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September 26, 2017
Paul Gipe

Geothermal Power Generation: Developments and Innovation--a Review

Geothermal energy is one of the dark horses of renewable energy. Few “renewable energy advocates” know much—if anything—about it. They don’t know what geothermal contributes today and have no clue what its role could be in a 100% renewable energy future. This is a grave mistake.

Where the resource exists—and there’s a lot more of it out there than most people realize—geothermal should be an essential part of the generation mix.

I’ve always kept an eye on geothermal’s role in California. In 2016 geothermal produced 12 TWh or 4% of California’s generation. This is nearly as much as the more well known contribution by wind energy. And geothermal has been producing steadily at this level far longer than wind has.

Iceland, of course, is famous for geothermal energy, sitting as it does on the Mid-Atlantic Ridge. The island generates one-quarter of its electricity (4 TWh) from geothermal power plants. That’s not the whole story. 85% of homes in Iceland use geothermal heating. All told geothermal provides two-thirds of Iceland’s primary energy.

That’s why I was happy to get a copy of Geothermal Power Generation: Developments and Innovation by Ron DiPippo. The book is a tour de force for geothermal engineers. DiPippo, Chancellor Professor Emeritus of Mechanical Engineering and the former Associate Dean of Engineering at the University of Massachusetts in Dartmouth, Mass.

The 854-page tome is a companion to DiPippo’s previous Geothermal Power Plants, one of the definitive texts on geothermal technology. The new book is a continuation of his work, this time in collaboration with other experts in the field.

As a generalist, I found Part Four the most useful. There are eight case studies, beginning with the birthplace of geothermal: Larderello in Tuscany. This is followed by a review of geothermal in California, including the Geysers, a giant field in Northern California. Famous fields in New Zealand, Mexico, Indonesia, and Central America are also covered.

Italy’s Larderello

I was hooked as soon as I opened up the book to the chapter on Larderello. The subtitle described the history of the “boraciferous region” in what the Italians call the Colline Metallifere between Pisa and Florence. It was here geothermal fluids boiled to the surface carrying solutions of borates.

It’s obscure, very obscure, but borates from Tuscany’s geothermal fields are linked to the history of California and specifically the region where I live.

Borates are one of the major mineral products of California and the mining for borates—the search for them, and their exploitation--are integral to many famous tales from California’s period of European settlement.

Death Valley National Park is a direct result of the borate boom as is the famous 20 mule team wagon trains that carried the borates from Death Valley to Mojave, California. One of the world’s largest borate mines is not far from Mojave—well within view of the thousands of wind turbines that line the Tehachapi Pass.

And it was competition from California’s abundant borates that led inexorably to the collapse of Larderello’s borate industry and the rise of geothermal power generation. As the Italians continued to refine their mining of the borate solutions to stay competitive with California, they began drilling deeper and deeper wells. They also began using the hot geothermal fluids for the industrial process of concentrating the borates. Subsequently, they began electrifying the fields and when they could no longer sell the borates they turned to selling the electricity that they generated from geothermal energy. Today, the geothermal plants in and around Larderello generate from 5 TWh to 7 TWh per year for almost 2% of Italy’s total generation.

California’s Geysers

The “Geysers,” as they are called, remain one of the world’s largest geothermal fields. The region in Northern California has been producing electricity from geothermal energy since the 1960s!

I’d written about the Geysers long ago—in the mid-1980s. See Geysers Loosing Steam: a Finite Resource After All? At the time the field was in steep decline. As geologist Carl Austin said at the time, there were simply too many “straws in the bottle” for the field to maintain its pressure. The solution was known: reducing the number of wells and the extraction rate.

Two authors from California’s geothermal industry describe in this case study how the solutions were eventually implemented and thoroughly document the results.

While the field has never recovered its previous glory, the steps taken in the 1990s have arrested its rapid decline. The field’s depletion rate has dropped from a high of 4.8% per year in the 1980s to 2% per year in the 2000s. Nevertheless, steam production has been halved from its peak in the late 1980s, illustrating how much the field had been overdeveloped.

The data in this case study is the most succinct and up-to-date I’ve found for production from the Geysers. Companies operating in California are notoriously secretive about their generation. It was a sign of how serious the problem had become that the companies “mining” the geothermal resource in the Geysers had to share data and work together to prevent a complete collapse of the industry—and their costly investments.

