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Volume II: Low Enthalpy Geothermal Energy

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "H: Geo-Energy".

Deadline for manuscript submissions: closed (29 December 2019) | Viewed by 22366

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Special Issue Editors

DIATI—Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
Interests: ground water engineering; shallow geothermal energy
Special Issues, Collections and Topics in MDPI journals
Politecnico di Torino—Department of Environment, Land and Infrastructure Engineering (DIATI), Corso Duca Degli Abruzzi 24, 10129 Torino, Italy
Interests: shallow geothermal energy; groundwater engineering; carbon footprint
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Low enthalpy geothermal energy has a great potential in reducing the climate impact of building heating and cooling systems. The use of this renewable energy source involves a number of scientific disciplines, mainly but not limited to energy engineering, heat transfer, geology, hydrogeology, chemistry, and economy.

The focus of this Special Issue is to provide an overview of the ongoing research on low enthalpy geothermal resources. Possible topics include:

  • Innovative low enthalpy geothermal systems (ground source heat pumps, direct heat uses, free cooling);
  • Mathematical and numerical methods for the design of low enthalpy geothermal systems;
  • Assessment of low enthalpy geothermal resources and shallow geothermal potential;
  • International collaborative research, technology transfer, and/or policy development projects;
  • Statistic and economic studies on low enthalpy geothermal energy;
  • Assessment of environmental impacts, both positive (e.g., CO2 emissions, air quality) and negative (e.g., geochemical alterations, geological interferences).

Both original research papers and literature reviews will be taken into consideration for publication.

Prof. Dr. Rajandrea Sethi
Dr. Alessandro Casasso
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. Energies is an international peer-reviewed open access semimonthly 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 2600 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

  • Ground Source Heat Pump (GSHP)
  • Ground Coupled Heat Pump (GCHP)
  • Ground Water Heat Pumps (GWHP)
  • Energy Economics
  • Climate Change
  • Renewable Energy
  • Geothermal Energy

Published Papers (7 papers)

