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5 pages, 179 KiB

Open AccessEditorial

Special Issue: New Trends in Enhanced, Hybrid and Integrated Geothermal Systems

by Alireza Dehghani-Sanij and Jatin Nathwani

Appl. Sci. 2021, 11(9), 3765; https://doi.org/10.3390/app11093765 - 22 Apr 2021

Cited by 3 | Viewed by 1295

Abstract

The most important challenge for the global energy sector is to rapidly transform the entire system to one less dependent on fossil fuels and so reduce the harmful effects on the climate [...] Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

Research

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24 pages, 13275 KiB

Open AccessArticle

Sustainable Modularity Approach to Facilities Development Based on Geothermal Energy Potential

by Nataša Ćuković Ignjatović, Ana Vranješ, Dušan Ignjatović, Dejan Milenić and Olivera Krunić

Appl. Sci. 2021, 11(6), 2691; https://doi.org/10.3390/app11062691 - 17 Mar 2021

Cited by 4 | Viewed by 1635

Abstract

The study presented in this paper assessed the multidisciplinary approach of geothermal potential in the area of the most southeastern part of the Pannonian basin, focused on resources utilization. This study aims to present a method for the cascade use of geothermal energy [...] Read more.

The study presented in this paper assessed the multidisciplinary approach of geothermal potential in the area of the most southeastern part of the Pannonian basin, focused on resources utilization. This study aims to present a method for the cascade use of geothermal energy as a source of thermal energy for space heating and cooling and as a resource for balneological purposes. Two particular sites were selected—one in a natural environment; the other within a small settlement. Geothermal resources come from different types of reservoirs having different temperatures and chemical compositions. At the first site, a geothermal spring with a temperature of 20.5 °C is considered for heat pump utilization, while at the second site, a geothermal well with a temperature of 54 °C is suitable for direct use. The calculated thermal power, which can be obtained from geothermal energy is in the range of 300 to 950 kW. The development concept was proposed with an architectural design to enable sustainable energy efficient development of wellness and spa/medical facilities that can be supported by local authorities. The resulting energy heating needs for different scenarios were 16–105 kW, which can be met in full by the use of geothermal energy. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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16 pages, 29570 KiB

Open AccessArticle

Reuse of Decommissioned Hydrocarbon Wells in Italian Oilfields by Means of a Closed-Loop Geothermal System

by Martina Gizzi, Glenda Taddia and Stefano Lo Russo

Appl. Sci. 2021, 11(5), 2411; https://doi.org/10.3390/app11052411 - 9 Mar 2021

Cited by 11 | Viewed by 2485

Abstract

Geological and geophysical exploration campaigns have ascertained the coexistence of low to medium-temperature geothermal energy resources in the deepest regions of Italian sedimentary basins. As such, energy production based on the exploitation of available geothermal resources associated with disused deep oil and gas [...] Read more.

Geological and geophysical exploration campaigns have ascertained the coexistence of low to medium-temperature geothermal energy resources in the deepest regions of Italian sedimentary basins. As such, energy production based on the exploitation of available geothermal resources associated with disused deep oil and gas wells in Italian oilfields could represent a considerable source of renewable energy. This study used information available on Italian hydrocarbon wells and on-field temperatures to apply a simplified closed-loop coaxial Wellbore Heat Exchanger (WBHE) model to three different hydrocarbon wells located in different Italian oilfields (Villafortuna-Trecate, Val d’Agri field, Gela fields). From this study, the authors have highlighted the differences in the quantity of potentially extracted thermal energy from different analysed wells. Considering the maximum extracted working fluid temperature of 100 °C and imagining a cascading exploitation mode of the heat accumulated, for Villafortuna 1 WBHE was it possible to hypothesise a multi-variant and comprehensive use of the resource. This could be done using existing infrastructure, available technologies, and current knowledge. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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21 pages, 14475 KiB

Open AccessFeature PaperArticle

Numerical Investigation on the Influence of Surface Flow Direction on the Heat Transfer Characteristics in a Granite Single Fracture

by Xuefeng Gao, Yanjun Zhang, Zhongjun Hu and Yibin Huang

Appl. Sci. 2021, 11(2), 751; https://doi.org/10.3390/app11020751 - 14 Jan 2021

Cited by 11 | Viewed by 2275

Abstract

As fluid passes through the fracture of an enhanced geothermal system, the flow direction exhibits distinct angular relationships with the geometric profile of the rough fracture. This will inevitably affect the heat transfer characteristics in the fracture. Therefore, we established a hydro-thermal coupling [...] Read more.