Though the case study on the Geysers doesn’t disprove whether or not geothermal energy is a finite resource, it does address the question—with 55 years of stats—of how to successfully manage the resource with an eye toward sustainability.

DiPippo and his co-authors have produced a comprehensive reference work for those working in the geothermal industry and should be a reference work on the shelf of every environmental organization pursuing a 100% renewable energy supply.

Ron DiPippo, editor. Geothermal Power Generation: Developments and Innovation. London: Woodhead Publishing, 2016. 854 pages. ISBN: 9780081003374 cloth. $210.00, ISBN: 9780081003442, epub. $210.00. 9.5 x 6.25 x 1.75 inches. 1.5 lbs. Printed in England.

Table of Contents

  • Related titles
  • Woodhead Publishing Series in Energy
  • Author biographies
  • Preface
  • 1. Introduction to geothermal power generation
  • Part One. Resource exploration, characterizationand evaluation
    • 2. Geology of geothermal resources
      • 2.1. Introduction
      • 2.2. Heat flow and plate tectonics
      • 2.3. Geologic techniques
      • 2.4. Hydrothermal alteration
      • 2.5. Volcanic-hosted systems
      • 2.6. Sediment-hosted geothermal systems
      • 2.7. Extensional tectonic geothermal systems
      • 2.8. Unconventional geothermal resources
      • 2.9. Conclusions
    • 3. Geophysics and resource conceptual models in geothermal exploration and development
      • 3.1. Introduction
      • 3.2. Geophysics in the context of geothermal decision risk assessment
      • 3.3. Geothermal resource conceptual models
      • 3.4. Geothermal resource models with elements that differ from those in Fig. 3.1
      • 3.5. Formation properties and geophysical methods
      • 3.6. Choosing geophysical methods and designing surveys for geothermal applications
      • 3.7. Resistivity methods
      • 3.8. MT surveys
      • 3.9. TEM resistivity sounding for correction of MT static distortion
      • 3.10. Awibengkok MT model and validation
      • 3.11. Using MT to build conceptual models and define resource areas and targets
      • 3.12. Deep low-resistivity zones
      • 3.13. Gravity methods for exploration and development
      • 3.14. Magnetic methods
      • 3.15. Seismic monitoring
      • 3.16. Reflection/refraction seismic methods
      • 3.17. Borehole wireline logs
      • 3.18. SP method
      • 3.19. Geophysics management issues
    • 4. Application of geochemistry to resource assessment and geothermal development projects
      • 4.1. Introduction
      • 4.2. Early-phase resource assessment
      • 4.3. Contributions to conceptual models
      • 4.4. Geochemical contributions to geothermal power project design
      • 4.5. Geochemical tools for geothermal reservoir operation and maintenance
      • 4.6. Summary
    • 5. Geothermal well drilling
      • 5.1. Introduction
      • 5.2. Getting started
      • 5.3. Casing design
      • 5.4. Mud program
      • 5.5. Directional program
      • 5.6. Wellhead design and blow-out preventer systems
      • 5.7. Cementing program
      • 5.8. Cement placement
      • 5.9. Hydraulic and bit program
      • 5.10. Drilling curve
      • 5.11. Mud logging
      • 5.12. Drilling rig selection and special considerations
      • 5.13. Cost estimate
    • 6. Characterization, evaluation, and interpretation of well data
      • 6.1. Upward convective flow in reservoirs
      • 6.2. Pressure and temperature profile analysis
      • 6.3. Injection testing
      • 6.4. Discharge tests
      • 6.5. Pressure transient tests
      • 6.6. Wellbore heat loss
      • 6.7. Summary
    • 7. Reservoir modeling and simulation for geothermal resource characterization and evaluation
      • 7.1. Review of resource estimation methods
      • 7.2. Computer modeling methodology
      • 7.3. Computer modeling process
      • 7.4. Recent modeling experiences
      • 7.5. Current developments and future directions
  • Part Two. Energy conversion systems
    • 8. Overview of geothermal energy conversion systems: Reservoir-wells-piping-plant-reinjection
      • 8.1. Introduction
      • 8.2. It begins with the reservoir
      • 8.3. Getting the energy out of the reservoir
      • 8.4. Connecting the wells to the power station
      • 8.5. Central power station
      • 8.6. Geofluid disposal
      • 8.7. Conclusions and a look ahead