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Research

16 pages, 7058 KiB  
Article
Temperature Measurements on a Solar and Low Enthalpy Geothermal Open-Air Asphalt Surface Platform in a Cold Climate Region
by Caner Çuhac, Anne Mäkiranta, Petri Välisuo, Erkki Hiltunen and Mohammed Elmusrati
Energies 2020, 13(4), 979; https://doi.org/10.3390/en13040979 - 21 Feb 2020
Cited by 6 | Viewed by 2468
Abstract
Solar heat, already captured by vast asphalt fields in urban areas, is potentially a huge energy resource. The vertical soil temperature profile, i.e., low enthalpy geothermal energy, reveals how efficiently the irradiation is absorbed or radiated back to the atmosphere. Measured solar irradiation, [...] Read more.
Solar heat, already captured by vast asphalt fields in urban areas, is potentially a huge energy resource. The vertical soil temperature profile, i.e., low enthalpy geothermal energy, reveals how efficiently the irradiation is absorbed or radiated back to the atmosphere. Measured solar irradiation, heat flux on the asphalt surface and temperature distribution over a range of depths describe the thermal energy from an asphalt surface down to 10 m depth. In this study, those variables were studied by long-term measurements in an open-air platform in Finland. To compensate the nighttime heat loss, the accumulated heat on the surface should be harvested during the sunny daytime periods. A cumulative heat flux over one year from asphalt to the ground was 70% of the cumulative solar irradiance measured during the same period. However, due to the nighttime heat losses, the net heat flux during 5 day period was only 18% of the irradiance in spring, and was negative during autumn, when the soil was cooling. These preliminary results indicate that certain adaptive heat transfer and storage mechanisms are needed to minimize the loss and turn the asphalt layer into an efficient solar heat collector connected with a seasonal storage system. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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20 pages, 4337 KiB  
Article
Serial Laboratory Effective Thermal Conductivity Measurements of Cohesive and Non-cohesive Soils for the Purpose of Shallow Geothermal Potential Mapping and Databases—Methodology and Testing Procedure Recommendations
by Aleksandra Łukawska, Grzegorz Ryżyński and Mateusz Żeruń
Energies 2020, 13(4), 914; https://doi.org/10.3390/en13040914 - 18 Feb 2020
Cited by 6 | Viewed by 2832
Abstract
The article presents the methodology of conducting serial laboratory measurements of thermal conductivity of recompacted samples of cohesive and non-cohesive soils. The presented research procedure has been developed for the purpose of supplementing the Engineering–Geology Database and its part–Physical and Mechanical Properties of [...] Read more.
The article presents the methodology of conducting serial laboratory measurements of thermal conductivity of recompacted samples of cohesive and non-cohesive soils. The presented research procedure has been developed for the purpose of supplementing the Engineering–Geology Database and its part–Physical and Mechanical Properties of Soils and Rocks (abbr. BDGI-WFM) with a new component regarding thermal properties of soils. The data contained in BDGI-WFM are the basis for the development of maps and plans for the assessment of geothermal potential and support for the sustainable development of low enthalpy geothermal energy. Effective thermal conductivity of soils was studied at various levels of water saturation and various degrees of compaction. Cohesive soils were tested in initial moisture content and after drying to a constant mass. Non-cohesive soils were tested in initial moisture, fully saturated with water and after drying to a constant mass. Effective thermal conductivity of non-cohesive soils was determined on samples mechanically compacted to the literature values of bulk density. Basic physical parameters were determined for each of the samples. In total, 120 measurements of thermal conductivity were carried out, for the purposes of developing the guidelines which allowed statistical analysis of the results. The results were cross-checked with different measuring equipment and with the literature data. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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20 pages, 2799 KiB  
Article
Energy Efficiency of a Heat Pump System: Case Study in Two Pig Houses
by Hannah Licharz, Peter Rösmann, Manuel S. Krommweh, Ehab Mostafa and Wolfgang Büscher
Energies 2020, 13(3), 662; https://doi.org/10.3390/en13030662 - 04 Feb 2020
Cited by 17 | Viewed by 4292
Abstract
This study describes a 70-day investigation of three identical groundwater heat pumps (GWHP) for heating two pig houses located on the same farm in West Germany. Two of the three GWHPs were installed in a piglet-rearing barn, the third in a farrowing barn. [...] Read more.
This study describes a 70-day investigation of three identical groundwater heat pumps (GWHP) for heating two pig houses located on the same farm in West Germany. Two of the three GWHPs were installed in a piglet-rearing barn, the third in a farrowing barn. All three heat pumps were fed from the same extraction well. The aim of this study was firstly the empirical performance measurement of the GWHP systems and secondly the energetic evaluation of the systems on barn level by calculating the coefficient of performance (COP). Three different assessment limits were considered in order to better identify factors influencing the COP. In total, the heat pumps supplied thermal energy of 47,160 kWh (piglet-rearing barn) and 36,500 kWh (farrowing barn). Depending on the assessment limit considered, the COP in piglet-rearing barn and farrowing barn ranged between 2.6–3.4 and 2.5–3.0, respectively. A significant factor influencing the COP is the amount of electrical current required to operate the groundwater feeding pump. The average groundwater flow rate was 168.4 m3 d−1 (piglet-rearing barn) and 99.1 m3 d−1 (farrowing barn). In conclusion, by using energy from groundwater, GWHPs have the potential to substitute fossil fuels, thus saving them and avoiding CO2 emissions. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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19 pages, 4180 KiB  
Article
Long-Term Temperature Evaluation of a Ground-Coupled Heat Pump System Subject to Groundwater Flow
by Nehed Jaziri, Jasmin Raymond, Nicoló Giordano and John Molson
Energies 2020, 13(1), 96; https://doi.org/10.3390/en13010096 - 23 Dec 2019
Cited by 1 | Viewed by 2559
Abstract
The performance of ground-coupled heat pump systems (GCHPs) operating under significant groundwater flow can be difficult to predict due to advective heat transfer in the subsurface. This is the case of the Carignan-Salières elementary school located on the south shore of the St. [...] Read more.
