Potential Use of Aquifer Thermal Energy Storage System in Arid Regions

After the Oil Crises in 1973, which meant higher energy costs, the world started to look for other sources of energy. This led to the development of renewable energy techniques. Because of the intermittent nature of renewable energy, storage systems were also developed. Underground Thermal Energy Storage (UTES) systems spread and are now globally well known. In these systems, excess thermal energy (heat or cold) is stored (short term and/or long term) from the surplus period to periods of higher demand. The storage media in such systems are underground materials, e.g. rock, soil, and/or groundwater. The current study aims to examine the use of underground thermal energy storage systems in arid regions, in order to increase the efficiency of both cooling and heating systems in these regions, such that CO2 emissions and consumed electricity for these purposes are reduced. Three main parameters determine which type of Underground Thermal Energy Storage (UTES) systemis most suitable. These are site, design, and operation parameters. The site-specific parametersinclude soil properties and all geo-hydrological, environmental, geological, metrologicalconditions. Therefore, the site parameters cannot be changed after installing the storage system,since they majorly depend on the location, while the other parameters (design and operation) canbe changed after construction. The first primary goal of this study is to find how and what site parameters involved to specify the most suitable type of UTES systems in arid regions. Thus, the suitable type of UTES systems can be decided. The second primary goal is to answer how and where to select the best location to install the adopted system. To achieve the goals of the study, two arid regions within Iraq were used as case studies. They are Babylon and Karbala, where the former is characterized by its shallow aquifer, while the latter is characterized by a relatively deeper aquifer. The ArcMap-GIS software was used to prepare the relevant digital maps, e.g. maps of hydraulic conductivity, population, type of soil, aquifers, groundwater elevation, transmissivity, and slope. Then, the vulnerability (readiness for being polluted by the surface contaminants) maps of the available aquifers were determined, followed by finding the seepage velocity of the groundwater. Depending on the outputs of the vulnerability and the seepage velocity, the most suitable type of Underground Thermal Energy Storage (UTES) systems can be decided. This study, also, includes developing/inventing a general methodology that can be used to determine the best location to install Underground Thermal Energy Storage (UTES) systems, including Aquifer Thermal Energy Storage (ATES) systems. The last part of this study includes applying the suggested methodology to determine the best location to install the suitable type of Underground Thermal Energy Storage (UTES) system in the study area. The first study was in the Babylon Province. Here, groundwater table is very shallow (less than 2 m depth in some regions). The crystalline bedrock is at a depth of 9-12 km below the ground surface, overlaid by 9-12 km of sedimentary rocks on which there is a 2-50 m thick layer of alluvial silty clay sediments. The groundwater moves slowly in this aquifer (2.12*10-6 - 1.85*10-1) m/d, and it is brackish having salinity of 5000-10000 mg/l. The susceptibility (vulnerability) of the aquifer in northern part of Babylon province is low to very low having ranges from 80 to 120 on Drastic model scale, which has the overall range of 26 – 226 (i.e. 0.27- 0.47 on normalized vulnerability). The second study area was a part of Karbala Province. This area can be divided into two regions based on the geology and geo-hydrological conditions. An eastern part is located on the Mesopotamian plain, and a western part is located in Western Desert. In both parts, the groundwater table is relatively deeper than the Babylon province. In the eastern part, it is generally more than 4 mbgs (meter below ground surface). While, in the western part it is deeper and reaches to 48 mbgs in depth. The soil in the eastern part is alluvial silty clay, while the western part consists of gypcrete sandy deposits. The groundwater, which flows towards the east, has a seepage velocity range from 0 to 0.27 m/d. The salinity of the groundwater changes from slightly brackish (1000-3000) mg/l in the western parts to highly brackish (5000-10000) mg/l in the Mesopotamian parts of the province. By comparing the site parameters of each province with the different UTES systems, the type of thermal energy storage system was decided. The most important site parameters are the depth of the water table and the aquifer characteristics. For Babylon Province, the expected suitable underground thermal energy storage system is an aquifer thermal energy storage system in silty clay. For Karbala Province, two systems are suggested: for the eastern part, aquifer thermal energy storage system in silty clay is recommended, while for the western part, a deep (10-30 m depth) sandy aquifer thermal energy storage system is recommended. After that, a methodology was developed and used to determine the suitable location in which to install the Aquifer Thermal Energy Storage (ATES) system. For Babylon province, the site selection index ranges between 2.9 and 5.3 on 1 to 10 scale. About 71% of the region has a site selection index ranges between 4.71 and 5.3. Concerning Karbala study area, the site selection index ranges between 3.1 and 9.1. About 15% of the region has a site selection index between 8.1 and 9.1.The energy saving in neighboring countries to Iraq by using the Aquifer Thermal Energy Storage (ATES) system ranges from 55% to 72%. It is also expected that using a ground sink heat pump instead of a conventional air-to-air heat pump increases the COP (Coefficient Of Performance) of roughly (10) to (-17). The negative sign means that the heat is injected into the ground. More theoretical and field studies are required to cover the different aspects of the subject of potential use of Aquifer Thermal Energy Storage (ATES) system in an arid region, and to verify the improvement of COP (Coefficient Of Performance) due to using these systems

