Geothermal Literature Assessment:

Environmental Issues

Produced by: Karl Gawell Diana Bates

Geothermal Energy Association Washington, D.C.

May 2004

Prepared with the Support of:

Geothermal Literature Assessment: Environmental Issues

Produced by: Karl Gawell Diana Bates

Geothermal Energy Association Washington, D.C.

Prepared with the Support of:

Published by: Geothermal Energy Association

209 Pennsylvania Avenue, S.E., Washington, D.C. 20003

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This report was prepared under contract No. DE-FG01-02EE35227 UNITED STATES DEPARTMENT OF ENERGY

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect

the views of the Department of Energy.

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Executive Summary This collection contains article abstracts and brief reviews of publicly-accessible articles pertaining to environmental issues related to geothermal energy, with a focus on the United States geothermal industry. Together with an earlier literature review published by the Geothermal Resources Council (see below) these articles form the basis of a complete geothermal library on environmental issues. Our intent in producing this literature review is to provide an easily accessible synopsis of the published literature. In this review, the articles are divided into four main categories: water quality, liquid and solid wastes; air emissions; land use; and noise pollution. The beginning of each section and subsection contains a brief description of the issues at hand. The description is then followed by a list of the relevant articles on the subject, including an abstract and a brief review of each article. The abstract is usually taken verbatim from the abstract provided with the original publication. The article review seeks to put the article in a general context for readers, particularly with respect to the state of technology, laws and regulations, and industry practice today. The review may also guide the reader towards more current, relevant information if known or appropriate. However, the review is not meant to place judgment values on any articles or their respective authors. All publications were accessed via public libraries and online databases. This was done purposefully so that readers wishing to access the publications referenced in this collection may easily do so. Articles listed in this work are also available through GEA. We would like to thank the Geothermal Resources Council and Dan Entingh of Princeton Energy Resources International for use of their geothermal libraries. We would also like to thank our eight-member advisory panel for their guidance and review of our project: Susan Norwood of GeoPowering the West, Charlene Wardlow of Calpine Corporation, Jeff Hulen of the University of Utah, John Pritchett of Science Applications International Corporation, Ann Robertson-Tait of GeothermEx, Paul Dunlevy of the Bureau of Land Management, Anna Carter of Geothermal Support Services, Joel Renner of Idaho National Engineering and Environmental Laboratory, and Kevin Porter of Exeter Associates. Additionally, we would like to thank our volunteer reviewers who also helped in the review of our work: Laurie McClenahan Heitter of MHA Environmental Consulting, Inc., Marshall Reed of the Department of Energy, and Roger Hill of Sandia National Laboratories. Finally, we would like to thank the U.S. Department of Energy for their support in making this project possible. We also urge our readers to look at an earlier review of geothermal literature done by the Geothermal Resources Council in 1984-1985. This review, entitled Geothermal Energy Abstract Sets, Special Report No. 14, is available from the Geothermal Resources Council. This review examines geothermal industry publications done prior to the year 1984 on a variety of subjects and provides abstracts for each article. Our publication complements and expands upon the environmental section of Geothermal Energy Abstract Sets, Special Report No. 14, and we urge our readers to use this document as well when reviewing geothermal literature pertaining to environmental issues.

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This literature review is the first step in GEA's efforts to provide updated information on the environmental, socio-economic and technological status of geothermal energy. GEA will build upon this work to produce additional papers in the future. Conducting this literature review has clearly brought about recognition of serious gaps and shortcomings in the available literature. In general, there is a lack of up-to-date information in the published literature. The bulk of the environmental articles listed in this review were written in the late 1970s and early 1980s, and much has changed in the geothermal industry since that time. It is our goal to publish a paper on the subject of environmental issues that will bring the available literature up-to-date in this regard. We anticipate that this paper will be completed in late 2004, and intend to make it available on GEA's website: www.geo-energy.org. Karl Gawell Diana Bates Executive Director Research Associate NOTE: The data and conclusions contained in the abstracts are those of the specific authors of the abstracts and do not necessarily represent the official views, policies or recommendations of the Geothermal Energy Association or the U.S. Department of Energy. Any views or conclusions expressed in the reviews of these articles are solely those of the authors of this literature review, and do not necessarily represent the official views, policies or recommendations of the Geothermal Energy Association or the U.S. Department of Energy.

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Table of Contents Section I: Air Emissions.................................................................................................1-32 Air Emissions Article Index.....................................................................................2 Air Emissions Abstracts and Reviews.....................................................................6 Mercury........................................................................................................6 Carbon Dioxide..........................................................................................12 Hydrogen Sulfide.......................................................................................17 Arsenic.......................................................................................................26 Particulate Matter.......................................................................................29 Nitrogen Oxides.........................................................................................30 Miscellaneous............................................................................................31 Section II: Land Use.....................................................................................................33-47 Land Use Article Index..........................................................................................34 Land Use Abstracts and Reviews..........................................................................36 Induced Seismicity.....................................................................................36 Subsidence and Land Slides.......................................................................38 Land Use Conflicts....................................................................................44 Section III: Water Quality, Brine and Solid Wastes.....................................................48-64 Water Quality, Brine and Solid Wastes Article Index...........................................49 Water Quality, Brine and Solid Wastes Abstracts and Reviews...........................52 Geothermal Brines.....................................................................................52 Geothermal Sludge.....................................................................................57 Reinjection Technology.............................................................................60 Surface Water Quality and Use..................................................................62 Section IV: Noise Pollution..........................................................................................65-71 Noise Pollution Article Index................................................................................66 Noise Pollution Abstracts and Reviews.................................................................67

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Section I: Air Emissions

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Air Emissions Article Index GEA-001 CO2 Emissions from Geothermal Energy Facilities are Insignificant Compared to Power Plants Burning Fossil Fuels

Bloomfield, K.K., Moore, J.N., & Neilson, R. (2003, March-April). CO2 Emissions from Geothermal Energy Facilities are Insignificant Compared to Power Plants Burning Fossil Fuels. Geothermal Resources Council Bulletin, 77-79.

GEA-002 Mercury Emissions from Geothermal Plants Located at The Geysers,

California Carlsen, B. (2003, May). Mercury Emissions from Geothermal Plants Located at The Geysers, California. [Personal Letter to Anne Pope of the Environmental Protection Agency].

GEA-003 Production of Greenhouse Gases from Geothermal Power Plants

Bloomfield, K.K. & Moore, J.N. (1999). Production of Greenhouse Gases from Geothermal Power Plants. Geothermal Resources Council Transactions, 178, 221-223.

GEA-004 Monitoring of Arsenic, Boron and Mercury by Lichen and Soil Analysis

in the Mt. Amiata Geothermal Area (Central Italy) Loppi, S. (1997, September/October). Monitoring of Arsenic, Boron and Mercury by Lichen and Soil Analysis in the Mt. Amiata Geothermal Area (Central Italy). Geothermal Resources Council Transactions, 21, 137-140.

GEA-005 Emission Factors of Geothermal Power Plants in California Tiangco, V., Hare, R., Birkinshaw, K. & Johannis, M. (1995). Emission Factors of Geothermal Power Plants in California. Geothermal Resources Council Transactions, 19, 147-151.

GEA-006 Non-Condensible Gas Trends and Emissions at Dixie Valley, Nevada

Benoit, D. & Hirtz, P. (1994). Non-Condensible Gas Trends and Emissions at Dixie Valley, Nevada. Geothermal Resources Council Transactions, 18, 113-119.

GEA-007 Ambient Air H2S Monitoring at The Geysers: From Nonattainment to

Attainment Altshuler, S.L., & Arcado, T.D. (1991). Ambient Air H2S Monitoring at The Geysers: From Nonattainment to Attainment. Geothermal Resources Council Special Report No. 17, 297-301.

GEA-008 Arsenic Speciation in Atmospheric Aerosols at the Geysers

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Solomon, P., Altshuler, S.L. & Keller, M.L. (1991). Arsenic Speciation in Atmospheric Aerosols at the Geysers. Geothermal Resources Council Transactions, 15, 155-161.

GEA-009 Energy Fuel Sources and Their Contribution to Recent Global Air

Pollution Trends Goddard, W.B. & Goddard, C. (1990). Energy Fuel Sources and Their

Contribution to Recent Global Air Pollution Trends. Geothermal Resources Council Transactions, 14, 643-649.

GEA-010 The Potential Impact of Conservation and Alternative Energy Sources

on Carbon Dioxide Emissions Edenburn, M.W. & Aronson, E.A. (1990). The Potential Impact of

Conservation and Alternative Energy Sources on Carbon Dioxide Emissions. Geothermal Resources Council Transactions, 14, Part I, 631-638.

GEA-011 PM10 Source Apportionment Study in Pleasant Valley, Nevada

Egami, R.T., Crow, J.C., Watson, J.G. & Delong, T. (1990). PM10 Source Apportionment Study in Pleasant Valley, Nevada. Geothermal Resources Council Transactions, 14, Part II, 1115-1120.

GEA-012 Noncondensable Hydrogen Sulfide Incineration with Brine Scrubbing

Air Emissions Control System: Source Reduction Demonstration Project Goddard, W., Goddard, C. & McClain, D. (1990). Noncondensable Hydrogen Sulfide Incineration with Brine Scrubbing Air Emissions Control System: Source Reduction Demonstration Project. Geothermal Resources Council Transactions, 14, 1127-1131.

GEA-013 Ambient Air Mercury Concentrations at the Geysers Arcado, T. & Altshuler, S. (1989). Ambient Air Mercury Concentrations at the Geysers. Geothermal Resources Council

Transactions, 13, 75-81. GEA-014 Ambient Air Monitoring at The Geysers: A Historical Perspective and

Current Status Altshuler, S.L. & Arcado, T.D. (1989). Ambient Air Monitoring at The Geysers: A Historical Perspective and Current Status. Geothermal Resources Council Transactions, 13, 71-74.

GEA-015 Future Air Quality Maintenance and Improvements Through the

Expanded Use of Geothermal Energy Goddard, W.B, Ph.D., Goddard, C.B., M.A. & McClain, D.W., M.S. (1989). Future Air Quality Maintenance and Improvements Through the Expanded Use of Geothermal Energy. Geothermal Resources Council Transactions, 13, 27-34.

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GEA-016 Hazardous Waste Reduction Potential of Noncondensible Gas Injection, Incineration, and Flash Suppression in Geothermal Power Plant Air Emissions Control Systems – A Technical Feasibility Study Progress Report Goddard, W.B., Ph.D., Goddard, C.B., M.A. & McClain, D.W., M.S. (1989). Hazardous Waste Reduction Potential of Noncondensible Gas Injection, Incineration, and Flash Suppression in Geothermal Power Plant Air Emissions Control Systems – A Technical Feasibility Study Progress Report. Geothermal Resources Council Transactions, 13, 399-401.

GEA-017 Operating Experiences of Converting a Stretford to a LO-CAT(R) H2S Abatement System at Pacific Gas and Electric Company's Geysers Unit 15

Henderson, J.M., Dorighi, G.P. (1989). Operating Experiences of Converting a Stretford to a LO-CAT(R) H2S Abatement System at Pacific Gas and Electric Company's Geysers Unit 15. Geothermal Resources Council Transactions, 13, 593-595.

