This book is the outcome of more than a decade of research and technical development activities at Spain’s Geological Survey (IGME) concerning shallow geothermal energy, which were pursued in collaboration with other public bodies and European entities. It presents a compilation of papers on the theoretical foundations of, and practical aspects needed to understand the thermal regime of the topmost subsoil, up to 400 m deep, and the exceptional properties that this underground environment offers, which make it the ideal thermal reservoir for heating, ventilation, and air conditioning (HVAC).
In the book’s first section, the basic theory of thermodynamics as applied to shallow geothermal energy, heat transfer and fluid mechanics in the geological porous medium is developed. The nature of the subsoil’s thermal regime in general and in the urban environment in particular is described. The second section introduces readers to the fundamental aspects of thermal installations equipped with geothermal heat pumps, describes the types of geothermal exchangers most commonly used, and reviews the techniques used to obtain the thermal parameters of the terrain. It also discusses the potential environmental impacts of shallow geothermal activity and corresponding management strategies, as well as the legal aspects of its regulation for the governance of shallow geothermal resources in the EU in general and Spain in particular. In closing, the book highlights examples of the methodologies’ applications, developed by IGME in the city of Zaragoza and the Canary Islands.
The theoretical foundations, systematics and concrete applications make the book a valuable reference source for hydrogeologists, engineers and specialized technicians alike.
Author(s): Alejandro García Gil, Eduardo Antonio Garrido Schneider, Miguel Mejías Moreno, Juan Carlos Santamarta Cerezal
Series: Springer Hydrogeology
Publisher: Springer
Year: 2022
Language: English
Pages: 365
City: Cham
Contents
About the Authors
Abbreviations
Symbols
Superscripts
Superscripts
1 Introduction
1.1 Background
1.2 Shallow Geothermal Energy
1.2.1 Geothermal Energy
1.2.2 Types and Classification of Geothermal Energy
1.2.3 Shallow Geothermal Energy
1.2.4 Brief History of Shallow Geothermal Energy
References
2 Theoretical Background
2.1 Thermodynamic Principles
2.1.1 Concept of Energy
2.1.2 Temperature and Heat
2.1.3 Heat Transfer Mechanisms
2.1.4 First Law of Thermodynamics
2.1.5 Carnot Cycle
2.1.6 Second Law of Thermodynamics
2.1.7 Isoentropic Process
2.2 Heat Transfer
2.2.1 Porous Media and Its Approximation to a Continuous Media
2.2.2 Heat Conduction Mechanism
2.2.3 Heat Convection Mechanism
2.2.4 Hydrodynamic Heat Dispersion
2.2.5 Conduction–Convection-Heat Dispersion in a Porous Media
2.3 Parameters of Interest in Shallow Geothermal Energy
2.3.1 Thermal Conductivity (W m−1 K−1)
2.3.2 Thermal Resistivity R (K W−1)
2.3.3 Thermal Expansion (K−1)
2.3.4 Density (kg m−3)
2.3.5 Specific Heat Capacity c (J kg−1 K−1)
2.3.6 Thermal Diffusivity α (m2 s−1)
2.3.7 Viscosity µ (Pa s)
2.3.8 Reynolds Number Re (−)
2.3.9 Fourier Number Fo (−)
2.3.10 Peclet Number Pe (−)
2.3.11 Porosity φ (−)
2.4 Fluid Mechanics in Porous Media
2.4.1 Darcy’s Law
2.4.2 General Groundwater Flow Equation
References
3 Underground Thermal Regime
3.1 Energy Balance of the Earth-Atmosphere System
3.2 Deep Geothermal Upward Heat Flow
3.2.1 Underground Temperature Profile
3.3 Regional Groundwater Flow and Heat Advection
3.4 Heat Exchange with Surface Water Bodies
3.5 Heat Exchange with Urban Structures
References
4 Geothermal Heat Pump
4.1 Thermal Installations
4.1.1 External Heat Exchange Systems
4.1.2 Heat Production Systems
4.1.3 Heat Distribution Systems
4.1.4 Internal Heat Exchange Systems
4.2 Heat Pumps
4.3 Heat Transfer Through the Vapour Compression Cycle
4.3.1 Ideal Vapour Compression Cycle
4.3.2 Real Vapour Compression Cycle
4.4 Reversibility
4.5 Operating Mode of Heat Pumps
4.6 Performance
4.7 CO2 Emissions
4.8 Types of Heat Pumps
4.9 Geothermal Heat Pumps
References
5 Shallow Geothermal Systems with Closed-Loop Geothermal Heat Exchangers
5.1 General Characteristics
5.2 Closed-Loop Geothermal Heat Exchangers
5.2.1 Types of Geothermal Heat Exchangers
5.2.2 Grids of Closed-Loop Geothermal Heat Exchangers (BHEs)
5.2.3 Drilling Systems in the Construction of Geothermal Heat Exchangers
5.3 Heat Transfer in Closed Geothermal Heat Exchangers
5.3.1 Heat Transfer Equation for Multicomponent Systems
5.3.2 General Heat Transfer Equation for Closed Geothermal Heat Exchangers
