An Introduction to Thermogeology: Ground Source Heating and Cooling

347 Pages·2008·5.88 MB·English

by  David Banks(auth.)

An Introduction to Thermogeology:
Ground Source Heating and Cooling
An Introduction to Thermogeology: Ground Source Heating and Cooling David Banks
© 2008 David Banks. ISBN: 978-1-4051-7061-1
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For Jenny ‘the Bean’
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An Introduction to Thermogeology:
Ground Source Heating and Cooling
David Banks
Holymoor Consultancy, Chesterfield, Derbyshire
and
Senior Research Associate in Thermogeology
University of Newcastle-upon-Tyne
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©2008byDavidBanks
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Banks,David.
Anintroductiontothermogeology:groundsourceheatingandcooling/DavidBanks.
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Contents
AbouttheAuthor ix
Acknowledgements xi
1 AnIntroduction 1
1.1 Whoshouldreadthisbook? 2
1.2 Whatwillthisbookdoandnotdo? 2
1.3 Whyshouldyoureadthisbook? 3
1.4 Thermogeologyandhydrogeology 4
2 GeothermalEnergy 8
2.1 Geothermalenergyandgroundsourceheat 8
2.2 LordKelvin’sconducting,coolingearth 9
2.3 Geothermalgradient,heatfluxandthestructureoftheearth 11
2.4 Internalheatgenerationinthecrust 13
2.5 Theconvectingearth? 14
2.6 Geothermalanomalies 14
2.7 Typesofgeothermalsystem 22
2.8 Useofgeothermalenergybysteamturbines 23
2.9 Binarysystems 23
2.10 Directuse 25
2.11 Cascadinguse 25
2.12 Hotdryrocksystems(a.k.a.‘enhancedgeothermalsystems’) 26
2.13 The‘sustainability’ofgeothermalenergyandits
environmentalimpact 28
2.14 AndifwedonotliveinIceland? 31
3 TheSubsurfaceasaHeatStorageReservoir 33
3.1 Specificheatcapacity:theabilitytostoreheat 35
3.2 Movementofheat 37
3.3 Thetemperatureoftheground 42
3.4 Geothermalgradient 49
3.5 Geochemicalenergy 52
3.6 Theheatenergybudgetofoursubsurfacereservoir 54
4 WhatIsaHeatPump? 57
4.1 Engines 58
4.2 Pumps 60
4.3 Heatpumps 62
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vi Contents
4.4 Therudemechanicsoftheheatpump 62
4.5 Heatpumpsforspaceheating 67
4.6 Theefficiencyofheatpumps 68
4.7 Groundsourceheatpumps 70
4.8 GSHPsforcooling 71
4.9 Otherenvironmentalsourcesofheat 73
4.10 ThebenefitsofGSHPs 73
4.11 Capitalcost 76
4.12 Otherpracticalconsiderations 79
4.13 Summary 80
4.14 Challenges:thefuture 80
5 HeatPumpsandThermogeology:ABriefHistoryandInternational
Perspective 84
5.1 Refrigerationbeforetheheatpump 84
5.2 Theoverseasicetrade 86
5.3 Artificialrefrigeration:whoinventedtheheatpump? 89
5.4 ThehistoryoftheGSHP 91
5.5 Theglobalenergybudget:howsignificantareGSHPs? 98
5.6 Groundsourceheat:acompetitorinenergymarkets? 100
6 OptionsandApplicationsforGroundSourceHeatPumps 101
6.1 HowmuchheatdoIneed? 101
6.2 SizingaGSHP 107
6.3 Typesofgroundsourceheatsystem:open-loopsystems 111
6.4 Closed-loopsystems 124
6.5 Domestichotwaterbygroundsourceheatpumps? 139
6.6 Heatingandcoolingdeliveryincomplexsystems 142
6.7 Heatfromice 146
7 TheDesignofGroundwater-BasedOpen-LoopSystems 147
7.1 Commondesignflawsofopen-loopgroundwatersystems 148
7.2 Aquifers,aquitardsandfractures 148
7.3 Transmissivity 150
7.4 Confinedandunconfinedaquifers 151
7.5 Abstractionwelldesigninconfinedandunconfinedaquifers 153
7.6 Designyield,depthanddrawdown 155