GEA-018 Geothermal Energy and the Greenhouse Effect

DiPippo, R. (1988). Geothermal Energy and the Greenhouse Effect. The Geothermal Hotline, 18 (2) California Department of Conservation Division of Oil and Gas, 84-85.

GEA-019 Chelation Chemistry in Geothermal H2S Abatement

Bedell, S.A., Hammond, C.A. (1987). Chelation Chemistry in Geothermal H2S Abatement. Geothermal Resources Council Bulletin, 16(3), 3-6.

GEA-020 Concentrations of Non-Criteria Air Pollutants in the Vicinity of the

Geysers, California Altshuler, S.L., Arcado, T.D. & Lin, C. (1985). Concentrations of Non-Criteria Air Pollutants in the Vicinity of the Geysers, California. Geothermal Resources Council Transactions, 9-Part 1, 203-208.

GEA-021 Steam Stripping: A New Process for Control of H2S Emissions From

Geothermal Power Plants Houston, R.M. & Domahidy, G. (1981). Steam Stripping: A New Process for Control of H2S Emissions From Geothermal Power Plants. Geothermal Resources Council Transactions, 5, 471-474.

GEA-022 An Effective H2S Abatement Process Using Geothermal Brine Effluents

Quong, R., Knauss, K.G., Stout, N.D. & Owen, L.B. (1979). An Effective H2S Abatement Process Using Geothermal Brine Effluents. Geothermal Resources Council Transactions, 3, 557-559.

GEA-023 Imperial Valley Environmental Project: Air Quality Assessment

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Ermak, D.L., Nyholm, R.A. & Gudiksen, P.H. (1979). Imperial Valley Environmental Project: Air Quality Assessment. Lawrence Livermore Laboratory UC-66, 1-17.

GEA-024 Chemical Characterization of Gases and Volatile Heavy Metals in Geothermal Effluents Robertson, D.E., Fruchter, J.S., Ludwick, J.D., Wilkerson, C.L., Crecelius, E.A. & Evans, J.C. (1978). Chemical Characterization of Gases and Volatile Heavy Metals in Geothermal Effluents. Geothermal Resources Council Transactions, 2, 579-582.

GEA-025 The Hawaii Geothermal Project: An Aerometric Study of Mercury and

Sulfur Emissions Siegel, B.Z. & Siegle, S.M. (1978). The Hawai Geothermal Project: An Aerometric Study of Mercury and Sulfur Emissions. Geothermal Resources Council Transactions, 2, 597-599.

GEA-026 Removal of Hydrogen Sulfide from Geothermal Steam

Li, C.T., Alzheimer, D.P., Wilcox, W.A., Roberts, G.L. & Riemath, W.F. (1978) Removal of Hydrogen Sulfide from Geothermal Stream. Geothermal Resources Council Transactions, 2, 403-406.

GEA-027 Mercury Emissions from Geothermal Power Plants Robertson, D.E., Crecelius, E.A., Fruchter, J.S., Ludwick, J.D. (1977,

June). Mercury Emissions from Geothermal Power Plants. Science, 196, 1094-1097.

GEA-028 Abatement of Hydrogen Sulfide Emissions from the Geysers Geothermal Power Plant

Allen, G.W. & McCluer, H.K. (1975, May 20-29). Abatement of Hydrogen Sulfide emissions from the Geysers Geothermal Power Plant. Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, San Francisco, CA, 1313-1315.

GEA-029 Geothermal Hazards: Mercury Emission Siegel, S.M. & Siegel, B. (1975). Geothermal Hazards: Mercury Emission Environmental Science & Technology, 9 (5), 473-474.

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Air Emissions Abstracts and Reviews MERCURY (Hg) Within the United States, the Environmental Protection Agency (EPA) and other government agencies widely cite a mercury study done by Robertson et al. in 1977 which reported mercury emissions coming from The Geysers to be significantly high. Since that time, mercury emissions coming from The Geysers have been drastically reduced thanks to hydrogen sulfide abatement systems put in place in the late 1970s. However, although these changes took place over twenty years ago, new mercury emissions data went unrecognized by the EPA until 2003. Moreover, no major published study has been produced to update the Robertson study, and at present mercury emissions continue to be an unnecessary point of contention and concern at various times. GEA-002 Carlsen, B. (2003, May). Mercury Emissions from Geothermal Plants

Located at The Geysers, California. [Personal Letter to Anne Pope of the Environmental Protection Agency]. ReviewThis letter written to the EPA by Calpine notes that mercury emission data used by the EPA is out-of-date. It states that since the implementation of a hydrogen sulfide abatement system in 1979, mercury emissions at The Geysers have been drastically reduced, and yet this change has gone unrecognized. Abstract/IntroductionNone provided.

GEA-004 Loppi, S. (1997, September/October). Monitoring of Arsenic, Boron and

Mercury by Lichen and Soil Analysis in the Mt. Amiata Geothermal Area (Central Italy). Geothermal Resources Council Transactions, 21, 137-140. ReviewThis study tried to determine the role that geothermal plants play in regards to environmental contamination by comparing soil samples and lichen samples from a geothermal field to that of a “normal” piece of land. More specifically, the study looked at arsenic, boron, and mercury soil samples. Essentially, the study found that there were not significant amounts of arsenic or boron in the soil or lichen samples from the geothermal field, nor was there a significant amount of mercury in the soil samples from the geothermal field. However, there was a significant amount of mercury in the lichens, which the author implied to mean that geothermal plants may be a significant contributor to mercury air emissions.

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Although the author theorizes that geothermal power production contributes to mercury emissions based on the finding of the lichen samples, some have hypothesized that the mercury found in the lichen samples could have traveled from other sources. Abstract/IntroductionEpiphytic lichens and top-soils from the Mt. Amiata geothermal field (central Italy) were analyzed for their As, B and Hg content. Three areas were selected: 1) Abbadia S. Salvatore, where a large Hg mine with smelting and roasting plant was located; 2) Piancastagnaio, where there are geothermal power plants; 3) a remote site far from mines and geothermal power plants. The results showed that the geothermal power plants do not represent a macroscopic source of arsenic and boron contamination in the area. As far as mercury is concerned, at the Hg mining area of Abbadia S. Salvatore concentrations were extremely high both in soil and epiphytic lichens, and the anomalous content in these organisms was due to the uptake of elemental mercury origination from soil degassing. At the geothermal area of Piancastagnaio, soil mercury was not different from that in the control area, but Hg in lichens was almost twice the control levels, suggesting that the gaseous emissions from the geothermal power plants are an important source of air contamination.

GEA-013 Arcado, T. & Altshuler, S. (1989). Ambient Air Mercury Concentrations at the Geysers. Geothermal Resources Council

Transactions, 13, 75-81.

ReviewThis study measured gaseous mercury in several locations around The Geysers. The study showed that there is a correlation between gaseous mercury levels and air temperature. This suggests that the gaseous mercury in the area around The Geysers comes from the outgassing of mercury-laden soils, rather than from plant emissions. More importantly, the average gaseous mercury levels found in the air were only half those of the world-wide average for mercury levels.

Abstract/Introduction

From June 19 to December 16, 1986, PG&E conducted ambient air mercury measurements at six stations downwind of The Geysers in Lake County. The stations were located in populated areas on the eastern side, within the geothermal field at worst-case locations, and adjacent to geothermal plants and old mercury mining facilities. The mercury measurements were taken for 24 hours on a six-day cycle. The lower detection limit of this technique was approximately 1 ng/m3 (nanogram per cubic meter) of air.

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Overall, the ambient levels of gaseous mercury were low. The average was 5.8 ng/m3 for the test period, with a maximum concentration of 23.6 ng/m3. These data are similar to the estimated average atmospheric levels worldwide, 10 ng/m3. A statistically significant relationship was determined to exist between ambient mercury and air temperature. A correlation was also evident between rainfall and a decrease of mercury concentrations during the testing period.

GEA-020 Altshuler, S.L., Arcado, T.D. & Lin, C. (1985). Concentrations of Non-

Criteria Air Pollutants in the Vicinity of the Geysers, California. Geothermal Resources Council Transactions, 9-Part 1, 203-208. Review This study measured levels of several non-criteria air pollutants emitted from geothermal plants, including mercury, ammonia, radon, PM10 boron, benzene, and sulfates. The study concludes that mercury vapor levels are correlated with air temperature, suggesting that mercury vapor in the air is related to the natural cinnabar deposits in the area, not to emissions from geothermal plants. There is one unexplained discrepancy between this study and a more recent one done by the same authors (GEA-013). This study recorded more “spikes” in mercury levels than GEA-013, making the overall results higher than those from GEA-013. Abstract/IntroductionAmbient air monitoring for non-criteria pollutants was conducted to assess the impact of geothermal steam utilization on the ambient air at The Geysers. The measurements revealed no exceeds of any ambient air quality standards, state, federal, or foreign. Except for mercury vapor, radon, and ammonia, all of the pollutants were measured at near detection limit concentrations using methods that are state-of-the-art. Mercury vapor seems to be more related to the known geologic cinnabar deposits and post mining operations in the area than to geothermal steam utilization at The Geysers.

GEA-023 Ermak, D.L., Nyholm, R.A. & Gudiksen, P.H. (1979). Imperial Valley Environmental Project: Air Quality Assessment. Lawrence Livermore Laboratory UC-66, 1-17.

ReviewThe authors of this study calculated emissions rates from geothermal power plants in Imperial Valley using a computer program called ATMAS. This program takes into account wind direction and velocity as

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well as composition of geothermal fluids to estimate emissions. The results showed hydrogen sulfide to be the biggest concern, and other pollutants (including mercury, ammonia, radon, and carbon dioxide) to be insignificant. It is important to note that much has changed in the geothermal industry since this article was written, such as the installation of H2S abatement systems, and the information the authors present is possibly out-of-date. Abstract/IntroductionThis report is an assessment of the potential impact on air quality of geothermal development in California’s Imperial Valley. The assessment is based on the predictions of numerical atmospheric transport models. Emission rates derived from analyses of the composition of geothermal fluids in the region and meteorological data taken at six locations in the valley over a 1-yr period were used as input to the models. Scenarios based on 3000 MW, 2000 MW, 500 MW, and 100 MW of power production are considered. Hydrogen sulfide is the emission of major concern. Our calculations predict that at the 3000-MW level (with no abatement), the California 1-h standard for H2S (42 µg/m3) would be violated at least 1% of the time over an area of approximately 1500 km2 (about 1/3 of the valley area). The calculations indicate that an H2S emission rate below 0.8 g/s per 100-MW unit is needed to avoid violations of the standard beyond a distance of 1 km from the source. Emissions of ammonia, carbon dioxide, mercury and radon are not expected to produce significant ground level concentrations, nor is the atmospheric conversion of hydrogen sulfide to sulfur dioxide expected to result in significant SO2 levels.

GEA-024 Robertson, D.E., Fruchter, J.S., Ludwick, J.D., Wilkerson, C.L., Crecelius, E.A. & Evans, J.C. (1978). Chemical Characterization of Gases and Volatile Heavy Metals in Geothermal Effluents. Geothermal Resources Council Transactions, 2, 579-582. ReviewThis study sampled the level of mercury (among other things) leaving geothermal power plants as air emissions and brine effluents. The authors sampled mercury emissions from several different plants, and found that mercury concentrations at most sites were 106 times higher than mercury levels in the ambient air. This study was done prior to installation of hydrogen sulfide abatement systems on geothermal power plants, which have been shown to dramatically lower mercury emissions, and therefore is likely out-of-date.

