340 research outputs found
Transforming Ates To Ht-Ates, Insights From Dutch Pilot Project
No full textAquifer Thermal Energy Storage (ATES) systems combined with a heat pump save energy for space heating and cooling of buildings. In most countries the temperature of the stored heat is allowed up to 25-30°C. However, when heat is available at higher temperatures (e.g. waste heat, solar heat), it is more efficient to store higher temperatures because that improves heat pump performance or makes it unnecessary. Therefore, interest in HT-ATES development is growing. Next to developing new HT-ATES projects, there is also a large potential for additional energy savings by transforming ‘regular’ low-temperature LT-ATES systems to a HT-ATES. Such a transformation is tested for a greenhouse system in the Netherlands. This greenhouse has a LT-ATES system operational since 2012, and from 2015 onwards heat is stored in the warm well at temperatures up to 45°C. In this HT-ATES transformation pilot, water quality parameters are closely monitored as well as temperature distribution in the subsurface (using DTS). Together with the operators, the results from the ATES monitoring are used to continuously improve system performance. Numerical groundwater and heat flow simulations of actual and expected well pumping data are used to evaluate how well operation can be optimized. In this paper, the optimization using monitoring results and simulations is discussed as well as general and site specific lessons/conclusions for such transformations.Water Resource
Ates Smart Grids: Optimal Use Of Subsurface Space In High Density Ates Areas
No full textAquifer Thermal Energy Storage (ATES) systems provide buildings with sustainable space heating and cooling by seasonally storing and recovering thermal energy in the subsurface. The increased use of ATES in Dutch cities resulted in dense use of ATES in urban aquifers, often up to congestion level. Because thermal interactions among neighbouring systems may improve (same type of wells close together) or degrade (opposite type of wells together) system performance, the spatial layout of ATES wells is a key aspect for this novel energy storage technology. To prevent negative interaction, current policy requires ATES wells to be placed at relatively large distance from each other. However, several studies have shown that wells can be placed closer together, allowing ATES adoption for more buildings than under current policy with the spacious safety margins. Utilising the full storage potential of urban aquifers then requires increasing the density of ATES wells. This density can be further increased using a distributed energy management in which ATES wells can be controlled in order to prevent negative interactions during operation. In this research such a framework was developed. The delivered proof of concept of this framework is carried out by facilitating information exchange between ATES systems and the use of various (types of) model predictive control approaches. Simulated case studies, varying from small academic setting to full size complex urban conditions, have been used to develop and test the framework. Results show a significant decrease of CO2 emissions by allowing more ATES wells in the urban aquifer. Ongoing research focuses on using this framework in an aquifer beneath a densely populated district of Amsterdam. Results from this case/pilot will be presented.Water Resource
ATES systems performance in practice: analysis of operational data from ATES systems in the province of Utrecht, The Netherlands
No full textEnergy consumption for space heating and cooling of buildings can be decreased by 40-80% by use of Aquifer Thermal Energy Storage (ATES). ATES is a proven technique, however, it is not known how efficient currently operating systems are recovering stored energy from the subsurface and how this can be determined with available data. Recent research suggests that storage conditions have a large influence on the recovery (e.g. shape and size of stored volume). In addition, literature and previous research show that other aspects of ATES system are often unfavorable (e.g. subsurface energy imbalance, small ΔT). Therefore, the main goal of this research is to define a framework to determine overall performance of ATES systems by analysis of monitoring data from operational ATES systems. The province of Utrecht was selected for this. Monthly operational data of 57 ATES systems (40% of the ATES systems in the province) was provided by the authorities and pre-processed accordingly. Results showed that recovery efficiency is positively correlated to system size (stored volume) and that ambient groundwater temperature is site-specific and should be determined for each ATES system individually. Ambient groundwater temperature can vary more than 4 °C and are spatially correlated. Next to this, a large part of the analyzed systems are not equally storing heat and cold in the subsurface. More than 80% of the studied ATES systems have an subsurface heat imbalance larger than 10%. Altogether, results indicate that a big part of the ATES systems in the province of Utrecht can substantially improve their ATES system (management) to increase long-term energy savings. This research provides an useful assessment framework to determine if an ATES system is performing correctly and what aspect of the specific ATES system needs most improvement.Water Resource
Thermal deformation in High Temperature ATES systems
No full textHigh Temperature Aquifer Thermal Energy Storage (HT-ATES) is a technique for storing large amounts of residual heat in the subsurface. In this report, the thermal deformation resulting from the temperature change in the subsurface is investigated and the resulting risks for buildings are assessed. To do this a case study is done on the TU Delft campus subsurface. It has been determined that the thermal deformation due to HT-ATES systems is small with a maximal deformation of 14 cm. It has also been determined that the stability risks for buildings that are constructed in the vicinity of a HT-ATES system are very low.AESB341
Risk analysis of High-Temperature Aquifer Thermal Energy Storage (HT-ATES)
