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Volume III: 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 (31 October 2021) | Viewed by 8453

Special Issue Editors


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Guest Editor
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

E-Mail Website
Guest Editor
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 (3 papers)

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Research

25 pages, 3521 KiB  
Article
Different Approaches for Evaluation and Modeling of the Effective Thermal Resistance of Groundwater-Filled Boreholes
by Oleg Todorov, Kari Alanne, Markku Virtanen and Risto Kosonen
Energies 2021, 14(21), 6908; https://doi.org/10.3390/en14216908 - 21 Oct 2021
Cited by 4 | Viewed by 1939
Abstract
Groundwater-filled boreholes are a common solution in Scandinavian installations of ground source heat pumps (GSHP) due to the particular hydro-geological conditions with existing bedrock, and groundwater levels close to the surface. Different studies have highlighted the advantage of water-filled boreholes compared with their [...] Read more.
Groundwater-filled boreholes are a common solution in Scandinavian installations of ground source heat pumps (GSHP) due to the particular hydro-geological conditions with existing bedrock, and groundwater levels close to the surface. Different studies have highlighted the advantage of water-filled boreholes compared with their grouted counterparts since the natural convection of water within the borehole tends to decrease the effective thermal resistance Rb*. In this study, several methods are proposed for the evaluation and modeling of the effective thermal resistance of groundwater-filled boreholes. They are based on distributed temperature sensing (DTS) measurements of six representative boreholes within the irregular 74-single-U 300 m-deep borehole field of Aalto New Campus Complex (ANCC). These methods are compared with the recently developed correlations for groundwater-filled boreholes, which are implemented within the python-based simulation toolbox Pygfunction. The results from the enhanced Pygfunction simulation with daily update of Rb* show very good agreement with the measured mean fluid temperature of the first 39 months of system operation (March 2018–May 2021). It is observed that in real operation the effective thermal resistance Rb* can vary significantly, and therefore it is concluded that the update of Rb* is crucial for a reliable long-term simulation of groundwater-filled boreholes. Full article
(This article belongs to the Special Issue Volume III: Low Enthalpy Geothermal Energy)
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18 pages, 13422 KiB  
Article
Defining the Shallow Geothermal Heat-Exchange Potential for a Lower Fluvial Plain of the Central Apennines: The Metauro Valley (Marche Region, Italy)
by Marco Taussi, Walter Borghi, Michele Gliaschera and Alberto Renzulli
Energies 2021, 14(3), 768; https://doi.org/10.3390/en14030768 - 1 Feb 2021
Cited by 7 | Viewed by 2651
Abstract
In this work we assessed the shallow geothermal heat-exchange potential of a fluvial plain of the Central Apennines, the lower Metauro Valley, where about 90,000 people live. Publicly available geognostic drilling data from the Italian Seismic Microzonation studies have been exploited together with [...] Read more.
In this work we assessed the shallow geothermal heat-exchange potential of a fluvial plain of the Central Apennines, the lower Metauro Valley, where about 90,000 people live. Publicly available geognostic drilling data from the Italian Seismic Microzonation studies have been exploited together with hydrogeological and thermophysical properties of the main geological formations of the area. These data have been averaged over the firsts 100 m of subsoil to define the thermal conductivity, the specific heat extraction rates of the ground and to establish the geothermal potential of the area (expressed in MWh y−1). The investigation revealed that the heat-exchange potential is mainly controlled by the bedrock lithotypes and the saturated conditions of the sedimentary infill. A general increase in thermal conductivity, specific heat extraction and geothermal potential have been mapped moving from the coast, where higher sedimentary infill thicknesses have been found, towards the inland where the carbonate bedrock approaches the surface. The geothermal potential of the investigated lower Metauro Valley is mostly between ~9.0 and ~10 MWh y−1 and the average depth to be drilled to supply a standard domestic power demand of 4.0 kW is ~96 m (ranging from 82 to 125 m all over the valley). This investigation emphasizes that the Seismic Microzonation studies represent a huge database to be exploited for the best assessment of the shallow geothermal potential throughout the Italian regions, which can be addressed by the implementation of heating and cooling through vertical closed-loop borehole heat exchanger systems coupled with geothermal heat pumps. Full article
(This article belongs to the Special Issue Volume III: Low Enthalpy Geothermal Energy)
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18 pages, 2536 KiB  
Article
Environmental and Economic Impact of the Antifreeze Agents in Geothermal Heat Exchangers
by Nicola Bartolini, Alessandro Casasso, Carlo Bianco and Rajandrea Sethi
Energies 2020, 13(21), 5653; https://doi.org/10.3390/en13215653 - 29 Oct 2020
Cited by 19 | Viewed by 2908
Abstract
 Borehole heat exchangers (BHEs) generally employ water-antifreeze solutions to allow working fluid temperatures to fall below 0 °C. However, some local regulations have forbidden antifreeze additives (even non-toxic ones) to avoid groundwater pollution in case of pipe leakage. This paper presents a techno-economic [...] Read more.
 Borehole heat exchangers (BHEs) generally employ water-antifreeze solutions to allow working fluid temperatures to fall below 0 °C. However, some local regulations have forbidden antifreeze additives (even non-toxic ones) to avoid groundwater pollution in case of pipe leakage. This paper presents a techno-economic and environmental analysis of four different fluids: propylene glycol at 25% and 33% weight concentrations, calcium chloride at 20% weight concentration (CaCl2 20%), and pure water. Thermal loads from 36 case studies in six different climate zones are used to perform BHE sizing and compare the abovementioned fluids from the economic, operational, and environmental points of view. The economic analysis and the carbon footprint assessment are performed on a life cycle of 25 years considering the installation (BHE drilling, fluid) and operation (heat pump and ground-side circulation pump energy demand, fluid replacement) of the simulated GSHPs. Results highlight that using pure water as a heat carrier fluid is convenient for cooling-dominated buildings but, for heating-dominated buildings, this choice leads to a noticeable increase of the BHE needed length which is not compensated by the lower operational costs. On the other hand, avoiding the use of antifreeze additives generally leads to a reduction of the lifetime carbon footprint, with a few exceptions in very cold climates. CaCl2 20% proves to be a good choice in most cases, both from the economic and the environmental points of view, as it allows a strong reduction of the installed BHE length in cold climates with a low additional cost and carbon footprint. Full article
(This article belongs to the Special Issue Volume III: Low Enthalpy Geothermal Energy)
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