Aquifer thermal energy storage

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Aquifer thermal energy storage (ATES) is the storage and recovery of thermal energy in subsurface aquifers. ATES can heat and cool buildings. Storage and recovery is achieved by extraction and injection of groundwater using wells. Systems commonly operate in seasonal modes. Groundwater that is extracted in summer performs cooling by transferring heat from the building to the water by means of a heat exchanger. The heated groundwater is reinjected into the aquifer, which stores the heated water. In wintertime, the flow is reversed — heated groundwater is extracted (often fed to a heat pump).

Contents

An ATES system uses the aquifer to buffer seasonal reversals in heating and cooling demand. ATES can serve as a cost-effective technology to replace fossil fuel-dependent systems and associated CO2 emissions.

ATES can contribute significantly to emission reductions, as buildings consume some 40% of global energy, mainly for heating and cooling. [1] The number of ATES systems has increased dramatically, especially in Europe. [2] Belgium, Germany, Turkey, and Sweden are also increasing the application of ATES. ATES can be applied wherever the climatic conditions and geohydrological conditions are appropriate. [3] Optimisation of subsurface space requires attention in areas with suitable conditions. [4]

System types

Bidirectional ATES systems consist of two wells (a doublet). One well is used for heat storage, and the other for cold storage. During winter, (warm) groundwater is extracted from the heat storage well and injected in the cold storage well. During summer, the flow direction is reversed such that (cold) groundwater is extracted from the cold storage well and injected in the heat storage well. [5]

Mono-directional systems do not switch pumping direction, such that groundwater is always extracted at the natural aquifer temperature. Although thermal energy is stored in the subsurface, there is usually no intention to retrieve the stored energy.

Closed systems store energy by circulating a fluid through a buried heat exchanger that usually consists of a horizontal or vertical pipeline. These systems do not extract or inject groundwater. They are also known as borehole thermal energy storage or ground source heat pumps.

Geothermal energy production commonly uses the deeper subsurface where temperatures are higher.

History

The first reported deliberate storage of thermal energy in aquifers was in China around 1960. [6] The first ATES systems were built for industrial cooling in Shanghai. There, large amounts of groundwater were extracted to cool textile factories. [7] This led to substantial land subsidence. To inhibit the subsidence, cold surface water was reinjected into the aquifer. Subsequently, it was observed that the stored water remained cold after injection and could be used for cooling. Storage of thermal energy in aquifers was suggested in the 1970s which led to field experiments and feasibility studies in France, Switzerland, US and Japan. [8]

ATES was used as part of enhanced bioremediation in the Netherlands in 2009. [9]

As of 2018, more than 2800 ATES systems were in operation, providing more than 2.5 TWh of heating and cooling per year. [7] The Netherlands and Sweden dominated the market. [6] 85% of all systems were then located in the Netherlands, while a further 10% were found in Sweden, Denmark, and Belgium. [7]

Typical dimensions

Flow rates for typical applications are between 20 and 150 m3/hour/well. The volume of groundwater that is stored and recovered in a year generally varies between 10 000 m3 and 150 000 m3 per well. [10] ATES system depths is commonly between 20 and 200 meters. Temperature at these depths is generally close to the annual mean surface temperature. In moderate climates this is around 10 °C. In those regions cold storage is commonly applied between 5 and 10 °C and heat storage in the range 10 to 20 °C. Although less frequent, some projects store heat above 80 °C. [11] [12]

Hydrogeological constraints

Energy savings that can be achieved with ATES depend strongly on site geology. ATES requires the presence of a suitable aquifer that is able to accept and yield water. For example solid rock limits access to the aquifer. Thick (>10 m) sandy aquifers are optimal. Sufficient hydraulic conductivity is required, enough that water flows easily. However, excess groundwater flow may transport (part of) the stored energy outside of a well's capture zone during the storage phase. [13] To reduce advective heat loss, aquifers with a low hydraulic gradient are preferred. In addition, gradients in geochemical composition should be avoided, as mixing of water with heterogeneous geochemistry can increase clogging, which reduces performance and increases maintenance costs.