Possibilities of reducing energy consumption by Optimization of Ground Source Heat Pump Systems in Babylon, Iraq

Iraq is located in the Middle East with an area that reaches 437072 km2 and a population of about 36 million. This country is suffering from severe electricity shortage problems which are expected to increase with time. In this research, an attempt is made to minimize this problem by combining the borehole thermal energy storage (BTES) with a heat pump, the indoor temperature of a residential building or other facility may be increased or reduced beyond the temperature interval of the heat carrier fluid.Due to the relatively high ground temperature in Middle Eastern countries, the Seasonal thermal energy storages (STES) and Ground Source Heat Pump (GSHP) systems have a remarkable potential, partly because the reduced thermal losses from the underground storage and the expected high COP (ratio of thermal energy gain to required driving energy (electricity)) of a heat pump, partly because of the potential for using STES directly for heating and cooling. In this research, groundwater conditions of Babylon city in Iraq were investigated to evaluate the possibility of using GSHP to reduce energy consumption. It is believed that such system will reduce consumed energy by about 60%.Validerad; 2016; Nivå 1; 20160328 (nadhir

Assessment of Groundwater Vulnerability in Northern Babylon Governorate, Iraq

Groundwater is one of the main resources from the earth, especially for arid or semiarid countries. For this reason, it is very important to keep it unpolluted. Drastic Model is one of the widely used models to detect groundwater vulnerability to the contaminants that are found on ground surface. In this model, it is assumed that the vulnerability of the groundwater is affected by seven hydrological parameters. They are: depth from the surface ground to groundwater, net recharge into the aquifer from the surface, aquifer media, soil media, area topography, impact of vadose zone and aquifer hydraulic conductivity. In this study, the DRASTIC model was applied on the northern part of Babylon governorate in Iraq, to predict the vulnerability of Groundwater in that area. The results indicate that the vulnerability is very low to low grade.Validerad; 2017; Nivå 1; 2016-12-29 (andbra)</p

Effect of (B/D) ratio on ultimate load capacity for horizontally curved box steel beam under out of plane concentrated load

The intended of this research is to prepare an analytical study to investigate the best width to depth section ratio (b/d) of horizontally curved steel box beam with constant cross-sectional area (without stiffeners) under single concentrated load at mid-span of the beam. The research adopts three – dimensional nonlinear finite element analysis of steel box -section horizontally curved beams exposed to static load. The isoparametric brick element of twenty-node has been used to represent the steel element; also, the yield criterion used to compute the stress level of plastic deformation is Von-Mises. The simulation model of the behavior of steel under tension and compression stresses is elastic-perfect plastic. A semi-circular two-span continuous horizontally curved steel box beam was fabricated and tested under two point loads at midspan of the beam, the results was compared with the results of the computer program (NFHCBSL) used in this study. In general, it is found that the adopted finite element model to predict the structural response of horizontally curved steel box beam has a good agreement with the test results concerning estimate load-deflection response.The effect of b/d ratio is considered by taken different values (20–100) % with the identical area of cross-section. Also, the effect of curvature was studied by considering different values from beam with half circle to straight beam. The results appear that the best (b/d) ratio is in between (0.3 and 0.4) at curvature between (0° and 90°) and the best (b/d) ratio is in between (0.4 and 0.5) at curvature between (90° and 180°). Also, the result showed that the decrease in carrying load capacity as the beam curvature increased is independent on the value of b/d ratio

