Improving industrial energy efficiency is considered an important factor in reducing carbon dioxide emissions and counteract climate change. For many industrial companies in cold climates, heat generated at the site in summer will not be needed to fulfil the site heat demand during this time, and is thus removed to the outdoor air. Although a mismatch between heat generation and heat demand primarily being seasonal, a mismatch may also exist at times in the winter, e.g. during milder winter days or high production hours. If this excess heat instead of being sent to the outdoors was stored for later use when it is needed, purchased energy for the site could be decreased. One way to do this is by the use of a borehole thermal energy storage (BTES) system. A BTES system stores energy directly in the ground by using an array of closely drilled boreholes through which a heat carrier, often water, is circulated. So far, BTES systems used for heating purposes have mainly been used for storage of solar thermal energy. The BTES system has then been part of smaller district solar heating systems to reduce the seasonal mismatch between incoming solar radiation and heat demand, thus increasing system solar fraction. For this application of BTES systems, energy for storage can be controlled by the sizing of the solar collector area. At an industrial site, however, the energy that can be stored will be limited to the excess heat at the site, and the possible presence of several time-varying processes generating heat at different temperatures gives options as to which processes to include in the heat recovery process and how to design the BTES system. Moreover, to determine the available heat for storage at an industrial site, individual measurements of the heat streams to be included are required. Thus, this must be made more site-specific as compared to that of the traditional usage of BTES systems where solar thermal energy is stored, in which case long-time historic solar radiation data to do this is readily accessible for most locations. Furthermore, for performance predictions of industrial BTES systems to be used for both seasonal and short-term storage of energy, models that can treat the short-term effects are needed, as traditional models for predicting BTES performance do not consider this. Although large-scale BTES systems have been around since the 1970’s, little data is to be found in the literature on how design parameters such as borehole spacing and borehole depth affect storage performance, especially for industrial BTES applications. Most studies that can be found with regard to the designing of ground heat exchanger systems are for traditional ground source heat pumps, working at the natural temperature of the ground and being limited to only one or a few boreholes. In this work, the performance of the first and largest industrial BTES system in Sweden was first presented and evaluated with regard to the storage’s first seven years in operation. The BTES system, which has been used for both long- and short-term storage of energy, was then modelled in the IDA ICE 4.8 environment with the aim to model actual storage performance. Finally, the model was used to conduct a parametric study on the BTES system, where e.g. the impact on storage performance from borehole spacing and characteristics of the storage supply flow at heat injection were investigated. From the performance evaluation it could be concluded that lower than estimated quantities and/or quality of the excess heat at the site, resulting in lower storage supply flow temperatures at heat injection, has hindered the storage from reaching temperatures necessary for significant amounts of energy to be extracted. Based on the repeating annual storage behavior seen for the last years of the evaluation period, a long-term annual heat extraction and ratio of energy extracted to energy injected of approximately 400 MWh/year and 20% respectively are likely. For the comparison of predicted and measured storage performance, which considered a period of three years, predicted values for total injected and extracted energy deviated from measured values by less than 1 and 3% respectively, and predicted and measured values for injected and extracted energy followed the same pattern throughout the period. Furthermore, the mean relative difference for the storage temperatures was 4%. A time-step analysis confirmed that the intermittent heat injection and extraction, occurring at intervals down to half a day, had been captured in the three-year validation. This as predictions would become erroneous when the time step exceeded the time at which these changes in storage operation occur. Main findings from the parametric study include that 1) for investigated supply flows at heat injection, a high temperature was more important than a high flow rate in order to achieve high annual heat extractions and that 2) annual heat extraction would rapidly reduce as the borehole spacing was decreased from the one yielding the highest annual heat extraction, whereas the reduction in annual heat extraction was quite slow when the spacing was increased from this point. Another conclusion that came from the performance evaluation and the parametric study, as a consequence of the Emmaboda storage being designed as a high-temperature BTES system, intended working temperatures being 40–55 °C, was that the possibility of designing the BTES system for low working temperatures should be considered in the designing of a BTES system. Lower storage operation temperatures allow for more energy to be injected and in turn for more energy to be extracted and reduces storage heat losses to the surroundings. Ökad energieffektivisering inom industrin