Shallow (<400 m) geothermal installations' legal status is diverse among countries. [14] Regulations for installations concern the use of hazardous materials and proper backfilling of the borehole to avoid hydraulic short circuiting between aquifers. Other regulations concern protection of groundwater areas for potable water. [15] Some countries limit minimum and maximum storage temperatures. For example, Austria (5–20 °C), Denmark (2–25 °C) and Netherlands (5–25 °C). Other countries adopt a maximum change in groundwater temperature, for example Switzerland (3 °C) and France (11 °C). [14]

Contaminated groundwater

ATES is not allowed to process contaminated aquifers, due to the possible spreading of groundwater contamination, [16] especially in urban areas. The possibility of contamination encounter is however rising, because of the rapid increase of the number of ATES and slow progress of contaminated groundwater remediation in urban areas. Among the common contaminants, chlorinated ethenes have the most chance to interfere with ATES systems, as they are often found at similar depths. When chlorinated ethenes present as dense non-aqueous phase liquid (DNAPLs), the possible dissolution of DNAPLs by ATES will increase the impact on groundwater quality. [17]

Possible application

Illustration of relevant processes in the ATES-ENA system. Illustration of relevant processes in the ATES-ENA system.png
Illustration of relevant processes in the ATES-ENA system.

The presence of ATES and chlorinated ethenes offers the potential for of integration of sustainable energy technology and sustainable groundwater management. [18] Increased temperature around the warm well can enhance reductive dechlorination of chlorinated ethenes. Although low temperature in cold well can hamper biodegradation, seasonal operation of ATES can transfer contaminant from cold well to hot well for faster remediation. Such seasonal groundwater transport can homogenize the environmental condition.

ATES can be used as biostimulation, for example to inject electron donor or microorganisms needed for reductive dechlorination.

The lifespan of ATES (30 years) fits the required duration of in situ bioremediation.

Societal impacts

The combination concept of ATES and enhanced natural attenuation (ATES-ENA) can possibly be used in the Netherlands and China, especially in urbanized areas. These areas are confronted with organic groundwater contamination. Currently, the combination concept may be better applicable for the Netherlands which offers more mature technology and greater experience. However, for China where ATES is much less developed, demonstration pilot projects can be evaluated prior to production applications, and flexible systems can be developed because of the less intense pressure on subsurface use by ATES. [18]

A 2023 study reported that ATES could reduce the use of energy in heating and cooling US homes and businesses by 40 percent. [19]

Related Research Articles

<span class="mw-page-title-main">Aquifer</span> Underground layer of water-bearing permeable rock

An aquifer is an underground layer of water-bearing material, consisting of permeable or fractured rock, or of unconsolidated materials. Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude, which is a solid, impermeable area underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. The classification of aquifers is as follows: Saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; transboundary aquifer.

<span class="mw-page-title-main">Geothermal energy</span> Thermal energy generated and stored in the Earth

Geothermal energy is thermal energy extracted from the Earth's crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for millennia.

<span class="mw-page-title-main">Groundwater</span> Water located beneath the ground surface

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.

<span class="mw-page-title-main">Heat recovery ventilation</span> Method of reusing thermal energy in a building

Heat recovery ventilation (HRV), also known as mechanical ventilation heat recovery (MVHR) or energy recovery ventilation (ERV), is a ventilation system that recovers energy by operating between two air sources at different temperatures. It is used to reduce the heating and cooling demands of buildings.

<span class="mw-page-title-main">Geothermal heating</span> Use of geothermal energy for heating

Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of geothermal heating in 2004. As of 2007, 28 GW of geothermal heating capacity is installed around the world, satisfying 0.07% of global primary energy consumption. Thermal efficiency is high since no energy conversion is needed, but capacity factors tend to be low since the heat is mostly needed in the winter.

<span class="mw-page-title-main">Phase-change material</span> Substance with high latent heat of melting or solidifying

A phase-change material (PCM) is a substance which releases/absorbs sufficient energy at phase transition to provide useful heat or cooling. Generally the transition will be from one of the first two fundamental states of matter - solid and liquid - to the other. The phase transition may also be between non-classical states of matter, such as the conformity of crystals, where the material goes from conforming to one crystalline structure to conforming to another, which may be a higher or lower energy state.