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Abstract/IntroductionThe rapidly increasing number of successfully drilled geothermal production wells is a good indication that geothermal energy development may meet or exceed projected forecasts of its potential as a cheap, clean source of energy. However, geothermal energy is not without some environmental impact. Indeed, the very hot geothermal processes which create the steam or hot water used for energy production can also mobilize volatile and hot-water-leachable chemical constituents and bring them to the surface from great depths in the earth. Non-condensable gases such as hydrogen sulfide, ammonia, radon, carbon dioxide, methane, and other volatile elements such as mercury, boron, arsenic and selenium are vented to the air when geothermal resources are tapped. Thermal waters reaching the earth’s surface contain very high concentrations of a wide variety of dissolved chemical constituents, some of which are toxic in relatively low concentrations (H2S, NH3, Hg, As, Cu, Zn, Se, Pb, Ag, Zn, Sb and Cd). It is essential that the effluents from each specific site be characterized to define and quantify the releases of undesirable materials. During the past three years, under National Science Foundation (NSF) and Department of Energy (DOE) funding, our laboratory has been engaged in characterizing the above mentioned noxious gases and heavy metals released in effluents from two geothermal power plants and numerous test facilities. These areas include The Geysers, CA; Cerro Prieto, Baja CA; Raft River, Idaho; Tigre Lagoon, Louisiana; and the Imperial Valley, CA sites at Niland, East Mesa and Heber. This paper summarizes some of the results of our chemical characterizations of geothermal effluents.

GEA-025 Siegel, B.Z. & Siegle, S.M. (1978). The Hawai Geothermal Project: An

Aerometric Study of Mercury and Sulfur Emissions. Geothermal Resources Council Transactions, 2, 597-599. ReviewThis study showed that mercury degassing on the Hawaii islands occurs naturally in the Kilauea and East Rift from volcanic activity. The development of the Hawaii Geothermal Project on the Island of Hawaii was unrelated to the levels of mercury measured in the air according to this study. Abstract/IntroductionPredrilling environmental baseline studies and extensive ongoing comparative aerometry in volcanic and rift areas have made it possible to characterize the University Experimental Geothermal Well (HGP-A) as a low-Hg, low-H2S emitter and to account for high levels of Hg in the environs of HGP-A in terms of natural events and processes in Kilauea and the East Rift.

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GEA-027 Robertson, D.E., Crecelius, E.A., Fruchter, J.S., Ludwick, J.D. (1977, June). Mercury Emissions from Geothermal Power Plants. Science, 196, 1094-1097.

ReviewThis often-cited study reports Hg emissions of around 1.4tons/year. The study collected data from The Geysers and Cerro Prieto, and states that mercury emissions from geothermal plants are comparable to those of coal plants (on a MW basis). The data cited in this report was used in the EPA’s Mercury Study Report to Congress from December 1997. Today, the results of this study are generally considered out-of-date and inaccurate because the introduction of the hydrogen sulfide abatement system dramatically lowers mercury emission levels from geothermal plants.

Abstract/Introduction Geothermal steam used for power production contains significant

quantities of volatile mercury. Much of this mercury escapes to the atmosphere as elemental mercury vapor in cooling tower exhausts. Mercury emissions from geothermal power plants, on a per megawatt (electric) basis, are comparable to releases from coal-fired power plants.

GEA-029 Siegel, S.M. & Siegel, B. (1975). Geothermal Hazards: Mercury Emission

Environmental Science & Technology, 9 (5), 473-474. ReviewIn this study, the authors measured the levels of mercury emitted from thermal and volcanic sites, and noted that the levels were quite high. The authors cautioned that geothermal development should take this into consideration before development of resources. Abstract/IntroductionEnthusiasm for intensified geothermal exploration may induce many participants to overlook a long-term potential toxicity hazard possibly associated with the tapping of magmatic steam. The association of high atmospheric Hg levels with geothermal activity has been established both in Hawaii and Iceland, and it has been shown that mercury can be introduced into the atmosphere from fumaroles, hot springs, and magmatic sources. These arguments, extended to thallium, selenium, and other hazardous elements, underscore the need for environmental monitoring in conjunction with the delivery of magmatic steam to the surface.

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CARBON DIOXIDE (CO2) Based on the articles listed below, there appears to be a general consensus that carbon dioxide emissions from geothermal power plants are insignificant when compared with fossil-fired power plants. This is not to say that geothermal plants do not emit any CO2, because there are documented emissions from various power plants. However, the CO2 emissions from geothermal plants range anywhere from zero to only a mere fraction of their fossil-burning counterparts, depending on the type of technology utilized at the geothermal plant.

GEA-001 Bloomfield, K.K., Moore, J.N., & Neilson, R. (2003, March-April). CO2

Emissions from Geothermal Energy Facilities are Insignificant Compared to Power Plants Burning Fossil Fuels. Geothermal Resources Council Bulletin, 77-79. ReviewThis report updates a previous study published in 1999 (GEA-003). Like GEA-003, this article reports carbon dioxide emissions from geothermal power plants, and shows that geothermal plants emit far less than coal, oil, or gas plants on a per-megawatt basis. The original 1999 report was updated due to the addition of geothermal generation capacity in the United States. The study reports geothermal carbon dioxide emissions to be 0.20 lbs/kW-hr. Abstract/IntroductionThis article updates a previous Bloomfield and Moore (1999) estimate of the quantity of carbon dioxide (CO2), hydrogen sulfide (H2S), methane (CH4) and ammonia (NH3) emitted during geothermal power generation. Since that estimate in 1999, more geothermal power generation capacity has been added in the United States, primarily in the Imperial Valley of southern California. Formal reporting required for fossil-fuel power production provide updated estimates of emissions from generation by those sources.

GEA-003 Bloomfield, K.K. & Moore, J.N. (1999). Production of Greenhouse Gases from Geothermal Power Plants. Geothermal Resources Council Transactions, 178, 221-223.

ReviewThis study is an earlier version of a 2003 report by Bloomfield & Moore (GEA-001). The study reports CO2 emissions from geothermal power plants to be significantly lower than CO2 emissions from fossil-fired plants, and notes that an increased use of geothermal energy could help offset the effects of global warming. Carbon dioxide emission levels are reported to be 0.18 lbs/kW-hr from geothermal power plants.

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Abstract/IntroductionEmission of “greenhouse gases” into the environment has become an increasing concern. Deregulation of the electrical market will allow consumers to select power suppliers that utilize “green power.” Geothermal power is classed as “green power” and has lower emissions of carbon dioxide per kilowatt-hour of electricity than even the cleanest of fossil fuels, natural gas. However, previously published estimates of carbon dioxide emissions are relatively old and need revision. This study estimates that the average carbon dioxide emissions from geothermal and fossil fuel power plants are: geothermal 0.18, coal 2.13, petroleum 1.56, and natural gas 1.03 pounds of CO2 per kilowatt-hour respectively.

GEA-005 Tiangco, V., Hare, R., Birkinshaw, K. & Johannis, M. (1995). Emission

Factors of Geothermal Power Plants in California. Geothermal Resources Council Transactions, 19, 147-151. ReviewThis study measured H2S, CO2 and PM10 emissions from geothermal power plants in California by asking individual plants to submit emissions data. The study compares data from vapor-dominated systems, dual-flash systems, and binary systems, and notes that CO2 emissions are low compared to fossil-fired power plants. However, this study does not actually present emissions data from fossil-fired plants to compare with its data from geothermal plants, it simply notes that geothermal plants have lower emission levels. Abstract/IntroductionA survey of emission factors for the existing geothermal power plants in California was conducted in cooperation with Geothermal Energy Association (formerly Geothermal Resources Association). The key atmospheric emissions of primary concern for geothermal development are hydrogen sulfide (H2S) and carbon dioxide (CO2). Emissions of particulate matter less than ten microns in diameter (PM10) are considered insignificant and not deleterious to public health. Geothermal power plants emit no nitrogen oxides. The up-to-date H2S and CO2 controlled emissions for all the geothermal power plants at different known geothermal resource areas (KGRAs) in California are discussed in detail.

GEA-006 Benoit, D. & Hirtz, P. (1994). Non-Condensible Gas Trends and

Emissions at Dixie Valley, Nevada. Geothermal Resources Council Transactions, 18, 113-119. ReviewThis study notes that the amount of CO2 emissions from Dixie Valley have decreased over time; from 150 lbs/MW hr of CO2 in 1988 to 83.4 lbs/MW

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hr in 1993. This is due to the recycling of injectate as confirmed by changes in the general brine chemistry. Abstract/IntroductionAccurate measurements of the noncondensible gas in geothermal fluids produced during initial well testing at the Dixie Valley geothermal field were required for power plant design. Estimates of H2S emissions from the plant were of critical importance in determining if an abatement system would be required. Since preliminary estimates involving chemical modeling of the total H2S emissions from the plant were near the 249 ton/year emission limit set by the State of Nevada, a pilot plant test was conducted to determine the H2S partitioning through the first and second stage flash process. This testing predicted that enough H2S would remain in the brine after flashing to maintain emission below the required limit. Noncondensible gas sampling from two-phase flow lines during initial well testing at the Dixie Valley geothermal field documented specific biases in the results that were dependent on the sampling technique. However, later comparison of samples collected from single-phase lines after plant start-up with samples collected from the two-phase lines indicate that representative gas samples can be obtained from two-phase flow streams with proper sampling techniques. The noncondensible gas content of the pre-flash geothermal fluid averaged 1800 to 1900 ppm with carbon dioxide comprising about 98% of the total. The hydrogen sulfide content ranged from 2 to 17 ppm and showed a strong increasing trend with enthalpy. During the first six years of production, both CO2 and H2S contents have shown variable and large declines which correspond with the amount of injectate returning to the production wells. The amount of CO2 and H2S emitted from the power plant has also decreased substantially from 0.90 lbs/MW hr (238 tons/year) of H2S and 150 lbs/MW hr of CO2 in 1988, to 0.62 (171 tons/year) and 83.4 lbs/MW hr respectively in 1993. The current H2S emission rate is well below the 249 tons/year mandated by the State of Nevada.

GEA-010 Edenburn, M.W. & Aronson, E.A. (1990). The Potential Impact of Conservation and Alternative Energy Sources on Carbon Dioxide Emissions. Geothermal Resources Council Transactions, 14, Part I, 631-638.

ReviewThis study shows how CO2 emissions can be drastically reduced through the adoption of energy-saving techniques and renewable energy sources.

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The authors note that geothermal energy is not free of CO2 emissions, and they state that The Geysers emit CO2 at the rate of 2.2 MtC/EJ.

Abstract/IntroductionIn this report, we examine two global energy consumption scenarios to determine how each will contribute to the greenhouse effect and global warming. A steady emission trend scenario assumes only modest energy conservation and little change in the world’s energy consumption patterns. A reduced emissions trend scenario assumes significant conservation and switching from a more carbon-intensive energy source mix to a less intensive mix. Based on the difference between the two scenarios’ results, we conclude that it is possible to reduce carbon dioxide emissions by more than 50% by 2050 using a combination of conservation and efficiency improvements and increased use of nuclear, geothermal, and solar/renewable energy sources.