anses vara en nyckelkomponent för att minska koldioxidutsläpp och motarbeta klimatförändringar. För många industrier belägna i kallare klimat behövs under sommaren inte all den värme som alstras på anläggningen för att uppnå anläggningens värmebehov, och värmen avlägsnas därför till utomhusluften. Även om ett överskott av värme framförallt existerar under sommaren kan överskottsvärme även uppstå under vintern, till exempel under mildare vinterdagar eller högproduktionstimmar. Om överskottsvärmen istället för att avlägsnas till utomhusluften lagras till senare då den behövs skulle köpt energi till anläggningen kunna minskas. Ett sätt att åstadkomma detta är med hjälp av ett borrhålsvärmelager. Ett borrhålsvärmelager lagrar energi direkt i marken med hjälp av ett flertal närliggande borrhål genom vilka en värmebärare, vanligtvis vatten, cirkuleras. Hittills har borrhålsvärmelager med syfte att leverera värme framförallt använts för lagring av termisk solenergi. Borrhålsvärmelager har då ingått i solvärmesystem för uppvärmning av enstaka bostadskvarter, för att på så vis minska den säsongsbaserade missanpassningen mellan solinstrålning och värmebehov och öka värmesystemets solfraktion. För denna applikation av borrhålsvärmelager kan energimängder för lagring kontrolleras av storleken på solfångarkollektorytan. För industriella borrhålsvärmelagertillämpningar däremot, bestäms energimängder som kan lagras av den tillgängliga överskottsvärmen vid anläggningen. En industri har dessutom vanligtvis ett flertal energianvändande processer, vilka på grund av tidsvarierande drift och olika kvalitet på den alstrade värmen ger upphov till alternativ för vilka processer som bör integreras i värmeåtervinningssystemet och hur själva borrhålsvärmelagret bör utformas. För beräkning av värmemängder tillgängliga för lagring vid en industriell anläggning krävs dessutom mätdata för de individuella värmeströmmar som ska ingå i lagerprocessen, vilket betyder att detta måste genomföras mer fallspecifikt för industriella borrhålsvärmelagertillämpningar än för borrhålsvärmelager för lagring av solenergi, där historisk solinstrålningsdata för beräkning av detta är direkt tillgänglig för de flesta platser. För prediktioner av prestandan av borrhålsvärmelager användandes för både lång- och korttidslagring behövs dessutom modeller som kan hantera effekterna från korttidslagringen, vilket traditionella modeller för borrhålsvärmelagerprediktioner inte gör. Trots att storskaliga borrhålsvärmelager har byggts sedan 1970-talet finns lite data publicerat över hur olika systemparametrar så som borrhålsavstånd och borrhålsdjup påverkar lagerprestandan, särskilt med avseende på industriella borrhålsvärmelagertillämpningar. De flesta studier i litteraturen kopplat till utformning av borrhålsvärmeväxlarsystem avser traditionell bergvärme där värmepumpen arbetar mot marken vid sin naturliga temperatur och enbart ett fåtal borrhål används. I det här arbetet genomfördes först en utvärdering av det första borrhålsvärmelagret för lagring av industriell överskottsvärme i Sverige med avseende på lagrets första sju år i drift. Borrhålsvärmelagret, vilket har använts för både lång- och korttidslagring, modellerades sedan i IDA ICE 4.8 med målet att återskapa lagrets utfall. Slutligen användes den validerade borrhålsvärmelagermodellen för en parameterisering av lagret, där påverkan på inladdad och urladdad energi och borrhålsvärmelagerverkningsgrad från bland annat borrhålsavstånd och temperatur och storlek på flödet till lagret vid laddning studerades. Från uppföljningen av lagrets utfall konstaterades det att lägre än uppskattade mängder överskottsvärme och/eller kvalitet på överskottsvärmen, resulterande i lägre än uppskattade framledningstemperaturer till lagret vid laddning, har hindrat lagret från att nå temperaturer nödvändiga för att väsentliga mängder energi ska kunna hämtas upp från lagret. Baserat på det på årsbasis cykliska beteende noterat för lagret för de sista åren av utvärderingen är rimliga långsiktiga värden för urladdad energi och borrhålsvärmelagerverkningsgrad cirka 400 MWh/år respektive 20%. För jämförelsen mellan predikterad och uppmätt lagerprestanda, vilken avser en period om tre år, avvek predikterade värden för inladdad och urladdad energi från uppmätta värden med mindre än 1% respektive 3%. Värden för predikterad och uppmätt inladdad och urladdad energi följde dessutom varandra väl under de tre åren. Vidare var den genomsnittliga relativa skillnaden för lagertemperaturerna för valideringsperioden 4%. En tidsstegsanalys bekräftade att modellen hade fångat upp effekterna av den intermittenta driften av lagret, inträffande vid intervall ned till halva dygn, då prediktioner blev felaktiga när simuleringstidssteget överskred tiden för vilka ändringar mellan laddning och urladdning av lagret ägt rum. Huvudsakliga resultat från parameterstudien inkluderar att 1) för undersökta flöden till lagret vid laddning var en hög temperatur viktigare än ett stort massflöde för att uppnå en hög årlig urladdning av energi och 2) den mängd energi som på årsbasis kan hämtas upp från lagret sjönk hastigt när borrhålsavståndet minskades från det avstånd som resulterade i att mest energi kunde laddas ur, medan en långsam minskning sågs när borrhålsavståndet ökades från denna punkt. Ytterligare en slutsats kopplat till påverkan på lagerprestanda från ingående systemparametrar är att möjligheter för utformning av ett lågtemperaturlager bör beaktas vid planering av byggande av borrhålsvärmelager. Genom att reducera lagrets arbetstemperatur kan mer energi laddas in i lagret, vilket i sin tur innebär att mer energi kan laddas ur. En lägre arbetstemperatur innebär även lägre värmeförluster från lagret till dess omgivning.