<span class="mw-page-title-main">Thermal energy storage</span> Technologies to store thermal energy

Thermal energy storage (TES) is the storage of thermal energy for later reuse. Employing widely different technologies, it allows surplus thermal energy to be stored for hours, days, or months. Scale both of storage and use vary from small to large – from individual processes to district, town, or region. Usage examples are the balancing of energy demand between daytime and nighttime, storing summer heat for winter heating, or winter cold for summer cooling. Storage media include water or ice-slush tanks, masses of native earth or bedrock accessed with heat exchangers by means of boreholes, deep aquifers contained between impermeable strata; shallow, lined pits filled with gravel and water and insulated at the top, as well as eutectic solutions and phase-change materials.

Renewable heat is an application of renewable energy referring to the generation of heat from renewable sources; for example, feeding radiators with water warmed by focused solar radiation rather than by a fossil fuel boiler. Renewable heat technologies include renewable biofuels, solar heating, geothermal heating, heat pumps and heat exchangers. Insulation is almost always an important factor in how renewable heating is implemented.

<span class="mw-page-title-main">Waste heat</span> Heat that is produced by a machine that uses energy, as a byproduct of doing work

Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility than the original energy source. Sources of waste heat include all manner of human activities, natural systems, and all organisms, for example, incandescent light bulbs get hot, a refrigerator warms the room air, a building gets hot during peak hours, an internal combustion engine generates high-temperature exhaust gases, and electronic components get warm when in operation.

Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season. For example, heat from solar collectors or waste heat from air conditioning equipment can be gathered in hot months for space heating use when needed, including during winter months. Waste heat from industrial process can similarly be stored and be used much later or the natural cold of winter air can be stored for summertime air conditioning.

<span class="mw-page-title-main">Energy recovery</span>

Energy recovery includes any technique or method of minimizing the input of energy to an overall system by the exchange of energy from one sub-system of the overall system with another. The energy can be in any form in either subsystem, but most energy recovery systems exchange thermal energy in either sensible or latent form.

<span class="mw-page-title-main">Ground source heat pump</span> System to transfer heat to/from the ground

A ground source heat pump is a heating/cooling system for buildings that use a type of heat pump to transfer heat to or from the ground, taking advantage of the relative constancy of temperatures of the earth through the seasons. Ground-source heat pumps (GSHPs) – or geothermal heat pumps (GHP), as they are commonly termed in North America – are among the most energy-efficient technologies for providing HVAC and water heating, using far less energy than can be achieved by burning a fuel in a boiler/furnace or by use of resistive electric heaters.

Deep water source cooling (DWSC) or deep water air cooling is a form of air cooling for process and comfort space cooling which uses a large body of naturally cold water as a heat sink. It uses water at 4 to 10 degrees Celsius drawn from deep areas within lakes, oceans, aquifers or rivers, which is pumped through the one side of a heat exchanger. On the other side of the heat exchanger, cooled water is produced.

<span class="mw-page-title-main">Water resources</span> Sources of water that are potentially useful

Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. 97% of the water on Earth is salt water and only three percent is fresh water; slightly over two-thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air. Natural sources of fresh water include surface water, under river flow, groundwater and frozen water. Artificial sources of fresh water can include treated wastewater and desalinated seawater. Human uses of water resources include agricultural, industrial, household, recreational and environmental activities.

<span class="mw-page-title-main">Photovoltaic thermal hybrid solar collector</span>

Photovoltaic thermal collectors, typically abbreviated as PVT collectors and also known as hybrid solar collectors, photovoltaic thermal solar collectors, PV/T collectors or solar cogeneration systems, are power generation technologies that convert solar radiation into usable thermal and electrical energy. PVT collectors combine photovoltaic solar cells, which convert sunlight into electricity, with a solar thermal collector, which transfers the otherwise unused waste heat from the PV module to a heat transfer fluid. By combining electricity and heat generation within the same component, these technologies can reach a higher overall efficiency than solar photovoltaic (PV) or solar thermal (T) alone.

