Seasonal Aquifer Thermal Energy Storage Research Articles

Assessment of short-term aquifer thermal energy storage for demand-side management perspectives: Experimental and numerical developments

In the context of demand-side management and geothermal energy production, our proposal is to store thermal energy in shallow alluvial aquifers at shorter frequencies than classical seasonal aquifer thermal energy storage. We first conducted a one-week experiment in a shallow alluvial aquifer, which is characterized by a slow ambient groundwater flow, to assess its potential for thermal energy storage and recovery. This experiment has shown that up to 90% of the stored thermal energy can be recovered and would therefore suggest that aquifer thermal energy storage could be considered for demand-side management applications. We then conceptualized, developed, and calibrated a deterministic 3D groundwater flow and heat transport numerical model representing our study site, and we simulated 77 different scenarios to further assess this potential. This has allowed us to demonstrate that low-temperature aquifer thermal energy storage (temperature differences of −4 K for precooling and 3, 6, and 11 K for preheating) is efficient with energy recovery rates ranging from 78 to 87%, in a single aquifer thermal energy storage cycle. High-temperature aquifer thermal energy storage (temperature differences between 35 and 65 K) presents lower energy recovery rates, from 53 to 71%, with all other parameters remaining equals. Energy recovery rates decrease with increasing storage duration and this decrease is faster for higher temperatures. Retrieving directly useful heat (without upgrading with a groundwater heat pump) using only a single storage and recovery cycle appears to be complicated. Nevertheless, there is room for aquifer thermal energy storage optimization in space and time with regard to improving both the energy recovery rates and the recovered absolute temperatures.

Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface

Abstract. Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper, confined saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated (i.e., a continuous clay layer prevented rapid groundwater flow between both aquifers), intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and variable-density solute transport modeling (SEAWAT version 4; Langevin et al., 2007). The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the ASR system with multiple partially penetrating wells (MPPW-ASR) was observed. This leakage may lead to a lower recovery efficiency than based on current ASR performance estimations.

Assessment of Seasonal Aquifer Thermal Energy Storage as a Groundwater Ecosystem Service for the Brussels-Capital Region: Combining Groundwater Flow, and Heat and Reactive Transport Modeling

Seasonal aquifer thermal energy storage and recovery (ATES) help urbanized areas to contribute to their energy demands. We assess the potential of ATES in the Brussels-Capital Region, Belgium with groundwater flow, heat and reactive transport models. Situated in the phreatic Brussels Sand aquifer, they indicate that ATES systems are unfeasible for hydraulic conductivities of 4.2e-6 ms-1. At low groundwater flow velocities however, ATES are feasible for hydraulic conductivities of 1.4e-4 ms-1. Iron(hydr)oxide precipitation during ATES operation is investigated with reactive transport models. To avoid well clogging groundwater should be pumped only from above or below the aquifers redox boundary.

The impact of low-temperature seasonal aquifer thermal energy storage (SATES) systems on chlorinated solvent contaminated groundwater: Modeling of spreading and degradation

Groundwater systems are increasingly used for seasonal aquifer thermal energy storage (SATES) for periodic heating and cooling of buildings. Its use is hampered in contaminated aquifers because of the potential environmental risks associated with the spreading of contaminated groundwater, but positive side effects, such as enhanced contaminant remediation, might also occur. A first reactive transport study is presented to assess the effect of SATES on the fate of chlorinated solvents by means of scenario modeling, with emphasis on the effects of transient SATES pumping and applicable kinetic degradation regime. Temperature effects on physical, chemical, and biological reactions were excluded as calculations and initial simulations showed that the small temperature range commonly involved (ΔT<15 °C) only caused minor effects. The results show that a significant decrease of the contaminant mass and (eventually) plume volume occurs when degradation is described as sediment-limited with a constant rate in space and time, provided that dense non-aqueous phase liquid (DNAPL) is absent. However, in the presence of DNAPL dissolution, particularly when the dissolved contaminant reaches SATES wells, a considerably larger contaminant plume is created, depending on the balance between DNAPL dissolution and mass removal by degradation. Under conditions where degradation is contaminant-limited and degradation rates depend on contaminant concentrations in the aquifer, a SATES system does not result in enhanced remediation of a contaminant plume. Although field data are lacking and existing regulatory constraints do not yet permit the application of SATES in contaminated aquifers, reactive transport modeling provides a means of assessing the risks of SATES application in contaminated aquifers. The results from this study are considered to be a first step in identifying the subsurface conditions under which SATES can be applied in a safe or even beneficial manner.