This authoritative guide provides a basis for understanding the emerging technology of ground source heating and cooling. It equips engineers, geologists, architects, planners and regulators with the fundamental skills needed to manipulate the ground's huge capacity to store, supply and receive heat, and to implement technologies (such as heat pumps) to exploit that capacity for space heating and cooling. The author has geared the book towards understanding ground source heating and cooling from the ground side (the geological aspects), rather than solely the building aspects. He explains the science behind thermogeology and offers practical guidance on different design options. An Introduction to Thermogeology: ground source heating and cooling is aimed primarily at professionals whose skill areas impinge on the emerging technology of ground source heating and cooling. They will be aware of the importance of the technology and wish to rapidly acquire fundamental theoretical understanding and design skills. This second edition has been thoroughly updated and expanded to cover new technical developments and now includes end-of-chapter study questions to test the reader's understanding.

Advances in Ground-Source Heat Pump Systems relates the latest information on source heat pumps (GSHPs), the types of heating and/or cooling systems that transfer heat from, or to, the ground, or, less commonly, a body of water. As one of the fastest growing renewable energy technologies, they are amongst the most energy efficient systems for space heating, cooling, and hot water production, with significant potential for a reduction in building carbon emissions. The book provides an authoritative overview of developments in closed loop GSHP systems, surface water, open loop systems, and related thermal energy storage systems, addressing the different technologies and component methods of analysis and optimization, among other subjects. Chapters on building integration and hybrid systems complete the volume. - Provides the geological aspects and building integration covered together in one convenient volume - Includes chapters on hybrid systems - Presents carefully selected chapters that cover areas in which there is significant ongoing research - Addresses geothermal heat pumps in both heating and cooling modes

FEFLOW is an acronym of Finite Element subsurface FLOW simulation system and solves the governing flow, mass and heat transport equations in porous and fractured media by a multidimensional finite element method for complex geometric and parametric situations including variable fluid density, variable saturation, free surface(s), multispecies reaction kinetics, non-isothermal flow and multidiffusive effects. FEFLOW comprises theoretical work, modeling experiences and simulation practice from a period of about 40 years. In this light, the main objective of the present book is to share this achieved level of modeling with all required details of the physical and numerical background with the reader. The book is intended to put advanced theoretical and numerical methods into the hands of modeling practitioners and scientists. It starts with a more general theory for all relevant flow and transport phenomena on the basis of the continuum approach, systematically develops the basic framework for important classes of problems (e.g., multiphase/multispecies non-isothermal flow and transport phenomena, discrete features, aquifer-averaged equations, geothermal processes), introduces finite-element techniques for solving the basic balance equations, in detail discusses advanced numerical algorithms for the resulting nonlinear and linear problems and completes with a number of benchmarks, applications and exercises to illustrate the different types of problems and ways to tackle them successfully (e.g., flow and seepage problems, unsaturated-saturated flow, advective-diffusion transport, saltwater intrusion, geothermal and thermohaline flow).