FEHM is a groundwater model that has been developed in the Earth and Environmental Sciences Division at Los Alamos National Laboratory over the past 30 years. The executable is available free at the FEHM Website. The capabilities of the code have expanded over the years to include multiphase flow of heat and mass with air, water, and CO2, methane hydrate, plus multi-component reactive chemistry and both thermal and mechanical stress. Applications of this code include simulations of: flow and transport in basin scale groundwater systems , migration of environmental isotopes in the vadose zone, geologic carbon sequestration, oil shale extraction, geothermal energy, migration of both nuclear and chemical contaminants, methane hydrate formation, seafloor hydrothermal circulation, and formation of karst. The simulator has been used to generate results for more than 100 peer reviewed publications which can be found at FEHM Publications.

<span class="mw-page-title-main">Electro Thermal Dynamic Stripping Process</span>

Electro Thermal Dynamic Stripping Process (ET-DSP) is a patented in situ thermal environmental remediation technology, created by McMillan-McGee Corporation, for cleaning contaminated sites. ET-DSP uses readily available three phase electric power to heat the subsurface with electrodes. Electrodes are placed at various depths and locations in the formation. Electric current to each electrode is controlled continuously by computer to uniformly heat the target contamination zone.

<span class="mw-page-title-main">Non-aqueous phase liquid</span> Liquid solution contaminants that do not dissolve in or easily mix with water

Non-aqueous phase liquids, or NAPLs, are organic liquid contaminants characterized by their relative immiscibility with water. Common examples of NAPLs are petroleum products, coal tars, chlorinated solvents, and pesticides. Strategies employed for their removal from the subsurface environment have expanded since the late-20th century.

Renewable thermal energy is the technology of gathering thermal energy from a renewable energy source for immediate use or for storage in a thermal battery for later use.

<span class="mw-page-title-main">Cold district heating</span> District heating with very low temperatures

Cold district heating is a technical variant of a district heating network that operates at low transmission temperatures well below those of conventional district heating systems and can provide both space heating and cooling. Transmission temperatures in the range of approx. 10 to 25 °C are common, allowing different consumers to heat and cool simultaneously and independently of each other. Hot water is produced and the building heated by water heat pumps, which obtain their thermal energy from the heating network, while cooling can be provided either directly via the cold heat network or, if necessary, indirectly via chillers. Cold local heating is sometimes also referred to as an anergy network. The collective term for such systems in scientific terminology is 5th generation district heating and cooling. Due to the possibility of being operated entirely by renewable energies and at the same time contributing to balancing the fluctuating production of wind turbines and photovoltaic systems, cold local heating networks are considered a promising option for a sustainable, potentially greenhouse gas and emission-free heat supply.