GEA-015 Goddard, W.B., Ph.D., Goddard, C.B., M.A., & McClain, D.W., M.S. (1989). Future Air Quality Maintenance and Improvements Through the Expanded Use of Geothermal Energy. Geothermal Resources Council Transactions, 13, 27-34. ReviewThis article essentially states that geothermal power plants are a clean technology in comparison to dirtier fossil-fired plants. The authors provide several statistics regarding sulfide emissions and carbon dioxide emissions, which show geothermal as being remarkably cleaner than fossil-fuels. Abstract/IntroductionGeothermal development projects have experienced considerable slow down due to a combination of factors including the State of California change from a deficit to a surplus electrical generator and the low cost of imported oil. Environmental factors which are estimated to combine to change this situation and stimulate future geothermal growth are presented. The association between energy use and production and global air pollution which is prompting local, state and federal agencies to explore alternatives to fossil fuel use is described. All forms of fossil fuel use either in stationary sources such as electrical power plants or in mobile use such as in transportation are shown to be producing unacceptable quantities of air pollutants. The discussion includes infrared absorbing gasses, acid rain, ozone formation, hazardous waste generation and air toxics. Agencies’ strategies for maintaining and improving air quality in the future are discussed. An

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expanded role and opportunity for geothermal energy use is forecast if its inherent environmental advantages are utilized.

GEA-018 DiPippo, R. (1988). Geothermal Energy and the Greenhouse Effect. The Geothermal Hotline, 18 (2) California Department of Conservation Division of Oil and Gas, 84-85.

ReviewThis short article compares CO2 emission rates from different electrical power producers in the US. Geothermal is shown as having the low rate of 0.1 – 0.15 pounds/kWh, and the article notes that binary plants emit no CO2 at all. AbstractNone provided.

GEA-023 Ermak, D.L., Nyholm, R.A. & Gudiksen, P.H. (1979). Imperial Valley

Environmental Project: Air Quality Assessment. Lawrence Livermore Laboratory UC-66, 1-17.

ReviewThe authors of this study calculated emissions rates from geothermal power plants in Imperial Valley using a computer program called ATMAS. This program takes into account wind direction and velocity as well as composition of geothermal fluids to estimate emissions. The results showed hydrogen sulfide to be the biggest concern, and other pollutants (including mercury, ammonia, radon, and carbon dioxide) to be insignificant. It is important to note that much has changed in the geothermal industry since this article was written, such as the installation of H2S abatement systems, and the information the authors present is possibly out-of-date. Abstract/IntroductionThis report is an assessment of the potential impact on air quality of geothermal development in California’s Imperial Valley. The assessment is based on the predictions of numerical atmospheric transport models. Emission rates derived from analyses of the composition of geothermal fluids in the region and meteorological data taken at six locations in the valley over a 1-yr period were used as input to the models. Scenarios based on 3000 MW, 2000 MW, 500 MW, and 100 MW of power production are considered. Hydrogen sulfide is the emission of major concern. Our calculations predict that at the 3000-MW level (with no abatement), the California 1-h standard for H2S (42 µg/m3) would be violated at least 1% of the time over an area of approximately 1500 km2 (about 1/3 of the valley area). The calculations indicate that an H2S

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emission rate below 0.8 g/s per 100-MW unit is needed to avoid violations of the standard beyond a distance of 1 km from the source. Emissions of ammonia, carbon dioxide, mercury and radon are not expected to produce significant ground level concentrations, nor is the atmospheric conversion of hydrogen sulfide to sulfur dioxide expected to result in significant SO2 levels.

HYDROGEN SULFIDE (H2S) Of all the emissions put out by geothermal power plants, H2S is by far the greatest concern because it is considered to be a nuisance pollutant under California law, and can be toxic at high concentrations. However, unlike other emissions, H2S emissions from geothermal plants have been thoroughly studied and measured and it has been shown that geothermal plants do not exceed state air quality regulations regarding H2S due to abatement technology that has been developed and effectively employed. Also, there has been extensive research into different types of H2S abatement systems, and there is a good deal of knowledge about which systems work best. The most commonly used H2S abatement systems are the Stretford system (for non-condensible gases) and the LoCAT. GEA-005 Tiangco, V., Hare, R., Birkinshaw, K. & Johannis, M., (1995). Emission

Factors of Geothermal Power Plants in California. Geothermal Resources Council Transactions, 19, 147-151. ReviewThis study measured H2S, CO2 and PM10 emissions from geothermal power plants in California by asking individual plants to submit emissions data. The study compared data from vapor-dominated systems, dual-flash systems, and binary systems, and found that H2S emissions are the primary pollutant from geothermal plants, but that they are well below emission limits set by the state. The study reported that dual-flash plants’ average H2S emissions were 0.29 lbs/Mwh.

Abstract/IntroductionA survey of emission factors for the existing geothermal power plants in California was conducted in cooperation with Geothermal Energy Association (formerly Geothermal Resources Association). The key atmospheric emissions of primary concern for geothermal development are hydrogen sulfide (H2S) and carbon dioxide (CO2). Emissions of particulate matter less than ten microns in diameter (PM10) are considered insignificant and not deleterious to public health. Geothermal power plants emit no nitrogen oxides. The up-to-date H2S and CO2 controlled emissions for all the geothermal power plants at different known geothermal resource areas (KGRAs) in California are discussed in detail.

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GEA-006 Dick B. & Hirtz, P. (1994). Non-Condensible Gas Trends and Emissions at Dixie Valley, Nevada. Geothermal Resources Council Transactions, 18, 113-119. ReviewThis study measured H2S emissions in Dixie Valley to insure compliance with Nevada State air quality regulations. The authors recorded measurements of 0.90 lbs/MW hr (238 tons/yr) in 1988, which later dropped to 0.62 lbs/MW hr (171 tons/yr) in 1993. This emission rate is well below the 249 tons/yr mandated by the State of Nevada.

Abstract/IntroductionAccurate measurements of the noncondensible gas in geothermal fluids produced during initial well testing at the Dixie Valley geothermal field were required for power plant design. Estimates of H2S emissions from the plant were of critical importance in determining if an abatement system would be required. Since preliminary estimates involving chemical modeling of the total H2S emissions from the plant were near the 249 ton/year emission limit set by the State of Nevada, a pilot plant test was conducted to determine the H2S partitioning through the first and second stage flash process. This testing predicted that enough H2S would remain in the brine after flashing to maintain emission below the required limit. Noncondensible gas sampling from two-phase flow lines during initial well testing at the Dixie Valley geothermal field documented specific biases in the results that were dependent on the sampling technique. However, later comparison of samples collected from single-phase lines after plant start-up with samples collected from the two-phase lines indicate that representative gas samples can be obtained from two-phase flow streams with proper sampling techniques. The noncondensible gas content of the pre-flash geothermal fluid averaged 1800 to 1900 ppm with carbon dioxide comprising about 98% of the total. The hydrogen sulfide content ranged from 2 to 17 ppm and showed a strong increasing trend with enthalpy. During the first six years of production, both CO2 and H2S contents have shown variable and large declines which correspond with the amount of injectate returning to the production wells. The amount of CO2 and H2S emitted from the power plant has also decreased substantially from 0.90 lbs/MW hr (238 tons/year) of H2S and 150 lbs/MW hr of CO2 in 1988, to 0.62 (171 tons/year) and 83.4 lbs/MW hr respectively in 1993. The current H2S emission rate is well below the 249 tons/year mandated by the State of Nevada.

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GEA-007 Altshuler, S.L., & Arcado, T.D. (1991). Ambient Air H2S Monitoring at The Geysers: From Nonattainment to Attainment. Geothermal Resources Council Special Report No. 17, 297-301.

Review This article provides a positive overview of the development of H2S abatement systems at The Geysers. The authors give concrete numbers from three different studies to show that H2S emissions have gone down dramatically since 1976, despite an increase in electricity production. This is possibly the most definitive, up-to-date article regarding H2S emissions at The Geysers in the published literature. AbstractThe results of three ambient air monitoring programs performed downwind of The Geysers, California, are described. These studies, conducted since 1976, have monitored the declining ambient air concentrations of hydrogen sulfide (H2S) in Lake County. During the 13 years of monitoring, geothermal power production has increased from approximately 500 to 2,000 MW, H2S emissions from power plants have declined from 1,900 to less than 200 lb/hr, and ambient H2S concentrations have significantly declined. Annual average concentrations of H2S at four long-term sites have declines by a factor of 3.0, maximum H2S concentrations have declined by a factor of 3.6, and the frequency of violation of the California Air Quality Standard (0.03 ppm) averaged over 1 hour has declined from an average frequency of 52 times per year to almost 0. The area has not had a recorded violation of the air quality standard since August 1987. As such, the area has gone 3 years without a violation, and was classified by the California Air Resources Board as “attainment” during their November 1990 review process.

GEA-012 Goddard, W., Goddard, C. & McClain, D. (1990). Noncondensable

Hydrogen Sulfide Incineration with Brine Scrubbing Air Emissions Control System: Source Reduction Demonstration Project. Geothermal Resources Council Transactions, 14, 1127-1131.

ReviewThis is the second phase of a study started in GEA-015. This part of the study focuses on the design feasibility and cost-effectiveness of implementing an H2S incineration device to reduce hazardous waste in geothermal plants by creating a pilot device.

Abstract/Introduction The technical and institutional feasibility of incinerating hydrogen sulfide

(H2S) contained in geothermal noncondensable gases, and the use of geothermal brine for sulfur dioxide scrubbing and absorption as an Air Emissions Control System (AECS), have been documented through

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engineering analysis in the Phase I grant study funded through the California Department of Health Services (DOHS), Hazardous Materials Reduction Grant Program and hosted by California Energy Company (CECI). Grant funding for Phase II now has been approved to proceed with the project through the pilot plant design phase.

This innovative AECS does not necessitate the use of hazardous materials or produce hazardous wastes. Cost savings were documented compared to injection pump operation or conventional AECS without the use of hazardous materials. The Phase II project is to design, improve, research and develop a source reduction demonstration pilot plant geothermal noncondensable H2S incineration AECS.

GEA-014 Altshuler, S.L. & Arcado, T.D. (1989). Ambient Air Monitoring at The Geysers: A Historical Perspective and Current Status. Geothermal Resources Council Transactions, 13, 71-74. ReviewThis paper assesses data from three different programs which monitored H2S emissions from The Geysers from 1976-1988. By running statistical analysis, the authors found that H2S emissions from The Geysers had declined from over 1900 lb/hr to less than 200 lb/hr, although electric power production during the same period increased from 500 MW to 2000 MW. Abstract/IntroductionThe results of three ambient air monitoring programs performed downwind of The Geysers, California, are described. These studies, conducted since 1976, have monitored the declining ambient air concentrations of hydrogen sulfide (H2S) in Lake County. During the 13 years of monitoring, geothermal power production has increased from approximately 500 to 2000 megawatts, H2S emissions from power plants have declined from 1900 to less than 200 lb/hr, and ambient H2S concentrations have significantly declined. Annual average concentrations of H2S at four long-term sites have declined by a factor of 2.8, maximum H2S concentrations have declined by a factor of 3.4, and the frequency of exceedance of the California Air Quality Standard (0.03 ppm) averaged over 1 hour has declined from an average frequency of 52 times per year to less than 1.

