Advances in Integrated Geothermal Energy Systems

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Energy Systems".

Deadline for manuscript submissions: closed (25 June 2023) | Viewed by 10833

Special Issue Editors

Center for Energy, Austrian Institute of Technology, 1210 Vienna, Austria
Interests: low-temperature heating and cooling grids; integration of geothermal in refurbishment projects; assessment of geofluids in deep geothermal resources
Faculty of Mining & Geology, Department of Hydrogeology, University of Belgrade, Studentski trg 1, Belgrade, Serbia
Interests: hydrogeothermal energy; evaluation of groundwater resources; water supply and field hydrogeology techniques; mining hydrogeology

Special Issue Information

Dear Colleagues,

Heating and cooling account for about 50% of the final energy demand, and geothermal energy has, for decades, played its role as a reliable and renewable energy source. However, despite the growing number of geothermal installations, much of the huge potential of geothermal energy remains untapped. Furthermore, there are still many undeveloped deep geothermal resources for direct heating and/or for electricity generation. The global trend is shifting, with geothermal installations serving as single-use systems for individual cases toward integration in district heating and cooling grids for urban and sub-urban areas, integration of geothermal sources in decentral heating and cooling grids; use of the underground as seasonal thermal storage (e.g., in borehole heat exchanger fields or deep aquifer thermal energy storage), use of excess heat from geothermal energy and/or industrial high-temperature excess heat in heating and cooling grids, geothermal energy in energy communities, and numerous other examples.

This Special Issue on “Advances in Integrated Geothermal Energy Systems” aims to curate novel advances in the integration of geothermal energy sources. Topics of interest include, but are not limited to:

  • Methodologies, workflows, and concepts on the inclusion of deep and shallow geothermal resources in general;
  • Case studies for developing and evaluating concepts of integration of shallow and deep geothermal applications under real-life conditions;
  • Field laboratories and in situ experiments investigating detailed technical problems such as the coupled thermal–physical behavior of the subsurface or above-surface technical solutions for next-generation district heating and cooling systems;
  • Feasibility studies or best practices for underground thermal energy storage (use of the underground as thermal energy storage; UTES) including ATES, BTES, and CTES applications or demonstrations;
  • Existing demonstrations scientifically monitored and evaluated.

Dr. Edith Haslinger
Prof. Dr. Dejan Milenic
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • geothermal district heating
  • geothermal heating
  • geothermal cooling
  • low-temperature heating and cooling grids
  • integrated geothermal energy grids
  • underground thermal energy storage (UTES)
  • aquifer thermal energy storage (ATES) borehole thermal energy storage (BTES)
  • cavern thermal energy storage (CTES)
  • direct use
  • electricity

Published Papers (4 papers)