References

  1. ↑ De Rosa, Mattia; Bianco, Vincenzo; Scarpa, Federico; Tagliafico, Luca A. (2014). "Heating and cooling building energy demand evaluation; a simplified model and a modified degree days approach". Applied Energy. 128: 217–229. doi:10.1016/j.apenergy.2014.04.067.
  2. ↑ Godschalk, M.S.; Bakema, G. (2009). "20,000 ATES Systems in the Netherlands in 2020 – Major step towards a sustainable energy supply" (PDF). Proceedings Effstock. S2CID   110151280. Archived from the original (PDF) on 2013-06-13. Retrieved 2016-10-14.
  3. ↑ Bloemendal, M.; Olsthoorn, T.O.; van de Ven, F. (2015). "Combining climatic and geo-hydrological preconditions as a method to determine world potential for aquifer thermal energy storage". Science of the Total Environment. 538: 104–114. Bibcode:2015ScTEn.538..621B. doi:10.1016/j.scitotenv.2015.07.084. PMID   26322727.
  4. ↑ Bloemendal, M.; Olsthoorn, T.O.; Boons, F. (2014). "How to achieve optimal and sustainable use of the subsurface for Aquifer Thermal Energy Storage". Energy Policy. 66: 621. Bibcode:2014EnPol..66..104B. doi:10.1016/j.enpol.2013.11.034.
  5. ↑ Dickinson, J. S.; Buik, N.; Matthews, M. C.; Snijders, A. (2009). "Aquifer thermal energy storage: theoretical and operational analysis". Geotechnique. 59 (3): 249–260. Bibcode:2009Getq...59..249D. doi:10.1680/geot.2009.59.3.249. ISSN   0016-8505.
  6. 1 2 Paksoy, Halime Ö., ed. (2007). Thermal energy storage for sustainable energy consumption: fundamentals, case studies and design. NATO science series. Series II, Mathematics, physics, and chemistry. Vol. 234. Springer Science & Business Media. ISBN   9781402052903. LCCN   2007475275. OCLC   80331468.
  7. 1 2 3 Fleuchaus, Paul; Godschalk, Bas; Stober, Ingrid; Blum, Philipp (October 2018). "Worldwide application of aquifer thermal energy storage – A review". Renewable and Sustainable Energy Reviews. 94: 861–876. doi:10.1016/j.rser.2018.06.057. S2CID   115368924.
  8. ↑ Tsang, C.F., D. Hopkins, and G. Hellstrom, Aquifer thermal energy storage – a survey. 1980, Lawrence Berkeley Laboratory.
  9. ↑ "Meermetbodemenergie.nl". Archived from the original on 2015-08-23. Retrieved 2015-09-03.
  10. ↑ Bakr, Mahmoud; van Oostrom, Niels; Sommer, Wijb (December 2013). "Efficiency of and interference among multiple Aquifer Thermal Energy Storage systems; A Dutch case study". Renewable Energy. 60: 53–62. doi:10.1016/j.renene.2013.04.004.
  11. ↑ Kabus, F., Wolfgramm, M., Seibt, A., Richlak, U. and Beuster, H., 2009. Aquifer thermal energy storage in Neubrandenburg-monitoring throughout three years of regular operation”, Proceedings of the 11th International Conference on Energy Storage.
  12. ↑ Sanner, B., Kabus, F., Seibt, P. and Bartels, J., 2005. Underground thermal energy storage for the German Parliament in Berlin, system concept and operational experiences, Proceedings world geothermal congress, pp. 1–8. S2CID   55759051
  13. ↑ Sommer, Wijb; Valstar, Johan; van Gaans, Pauline; Grotenhuis, Tim; Rijnaarts, Huub (December 2013). "The impact of aquifer heterogeneity on the performance of aquifer thermal energy storage". Water Resources Research. 49 (12): 8128–8138. doi:10.1002/2013WR013677.
  14. 1 2 Haehnlein, Stefanie; Bayer, Peter; Blum, Philipp (December 2010). "International legal status of the use of shallow geothermal energy". Renewable and Sustainable Energy Reviews. 14 (9): 2611–2625. doi:10.1016/j.rser.2010.07.069.
  15. ↑ Bonte, Matthijs; Stuyfzand, Pieter J.; Hulsmann, Adriana; Van Beelen, Patrick (2011). "Underground Thermal Energy Storage: Environmental Risks and Policy Developments in the Netherlands and European Union". Ecology and Society. 16 (1): 22. doi: 10.5751/ES-03762-160122 . JSTOR   26268838 .}
  16. ↑ Zuurbier, Koen G.; Hartog, Niels; Valstar, Johan; Post, Vincent E.A.; van Breukelen, Boris M. (April 2013). "The impact of low-temperature seasonal aquifer thermal energy storage (SATES) systems on chlorinated solvent contaminated groundwater: Modeling of spreading and degradation". Journal of Contaminant Hydrology. 147: 1–13. Bibcode:2013JCHyd.147....1Z. doi:10.1016/j.jconhyd.2013.01.002. PMID   23435174.
  17. ↑ Parker, J. C.; Park, E. (May 2004). "Modeling field-scale dense nonaqueous phase liquid dissolution kinetics in heterogeneous aquifers". Water Resources Research. 40 (5). Bibcode:2004WRR....40.5109P. doi: 10.1029/2003WR002807 .
  18. 1 2 Ni, Z. (2015) Bioremediation in aquifer thermal energy storage. Dissertation (in press), Wageningen University.
  19. ↑ Simon, Matt (April 12, 2023). "The Massive 'Batteries' Hidden Beneath Your Feet". Wired. ISSN   1059-1028 . Retrieved 2023-04-13.
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