Geothermal Power Plants

518 Pages·2007·12.53 MB·English

Geothermal Power Plants:
Principles, Applications,
Case Studies and
Environmental Impact
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Geothermal Power Plants:
Principles, Applications,
Case Studies and
Environmental Impact
Second Edition
Ronald DiPippo, Ph.D.
Chancellor Professor Emeritus
University of Massachusetts Dartmouth
North Dartmouth, Massachusetts
AMSTERDAM (cid:129) BOSTON (cid:129) HEIDELBERG (cid:129) LONDON (cid:129) NEW YORK (cid:129) OXFORD
PARIS (cid:129) SAN DIEGO (cid:129) SAN FRANCISCO (cid:129) SINGAPORE (cid:129) SYDNEY (cid:129) TOKYO
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First edition 2005
Second edition 2008
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08 09 10 11 10 9 8 7 6 5 4 3 2
Dedication
For my grandchildren,
Kaiya Lee DiPippo
Ella Rae DiPippo
and
Lucas Jasper Sincero Larson
in the hope that
their generation will reap the benefi ts of geothermal energy
to a far greater extent than we did.
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Contents
Preface and Acknowledgements to the Second Edition xvii
Preface to the First Edition xix
Acknowledgements to the First Edition xxiii
PART ONE RESOURCE IDENTIFICATION AND DEVELOPMENT 1
1. Geology of Geothermal Regions 3
1.1 Introduction 4
1.2 The earth and its atmosphere 4
1.3 Active geothermal regions 7
1.4 Model of a hydrothermal geothermal resource 10
1.5 Other types of geothermal resources 11
1.5.1 Hot dry rock, HDR 11
1.5.2 Geopressure 13
1.5.3 Magma energy 14
References 16
Problems 17
2. Exploration Strategies and Techniques 19
2.1 Introduction 20
2.2 Objectives of an exploration program 20
2.3 Phases of an exploration program 21
2.3.1 Literature survey 21
2.3.2 Airborne survey 22
2.3.3 Geologic survey 23
2.3.4 Hydrologic survey 25
2.3.5 Geochemical survey 26
2.3.6 Geophysical survey 30
2.4 Synthesis and interpretation 34
2.5 The next step: drilling 35
References 35
Problems 37
3. Geothermal Well Drilling 39
3.1 Introduction 40
3.2 Site preparation and drilling equipment 41
viii Contents
3.3 Drilling operations 42
3.4 Safety precautions 46
References 47
4. Reservoir Engineering 49
4.1 Introduction 50
4.2 Reservoir and well flow 50
4.2.1 Darcy’s Law 50
4.2.2 Reservoir-well model: ideal case 51
4.2.3 Reservoir-well model: basic principles 52
4.2.4 Liquid-only flow 54
4.2.5 Location of the flash horizon 54
4.2.6 Two-phase flow in the well 57
4.2.7 Complete model: reservoir to wellhead with
wellbore flashing 59
4.3 Well testing 61
4.3.1 Desired information 62
4.3.2 Pressure and temperature instrumentation 62
4.3.3 Direct mass flow rate measurements 63
4.3.4 Indirect mass flow rate measurements 65
4.3.5 Transient pressure measurements and analysis 66
4.4 Calcite scaling in well casings 68
4.5 Reservoir modeling and simulation 70
4.5.1 Input 71
4.5.2 Architecture 71
4.5.3 Calibration and validation 72
4.5.4 History matching 73
4.5.5 Use of the model 73
4.5.6 Examples of reservoir simulators 74
References 74
Problems 77
PART TWO GEOTHERMAL POWER GENERATING SYSTEMS 79
5. Single-Flash Steam Power Plants 81
5.1 Introduction 82
5.2 Gathering system design considerations 82
5.2.1 Piping layouts 82
5.2.2 Pressure losses 84
5.3 Energy conversion system 87
5.4 Thermodynamics of the conversion process 91
5.4.1 Temperature-entropy process diagram 91
5.4.2 Flashing process 91
5.4.3 Separation process 92
5.4.4 Turbine expansion process 92
5.4.5 Condensing process 94
Contents ix
5.4.6 Cooling tower process 95
5.4.7 Utilization efficiency 97
5.5 Example: Single-flash optimization 98
5.5.1 Choked well flow 98
5.5.2 Non-choked well flow 100
5.6 Optimum separator temperature: An approximate
formulation 102
5.7 Environmental aspects for single-flash plants 104
5.7.1 General considerations 104
5.7.2 Considerations pertaining to single-flash plants 104
5.8 Equipment list for single-flash plants 107
5.8.1 Wellhead, brine and steam supply system 107
5.8.2 Turbine-generator and controls 108
5.8.3 Condenser, gas ejection and pollution control
(where needed) 108
5.8.4 Heat rejection system 108
5.8.5 Back-up systems 109
5.8.6 Noise abatement system (where required) 109
5.8.7 Geofluid disposal system 109
References 109
Nomenclature for figures in Chapter 5 110
Problems 111
6. Double-Flash Steam Power Plants 113
6.1 Introduction 114
6.2 Gathering system design considerations 114
6.3 Energy conversion system 116
6.4 Thermodynamics of the conversion process 117
6.4.1 Temperature-entropy process diagram 117
6.4.2 Flash and separation processes 118
6.4.3 HP- and LP-turbine expansion processes 118
6.4.4 Condensing and cooling tower processes;
utilization efficiency 120
6.4.5 Optimization methodology 120
6.5 Example: Double-flash optimization 121
6.6 Scale potential in waste brine 123
6.6.1 Silica chemistry 124
6.6.2 Silica scaling potential in flash plants 126
6.7 Environmental aspects for double-flash plants 128
6.8 Equipment list for double-flash plants 128
6.8.1 Wellhead, brine and steam supply system 128
6.8.2 Turbine-generator and controls 128
6.8.3 Condenser, gas ejection and pollution control
(where needed) 129
6.8.4 Heat rejection system 129
6.8.5 Back-up systems 129