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Research

17 pages, 3394 KiB  
Article
Numerical Validation of a New Analytical Solution for Helical (Earth-Basket) Type Ground Heat Exchangers
by Christoph Reichl and Henk J. L. Witte
Processes 2023, 11(5), 1418; https://doi.org/10.3390/pr11051418 - 08 May 2023
Viewed by 948
Abstract
In this paper, we show that an analytical solution based on the Finite Line Source and G-function approach is both sufficiently fast and accurate for design calculations of ground heat exchangers with a complex (spiral) geometry. Detailed validations were performed for the steady-state [...] Read more.
In this paper, we show that an analytical solution based on the Finite Line Source and G-function approach is both sufficiently fast and accurate for design calculations of ground heat exchangers with a complex (spiral) geometry. Detailed validations were performed for the steady-state and transient responses of analytical models with different time scales (10 h and 250 h). A comparison with a detailed computational fluid dynamics model (Ansys Fluent) and the analytical method for different boundary conditions showed a very good agreement (maximum root mean square error) smaller than 0.25 K. Full article
(This article belongs to the Special Issue Advances in Integrated Geothermal Energy Systems)
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14 pages, 3940 KiB  
Article
Geothermal Potential of the Brenner Base Tunnel—Initial Evaluations
by Thomas Geisler, Klaus Voit, Ulrich Burger, Tobias Cordes, Florian Lehner, Gregor Götzl, Magdalena Wolf and Thomas Marcher
Processes 2022, 10(5), 972; https://doi.org/10.3390/pr10050972 - 12 May 2022
Cited by 6 | Viewed by 3201
Abstract
Increasing demands on mobility and transport, but limited space above ground, lead to new traffic routes being built, even more underground in the form of tunnels. In addition to improving the traffic situation, tunnels offer the possibility of contributing to climate-friendly heating by [...] Read more.
Increasing demands on mobility and transport, but limited space above ground, lead to new traffic routes being built, even more underground in the form of tunnels. In addition to improving the traffic situation, tunnels offer the possibility of contributing to climate-friendly heating by indirectly serving as geothermal power plants. In this study, the geothermal potential of the future longest railway tunnel in the world, the Brenner Base Tunnel, was evaluated. At the Brenner Base Tunnel, warm water naturally flows from the apex of the tunnel towards the city of Innsbruck, Austria. In order to estimate its geothermal potential, hydrological data of discharge rates and temperatures were investigated and analyzed. The investigations indicated the highest geothermal potential in the summertime, while the lowest occurs during winter. It could be shown that these variations were a result of cooling during discharge through areas of low overburden (mid mountain range), where the tunnel atmosphere is increasingly influenced by the air temperatures outside the tunnel. Nevertheless, the calculations showed that there will be a usable potential after completion of the tunnel. Full article
(This article belongs to the Special Issue Advances in Integrated Geothermal Energy Systems)
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18 pages, 8886 KiB  
Article
Thermophysical Properties of a Subsoil Drill Core for Geothermal Energy Applications
by Daniel Lager, Edith Haslinger, Robin Friedrich, Stefan Hoyer and Doris Rupprecht
Processes 2022, 10(3), 496; https://doi.org/10.3390/pr10030496 - 01 Mar 2022
Viewed by 1537
Abstract
Urban heat islands (UHI) occur especially in inner-city areas due to small green areas, an excess of high solar heat, and low air circulation. One solution is the “harvesting” of excess solar urban heat through shallow absorber ducts, which are then used in [...] Read more.
Urban heat islands (UHI) occur especially in inner-city areas due to small green areas, an excess of high solar heat, and low air circulation. One solution is the “harvesting” of excess solar urban heat through shallow absorber ducts, which are then used in borehole heat exchanger (BHE) fields for later use for heat or cold storage. Knowing the thermophysical properties of the subsurface as accurately as possible is of great importance in the design and configuring of a borehole heat exchanger field as a thermal energy storage system. In this study, a subsoil drill core from a BHE, with a depth of 80 m, was used to determine temperature dependent effective thermal conductivity based on the heat flow meter method, the specific heat capacity based on differential scanning calorimetry, and thermal expansion based on dilatometry in moist and dry states. The results have shown that the actual moisture content of the subsoil sample has a strong impact on the thermal conductivity, as well as on the heat capacity. Thermal expansion measurements have shown the influence of the drying process on the shrinkage of drill core samples and the low thermal expansion of the dry subsoil itself. Full article
(This article belongs to the Special Issue Advances in Integrated Geothermal Energy Systems)
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20 pages, 3505 KiB  
Article
Thermo-Economic Analysis of Near-Surface Geothermal Energy Considering Heat and Cold Supply within a Low-Temperature District Heating Network
by Sebastian Kutzner, Florian Heberle and Dieter Brüggemann
Processes 2022, 10(2), 421; https://doi.org/10.3390/pr10020421 - 21 Feb 2022
Cited by 2 | Viewed by 2123
Abstract
This study evaluates low-temperature district heating (LTDH) networks with different geothermal heat sources under thermo-economic criteria. In particular, the heat and cold supply of modern neighbourhoods are taken into account in a dynamic simulation model built on the modelling language Modelica. Both horizontal [...] Read more.
This study evaluates low-temperature district heating (LTDH) networks with different geothermal heat sources under thermo-economic criteria. In particular, the heat and cold supply of modern neighbourhoods are taken into account in a dynamic simulation model built on the modelling language Modelica. Both horizontal and vertical ground heat exchangers (GHE) were investigated in respect to the load profiles of the consumers, depending on dimension as well as location. The selected base case represents a LTDH network near Stuttgart (Germany). The corresponding results of an annual simulation show that a horizontal GHE is suitable for pure heat supply and can reduce costs by up to 12% compared to a vertical system. This economic advantage remains when the cooling demand is considered. Subsequently, a variation of the system location was carried out. It is shown that horizontal GHEs operate more economically in northern regions, whereas vertical ones are more advantageous in regions with increased cooling demand. For both cases, possible savings of between 3.0% and 4.2% resulted from the simulations. The heating-to-cooling demand ratio was used as a first decision criteria to weigh-up between the two systems. Vertical GHEs were more economical than horizontal systems as soon as the ratio dropped below 1.5. Full article
(This article belongs to the Special Issue Advances in Integrated Geothermal Energy Systems)
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