Seepage Velocity Mapping Using ArcMap/GIS Software

Groundwater flows from high to low hydraulic head regions. This flow is controlled by Darcy velocity equation. Darcy velocity represents the flow velocity within the cross-sectional area of the soil. Actually, however, groundwater flows at a higher velocity than that of Darcy’s, called seepage velocity. Seepage velocity considers the real area (pores area) that is available for groundwater flow in calculations. There are many applications which are affected by the seepage/Darcy velocity, e.g., underground thermal energy storage systems and contaminants transfer in soil. In spite of the importance of Darcy/seepage velocity in many applications, there is no specific method to depict these velocities on a large-scale map. This paper proposed a tool that can be used to depict the seepage velocity on a large scale. The considered tool is offered by ArcMap/GIS software. To explain how this tool works, Babylon (Iraq) was considered as a study area. ISBN för värdpublikation: 978-3-030-51209-5, 978-3-030-51212-5, 978-3-030-51210-1</p

Site Selection of Aquifer Thermal Energy Storage Systems in Shallow Groundwater Conditions

Underground thermal energy storage (UTES) systems are widely used around the world, due to their relations to heating ventilating and air conditioning (HVAC) applications [1]. To achieve the required objectives of these systems, the best design of these systems should be accessed first. The process of determining the best design for any UTES system has two stages, the type selection stage and the site selection stage. In the type selection stage, the best sort of UTES system is determined. There are six kinds of UTES systems, they are: boreholes, aquifer, bit, tank, tubes in clay, and cavern [2–5]. The selection of a particular type depends on three groups of parameters. They are: Site specific, design, and operation parameters (Figure 1). Apart from site specific parameters, the other two types can be changed through the life time of the system. The site specific parameters, e.g., geological, hydrogeological, and metrological, cannot be changed during the service period of the  ystem. Therefore, the design of the best type should depend, at first consideration, on site specific parameters.Validerad;2019;Nivå 2;2019-07-12 (johcin)</p

Seepage Velocity : Large Scale Mapping and the Evaluation of Two Different Aquifer Conditions (Silty Clayey and Sandy)

Seepage velocity is a very important criterion in infrastructure construction. The planning of numerous large infrastructure projects requires the mapping of seepage velocity at a large scale. To date, however, no reliable approach exists to determine seepage velocity at such a scale. This paper presents a tool within ArcMap/Geographic Information System (GIS) software that can be used to map the seepage velocity at a large scale. The resultant maps include both direction and magnitude mapping of the seepage velocity. To verify the GIS tool, this study considered two types of aquifer conditions in two regions in Iraq: silty clayey (Babylon province) and sandy (Dibdibba in Karbala province). The results indicate that, for Babylon province, the groundwater flows from the northwest to southeast with a seepage velocity no more than 0.19 m/d; for the Dibdibba region, the groundwater flows from the west to the east with a seepage velocity not exceeding 0.27 m/d. The effectiveness of the presented tool in depicting the seepage velocity was thus demonstrated. The accuracy of the resultant maps depends on the resolution of the four essential maps (groundwater elevation head, effective porosity, saturated thickness, and transmissivity) and locations of wells that are used to collect the data.Validerad;2020;Nivå 2;2020-08-25 (alebob)</p

The Influence of Regional Groundwater Flow and a Neighbouring River on the Behaviour of an Aquifer Thermal Energy Storage System