Analysis and Design of Energy Geostructures gathers in a unified framework the theoretical and experimental competence available on energy geostructures: innovative multifunctional earth-contact structures that can provide renewable energy supply and structural support to any built environment. The book covers the broad, interdisciplinary and integrated knowledge required to address the analysis and design of energy geostructures from energy, geotechnical and structural perspectives. This knowledge includes (Part A) an introduction to the technology; (Part B) the fundamentals of heat and mass transfers as well as of the mechanics of geomaterials and structures required to address the unprecedented behavior of energy geostructures; (Part C) the experimental evidence characterizing the considered geostructures; (Part D) various analytical and numerical modeling approaches to analyze the response of energy geostructures; and (Part E) the performance-based design and detailing essentials of energy geostructures. - Proposes the theoretical and practical application essentials required to address the analysis and design of energy geostructures from energy, geotechnical and structural perspectives - Presents a substantial amount of resolved exercises on key aspects governing the behavior and performance of energy geostructures to be considered in analysis and design - Summarizes and discusses the most recent scientific and technical knowledge about energy geostructures, including energy piles, energy tunnels and energy walls

Heat pumps (HPs) allow for providing heat without direct combustion, in both civil and industrial applications. They are very efficient systems that, by exploiting electrical energy, greatly reduce local environmental pollution and CO2 global emissions. The fact that electricity is a partially renewable resource and because the coefficient of performance (COP) can be as high as four or more, means that HPs can be nearly carbon neutral for a full sustainable future. The proper selection of the heat source and the correct design of the heat exchangers is crucial for attaining high HP efficiencies. Heat exchangers (also in terms of HP control strategies) are hence one of the main elements of HPs, and improving their performance enhances the effectiveness of the whole system. Both the heat transfer and pressure drop have to be taken into account for the correct sizing, especially in the case of mini- and micro-geometries, for which traditional models and correlations can not be applied. New models and measurements are required for best HPs system design, including optimization strategies for energy exploitation, temperature control, and mechanical reliability. Thus, a multidisciplinary approach of the analysis is requested and become the future challenge.

A Step-by-step Guide to Developing Innovative Computational Tools for Shallow Geothermal Systems Geothermal heat is a viable source of energy and its environmental impact in terms of CO2 emissions is significantly lower than conventional fossil fuels. Shallow geothermal systems are increasingly utilized for heating and cooling of buildings and greenhouses. However, their utilization is inconsistent with the enormous amount of energy available underneath the surface of the earth. Projects of this nature are not getting the public support they deserve because of the uncertainties associated with them, and this can primarily be attributed to the lack of appropriate computational tools necessary to carry out effective designs and analyses. For this energy field to have a better competitive position in the renewable energy market, it is vital that engineers acquire computational tools, which are accurate, versatile and efficient. This book aims at attaining such tools. This book addresses computational modeling of shallow geothermal systems in considerable detail, and provides researchers and developers in computational mechanics, geosciences, geology and geothermal engineering with the means to develop computational tools capable of modeling the complicated nature of heat flow in shallow geothermal systems in rather straightforward methodologies. Coupled conduction-convection models for heat flow in borehole heat exchangers and the surrounding soil mass are formulated and solved using analytical, semi-analytical and numerical methods. Background theories, enhanced by numerical examples, necessary for formulating the models and conducting the solutions are thoroughly addressed. The book emphasizes two main aspects: mathematical modeling and computational procedures. In geothermics, both aspects are considerably challenging because of the involved geometry and physical processes. However, they are highly stimulating and inspiring. A good combination of mathematical modeling and computational procedures can greatly reduce the computational efforts. This book thoroughly treats this issue and introduces step-by-step methodologies for developing innovative computational models, which are both rigorous and computationally efficient.

The thermal use of the shallow subsurface is increasingly being promoted and implemented as one of many promising measures for saving energy. A series of questions arises concerning the design and management of underground and groundwater heat extraction systems, such as the sharing of the thermal resource and the assessment of its long-term potent