GEA-016 Goddard, W.B., Ph.D., Goddard, C.B., M.A. & McClain, D.W., M.S. (1989). Hazardous Waste Reduction Potential of Noncondensible Gas Injection, Incineration, and Flash Suppression in Geothermal Power Plant Air Emissions Control Systems – A Technical Feasibility Study Progress Report. Geothermal Resources Council Transactions, 13, 399-401.

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ReviewThis article is basically just a progress report of the first phase of a study that is continued in GEA-011. This study tests the possibility of reducing the hazardous waste generation from H2S emission control systems by burning the H2S. The incineration of H2S results in sulfur dioxide and water vapor as byproducts. Abstract/IntroductionMany hydrogen sulfide Air Emissions Control Systems (AECS) for geothermal power plants and well/steam field vented emissions control use hazardous materials and generate hazardous waste. The costs and complexities of handling, transporting, processing and storage of hazardous materials and waste have risen dramatically over the last few years. Development of alternative AECS of innovative design which result in no hazardous materials use or hazardous waste generation will have substantial environmental and economic rewards. A technical feasibility study of noncondensable gas injection, incineration and flash suppression as alternative AECS which do not use hazardous materials or generate hazardous waste is being undertaken with funding from the California Department of Health Services, Hazardous Waste Reduction Grant Program. This one years feasibility project is assessing both the technical and institutional feasibility and further adoption of these innovative AECS systems.

GEA-017 Henderson, J.M., Dorighi, G.P. (1989). Operating Experiences of Converting a Stretford to a LO-CAT(R) H2S Abatement System at Pacific Gas and Electric Company's Geysers Unit 15. Geothermal Resources Council Transactions, 13, 593-595. Review This article describes the experience of switching H2S abatement mechanisms at The Geysers unit 15. This unit originally used the Stretford system to abate H2S, but it switched use to the LO-CAT(R). The authors describe some of the technical difficulties encountered in converting systems and also talk about some of the cost benefits to switching. AbstractIn January 1988, Pacific Gas and Electric Company (PG&E) converted the Stretford H2S abatement system at Unit 15 to use LO-CAT(R) H2S liquid redox process chemistry. The Stretford process is a vanadium-based aqueous phase H2S scrubbing system, while the LO-CAT(R) technology uses a solution of chelated iron for H2S treatment.

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This paper describes the plant modifications required for the conversion. It characterizes the operating experience and H2S abatement performance over the past year of evaluating the process. Overall plant operability and H2S removal efficiency of the LO-CAT(R) solution is at least as good as, or better than, Stretford. However, a plant considering the Stretford to LO-CAT(R) conversion needs to evaluate for its own situation the apparent redistribution of operating costs outlined in this report. Once must also pay attention to the subtle changes in operating procedures required to use the LO-CAT(R) solution with existing Stretford process equipment.

GEA-019 Bedell, S.A., Hammond, C.A. (1987). Chelation Chemistry in Geothermal H2S Abatement. Geothermal Resources Council Bulletin, 16(3), 3-6. Review This article discusses the use of iron chelating agents for H2S abatement. A solid understanding of chemistry is necessary to read this article. Abstract None provided.

GEA-022 Quong, R., Knauss, K.G., Stout, N.D. & Owen, L.B. (1979). An Effective H2S Abatement Process Using Geothermal Brine Effluents. Geothermal Resources Council Transactions, 3, 557-559. ReviewThe author describes an effective, inexpensive method of removing H2S by scrubbing with spent brine effluents. The author notes that this process may only be a viable option at Salton Sea and Brawley Geothermal Field because of their unique mineral concentrations in the steam. Abstract/IntroductionA simple and potentially inexpensive method for removal of H2S from noncondensible gases evolved in geothermal flash processes has been successfully tested on a small scale in the field. The method consists of scrubbing the noncondensible gases of H2S with brine effluents which contain relatively high concentrations of Pb, Zn, and Fe such as those of the Salton Sea and Brawley Geothermal Fields in the Imperial Valley, California. For plant applications, noncondensibles including H2S would be ejected from a surface steam condenser (necessary to minimize the volume of liquid in contract with H2S) and scrubbed with effluent brine just prior to preinjection clarification. The metal sulfide precipitates are removed in the clarification step and the noncondensibles, less H2S, are vented as usual.

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GEA-023 Ermak, D.L., Nyholm, R.A. & Gudiksen, P.H. (1979). Imperial Valley Environmental Project: Air Quality Assessment. Lawrence Livermore Laboratory UC-66, 1-17.

ReviewThe authors of this study calculated emissions rates from geothermal power plants in Imperial Valley using a computer program called ATMAS. This program takes into account wind direction and velocity as well as composition of geothermal fluids to estimate emissions. The results showed hydrogen sulfide to be the biggest concern, and other pollutants (including mercury, ammonia, radon, and carbon dioxide) to be insignificant. It is important to note that much has changed in the geothermal industry since this article was written, such as the installation of H2S abatement systems, and the information the authors present is possibly out-of-date. Abstract/IntroductionThis report is an assessment of the potential impact on air quality of geothermal development in California’s Imperial Valley. The assessment is based on the predictions of numerical atmospheric transport models. Emission rates derived from analyses of the composition of geothermal fluids in the region and meteorological data taken at six locations in the valley over a 1-yr period were used as input to the models. Scenarios based on 3000 MW, 2000 MW, 500 MW, and 100 MW of power production are considered. Hydrogen sulfide is the emission of major concern. Our calculations predict that at the 3000-MW level (with no abatement), the California 1-h standard for H2S (42 µg/m3) would be violated at least 1% of the time over an area of approximately 1500 km2 (about 1/3 of the valley area). The calculations indicate that an H2S emission rate below 0.8 g/s per 100-MW unit is needed to avoid violations of the standard beyond a distance of 1 km from the source. Emissions of ammonia, carbon dioxide, mercury and radon are not expected to produce significant ground level concentrations, nor is the atmospheric conversion of hydrogen sulfide to sulfur dioxide expected to result in significant SO2 levels.

GEA-024 Robertson, D.E., Fruchter, J.S., Ludwick, J.D., Wilkerson, C.L., Crecelius,

E.A. & Evans, J.C. (1978). Chemical Characterization of Gases and Volatile Heavy Metals in Geothermal Effluents. Geothermal Resources Council Transactions, 2, 579-582. ReviewThis study sampled the level of H2S (among other things) leaving geothermal power plants as air emissions and brine effluents. The authors

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sampled H2S emissions from several different plants, and found that H2S concentrations were variable depending on location. This study was done prior to installation of hydrogen sulfide abatement systems on geothermal power plants, which have been shown to dramatically lower mercury emissions, and therefore is likely out-of-date.

Abstract/IntroductionThe rapidly increasing number of successfully drilled geothermal production wells is a good indication that geothermal energy development may meet or exceed projected forecasts of its potential as a cheap, clean source of energy. However, geothermal energy is not without some environmental impact. Indeed, the very hot geothermal processes which create the steam or hot water used for energy production can also mobilize volatile and hot-water-leachable chemical constituents and bring them to the surface from great depths in the earth. Non-condensable gases such as hydrogen sulfide, ammonia, radon, carbon dioxide, methane, and other volatile elements such as mercury, boron, arsenic and selenium are vented to the air when geothermal resources are tapped. Thermal waters reaching the earth’s surface contain very high concentrations of a wide variety of dissolved chemical constituents, some of which are toxic in relatively low concentrations (H2S, NH3, Hg, As, Cu, Zn, Se, Pb, Ag, Zn, Sb and Cd). It is essential that the effluents from each specific site be characterized to define and quantify the releases of undesirable materials. During the part three years, under National Science Foundation (NSF) and Department of Energy (DOE) funding, our laboratory has been engaged in characterizing the above mentioned noxious gases and heavy metals released in effluents from two geothermal power plants and numerous test facilities. These areas include The Geysers, CA; Cerro Prieto, Baja CA; Raft River, Idaho; Tigre Lagoon, Louisiana; and the Imperial Valley, CA sites at Niland, East Mesa and Heber. This paper summarizes some of the results of our chemical characterizations of geothermal effluents.

GEA-025 Siegel, B.Z. & Siegle, S.M. (1978). The Hawai Geothermal Project: An Aerometric Study of Mercury and Sulfur Emissions. Geothermal Resources Council Transactions, 2, 597-599. ReviewThe authors of this study determined that high Hg and H2S concentrations in the ambient air on Hawaii Island were attributed to volcanic activity in Kilauea and the East Rift, rather than the geothermal project on the island.

Abstract/IntroductionPredrilling environmental baseline studies and extensive ongoing comparative aerometry in volcanic and rift areas have made it possible to

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characterize the University Experimental Geothermal Well (HGP-A) as a low-Hg, low-H2S emitter and to account for high levels of Hg in the environs of HGP-A in terms of natural events and processes in Kilauea and the East Rift.

GEA-026 Li, C.T., Alzheimer, D.P., Wilcox, W.A., Roberts, G.L. & Riemath, W.F. (1978) Removal of Hydrogen Sulfide from Geothermal Stream. Geothermal Resources Council Transactions, 2, 403-406. ReviewThis paper cites H2S emissions from The Geysers to be as high as 1600 ppm, although the average is 225 ppm. The authors analyze two processes that have been studied to abate H2S emissions: sorption and oxidation. The authors seem to view the oxidation process as having more potential, although they admit that there are still technological hurdles to be overcome before these technologies can be fully utilized. This study was done prior to installation of hydrogen sulfide abatement systems on geothermal power plants, which have greatly reduced H2S emissions, and therefore is likely out-of-date.

Abstract/IntroductionDevelopment of many geothermal energy sources is hindered because geothermal fluids contain impurities. Hydrogen sulfide (H2S) is present in steam from most geothermal sources. The direct use of geothermal steam for power generation may therefore be both corrosive to the power generation-transmission equipment and offensive to the environment. Concentrations of H2S as high as 1,600 ppm have been reported at the Geysers. However, the concentration of H2S in geothermal steam usually ranges from 60 to 1,000 ppm. The H2S problem in using geothermal steam for power generation has been illustrated by Bowen in the following situation. A power plant with a capacity of 1,000 MWe requires 430 million pounds of steam per day. If the concentration of H2S in the steam is 225 ppm (the average H2S concentration in steam produced at the Geysers) a total of 48.4 tons of H2S per day is carried by the steam to the surface. If 30 percent of H2S is returned to the reservoir with steam condensate the total H2S released to the atmosphere would be 33.9 tons per day. An H2S release of this magnitude could lead to atmospheric concentrations such that corrosion of power generation and transmission equipment could occur as well as environmental impacts. Since early 1976, Pacific Northwest Laboratories (PNL) under sponsorship of DOE (then ERDA) has been developing processes to

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remove H2S from geothermal steam. The following criteria were established for such removal processes:

They should be applicable at the upstream of power generation equipment to reduce H2S corrosion problems.

