An Introduction to Thermogeology: Ground Source Heating and Cooling

by David Banks (Holymoor Consultancy, Chesterfield, UK)

• ISBN13: 9781405170611
• ISBN10: 1405170611
• Format: Hardcover
• Copyright: 2008-05-01
• Publisher: Wiley-Blackwell

Summary

The use of the heat stored in the shallow subsurface for space heating (ground source heat) is widely used in North America and many European nations, such as Sweden, and is regarded as the most important and reliable 'green' space heating technology. In many nations, including Britain, the technology remains poorly understood and under used. This situation is about to change, however, with the UK market for ground source heat pumps growing at over 100% per annum. This book offers practical guidance and will equip engineers, planners and geologists with the fundamental skills to assess and implement this new technology and to introduce them to the science behind thermogeology.

Author Biography

David Banks is one of the Britain's leading hydrogeologists and is a key player in promoting ground source heat technology in the UK. He has over 20 years experience from consultancy, the public sector, academia and commercial training . He runs Holymoor Consultancy and is Senior Research Associate in Thermogeology at the University of Newcastle-upon-Tyne.

Table of Contents

About the Author	p. ix
Acknowledgements	p. xi
An Introduction	p. 1
Who should read this book?	p. 2
What will this book do and not do?	p. 2
Why should you read this book?	p. 3
Thermogeology and hydrogeology	p. 4
Geothermal Energy	p. 8
Geothermal energy and ground source heat	p. 8
Lord Kelvin's conducting, cooling earth	p. 9
Geothermal gradient, heat flux and the structure of the earth	p. 11
Internal heat generation in the crust	p. 13
The convecting earth?	p. 14
Geothermal anomalies	p. 14
Types of geothermal system	p. 22
Use of geothermal energy by steam turbines	p. 23
Binary systems	p. 23
Direct use	p. 25
Cascading use	p. 25
Hot dry rock systems (a.k.a. 'enhanced geothermal systems')	p. 26
The 'sustainability' of geothermal energy and its environmental impact	p. 28
And if we do not live in Iceland?	p. 31
The Subsurface as a Heat Storage Reservoir	p. 33
Specific heat capacity: the ability to store heat	p. 35
Movement of heat	p. 37
The temperature of the ground	p. 42
Geothermal gradient	p. 49
Geochemical energy	p. 52
The heat energy budget of our subsurface reservoir	p. 54
What Is a Heat Pump?	p. 57
Engines	p. 58
Pumps	p. 60
Heat pumps	p. 62
The rude mechanics of the heat pump	p. 62
Heat pumps for space heating	p. 67
The efficiency of heat pumps	p. 68
Ground source heat pumps	p. 70
GSHPs for cooling	p. 71
Other environmental sources of heat	p. 73
The benefits of GSHPs	p. 73
Capital cost	p. 76
Other practical considerations	p. 79
Summary	p. 80
Challenges: the future	p. 80
Heat Pumps and Thermogeology: A Brief History and International Perspective	p. 84
Refrigeration before the heat pump	p. 84
The overseas ice trade	p. 86
Artificial refrigeration: who invented the heat pump?	p. 89
The history of the GSHP	p. 91
The global energy budget: how significant are GSHPs?	p. 98
Ground source heat: a competitor in energy markets?	p. 100
Options and Applications for Ground Source Heat Pumps	p. 101
How much heat do I need?	p. 101
Sizing a GSHP	p. 107
Types of ground source heat system: open-loop systems	p. 111
Closed-loop systems	p. 124
Domestic hot water by ground source heat pumps?	p. 139
Heating and cooling delivery in complex systems	p. 142
Heat from ice	p. 146
The Design of Groundwater-Based Open-Loop Systems	p. 147
Common design flaws of open-loop groundwater systems	p. 148
Aquifers, aquitards and fractures	p. 148
Transmissivity	p. 150
Confined and unconfined aquifers	p. 151
Abstraction well design in confined and unconfined aquifers	p. 153
Design yield, depth and drawdown	p. 155
Real wells and real aquifers	p. 159
Sources of information	p. 161
Multiple wells in a wellfield	p. 165
Hydraulic feedback in a well doublet	p. 169
Heat migration in the groundwater environment	p. 174
Theoretical and real examples	p. 177
ATES: thermally balanced systems and seasonal reversal	p. 179
Groundwater modelling	p. 181
Further reading	p. 182
Horizontal Closed-Loop Systems	p. 183
Depth of burial	p. 186
Loop material	p. 188
Carrier fluid	p. 189
Carrier fluid flow conditions	p. 191
Geometry of installation	p. 192
Horizontal ground collectors and soil properties	p. 198
Earth tubes: air as a carrier fluid	p. 199
Pond- and Lake-Based Ground Source Heat Systems	p. 202
The physics of lakes	p. 202
Some rules of thumb	p. 204
The heat balance of a lake	p. 205
Open-loop lake systems	p. 209
Closed-loop surface water systems	p. 209
Closed-loop systems - environmental considerations	p. 212
Subsurface Heat Conduction and the Design of Borehole-Based Closed-Loop Systems	p. 214
Rules of thumb?	p. 214
Common design flaws	p. 217
Subsurface heat conduction	p. 217
Analogy between heat flow and groundwater flow	p. 219
Claesson and Eskilson's solutions	p. 223
Real closed-loop boreholes	p. 227
Application of theory - an example	p. 234
Multiple borehole arrays	p. 239
Balanced UTES (Underground Thermal Energy Storage) systems	p. 246
Standing Column Wells	p. 251
'Standing column' systems	p. 251
The maths	p. 255
The cost of SCWs	p. 256
SCW systems in practice	p. 257
A brief case study: Grindon camping barn	p. 258
A final twist - the Jacob Doublet Well	p. 259
Thermal Response Testing	p. 261
Sources of thermogeological data	p. 261
The thermal response test	p. 262
Sources of uncertainty	p. 264
Non-uniform geology	p. 266
The practicalities: the test rig	p. 267
Test procedure	p. 269
Non-constant power input	p. 271
Analogies with hydrogeology	p. 271
Environmental Impact, Regulation and Subsidy	p. 273
Introduction	p. 273
Heat as a pollutant	p. 277
Environmental impact of closed-loop systems	p. 281
Environmental impact of groundwater-based open-loop systems	p. 286
Decommissioning of boreholes	p. 290
A whistle-stop tour of regulatory environments	p. 290
Promoting technology: subsidy	p. 294
The final word	p. 296
References	p. 299
Glossary	p. 319
Symbols	p. 325
Units	p. 329
Index	p. 333
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