As fluid passes through the fracture of an enhanced geothermal system, the flow direction exhibits distinct angular relationships with the geometric profile of the rough fracture. This will inevitably affect the heat transfer characteristics in the fracture. Therefore, we established a hydro-thermal coupling model to study the influence of the fluid flow direction on the heat transfer characteristics of granite single fractures and the accuracy of the numerical model was verified by experiments. Results demonstrate a strong correlation between the distribution of the local heat transfer coefficient and the fracture morphology. A change in the flow direction is likely to alter the transfer coefficient value and does not affect the distribution characteristics along the flow path. Increasing injection flow rate has an enhanced effect. Although the heat transfer capacity in the fractured increases with the flow rate, a sharp decline in the heat extraction rate and the total heat transfer coefficient is also observed. Furthermore, the model with the smooth fracture surface in the flow direction exhibits a higher heat transfer capacity compared to that of the fracture model with varying roughness. This is attributed to the presence of fluid deflection and dominant channels. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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18 pages, 2493 KiB

Open AccessFeature PaperArticle

Well-Doublets: A First-Order Assessment of Geothermal SedHeat Systems

by Seyed Bijan Mahbaz, Ali Yaghoubi, Alireza Dehghani-Sanij, Erfan Sarvaramini, Yuri Leonenko and Maurice B. Dusseault

Appl. Sci. 2021, 11(2), 697; https://doi.org/10.3390/app11020697 - 13 Jan 2021

Cited by 15 | Viewed by 3557

Abstract

Renewable and sustainable energy sources can play an important role in meeting the world’s energy needs and also in addressing environmental challenges such as global warming and climate change. Geothermal well-doublet systems can produce both electrical and thermal energy through extracting heat from [...] Read more.

Renewable and sustainable energy sources can play an important role in meeting the world’s energy needs and also in addressing environmental challenges such as global warming and climate change. Geothermal well-doublet systems can produce both electrical and thermal energy through extracting heat from hot-water aquifers. In this paper, we examine some potential challenges associated with the operation of well-doublet systems, including heat conductivity, chemical, and mechanical issues. In these systems, geomechanics issues such as thermal short-circuiting and induced seismicity arise from temperature and pressure change impacts on the stress state in stiff rocks and fluid flow in fractured rock masses. Coupled chemical processes also can cause fluid channeling or formation and tubular goods plugging (scaling) with precipitates. Mechanical and chemical disequilibrium conditions lead to increased production uncertainties; hence risk, and therefore coupled geo-risk assessments and optimization analyses are needed for comparative commercialization evaluations among different sites. The challenges related to heat transfer processes are also examined. These studies can help better understand the issues that may arise during the operation of geothermal well-doublet systems and improve their effectiveness, subsequently reducing associated costs and risks. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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10 pages, 5440 KiB

Open AccessArticle

Geothermal Assessment of Target Formations Using Recorded Temperature Measurements for the Alberta No. 1 Geothermal Project

by Katherine Y. Huang, Catherine J. Hickson, Darrell Cotterill and Yannick Champollion

Appl. Sci. 2021, 11(2), 608; https://doi.org/10.3390/app11020608 - 10 Jan 2021

Cited by 9 | Viewed by 2746

Abstract

The Alberta No. 1 project is a planned power and heat (direct use) geothermal project located within the County of Grande Prairie and Municipal District of Greenview. For the project to successfully produce power and heat on a commercial scale, temperatures of 120 [...] Read more.

The Alberta No. 1 project is a planned power and heat (direct use) geothermal project located within the County of Grande Prairie and Municipal District of Greenview. For the project to successfully produce power and heat on a commercial scale, temperatures of 120 °C are desirable. The produced fluids must also be from highly permeable formations from depths of less than 4500 m. Bottomhole temperature measurements and wireline logs from Alberta’s extensive oil and gas database were used to determine the depths to target formations and temperatures within these formations in the project area. The target formations include the dolomitized carbonate units of Devonian age from the Beaverhill Lake Group to the top of the Precambrian Basement. Permeable Devonian-aged sandstone units such as the Granite Wash Formation are also targets. Results suggest that elevation to the top of the Beaverhill Lake Group range from 3104 m to 4094 m and temperatures at the top of the formation range from 87 °C to 123 °C in the study area. Elevation to the top of the Precambrian Basement ranges from 3205 m to 4223 m and temperatures at the formation top range from 74 °C to 124 °C. Within the area where Alberta No. 1 plans to drill, temperatures close to and exceeding 120 °C are expected within the target formations. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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19 pages, 4748 KiB

Open AccessFeature PaperArticle

Dynamic and Static Investigation of Ground Heat Exchangers Equipped with Internal and External Fins

by Atefeh Maleki Zanjani, Kobra Gharali, Armughan Al-Haq and Jatin Nathwani

Appl. Sci. 2020, 10(23), 8689; https://doi.org/10.3390/app10238689 - 4 Dec 2020

Cited by 7 | Viewed by 2264

Abstract

Using fins on the inner and outer surfaces of pipes is one method to improve the heat transfer rate of ground heat exchangers (GHEs), thereby reducing the borehole depth and construction and operation costs. Results of 3D numerical studies of simple and finned [...] Read more.