They should cause minimum degradation of steam quality. They should produce useful of environmentally innocuous

byproducts. They should be inexpensive and simple to operate.

GEA-028 Allen, G.W. & McCluer, H.K. (1975, May 20-29). Abatement of

Hydrogen Sulfide emissions from the Geysers Geothermal Power Plant. Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, San Francisco, CA, 1313-1315.

ReviewThis paper looks at two different H2S abatement systems that could be used at The Geysers to reduce emissions. At the time this paper was written no H2S emission control system was in place. Reports H2S emission from The Geysers as 222 ppm. This study was done prior to installation of hydrogen sulfide abatement systems on geothermal power plants, which have greatly reduced H2S emissions, and therefore is likely out-of-date.

Abstract/Introduction The hydrogen sulfide (H2S) emissions abatement program at The Geysers

geothermal power plant is summarized, and the actions currently under way to reduce these emissions are described. The Geysers steam averages 223 ppm H2S by weight which, after passing through the turbines, leaves the power-generating units both through the gas ejector system and by air-stripping in the cooling towers. The hydrogen sulfide dissolved in the cooling water can be controlled by the use of an oxidation catalyst, such as an iron salt, so that it is reacted to sulfur before entering the cooling tower. The H2S in the low-heat-value ejector off-gasses may be burned to sulfur dioxide and scrubbed directly into the circulating water for reinjection into the steam field with the excess condensate. The disposal of the impure sulfur produced, design requirements for retrofitting existing plants, and modified plant operating procedures are also described. Discussions of future research aimed at improved H2S abatement systems are included.

ARSENIC (As) Arsenic emission levels from geothermal power plants, particularly in California, have been well defined over the past 20 years as a result of emission inventories conducted under AB2588, Air Toxic “Hot Spots” program, and The Geysers (GAMP) and COSO

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Air Monitoring Programs. Unfortunately, there has been no formal documentation of this data into the literature. Rather, bits and pieces of the data have made their way into formal documentation in the literature, which has only served to add confusion to the situation. For example, GEA-008, which was written based on data collected from GAMP during the 1980s, raises questions about the California Air Resources Board (CARB) reporting of arsenic emissions from geothermal power plants. However, the GAMP data, which has been collected for over 20 years, including data on arsenic, has shown no air quality impact at the air quality monitoring stations surrounding The Geysers project. It is generally known that arsenic is found in pipeline scale and within the liquid phase of geothermal fluids, as opposed to the steam or in the non-condensable gasses. Thus, geothermal power plants are not to be considered high arsenic emitters.

GEA-008 Solomon, P., Altshuler, S.L. & Keller, M.L. (1991). Arsenic Speciation in

Atmospheric Aerosols at the Geysers. Geothermal Resources Council Transactions, 15, 155-161. ReviewIn this study arsenic levels in the air around The Geysers were measured in 1989. The authors reference the GAMP (Geysers Air Monitoring Program) measurements taken by PG&E that measured arsenic levels in 1982/83 and again in 1986/87. They note that the CARB summarized the GAMP data and claims that arsenic emissions at The Geysers range from 1-2 ng m-3. But, the authors think that arsenic emissions are actually not that serious because GAMP did not collect arsenic speciation data; meaning that the data did take into account the fact that there are two different types of arsenic, one vastly more toxic than the other. In this study, the researchers did collect arsenic speciation data, and although the actual arsenic levels they measured were consistent with the GAMP data, the majority of the arsenic present was in the less toxic form, a distinction that is unrecognized by CARB. More importantly, the arsenic concentrations measured at The Geysers were only slightly higher than the corresponding average value for air throughout California. It should be noted that the information presented in this article seems to contrast with information maintained on arsenic emissions at The Geysers. Apparently, arsenic emissions from The Geysers have been well defined over the past 15-years as a result of emission inventories conducted under AB2588, Air Toxic “Hot Spots” program, and GAMP, although this information has not made its way into the formal literature. Based on the prioritization scoring required by AB2588, none of the power plants at The Geysers triggered a risk assessment based on the non-speciated (i.e. total) arsenic emissions reported. This, if total arsenic did not trigger a 1 in 1 million risk then any arsenic species (compound or elemental) would not either. Additionally, the GAMP data, which has been collected for over 20-years, including data on arsenic, has shown no air quality impact at the air quality monitoring stations surrounding The Geysers project.

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Abstract/IntroductionGeothermal energy production in California has been identified as a major source of arsenic by the California Air Resources Board. New regulations have been implemented by the state of California. These regulations require information on ambient levels and emissions of inorganic arsenic. However, these laws consider only total arsenic and do not take into account the potential differences in toxicity or possibly carcinogenicity of the different arsenic species present in the ambient atmosphere. To provide information on the ambient levels of As(III) and As(V), atmospheric particulate matter samples were collected at The Geysers geothermal development area in Lake County, California, over a 2-month period in 1989. Each sample was analyzed for As(III), As(V), and total arsenic. This paper describes those results and provides a unique insight into the atmospheric loadings of the inorganic species of arsenic, As(III) and As(V), at geothermal power facilities.

GEA-024 Robertson, D.E., Fruchter, J.S., Ludwick, J.D., Wilkerson, C.L., Crecelius, E.A. & Evans, J.C. (1978). Chemical Characterization of Gases and Volatile Heavy Metals in Geothermal Effluents. Geothermal Resources Council Transactions, 2, 579-582. ReviewThis study sampled the level of arsenic (among other things) leaving geothermal power plants as air emissions and brine effluents. The authors sampled arsenic emissions from several different plants, and found that only a small fraction of the arsenic found in geothermal brine follows the steam phase. In addition, the chemical forms of arsenic in the condensates and brines were found to gradually oxidize to the least toxic form of inorganic arsenic when exposed to the atmosphere. Abstract/IntroductionThe rapidly increasing number of successfully drilled geothermal production wells is a good indication that geothermal energy development may meet or exceed projected forecasts of its potential as a cheap, clean source of energy. However, geothermal energy is not without some environmental impact. Indeed, the very hot geothermal processes which create the steam or hot water used for energy production can also mobilize volatile and hot-water-leachable chemical constituents and bring them to the surface from great depths in the earth. Non-condensable gases such as hydrogen sulfide, ammonia, radon, carbon dioxide, methane, and other volatile elements such as mercury, boron, arsenic and selenium are vented to the air when geothermal resources are tapped. Thermal waters reaching the earth’s surface contain very high concentrations of a wide variety of dissolved chemical constituents, some of which are toxic in relatively low concentrations (H2S, NH3, Hg, As, Cu, Zn, Se, Pb, Ag, Zn, Sb and Cd). It

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is essential that the effluents from each specific site be characterized to define and quantify the releases of undesirable materials. During the part three years, under National Science Foundation (NSF) and Department of Energy (DOE) funding, our laboratory has been engaged in characterizing the above mentioned noxious gases and heavy metals released in effluents from two geothermal power plants and numerous test facilities. These areas include The Geysers, CA; Cerro Prieto, Baja CA; Raft River, Idaho; Tigre Lagoon, Louisiana; and the Imperial Valley, CA sites at Niland, East Mesa and Heber. This paper summarizes some of the results of our chemical characterizations of geothermal effluents.

PARTICULATE MATTER (PM10) Particulate matter does not seem to be of great concern in geothermal plants, as emissions are well below the federal limits. Only plants with cooling towers emit small amounts of particulate matter. GEA-005 Tiangco, V., Hare, R., Birkinshaw, K. & Johannis, M. (1995). Emission

Factors of Geothermal Power Plants in California. Geothermal Resources Council Transactions, 19, 147-151. Review This study measured H2S, CO2 and PM10 emissions from geothermal power plants in California by asking individual plants to submit emissions data. The study compares data from vapor-dominated systems, dual-flash systems, and binary systems, and notes that PM10 emissions were reported at zero.

Abstract/IntroductionA survey of emission factors for the existing geothermal power plants in California was conducted in cooperation with Geothermal Energy Association (formerly Geothermal Resources Association). The key atmospheric emissions of primary concern for geothermal development are hydrogen sulfide (H2S) and carbon dioxide (CO2). Emissions of particulate matter less than ten microns in diameter (PM10) are considered insignificant and not deleterious to public health. Geothermal power plants emit no nitrogen oxides. The up-to-date H2S and CO2 controlled emissions for all the geothermal power plants at different known geothermal resource areas (KGRAs) in California are discussed in detail.

GEA-011 Egami, R.T., Crow, J.C., Watson, J.G. & Delong, T. (1990). PM10 Source Apportionment Study in Pleasant Valley, Nevada. Geothermal Resources Council Transactions, 14, Part II, 1115-1120.

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AnalysisThis study measured PM10 levels in the air around Pleasant Valley, NV in 1988. The study found that PM10 levels were far below federal standards, and it found that chemical composition of the PM10 to be mostly sulfate, ammonium, and chloride.

Abstract/Introduction A source apportionment study was conducted between March 18 and April

4, 1988, at Pleasant Valley, Nevada, to evaluate air pollutant concentrations to which community residents were exposed and the source contributions to those pollutants. Daily PM10 samples were taken for chemical speciation of 40 trace elements, ions, and organic and elemental carbon. Hourly hydrogen sulfide, wind speed and direction, sigma theta, temperature, and relative humidity data were also collected. The objectives of this case study are: (1) to determine the emissions source composition of the potential upwind source, a geothermal plant; (2) to measure the ambient particulate concentration and its chemical characteristics in Pleasant Valley; and (3) to estimate the contributions of different emissions sources to PM10.

NITROGEN OXIDES (NOx) Some geothermal plants emit only minor amounts of nitrogen oxides through the process of H2S incineration. GEA-005 Tiangco, V., Hare, R., Birkinshaw, K. & Johannis, M. (1995). Emission

Factors of Geothermal Power Plants in California. Geothermal Resources Council Transactions, 19, 147-151. ReviewThis study measured H2S, CO2, NOx and PM10 emissions from geothermal power plants in California by asking individual plants to submit emissions data. The study compares data from vapor-dominated systems, dual-flash systems, and binary systems, and notes that NOx emissions were reported at zero.

Abstract/IntroductionA survey of emission factors for the existing geothermal power plants in California was conducted in cooperation with Geothermal Energy Association (formerly Geothermal Resources Association). The key atmospheric emissions of primary concern for geothermal development are hydrogen sulfide (H2S) and carbon dioxide (CO2). Emissions of particulate matter less than ten microns in diameter (PM10) are considered insignificant and not deleterious to public health. Geothermal power plants emit no nitrogen oxides. The up-to-date H2S and CO2 controlled

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emissions for all the geothermal power plants at different known geothermal resource areas (KGRAs) in California are discussed in detail.