No full textThe storage of heat in aquifers, also referred to as Aquifer Thermal Energy Storage (ATES), bears a high potential to bridge the seasonal gap between periods of highest thermal energy demand and supply. With storage temperatures higher than 50 °C, High-Temperature (HT) ATES is capable to facilitate the integration of (non-)renewable heat sources into complex energy systems. While the complexity of ATES technology is positively correlated to the required storage temperature, HT-ATES faces multidisciplinary challenges and risks impeding a rapid market uptake worldwide. Therefore, the aim of this study is to provide an overview and analysis of these risks of HT-ATES to facilitate global technology adoption. Risk are identified considering experiences of past HT-ATES projects and analyzed by ATES and geothermal energy experts. An online survey among 38 international experts revealed that technical risks are expected to be less critical than legal, social and organizational risks. This is confirmed by the lessons learned from past HT-ATES projects, where high heat recovery values were achieved, and technical feasibility was demonstrated. Although HT-ATES is less flexible than competing technologies such as pits or buffer tanks, the main problems encountered are attributed to a loss of the heat source and fluctuating or decreasing heating demands. Considering that a HT-ATES system has a lifetime of more than 30 years, it is crucial to develop energy concepts which take into account the conditions both for heat sources and heat sinks. Finally, a site-specific risk analysis for HT-ATES in the city of Hamburg revealed that some risks strongly depend on local boundary conditions. A project-specific risk management is therefore indispensable and should be addressed in future research and project developments.Accepted Author ManuscriptWater Resource
Methods for planning of ATES systems
No full textAquifer Thermal Energy Storage (ATES) systems contribute to reducing fossil energy consumption by providing sustainable space heating and cooling for buildings by seasonal storage of heat. ATES is important for the energy transition in many urban areas in North America, Europe and Asia. Despite the modest current ATES adoption level of about 0.2% of all buildings in the Netherlands, ATES subsurface space use has already grown to congestion levels in many Dutch urban areas. This problem is to a large extent caused by the current planning and permitting approach, which uses too spacious safety margins between wells and a 2D rather than 3D perspective. The current methods for permitting and planning of ATES do not lead to optimal use of available subsurface space, and, therefore, prevent realization of the expected contribution of the reduction of greenhouse gas (GHG) emissions by ATES. Optimal use of subsurface space in dense urban settings can be achieved with a coordinated approach towards the planning and operation of ATES systems, so-called ATES planning. This research identifies and elaborates crucial practical steps to achieve optimal use of subsurface space that are currently missing in the planning method. Analysis from existing ATES plans and exploratory modeling, coupling agent-based and groundwater models were used to demonstrate that minimizing GHG emissions requires progressively stricter regulation with intensifying demand for ATES. The simulations also quantified both the thresholds beyond which such stricter rules are needed as well as the effectiveness of different planning strategies, which can now effectively be used for ATES planning in practice. The results provide scientific insight in how technical choices in ATES well design, location and operation affect optimal use of subsurface space, and what trade-offs exist between the energy efficiency of individual systems and the combined reduction of the GHG emissions from a plan area. The presented ATES planning method following from the obtained insights now fosters practical planning and design rules suitable to ensure optimal and sustainable use of subsurface space – that is, maximizing GHG emission reductions by accommodating as many ATES systems as possible in the available aquifer, while maintaining a high efficiency for the individual ATES systems.Water ResourcesPolicy Analysi
Improving identification of HT-ATES performance drivers and -barriers
No full textHigh temperature aquifer thermal energy storage (HT-ATES) can potentially solve the mismatch between heat supply and demand. It can provide a large scale seasonal heat storage solution. Thereby it enables an increase in full load hours of the base heat source, which can benefit project performance on both costs and emissions. However, the limited number of successful pilot projects indicates the technology has not escaped its state of infancy. There is a gap from concept to implementation, which is signified by the disagreement of experts on performance drivers and barriers of HT-ATES. This research aims to narrow the described knowledge gap, by improving identification of HT-ATES performance drivers and barriers. Thereby it strives to improve decision making of HT-ATES implementation, and further enhance future HT-ATES application in heating projects. The broad scope of research demands both a diagnostic and design-orientated approach, and fits seamlessly with a multi-criteria decision analysis. The analysis entails the stages of creating, evaluating, comparing and ranking of case-specific scenarios. Parametric variation changes the conditions for HT-ATES implementation across the scenarios. A simulation model is developed and connected to a groundwater model to apply the parametric variation, to create the different scenarios, and consequently to produce the quantitative information for further evaluation. During the stages of creating, evaluating, comparing and ranking, the methodology systematically produces new results on the opportunities and risks introduced by HT-ATES, and additionally on the HT-ATES performance drivers and barriers. The results show that HT-ATES enables the opportunity of improving project performance with respect to the internal rate of return and emissions. Groundwater impact remains the greatest risk, but it can be minimised with smart decision making. To support the decision maker and to overcome the risk of groundwater impact, the research proposes several performance-enhancing, non-explicit guidelines. The guidelines focus on realising an HT-ATES implementation, where project performance with respect to internal rate of return, emissions and groundwater impact are balanced. Thereby they explain the major HT-ATES performance drivers and barriers. The guidelines are summarised below. The decision maker is recommended to .. 1. .. minimise the uncertainty, through thorough subsurface characterization before implementation. Secondly, to focus on aquifers with a minimum depth of 200 [m] and a minimum hydraulic conductivity of 5 [m/d] 2. .. assure network return temperatures during peak demand are below expected storage temperatures 3. .. not consider project life-times exceeding 20 years 4. .. assure yearly maximum base source heat production is always lower than yearly consumer heat demand 5. .. to strive for a flat demand curve and apply peak-shaving, by means of, for example, variable heat prices Currently, the guidelines have the purpose of giving direction to the decision maker, but they will become more explicit once the methodology is improved, and the uncertainty and number of assumptions in the model is decreased.Electrical Engineering | Sustainable Energy Technolog