7.7 Realwellsandrealaquifers 159
7.8 Sourcesofinformation 161
7.9 Multiplewellsinawellfield 165
7.10 Hydraulicfeedbackinawelldoublet 169
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Contents vii
7.11 Heatmigrationinthegroundwaterenvironment 174
7.12 Theoreticalandrealexamples 177
7.13 ATES:thermallybalancedsystemsandseasonalreversal 179
7.14 Groundwatermodelling 181
7.15 Furtherreading 182
8 HorizontalClosed-LoopSystems 183
8.1 Depthofburial 186
8.2 Loopmaterial 188
8.3 Carrierfluid 189
8.4 Carrierfluidflowconditions 191
8.5 Geometryofinstallation 192
8.6 Horizontalgroundcollectorsandsoilproperties 198
8.7 Earthtubes:airasacarrierfluid 199
9 Pond-andLake-BasedGroundSourceHeatSystems 202
9.1 Thephysicsoflakes 202
9.2 Somerulesofthumb 204
9.3 Theheatbalanceofalake 205
9.4 Open-looplakesystems 209
9.5 Closed-loopsurfacewatersystems 209
9.6 Closed-loopsystems–environmentalconsiderations 212
10 SubsurfaceHeatConductionandtheDesignofBorehole-Based
Closed-LoopSystems 214
10.1 Rulesofthumb? 214
10.2 Commondesignflaws 217
10.3 Subsurfaceheatconduction 217
10.4 Analogybetweenheatflowandgroundwaterflow 219
10.5 ClaessonandEskilson’ssolutions 223
10.6 Realclosed-loopboreholes 227
10.7 Applicationoftheory–anexample 234
10.8 Multipleboreholearrays 239
10.9 BalancedUTES(UndergroundThermalEnergyStorage)
systems 246
11 StandingColumnWells 251
11.1 ‘Standingcolumn’systems 251
11.2 Themaths 255
11.3 ThecostofSCWs 256
11.4 SCWsystemsinpractice 257
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viii Contents
11.5 Abriefcasestudy:Grindoncampingbarn 258
11.6 Afinaltwist–theJacobDoubletWell 259
12 ThermalResponseTesting 261
12.1 Sourcesofthermogeologicaldata 261
12.2 Thethermalresponsetest 262
12.3 Sourcesofuncertainty 264
12.4 Non-uniformgeology 266
12.5 Thepracticalities:thetestrig 267
12.6 Testprocedure 269
12.7 Non-constantpowerinput 271
12.8 Analogieswithhydrogeology 271
13 EnvironmentalImpact,RegulationandSubsidy 273
13.1 Introduction 273
13.2 Heatasapollutant 277
13.3 Environmentalimpactofclosed-loopsystems 281
13.4 Environmentalimpactofgroundwater-basedopen-loopsystems 286
13.5 Decommissioningofboreholes 290
13.6 Awhistle-stoptourofregulatoryenvironments 290
13.7 Promotingtechnology:subsidy 294
13.8 Thefinalword 296
References 299
Glossary 319
Symbols 325
Units 329
Index 333
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About the Author
Dave BANKS is a hydrogeologist with 22 years experience of investigating
groundwater-related issues. He started his career with the Thames Water Authority
in southern England, then moved across the North Sea to the Geological Survey of
Norway, where he eventually headed the Section for Geochemistry and Hydrogeol-
ogy. Since returning to the UK in 1998, he has worked as a consultant from a base in
Chesterfield,sandwichedbetweenthegritstoneofthePeakDistrictNationalParkand
theabandonedminesofBritain’slargestcoalfield.Hehasinternationalexperiencefrom
locations as diverse as Afghanistan, the Bolivian Altiplano, Somalia, Western Siberia
and Huddersfield. During the past few years his attention has turned to the emerging
scienceofthermogeology:Hehasworkedcloselywiththegroundsourceheatindustry
and has recently been appointed Senior Research Associate in Thermogeology at the
UniversityofNewcastle-upon-Tyne.
