solubility
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The neutral "exchangeable" complex
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SrC12 elution of Delft sediment, sh
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The saturation ratios can be used i
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Recovered water in the long term te
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Cumulat~ve Flow (103m3) Cumulative
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Dissolution of silicates is in much
Page 112 and 113:
KIRKNER, D.J., and REEVES, H.; 1988
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WATER TREATMENT AND ENVIRONMENTAL E
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Table 1 Ove~iew of chemical treatme
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calculated with a computer model th
Page 120:
Figure 1 Schematic representation o
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addition shows an increase in neces
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Table 4 summarizes the primary envi
Page 127 and 128:
wsts for this overdimensioning may
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_? Primary circuit Figure 7 Reactor
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Problems with iron precipitation ca
Page 134 and 135:
RESEARCH ON HYDROCHEMISTRY AND WATE
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ANNEX XI L - -1 I Figure 1 Relation
Page 138 and 139:
stores. F. To test selected water t
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(Fe, Ca, Mg) solid solutions. The p
Page 142 and 143:
corrosion and scaling rates under d
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the industry. For this treatment no
Page 149 and 150:
Water nuisance. Proceedings of Tech
Page 151:
No. 36 No. 37 No. 38 Urban storm wa
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