Using fins on the inner and outer surfaces of pipes is one method to improve the heat transfer rate of ground heat exchangers (GHEs), thereby reducing the borehole depth and construction and operation costs. Results of 3D numerical studies of simple and finned U-tubes with outer and inner fins are evaluated for GHEs under similar physical conditions. Dynamic and static simulations show the effects of longitudinal fins on the thermal performance of borehole heat exchangers (BHEs) and heat transfer rate between circulating fluid and soil around pipes, while the dynamic tests include short timescale and frequency response tests. The results indicate that the maximum fluid temperature change is about 2.9% in the external finned pipe and 11.3% in the internal finned pipe compared to the finless pipe. The effects of the inlet velocity on temperature profiles, the patterns of the velocity and temperature contours due to the borehole curvature and the response times of the systems under various frequencies are also investigated in detail. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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18 pages, 2701 KiB

Open AccessArticle

Smart Heating and Cooling Heat Pump System by Standing Column Well and Cross-Mixing Balancing Well Heat Exchangers

by Donggyu Kim, Myungkwan Lim, Byeongseok Yu and Changhee Lee

Appl. Sci. 2020, 10(21), 7643; https://doi.org/10.3390/app10217643 - 29 Oct 2020

Cited by 1 | Viewed by 2152

Abstract

Standing column well (SCW) geothermal heat exchanger permits a bleeding discharge of less than 20% in the event of a maximum load, which is an inappropriate method of using underground water. In this study, the existing operational method of two adjacent SCW geothermal [...] Read more.

Standing column well (SCW) geothermal heat exchanger permits a bleeding discharge of less than 20% in the event of a maximum load, which is an inappropriate method of using underground water. In this study, the existing operational method of two adjacent SCW geothermal heat exchangers, each with a single well, was modified. This technology aims to improve the coefficient of performance (COP) of the geothermal system by fundamentally preventing underground water discharge and maintaining a constant temperature of the underground heat exchanger. To curb the bleed water discharge, two balancing wells of cross-mixing methods were employed. The result of the cooling and heating operations with the existing SCW heat exchange system and the balancing well cross-combined heat exchange system showed that the measured COP increases by 23% and 12% during the cooling and heating operations, respectively. When operating with a balanced well cross-mixed heat exchange system, the initial temperature of the underground was constant with a small standard deviation of 0.08–0.12 °C. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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20 pages, 2419 KiB

Open AccessArticle

Evaluation and Optimization of the Annual Performance of a Novel Tri-Generation System Driven by Geothermal Brine in Off-Design Conditions

by Mehri Akbari Kordlar, Florian Heberle and Dieter Brüggemann

Appl. Sci. 2020, 10(18), 6532; https://doi.org/10.3390/app10186532 - 18 Sep 2020

Cited by 7 | Viewed by 2811

Abstract

The difference in heating or cooling to power ratio between required demands for district networks and the proposed tri-generation system is the most challenging issue of the system configuration and design. In this work, an adjustable, novel tri-generation system driven by geothermal resources [...] Read more.

The difference in heating or cooling to power ratio between required demands for district networks and the proposed tri-generation system is the most challenging issue of the system configuration and design. In this work, an adjustable, novel tri-generation system driven by geothermal resources is proposed to supply the thermal energies of a specific district network depending on ambient temperature in Germany. The tri-generation system is a combination of a modified absorption refrigeration cycle and a Kalina cycle using NH₃-H₂O mixture as a working fluid for the whole tri-generation system. A sensitive analysis of off-design conditions is carried out to study the effect of operational parameters on the system performances prior to optimizing its performance. The simulation show that the system is able to cover required heating and cooling demands. The optimization is applied considering the maximum exergy efficiency (scenario 1) and minimum total exergy destruction rate (scenario 2). The optimization results show that the maximum mean exergy efficiency in scenario 1 is achieved as 44.67% at the expense of 14.52% increase in the total exergy destruction rate in scenario 2. The minimum mean total exergy destruction rate in scenario 2 is calculated as 2980 kW at the expense of 8.32% decrease in the exergy efficiency in scenario 1. Full article

(This article belongs to the Special Issue New Trends in Enhanced, Hybrid and Integrated Geothermal Systems)

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