    • 9. Elements of thermodynamics, fluid mechanics, and heat transfer applied to geothermal energy conversion systems
      • 9.1. Introduction
      • 9.2. Definitions and terminology
      • 9.3. First law of thermodynamics for closed systems
      • 9.4. First law of thermodynamics for open steady systems
      • 9.5. First law of thermodynamics for open unsteady systems
      • 9.6. Second law of thermodynamics for closed systems
      • 9.7. Second law of thermodynamics for open systems
      • 9.8. Exergy and exergy destruction
      • 9.9. Thermodynamic state diagrams
      • 9.10. Bernoulli equation
      • 9.11. Pressure loss calculations
      • 9.12. Principles of heat transfer applied to geothermal power plants
      • 9.13. Example analyses for elements of geothermal power plants
      • 9.14. Conclusions
      • Sources of further information
    • 10. Flash steam geothermal energy conversion systems: Single-, double-, and triple-flash and combined-cycle plants
      • 10.1. Flash steam cycles
      • 10.2. Mixed and combined cycles
      • 10.3. Cogeneration and coproduction from flashed brines
      • 10.4. Equipment research and development
      • 10.5. Summary
    • 11. Direct steam geothermal energy conversion systems: Dry steam and superheated steam plants
      • 11.1. Introduction
      • 11.2. Power cycle
      • 11.3. Steam quality
      • 11.4. Steam systems
      • 11.5. Turbine-generators
      • 11.6. Condensers
      • 11.7. Gas removal systems
      • 11.8. Cooling systems
      • 11.9. Plant auxiliaries
      • 11.10. Engineering materials
      • 11.11. Summary
    • 12. Total flow and other systems involving two-phase expansion
      • 12.1. Total flow
      • 12.2. Alternative systems for power recovery based on two-phase expansion
    • 13. Binary geothermal energy conversion systems: Basic Rankine, dual–pressure, and dual–fluid cycles
      • 13.1. Introduction
      • 13.2. Binary power cycle
      • 13.3. Binary cycle performance
      • 13.4. Types of binary cycles
      • 13.5. Selection of working fluid
      • 13.6. Cycle performance comparison
      • 13.7. Design considerations
      • 13.8. Economic considerations
    • 14. Combined and hybrid geothermal power systems
      • 14.1. Introduction and definitions
      • 14.2. General thermodynamic considerations
      • 14.3. Combined single- and double-flash systems
      • 14.4. Combined flash and binary systems
      • 14.5. Geothermal-fossil hybrid systems
      • 14.6. Geothermal-solar hybrid systems
      • 14.7. Conclusions
      • Nomenclature
  • Part Three. Design and economic considerations
    • 15. Waste heat rejection methods in geothermal power generation
      • 15.1. Introduction: overview and scope
      • 15.2. Condensers in geothermal power plants
      • 15.3. Water-cooled condensers
      • 15.4. Air-cooled condensers
      • 15.5. Evaporative (water- and air-cooled) condensers
      • 15.6. Concluding summary and future trends
    • 16. Silica scale control in geothermal plants—historical perspective and current technology
      • 16.1. Introduction
      • 16.2. Geochemistry of silica
      • 16.3. Thermodynamics of silica solubility
      • 16.4. Silica precipitation kinetics
      • 16.5. Silica scaling experience in geothermal power production
      • 16.6. Historical techniques for silica/silicate scale inhibition
      • 16.7. Current scale control techniques at high supersaturation
      • 16.8. Case study for scale control in a combined-cycle plant design
      • 16.9. Pilot-plant testing for bottoming cycle optimization
      • 16.10. Guidelines for optimum pH-mod system design
      • 16.11. Summary
    • 17. Environmental benefits and challenges associated with geothermal power generation
      • 17.1. Introduction
      • 17.2. Environmental, social, and cultural benefits and challenges of geothermal power generation
      • 17.3. Developing an environmentally sound and socially responsible project
      • 17.4. Geothermal energy in the context of sustainable development
      • 17.5. Conclusions
    • 18. Project permitting, finance, and economics for geothermal power generation
      • 18.1. Introduction
      • 18.2. Finance background
      • 18.3. Recent evidence in geothermal drilling and construction
      • 18.4. Cost and financing issues