H201 帯水層蓄熱の可能性、昼夜間蓄熱の検討(OS4 省エネルギー・コジェネヒートポンプ)

There are many seasonal Aquifer Thermal Energy Storage (ATES) system for HVAC in Europe. On the other hand, there is no such system in Japan for national regulation of groundwater pumping in urban area. Now we start to research with daily aquifer thermal energy storage using inner shielding membrane around buildings for realize low cost TES system and contribute daily electric-load leveling. In this time, we make experimental water well, do cyclic hot water injection-abstraction, trace underground water flow simulation with FEM. So we have approximately 70-80% daily energy storage efficiency.

Thermal energy storage in an unconfined aquifer: 2. Model development, validation, and application

A fully three‐dimensional numerical model for simulating coupled density‐dependent groundwater flow and thermal energy transport is developed and validated. The transport solution is based on a finite element time integration algorithm which generates a symmetric coefficient matrix while retaining second‐order accuracy in time. The use of a symmetric conjugate gradient solver for both the flow and transport matrices results in a high degree of computational efficiency. Three‐dimensional deformable block elements are used to allow the model to conform to domains with irregular geometry. The thermal transport model is validated against the results of the Borden thermal injection field experiment presented in the companion paper. The model simulations provide an excellent match with the observed temperature distribution over time, with the effects of thermal buoyancy and losses across the ground surface accurately reproduced by the model. The model is shown to be a practical tool for simulating the type of low‐temperature thermal transport problems that arise in connection with seasonal aquifer thermal energy storage and ground source heat extraction systems.

Aquifer thermal energy storage: A numerical simulation of field experiments in China

This paper describes the results of computer simulations for three seasonal aquifer thermal energy storage experiments which have been carried out recently in China. The governing equation of the mathematical model used to simulate the experiments contains convection, conduction and heat dispersion terms. A general description of the experiments, three‐dimensional mathematical model and numerical method used is presented. The simulated temperatures agree very well with the observed field data. Total mean values of the absolute errors are 0.5°C for the single‐well experiment, 0.7°C for the double‐well experiment and 0.4°C for the multiwell experiment; relative error ranges from 2.8% to 4.5%. The simulated production temperatures and energy recovery ratios, ϵ, (ϵsimu = 0.638 versus ϵobs = 0.640 and ϵsimu = 0.729 versus ϵobs = 0.753 for different experiments) also agree very well with the field data. Discussions are also given on the determination and choice of various parameters used in the simulations. The results strongly indicate the validity of the model and simulation procedures used. It is necessary to consider the heat transfer through the fluid phase by heat dispersion in the governing equation.

Aquifer Thermal Energy Storage in Finland

The rapid changes and crises in the field of energy during the 1970s and 1980s have forced us to examine the use of energy more critically and to look for new ideas. Seasonal aquifer thermal energy storage (T &amp;lt; 100°C) on a large scale is one of the grey areas which have not yet been extensively explored. However, projects are currently underway in a dozen countries. In Finland there have been three demonstration projects from 1974 to 1987. International co-operation under the auspices of the International Energy Agency, Annex VI, ‘Environmental and Chemical Aspects of Thermal Energy Storage in Aquifers and Research and Development of Water Treatment Methods' started in 1987. The research being undertaken in 8 countries includes several elements fundamental to hydrochemistry and biochemistry.

Prediction and analysis of a field experiment on a multilayered aquifer thermal energy storage system with strong buoyancy flow

The results of the first two cycles of the seasonal aquifer thermal energy storage field experiment conducted by Auburn University near Mobile, Alabama in 1981–1982 (injection temperatures 59°C and 82°C) were predicted by numerical modeling before their conclusion with good accuracy. Subsequent comparison of experimental and calculated results provided important insight into areas of model improvement and alternative experimental designs. Key factors influencing energy recovery appear to be aquifer heterogeneity (layering) and strong buoyancy flow in the aquifer. An optimization study based on second‐cycle conditions calculated a series of scenarios, each using a different injection and production scheme, to study possible ways to improve energy recovery. The results of this optimization study were used by Auburn University in the design of the third‐cycle experiment.

Aquifer thermal energy storage: A numerical simulation of Auburn University Field Experiments

This paper describes the computer simulation of two cycles of a seasonal aquifer thermal energy storage experiment recently carried out by Auburn University. The simulated production temperatures and energy recovery factors agree very well with the field data. A general description of the experiments and the numerical model used are given. Discussions are also given on the determination and choice of various parameters used in the simulations. These are followed by a detailed comparison of simulated and observed temperature distributions.