The performance of ground-coupled heat pump systems (GCHPs) operating under significant groundwater flow can be difficult to predict due to advective heat transfer in the subsurface. This is the case of the Carignan-Salières elementary school located on the south shore of the St. Lawrence River near Montréal, Canada. The building is heated and cooled with a GCHP system including 31 boreholes subject to varying groundwater flow conditions due to the proximity of an active quarry being irregularly dewatered. A study with the objective of predicting the borehole temperatures in order to anticipate potential operational problems was conducted, which provided an opportunity to evaluate the impact of groundwater flow. For this purpose, a numerical model was calibrated using a full-scale heat injection test and then run under different scenarios for a period of twenty years. The heat exchange capacity of the GCHP system is clearly enhanced by advection when the Darcy flux changes from 6 × 10−8 m s−1 (no dewatering) to 8 × 10−7 m s−1 (high dewatering). This study further suggests that even the lowest groundwater flow condition can be beneficial to avoid a progressive cooling of the subsurface due to the unbalanced building loads, which can have important impacts for design of new systems. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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14 pages, 4197 KiB  
Article
Comparative Analysis of Different Methodologies Used to Estimate the Ground Thermal Conductivity in Low Enthalpy Geothermal Systems
by Cristina Sáez Blázquez, Ignacio Martín Nieto, Arturo Farfán Martín, Diego González-Aguilera and Pedro Carrasco García
Energies 2019, 12(9), 1672; https://doi.org/10.3390/en12091672 - 02 May 2019
Cited by 9 | Viewed by 2376
Abstract
In ground source heat pump systems, the thermal properties of the ground, where the well field is planned to be located, are essential for proper geothermal design. In this regard, estimation of ground thermal conductivity has been carried out by the implementation of [...] Read more.
In ground source heat pump systems, the thermal properties of the ground, where the well field is planned to be located, are essential for proper geothermal design. In this regard, estimation of ground thermal conductivity has been carried out by the implementation of different techniques and laboratory tests. In this study, several methods to obtain the thermal properties of the ground are applied in order to compare them with the reference thermal response test (TRT). These methods (included in previous research works) are carried out in the same geological environment and on the same borehole, in order to make an accurate comparison. All of them provide a certain value for the thermal conductivity of the borehole. These results are compared to the one obtained from the TRT carried out in the same borehole. The conclusions of this research allow the validation of alternative solutions based on the use of a thermal conductive equipment and the application of geophysics techniques. Seismic prospecting has been proven as a highly recommendable indicator of the thermal conductivity of a borehole column, obtaining rate errors of below 1.5%. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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17 pages, 5885 KiB  
Article
Investigation of Steady-State Heat Extraction Rates for Different Borehole Heat Exchanger Configurations from the Aspect of Implementation of New TurboCollector™ Pipe System Design
by Tomislav Kurevija, Adib Kalantar, Marija Macenić and Josipa Hranić
Energies 2019, 12(8), 1504; https://doi.org/10.3390/en12081504 - 20 Apr 2019
Cited by 6 | Viewed by 3328
Abstract
When considering implementation of shallow geothermal energy as a renewable source for heating and cooling of buildings, special care should be taken in the hydraulic design of the borehole heat exchanger system. Laminar flow can occur in pipes due to the usage of [...] Read more.
When considering implementation of shallow geothermal energy as a renewable source for heating and cooling of buildings, special care should be taken in the hydraulic design of the borehole heat exchanger system. Laminar flow can occur in pipes due to the usage of glycol mixtures at low temperature or inadequate flow rates. This can lead to lower heat extraction and rejection rates of the exchanger because of higher thermal resistance. Furthermore, by increasing the flow rate to achieve turbulent flow and satisfactory heat transfer rate can lead to an increase in the pressure drop of the system and oversizing of the circulation pump which leads to impairment of the seasonal coefficient of performance at the heat pump. The most frequently used borehole heat exchanger system in Europe is a double-loop pipe system with a smooth inner wall. Lately, development is focused on the implementation of a different configuration as well as with ribbed inner walls which ensures turbulent flow in the system, even at lower flow rates. At a location in Zagreb, standard and extended thermal response tests were conducted on three different heat exchanger configurations in the same geological environment. With a standard TRT test, thermogeological properties of the ground and thermal resistance of the borehole were determined for each smooth or turbulator pipe configuration. On the other hand, extended Steady-State Thermal Response Step Test (TRST) incorporates a series of power steps to determine borehole extraction rates at the defined steady-state heat transfer conditions of 0/−3 °C. When comparing most common exchanger, 2U-loop D32 smooth pipe, with novel 1U-loop D45 ribbed pipe, an increase in heat extraction of 6.5% can be observed. Also, when the same comparison is made with novel 2U-loop D32 ribbed pipe, an increase of 18.7% is achieved. Overall results show that heat exchangers with ribbed inner pipe wall have advantages over classic double-loop smooth pipe designs, in terms of greater steady-state heat extraction rate and more favorable hydraulic conditions. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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24 pages, 5113 KiB  
Article
Techno-Economic Mapping for the Improvement of Shallow Geothermal Management in Southern Switzerland
by Rodolfo Perego, Sebastian Pera and Antonio Galgaro
Energies 2019, 12(2), 279; https://doi.org/10.3390/en12020279 - 16 Jan 2019
Cited by 16 | Viewed by 3671
Abstract
Cantone Ticino, a mountainous region located in the southern part of Switzerland, is greatly affected by the continuous growth of subsurface exploitation through the use of both closed-loop and open-loop geothermal systems. In this study, techno-economic maps for shallow geothermal potential of Cantone [...] Read more.
Cantone Ticino, a mountainous region located in the southern part of Switzerland, is greatly affected by the continuous growth of subsurface exploitation through the use of both closed-loop and open-loop geothermal systems. In this study, techno-economic maps for shallow geothermal potential of Cantone Ticino are produced, considering closed-loop systems. The work starts with the identification of the main parameters affecting the techno-economic potential such as GST and thermal conductivity. Maps for different indicators of techno-economic feasibility are created and compared against real data/measurements. An empirical method is tailored to derive a map of the techno-economic geothermal potential, expressed as meters required to provide 1 kW of installed power. The produced map shows an overall discrepancy from real installed length data of approximately ±23%. Moreover, compared with current regulation, the produced maps show an unoptimized management of the shallow geothermal resource, since high potential zones are commonly located where the installation of BHE is not permitted and often closed-loop systems are installed where the estimated potential is lower, mainly in alluvial fans. In light of these considerations, the authorization process in Cantone Ticino for BHE should be revised taking into account the real techno-economic potential. Full article
(This article belongs to the Special Issue Volume II: Low Enthalpy Geothermal Energy)
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