MISCELLANEOUS GEA-009 Goddard, W.B. & Goddard, C. (1990). Energy Fuel Sources and Their

Contribution to Recent Global Air Pollution Trends. Geothermal Resources Council Transactions, 14, 643-649. Review One of the most commonly referenced papers on gaseous emissions from U.S. geothermal plants, which determined emissions based on data from utility power producers – mainly from the Geysers. Abstract/IntroductionIncreased global energy use and accompanying air pollution has resulted in greater evidence of global and local climate modifications. The detrimental effects include “greenhouse” warming, sulfuric and nitric acid rains, photochemical smog produced ozone, loss of the stratospheric ozone ultraviolet shield, increased airborne particulates, adverse health effects, decreased agricultural productivity, increased material corrosion, and destruction of and irreversible changes to natural ecological systems. A global understanding of the geophysical processes which result from increased world wide air pollution is essential to developing strategies for maintaining and improving air quality. Fossil and biomass fuel burning for energy use and deforestation are the primary generators of air pollutants. Air pollutant transport does not respect national boundaries. Development and production of alternative energy sources and shown to have minimal air quality impacts when compared to traditional fossil and biomass fuels. Geothermal energy and other alternative energy sources must play an increased role in displacing fossil and biomass fuel if worsening trends in deteriorating air quality are to be reversed.

GEA-015 Goddard, W.B, Ph.D., Goddard, C.B., M.A. & McClain, D.W., M.S.

(1989). Future Air Quality Maintenance and Improvements Through the Expanded Use of Geothermal Energy. Geothermal Resources Council Transactions, 13, 27-34. ReviewThis article essentially states that geothermal power plants are a clean technology in comparison to dirtier fossil-fired plants. The authors provide several statistics regarding emissions which show geothermal as being remarkably cleaner than fossil-fuels.

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Abstract/IntroductionGeothermal development projects have experienced considerable slow down due to a combination of factors including the State of California change from a deficit to a surplus electrical generator and the low cost of imported oil. Environmental factors which are estimated to combine to change this situation and stimulate future geothermal growth are presented. The association between energy use and production and global air pollution which is prompting local, state and federal agencies to explore alternatives to fossil fuel use is described. All forms of fossil fuel use either in stationary sources such as electrical power plants or in mobile use such as in transportation are shown to be producing unacceptable quantities of air pollutants. The discussion includes infrared absorbing gasses, acid rain, ozone formation, hazardous waste generation and air toxics. Agencies’ strategies for maintaining and improving air quality in the future are discussed. An expanded role and opportunity for geothermal energy use is forecast if its inherent environmental advantages are utilized.

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Section II: Land Use

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Land Use Article Index GEA-101 Effects of Geothermal Induced Subsidence

Bloomer, A. & Currie, S. (2001). Effects of Geothermal Induced Subsidence. Proceedings of 23rd Geothermal Workshop, New Zealand, 3-8.

GEA-102 Environmental Compatibility of Geothermal Energy

Reed, M.J. & Renner, J.L. (1995). Environmental Compatibility of Geothermal Energy. In F.S. Sterrett (Ed.), Alternative Fuels and the Environment. (pp. 27). Boca Raton: CRC Press, Inc.

GEA-103 Changes in Surficial Features Associated with Geothermal Development

in Long Valley, California, 1985-1997 Sorey, M.L. & Farrar, C.D. (1998). Changes in Surficial Features

Associated with Geothermal Development in Long Valley, California, 1985-1997. Geothermal Resources Council Transactions, 22, 61-63.

GEA-104 Subsidence at The Geysers Geothermal Field: Results and Simple

Models Mossop, A., Murray, M., Owen, S. & Segall, P. (1997). Subsidence at The Geysers Geothermal Field: Results and Simple Models. Proceedings of 22nd Geothermal Reservoir Engineering Workshop, Standford University, 377-382.

GEA-105 Causes of Landslides: Conventional Factors and Special Considerations

for Geothermal Sites and Volcanic Regions Voight, B. (1992). Causes of Landslides: Conventional Factors and Special Considerations for Geothermal Sites and Volcanic Regions. Geothermal Resources Council Transactions, 16, 529-533.

GEA-106 Subsidence at Wairakei Field, New Zealand

Allis, R.G. (1990). Subsidence at Wairakei Field, New Zealand. Geothermal Resources Council Transactions, 14 – Part II, 1081-1087.

GEA-107 Towards Solving the Conflict Between Geothermal Resource Uses

Intman, P.R. (1983). Towards Solving the Conflict Between Geothermal Resource Uses. Geothermal Resources Counil Transactions, 7, 357-360.

GEA-108 Land and Resource Use Issues at the Valles Caldera

Intemann, P. (1981). Land and Resource Use Issues at the Valles Caldera. Geothermal Resources Council Transactions, 5, 599-602.

GEA-109 Impacts of Geothermal Power Transmission on Agricultural Operations

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Round, F.O., Jr., Kingery, F.A. & Gardner, R.J. (1979). Impacts of Geothermal Power Transmission on Agriculture Operation. Geothermal Resources Council Transactions, 3, 601-604.

GEA-110 A Summary of Geothermal Resources and Conflicting Concerns in the Alvord Valley, Oregon Wassinger, C.E. & Koza, D.M. (1979). A Summary of Geothermal Resources and Conflicting Concerns in the Alvord Valley, Oregon. Geothermal Resources Council Transactions, 3, 765-768.

GEA-111 An Environmental Overview of Geothermal Development: The Geysers-Calistoga KGRA, Volume 4, Environmental Geology Crow, N.B. (1978). An Environmental Overview of Geothermal Development: The Geysers-Calistoga KGRA, Volume 4, Environmental Geology. Lawrence Livermore Laboratory UC-66a, 1-10, 21-37.

GEA-112 Monitoring Natural Subsidence and Seimicity in the Imperial Valley as

a Basis for Evaluating Potential Impacts of Geothermal Production Crow, N.B. & Kasameyer, P.W. (1978). Monitoring Natural Subsidence and Seismicity in the Imperial Valley as a Basis for Evaluating Potential Impacts of Geothermal Production. Geothermal Resources Council Transactions, 2, 125-128.

GEA-113 Environmental Impacts of Geothermal Resource Development on

Commercial Agriculture: A Case Study of Land Use Conflict Anderson, S. O. (1975). Environmental Impacts of Geothermal Resource Development on Commercial Agriculture: A Case Study of Land Use Conflict. Second United Nation’s Symposium on Geothermal Energy, 1, 1317-1321.

GEA-114 Ground Movement in New Zealand Geothermal Fields

Stilwell, W.B., Hall, W.K. & Tawhai, J. (1975, May). Ground Movement in New Zealand Geothermal Fields. Proceedings of the Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, 1427-1434.

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Land Use Abstracts and Reviews INDUCED SEISMICITY Geothermal resources are almost always found in places that are very tectonically active, which means that these areas will be subject to a great deal of geological activity even in the absence of field development. Therefore, seismic activity in geothermal regions raises questions about whether the calamity was due to natural causes or was man-made. The literature appears to indicate that geothermal operations can indeed cause some seismic activity, but the earthquakes that are generated are extremely small and weak, and usually require sensitive instrumentation to be detected at all, even directly above the epicenter. These microeaerthquakes appear to be associated with the subsurface pressure changes caused by production and injection operations. GEA-111 Crow, N.B. (1978). An Environmental Overview of Geothermal

Development: The Geysers-Calistoga KGRA, Volume 4, Environmental Geology. Lawrence Livermore Laboratory UC-66a, 1-10, 21-37.

Review This study presents a literary overview of information written prior to 1978 on the topics of landslides, ground water, subsidence and seismicity as they pertain to geothermal energy. The authors do a good job of giving the reader a brief introduction to each topic, highlighting key points, and then discussing the relevant articles written on the subject. Abstract/IntroductionThis report is one of a series of volumes reporting the results of an overview study of environmental issues in The Geysers-Calistoga Known Geothermal Resource Area region in the Northern California Coast Ranges. Part I presents the recommended projects together with supporting discussions of the environmental issues and related geologic information, thus serving as an executive summary. These recommendations are intended as a guide to detailed planning, and are not project work statements. Part II is a review of the published and open-file earth sciences literature about the region. It describes the regional framework of the geology, geophysics, and hydrology and provides information about the geothermal resources and the several kinds of geologic hazards – accelerated erosion including landslides, potential interrelationships between geothermal fluids and both potable and thermal ground water, subsidence, and induced seismicity – that may affect the environment as consequences of geothermal development. Studies should be concentrated in relatively small areas where geothermal development is likely. Some of the projects recommended are:

• Planning assessments (normally at map scales of 1:24,000) of the

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potential for accelerated erosions, landslides, and related hazards for small key localities likely to be developed for geothermal production.

• Characterizing potable and thermal ground-water resources likely to be affected by geothermal development. This includes a reconnaissance geohydrologic study and periodic collection of water chemistry and flow data from important ground-water sources for a period of 1-3 years.

• Continuing existing land surface movement and seismograph networks around The Geysers field, and extending them to the region to the northeast of present production.

The appendix to this report is a comprehensive bibliography of scientific information about the Clear Lake-The Geysers region, compiled by David P. Adam of the U.S. Geological Survey, Menlo Park, California.

GEA-112 Crow, N.B. & Kasameyer, P.W. (1978). Monitoring Natural Subsidence

and Seismicity in the Imperial Valley as a Basis for Evaluating Potential Impacts of Geothermal Production. Geothermal Resources Council Transactions, 2, 125-128. ReviewThis paper was written for the Department of Energy (DOE) as part of the Imperial Valley Environmental Project (IVEP), which assessed environmental and socio-economic effects of geothermal development in the Imperial Valley. This study examined geological issues for the IVEP, including subsidence and seimicity. It concluded that geothermal production probably contributes to the subsidence measured in the region, but that it cannot definitively be connected to the measured seimicity in the area, since high levels of seimicty in Imperial Valley have been well documented for many years. Abstract/Introduction The Imperial Valley Environmental Project (IVEP) is being carried out by LLL for the U.S. Department of Energy. Objectives of the project are to identify the key environmental issues about geothermal energy development in the Imperial Valley, to assemble and evaluate available information about these issues, and to develop the additional information necessary for complete environmental assessments. The process is designed to ensure environmentally acceptable development. The IVEP studies cover many technical areas, including air, water and ecosystem quality and socio-economic effects; this paper reports the results of work done on potential geologic effects of geothermal development.

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SUBSIDENCE & LANDSLIDES Because geothermal operations take place in areas that are very tectonically active, it is often difficult to distinguish between geothermal-induced and naturally occuring events. However, geothermal energy production has been shown to at times results in land subsidence. This occurs when the withdrawal of a fluid from an underground reservoir results in a reduction of pressure; thereby causing subsidence. However, subsidence can generally be defined as any slow ground movement, whether is be horizontal movement or vertical movement. Such subsidence occurs not only in geothermal fields, but in petroleum reservoirs as well. The most serious problems have occurred outside of the U.S. and may be the result of different approaches to reinjection technology. Weakening of underground support is suspected as being the cause of massive subsidence at Wairakei geothermal field in New Zealand – the largest subsidence ever recorded which is generally thought to be human-induced. It is also suspected as being responsible for the large landslide at the Zunil geothermal field in Guatemala. Reinjection has been shown to help reduce the effects of subsidence. GEA-101 Bloomer, A. & Currie, S. (2001). Effects of Geothermal Induced

Subsidence. Proceedings of 23rd Geothermal Workshop, New Zealand, 3-8.