One promising solution for mitigating CO2 emissions in arid regions is to use Aquifer Thermal Energy Storage (ATES) systems in cooling and heating systems. However, ATES systems need to be subjected to geohydrological investigations before their installation to ensure high performance. Two geohydrological properties are considered: regional groundwater flow and the influence of neighbouring rivers. This study considers a hypothetical ATES system within the city of Hilla, Iraq. MODFLOW 6.1 software was used to simulate the influence of the two properties. The simulation tested two locations situated at 75 m and 300 m from the river. Each location was explored using three flow rates: 10 m3/d, 50 m3/d, and 100 m3/d. The results indicate that the temperature change in the warm and cold wells increases proportionally with time of operation and rate of flow. For example, the temperature of the middle layer (for 10 m3/d operation) changes from 29 °C (after one year) to 34 °C (after twenty years operation), while it changes from 34 °C (one year) to 35 °C (twenty years) under 100 m3/d operation. Another result is that the available regional groundwater flow has a negligible influence on the storage system, while the neighbouring river has a high influence on the stored energy when the distance between them is 75 m or less. The paper recommends the installation of ATES systems at least 300 m from the bank of a river

Site Selection Criteria of UTES Systems in Hot Climate

Underground Thermal Energy Storage UTES systems are widely used around the world. The reason is that UTES is essential in utilizing Renewable Energy sources (RE). The efficiency of the energy system relies strongly on the efficiency of the storage system. Therefore, in the installation of a hyper-energy system, a lot of attention is to be paid in improving the storage system. In order to design an efficient storage system, firstly, standard criteria are to be investigated. These explain the process of making high efficiency storage system that must be specified. The criteria, mainly, depends on: best type and best location. These two variables are in high interference with each other. The bond between the two variables is represented by the geological, hydrological, meteorological, soil, hydrogeological properties/factors of the site. These factors are specified by geo-energy mapping. Despite the importance of this type of mapping, there is no specific criteria/formula that defines the choice. This paper aims to: give a brief literature review for UTES systems (types, classification, advantages/disadvantages for each type, and examples of an installed system). In addition, some factors within geo-energy mapping are highlighted and standard criteria to achieve good storage system are suggested. The suggested criterion comprises a process to transfer the quantity values to quality values according to the expert opinion. The suggested criteria are defined through the following stages: selecting the best type of UTES systems according to hydro-geological in site conditions; using the analytical hierarchy process to rank the best location to install the storage system and then using ArcMap (GIS-Software) to provide representative results as maps. Karbala Province (Iraq) is the study area used her

Water quality assessment along Tigris River (Iraq) using water quality index (WQI) and GIS software

Most of the third world countries having rivers passing through them suffer from the water contaminant problem. This problem is considered so difficult to get the water quality within the standard allowable limits for drinking, as well as for industrial and agricultural purposes. This research aims to assess the water quality of the Tigris River using the water quality index method and GIS software. Twelve parameters (Ca, Mg, Na, K, Cl, SO4, HCO3, TH, TDS, BOD5, NO3, and EC) were taken from 14 stations along the river. The weighted arithmetic method was applied to compute the water quality index (WQI). The interpolation method (IDW) was applied in ArcGIS 10.5 to produce the prediction maps for 12 parameters at 11 stations along the Tigris River during the wet and dry seasons in 2016. The regression prediction was applied on three stations in the Tigris River between observed values and predicted values, from the prediction maps, in both seasons. The results showed that the regression prediction for all parameters was given the acceptable values of the determination coefficient (R2). Furthermore, the state of water quality for the Tigris River was degraded downstream of the Tigris River, especially at the station (8) in Aziziyah in the wet and dry seasons and increase degradation clearly at Qurnah (Basrah province) in the south of Iraq. This paper considers the whole length of the Tigris River for the study. This is important to give comprehensive knowledge about the contamination reality of the river. Such that it becomes easier to understand the problem of contamination, analyze it, and then find the suitable treatments and solutions.Validerad;2020;Nivå 2;2020-08-17 (alebob)</p