      • 18.5. Permitting land use and interconnection
      • 18.6. Long-term economic and financing security
      • 18.7. Conclusions
  • Part Four. Case studies
    • 19. Larderello: 100years of geothermal power plant evolution in Italy
      • Prologue: historical outline on geothermal development in Italy up to 1960, with particular reference to the boraciferous region
      • 19.1. Introduction: background of geothermal power generation
      • 19.2. 1900–1910: first experiments of geo-power generation and initial applications
      • 19.3. 1910–1916: first geothermal power plant of the world, experimental generation, and start of geo-power production at the commercial scale
      • 19.4. 1917–1930: consolidation of geoelectric power production at the industrial scale and start of a new technology: the direct-cycle geo-power units
      • 19.5. 1930–1943: toward a balanced economic importance of chemical production and geo-power generation
      • 19.6. 1944–1970: destruction, reconstruction, relaunching, and modification of the geo-power system
      • 19.7. 1970–1990: from reinjection of spent fluids and processing of steam to the renewal of all power units and remote control of the whole generation system
      • 19.8. 1990–2014: recent technological advancements, with special regard to the “AMIS Project,” new materials, and environmental acceptability
      • 19.9. Other geothermal areas
    • 20. Fifty-five years of commercial power generation at The Geysers geothermal field, California: The lessons learned
      • 20.1. Introduction
      • 20.2. Background
      • 20.3. The fledgling years (1960–69)
      • 20.4. Geothermal comes of age (1969–79)
      • 20.5. The geothermal rush (1979–86)
      • 20.6. The troubled era (1986–95)
      • 20.7. The watershed years (1995–98)
      • 20.8. Stability at last (1998–2004)
      • 20.9. Renewed optimism (2004–15)
      • 20.10. The future (beyond 2015)
      • 20.11. Lessons learned
    • 21. Indonesia: Vast geothermal potential, modest but growing exploitation
      • 21.1. Introduction
      • 21.2. Geological background
      • 21.3. Vast geothermal potential
      • 21.4. History of geothermal development in Indonesia
      • 21.5. Geothermal law and other geothermal regulations
      • 21.6. National energy condition and policy
      • 21.7. Geothermal energy role in the National Energy Mix
      • 21.8. Geothermal development plan
      • 21.9. Geothermal exploitation growth
      • 21.10. Challenges in geothermal development
      • 21.11. Future planning of geothermal development
      • 21.12. Conclusions
    • 22. New Zealand: A geothermal pioneer expands within a competitive electricity marketplace
      • 22.1. Reform of the NZ electricity generation and supply industry
      • 22.2. Geothermal resource management
      • 22.3. Geothermal: a Maori treasure being actively and innovatively used
      • 22.4. Geothermal developments—2000 to 2015
      • 22.5. Field review of geothermal power, tourism, and direct use developments
      • 22.6. Geothermal outlook
    • 23. Central and South America: Significant but constrained potential for geothermal power generation
      • 23.1. Central America
      • 23.2. South America
      • 23.3. Final remarks
    • 24. Mexico: Thirty-three years of production in the Los Azufres geothermal field
      • 24.1. Geothermal power in Mexico
      • 24.2. Main features of the Los Azufres field
      • 24.3. Geothermal production
      • 24.4. Power plants and output
      • 24.5. Perspectives
    • 25. Enhanced geothermal systems: Review and status of research and development
      • 25.1. Introduction
      • 25.2. Characterization of geothermal energy systems
      • 25.3. Reservoir types applicable for EGS development
      • 25.4. Treatments to enhance productivity of a priori low-permeable rocks
      • 25.5. Environmental impact of EGS treatments
      • 25.6. Sustainable operation
      • 25.7. Outlook
    • 26. Geothermal energy in the framework of international environmental law
      • 26.1. Introduction
      • 26.2. Environmental international law and geothermal energy
      • 26.3. Environmental features in public and private companies developing geothermal projects; green sells
      • 26.4. Global interest in geothermal energy
      • 26.5. Conclusion
  • Index


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