5.3.3 Heat Transfer Equations for the Main Closed Geothermal Heat Exchanger Designs
5.3.4 Analytical Models of Heat Transfer in Closed Geothermal Heat Exchangers
5.4 Heat Transfer with the Ground
5.4.1 Infinite Linear Source Model (ILS)
5.4.2 Infinite Cylindrical Source (ICS) Model
5.4.3 Finite Linear Source Model (FLS)
5.4.4 Moving Infinite Linear Source Model (MILS)
5.4.5 Numerical Models
5.5 Horizontal Closed-Loop Geothermal Heat Exchangers
5.5.1 Types of Horizontal Geothermal Heat Exchangers
5.6 Borehole Thermal Energy Storage (BTES)
5.7 Thermoactive Geostructures
5.7.1 Thermoactive Piles
5.7.2 Thermoactive Walls
5.7.3 Thermoactive Tunnels
References
6 Shallow Geothermal Systems with Open-Loop Geothermal Heat Exchangers
6.1 Shallow Geothermal Installations with Open-Loop Geothermal Heat Exchangers
6.2 Components of an Open-Loop Geothermal Heat Exchanger
6.3 Design, Construction and Operation
6.4 Heat Transfer with the Ground
6.5 Chemical Quality of Groundwater
6.5.1 Reducing the Lifetime of Open-Loop Geothermal Heat Exchangers
6.6 Numerical Modelling of Groundwater Flow and Heat Transport
6.7 Aquifer Thermal Energy Storage (ATES)
6.7.1 Thermal Performance in ATES Systems
6.8 Thermal Use of Mine Water
References
7 Obtaining Terrain Thermal Parameters
7.1 Estimation of Laboratory Thermal Parameters
7.1.1 Tests for the Estimation of Thermal Conductivity in the Laboratory
7.2 Thermal Response Test (TRT)
7.2.1 Performance of TRTs
7.2.2 Interpretation of Results Obtained from TRT Testing
7.3 Thermal Tracer Test (TTT)
7.4 Field Estimation of Hydraulic Parameters
References
8 Environmental Impacts
8.1 Thermal Impacts
8.2 Geochemical Impacts
8.3 Ecological Impacts
8.4 Geotechnical Impacts
References
9 Management and Governance of Shallow Geothermal Energy Resources
9.1 Management of Shallow Geothermal Energy Resources
9.1.1 Shallow Geothermal Energy Potential
9.1.2 Existing Management Approaches
9.1.3 Management Concepts
9.2 Governance Policies
9.3 Overall Structure of the Management Framework
9.3.1 Sustainable Development and Exploitation of Shallow Geothermal Energy Resources
9.3.2 Environmentally Friendly Use of Shallow Geothermal Energy Resources
9.3.3 Exploitation of Shallow Geothermal Resources in Coordination with Other Subsoil Uses
9.3.4 Effective Management of Shallow Geothermal Resources
9.4 Governance Model
References
10 Legal Framework for Regulation
10.1 Policies, Strategies and Regulatory Standards in the European Union for the Promotion of Shallow Geothermal Energy
10.1.1 Policies and Strategies for the Promotion of Renewable Energies
10.1.2 Regulatory Standards for the Increase of Renewable Energies
10.2 European Regulatory Legal Framework for the Use of Shallow Geothermal Energy
10.2.1 Legal Framework at the National Level of Member States
10.2.2 European Regulatory Legal Framework for the Protection of the Groundwater Public Domain
10.3 Legal Framework for Regulation in Spain
10.3.1 Legal Definition of Shallow Geothermal Energy in Spain
10.3.2 Technical Guidelines for the Implementation of Good Practices
10.3.3 Regulations for the Use of Shallow Geothermal Installations
10.4 Special Requirements for the Installation and Operation of Shallow Geothermal Installations
10.5 Future Need for Adaptation of the Spanish Regulatory Framework
References
11 Example of Application (I): The Management of Shallow Geothermal Energy Resources in the City of Zaragoza
11.1 The Early Exploitation of Shallow Geothermal Energy Resources
11.2 Geological and Hydrogeological Framework
11.3 Characterisation of Geothermal Exploitation
11.4 The Zaragoza Geothermal Monitoring Network
11.5 Impact of Thermal Discharges from Shallow Geothermal Installations on the Aquifer
11.5.1 Thermal Impact
11.5.2 Chemical Impact
11.5.3 Microbiological Impact
11.6 The 3D Numerical Model of Groundwater Flow and Heat Transport
11.7 Criteria and Policy for Adopted by Resource Managers
11.8 Current Situation. The Procedure for Authorisation of Thermal Discharges and Thermal Impact Assessment Studies
11.8.1 Authorisation Procedure for a Thermal Discharge
References
12 Example of Application (II): The Exploitation of Shallow Geothermal Energy Resources in the Canary Islands
12.1 Renewable Energy in the Canary Islands
12.2 Shallow Geothermal Installations in the Canary Islands
12.2.1 Geological and Hydrogeological Framework
12.2.2 Impact of the Energy Transition Through Shallow Geothermal Energy
12.2.3 Environmental and Economic Benefits
References