Novel ATES triplet system for autarkic space heating and cooling
No full textGovernments and companies have set high targets in avoiding CO2 emissions and reducing energy. Aquifer Thermal Energy Storage (ATES) systems can contribute by overcoming the temporal mismatch between the availability of sustainable heat (during summer) and the demand for heat (during winter). Therefore, ATES is an increasingly popular technique; currently over 3000 low temperature ATES systems are operational in the Netherlands. Low-temperature ATES systems use heat pumps to allow the stored heat to be supplied at the required temperature for heating (usually around 40-50°C) and for cooling in summer. Although on average a conventional low-temperature ATES system produces 3-4 times lower CO2 emissions when compared to gas heating, the heat pumps still require substantial amounts of external electricity, causing over 60% of the remaining primary energy use. In the ATES triplet system, the temperatures in the hot and cold wells of an ATES system are increased and decreased respectively to match the required delivery temperatures and a third well is added at an intermediate temperature. With this strategy, other sources of sustainable heat and cooling capacity can supply the subsurface close to the temperatures required in the hot and the cold well. However, the return temperatures from the building systems do not conform with either of the hot or cold wells and an additional well is used to store water at the return temperature. Additional components are then required to supply the hot and cold wells (from the third well) by increasing the temperature in summer (e.g. solar collectors) and decreasing it in winter (e.g. dry coolers). In this study the feasibility of this concept is evaluated. Simulations and an economical evaluation show significant potential for triplet ATES with economic performance better than conventional ATES while the CO2 emissions are reduced by a factor of ten. As the temperature differences are larger, the volume of groundwater required to be pumped is considerably lowered, causing an additional energy saving. Ongoing research focusses on analysing the energy balance and energy loss in the subsurface, well design requirements, working/operational conditions of each well, as well as the integration of building system components, such as the influence of weather conditions on performance of system components. Water ResourcesGeo-engineerin
Aquifer Thermal Energy Storage (ATES) smart grids: Large-scale seasonal energy storage as a distributed energy management solution
No full textAquifer Thermal Energy Storage (ATES) is a building technology used to seasonally store thermal energy in the subsurface, which can reduce the energy use of larger buildings by more than half. The spatial layout of ATES systems is a key aspect for the technology, as thermal interactions between neighboring systems can degrade system performance. In light of this issue, current planning policies for ATES aim to avoid thermal interactions; however, under such policies, some urban areas already lack space for the further development of ATES, limiting achievable energy savings. We show how information exchange between ATES systems can support the dynamic management of thermal interactions, so that a significantly denser layout can be applied to increase energy savings in a given area without affecting system performance. To illustrate this approach, we simulate a distributed control framework across a range of scenarios for spatial planning and ATES operation in the city center of Utrecht, in The Netherlands. The results indicate that the dynamic management of thermal interactions can improve specific greenhouse gas savings by up to 40% per unit of allocated subsurface volume, for an equivalent level of ATES economic performance. However, taking advantage of this approach will require revised spatial planning policies to allow a denser development of ATES in urban areas.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Tamas KeviczkyPolicy AnalysisWater Resource
After the boom: Evaluation of Dutch ates-systems for energy efficiency
No full textAquifer thermal energy storage (ATES) is a technology to sustainably provide space heating and cooling. Particularly in The Netherlands the number of ATES systems has grown rapidly in the past decade, often with the (re)development of urban areas. To meet objectives for greenhouse gas emission reduction the number of ATES systems is expected and required to further rise in future both in The Netherlands and elsewhere. To evaluate the lessons learned and the role of practical aspects in the Dutch development of ATES systems, in this study the geohydrological conditions and well characteristics for 331 (~15% of total) Dutch ATES systems are evaluated with respect to optimal well design for maximal thermal energy recovery. The study shows that well design of most (70%) ATES systems is suboptimal. The well design criteria that have been used thus far in practice, focus on allowing maximum flow/capacity, disregarding the effect of groundwater flow on efficiency and the effect of well design on subsurface space use. Instead, well design should be based on a more representative value for the storage volume that takes into account . Based on monitoring data and analysis of variations and uncertainties of the actual storage volume, a guideline is defined to reflect these in the storage volume used for design. Also a guideline for well design is introduced that accounts for both conduction and dispersion losses as well as advection losses in case of high ambient groundwater flow
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