Inhissparetime,Daveenjoysmusic.WithhischumBjørnFrengstad,hehasformed
almost half of the sporadically active acoustic lo-fi stunt duo ‘The Sedatives’. They
have murdered songs by their musical heroes, Jarvis Cocker, Richard Thompson and
KathWilliamsinavarietyofseedylocations.
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Acknowledgements
In the late 1990s, I was working for the Norwegian Geological Survey’s Section for
Hydrogeology and Geochemistry. Despite the Section being choc-a-bloc with brainy
researchscientists,oneofmymostinnovativecolleagueswasanengineerwhocalled
me,onwhatseemedaweeklybasis,brimmingwithenthusiasmforsomewizardnew
idea.Onedayhestartedtellingmeallaboutsomethingcalled‘grunnvarme’orground
source heat, which was, apparently, very big in Sweden. Initially, it seemed to me to
◦
be something akin to perpetual motion – space heating from Norwegian rock at 6 C?
– and in violation of the Second Law of Thermodynamics to boot. Nevertheless, he
persuadedmethatitreallydidhaveasoundphysicalbasis.Infact,mychumwenton
toalmostsingle-handedlyselltheconceptofgroundsourceheattoaNorwegianmarket
thatwasonthebrinkofanenergycrisis.Asubsequentdrysummerthatpulledtheplug
onNorway’scheaphydroelectricsuppliesandsentpricessoaringwasthetriggerthat
groundsourceheatneededtotakeoff.So,first,‘abigthankyou’toHelgeSkarphagen
(foritwashe!),whofirstgotmeinterestedingroundsourceheat.
On my return to England in 1998, I tried to bore anyone who gave the appearance
of listening about the virtues of ground source heat (I was by no means the first to
try this – John Sumner and Robin Curtis, among others, had been evangelists for the
technologymuchearlier).Itwasnotuntilaround2003,however,thatinterestinground
sourceheatwasawakenedinBritainandIwasluckyenoughtofallinwithagroupof
entrepreneurs with an eye for turning it into a business. So, second, many thanks to
GeoWarmth of Hexham for the pleasure of working with you, and especially to Dave
Spearman,JonathanSteven,BraidandCharlieAitken,NickSmithandJohnWithers.
Iwouldliketothankthefollowingfortakingthetimetoreviewthevariouschapters
andfortheirinvaluablecomments:
• ProfessorPaulYoungeroftheUniversityofNewcastle-upon-Tyne.
• ProfessorKeithToveyoftheUniversityofEastAngliainNorwich.
• KarlDrageofGeothermalInternationalinCoventry.
• HelgeSkarphagenoftheNorwegianWaterResearchInstitute(NIVA)inOslo.
• JamesDoddsofJDIHWater&EnvironmentLtd.inCastleDonington.
• JonathanStevenandCharlieAitkenofGeoWarmthLtd.,Hexham.
• ProfessorGöranHellströmofLundTechnicalUniversity,Sweden.
• DrSimonReesofDeMontfortUniversity,Leicester.
• DrRobinCurtisofGeoScienceLtd.inFalmouth.
• MariusGreavesoftheEnvironmentAgency,inHatfield.
ThelyricsfromFirst&SecondLaw fromAtTheDropofAnotherHatbyFlanders&
Swann©1963arereproducedinChapter4bykindpermissionoftheEstatesofMichael
Flanders&DonaldSwann.TheAdministratorofTheFlanders&SwannEstates,Leon
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