ReviewThis article gives a broad overview of subsidence and also examines the case of Wairakei field in some detail. The authors argue that subsidence from geothermal development is no more damaging than the withdrawal of groundwater for irrigation or other purposes. Abstract/IntroductionSubsidence is a consequence of large scale geothermal development, although the magnitude varies greatly between fields. Subsidence is not unique to geothermal fields: it is common where fluids (oil or water) are drawn from aquifers. The greatest subsidence (measured by both area affected and cost of mitigation) arises from withdrawal of groundwater for irrigation or municipal use. Geothermal subsidence can be substantial – many metres – but generally has little practical consequence. Wairakei maximum subsidence is about 15 m, but the effects are relatively slight, whereas much less subsidence at Ohaaki means that the Waikato River may inundate adjacent land and structures. Although the subsidence may be relatively large (tens or hundreds of millimetres per year) because it occurs over distances of kilometres, specialized survey techniques are required to measure it accurately.

GEA-103 Sorey, M.L. & Farrar, C.D. (1998). Changes in Surficial Features

Associated with Geothermal Development in Long Valley, California, 1985-1997. Geothermal Resources Council Transactions, 22, 61-63.

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Review Discusses land surface changes that have occurred since the onset of

geothermal production in Long Valley Caldera, California. Surface changes include subsidence, decline in hot-spring discharge, and heat-induced vegetation kills, among others.

Abstract/Introducation Since 1985, Long Valley caldera in east central California has been the

site of a 40 MW binary-electric geothermal development utilizing water at temperatures near 170EC. During the course of this development, changes have occurred in surficial features, including declines in hot-spring discharge, increases in fumarolic discharge, heat-induced vegetation kills, and land subsidence. Factors responsible for such changes include seismic activity and related ground deformation, seasonal and annual variations in recharge, and changes in geothermal reservoir pressures and temperatures. To date, however, there have been no significant adverse impacts to thermal springs whose usage is important for recreational and economic reasons. A program of hydrologic monitoring has been in effect since 1988 under the direction of the Long Valley Hydrologic Advisory Committee. The monitoring data have provided useful information on the hydrothermal system and its response to development that can be used by regulatory agencies in designating permit conditions and mitigation measures for existing and future resource developments.

GEA-104 Mossop, A., Murray, M., Owen, S. & Segall, P. (1997). Subsidence at The

Geysers Geothermal Field: Results and Simple Models. Proceedings of 22nd Geothermal Reservoir Engineering Workshop, Standford University, 377-382.

ReviewThis study measured the average subsidence rate at The Geysers between 1977 and 1996. The authors determined the average subsidence rate to be 0.047 ± 0.003 m/yr, a miniscule rate compared to Wairakei field. Abstract/IntroductionA series of repeated first order leveling surveys across The Geysers geothermal field were carried out during the 1970’s. The results revealed that the region was apparently subsiding. Between 1973 and 1977 a maximum subsidence of some 0.19 m was observed at, what was then, the centre of steam production activities. During 1996 many of the leveling monuments were reoccupied using GPS receivers and their locations measured to a typical accuracy of σ H ≈ 0.006 m, σ V ≈ 0.02 m, where σ is one standard deviation and the subscript refers to horizontal, H, or vertical, V, measurements. Comparison of GPS to leveling heights is complicated by the fact that the GPS measurements are located within an ellipsoidal reference frame, in this case the WGS84 model, whilst leveling heights are

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relative to a geoid based reference frame, in this case NGVD29. The data were transformed to the same co-ordinate system using a high precision geoid model, GEOID96, plus some further datum corrections. These transformations add approximately 0.03 m of uncertainty to the results but allow direct comparison of measured heights over a 20 year period. Subsidence is clearly observed between the 1977 and 1996 surveys, throughout The Geysers, with a maximum of 0.9 ± 0.05 m. The subsidence can be closely modeled using a small number of simple dilatational point sources (Mogi sources). We note that the location of the best fitting sources corresponds to the mapped steam pressure lows within the reservoir.

GEA-105 Voight, B. (1992). Causes of Landslides: Conventional Factors and

Special Considerations for Geothermal Sites and Volcanic Regions. Geothermal Resources Council Transactions, 16, 529-533. ReviewThis article acknowledges the possibility that geothermal development could contribute to slope stress in areas, thereby triggering landslides. The authors discuss in detail the landslide in Guatemala at the Zunil geothermal field. This article gives an excellent overview of landslides, their causes, and their relation to geothermal energy. Abstract/IntroductionGeothermal sites and volcanic regions often exhibit significant landslide hazard. Such sites are typically characterized by sloping, hydrothermally-weakened saturated ground, and substantial seismic activity. Engineering works associated with geothermal sites, including wells, pipeline networks, and modification of ground by cuts and fills, also may contribute to landsliding. Such landslides are always produced by a combination of processes and circumstances, although specific individual factors may dictate legal responsibility. Thus the causes of landslides can be subdivided into natural causes and those provoked by the works of man. Causes may also be classified into those which increase driving stresses within a slope, and those which decrease ground strength. Of the latter, the role of fluid pressure enhancement is paramount in reducing frictional strength. In geothermal areas, landslides of small to moderate-size are typical; these may be lethal, but are typically understood in terms of conventional geotechnical aspects. The gigantic volcanic landslides may also characterize geothermal areas; there are relatively infrequent, and are also less well understood in terms of cause-and-effect.

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GEA-106 Allis, R.G. (1990). Subsidence at Wairakei Field, New Zealand. Geothermal Resources Council Transactions, 14 – Part II, 1081-1087. ReviewThis article gives an overview of the subsidence that has taken place at Wairakei Field, New Zealand. This article is widely cited in literature regarding subsidence. It gives an updated summary of the various work that has been done at Wairakei regarding subsidence over the years and it ties together much of the literature regarding Wairakei. Abstract/IntroductionThe maximum amount of subsidence at Wairakei Field due to fluid withdrawal reached 11.6 m during 1989. The maximum subsidence rate has decreased from 450 mm/y during the 1970s, to 350 mm/y during the late 1980s. Although the subsidence has caused a pond to form along a 1 km length of the Wairakei Stream passing through the center of subsidence, there has been remarkably little damage to structures around the borefield due to associated horizontal strains. Modeling of the subsidence suggests it originates from a compaction zone of about 150 m depth. This coincides with a pumice breccia unit sandwiched between lacustrine mudstone units. The rate of compaction appears to be controlled by the rate of steam pressure decline near the top of the reservoir. Modeled compressibilities of 10 kbar-1 are consistent with measurements on pumice breccias. Hydrothermal alteration near the original outflow zone of the field may have contributed to the location of the high compressibility zone.

GEA-111 Crow, N.B. (1978). An Environmental Overview of Geothermal

Development: The Geysers-Calistoga KGRA, Volume 4, Environmental Geology. Lawrence Livermore Laboratory UC-66a, 1-10, 21-37.

Review This study presents a literary overview of information written prior to 1978 on the topics of landslides, ground water, subsidence and seismicity as they pertain to geothermal energy. The authors do a good job of giving the reader a brief introduction to each topic, highlighting key points, and then discussing the relevant articles written on the subject. Abstract/IntroductionThis report is one of a series of volumes reporting the results of an overview study of environmental issues in The Geysers-Calistoga Known Geothermal Resource Area region in the Northern California Coast Ranges. Part I presents the recommended projects together with supporting discussions of the environmental issues and related geologic information, thus serving as an executive summary. These recommendations are intended as a guide to detailed planning, and are not

41

project work statements. Part II is a review of the published and open-file earth sciences literature about the region. It describes the regional framework of the geology, geophysics, and hydrology and provides information about the geothermal resources and the several kinds of geologic hazards – accelerated erosion including landslides, potential interrelationships between geothermal fluids and both potable and thermal ground water, subsidence, and induced seismicity – that may affect the environment as consequences of geothermal development. Studies should be concentrated in relatively small areas where geothermal development is likely. Some of the projects recommended are:

• Planning assessments (normally at map scales of 1:24,000) of the potential for accelerated erosions, landslides, and related hazards for small key localities likely to be developed for geothermal production.

• Characterizing potable and thermal ground-water resources likely to be affected by geothermal development. This includes a reconnaissance geohydrologic study and periodic collection of water chemistry and flow data from important ground-water sources for a period of 1-3 years.

• Continuing existing land surface movement and seismograph networks around The Geysers field, and extending them to the region to the northeast of present production.

The appendix to this report is a comprehensive bibliography of scientific information about the Clear Lake-The Geysers region, compiled by David P. Adam of the U.S. Geological Survey, Menlo Park, California.

GEA-112 Crow, N.B. & Kasameyer, P.W. (1978). Monitoring Natural Subsidence

and Seismicity in the Imperial Valley as a Basis for Evaluating Potential Impacts of Geothermal Production. Geothermal Resources Council Transactions, 2, 125-128. ReviewThis paper was written for the Department of Energy (DOE) as part of the Imperial Valley Environmental Project (IVEP), which assessed environmental and socio-economic effects of geothermal development in the Imperial Valley. This study examined geological issues for the IVEP, including subsidence and seimicity. It concluded that geothermal production probably contributes to the subsidence measured in the region, but that it cannot definitively be connected to the measured seimicity in the area, since high levels of seimicty in Imperial Valley have been well documented for many years.

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Abstract/Introduction The Imperial Valley Environmental Project (IVEP) is being carried out by LLL for the U.S. Department of Energy. Objectives of the project are to identify the key environmental issues about geothermal energy development in the Imperial Valley, to assemble and evaluate available information about these issues, and to develop the additional information necessary for complete environmental assessments. The process is designed to ensure environmentally acceptable development. The IVEP studies cover many technical areas, including air, water and ecosystem quality and socio-economic effects; this paper reports the results of work done on potential geologic effects of geothermal development.

GEA-114 Stilwell, W.B., Hall, W.K. & Tawhai, J. (1975, May). Ground Movement in New Zealand Geothermal Fields. Proceedings of the Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, 1427-1434. Review This article first broke the news on the extreme subsidence taking place at the Wairakei geothermal field in New Zealand. Although much has been written on the subject since, this is considered to be the first comprehensive work done that brought the issues of subsidence to the attention of the geothermal community. Abstract/IntroductionGround subsidence and horizontal movement in water-dominated geothermal fields has been clearly demonstrated following almost 20 years of exploitation of the Wairakei field and some 10 years of leveling and control surveys. Recent check surveys have indicated movement of local control points toward the area of greatest subsidence and have highlighted the difficulties in selecting basic control points. Establishing a comprehensive and reliable level network and survey control at the earliest possible opportunity is one of the major requirements of a geothermal exploration program, particularly in its application to the siting of and design of engineering structures. The new Broadlands field afforded an excellent opportunity to proceed on from the Wairakei experiences in establishing an adequate survey network. During a period of 5 years of exploitation, a distinct pattern of subsidence occurred although this may now be influenced to some extent by the discovery of a new feed zone. A further example is reported at Kawerau where a new exploration program is about to commence to assess the field potential. A large pulp and paper mill which draws on steam from a small part of the field may

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well influence the extent of development of the whole field, and hence careful monitoring takes on a very real significant.

LAND-USE CONFLICTS Although geothermal power development generally requires less land than coal or nuclear technologies, its use is still sometimes seen as controversial, and raises several land-use issues. Most frequently, geothermal fields and the surrounding areas are desired for agricultural, recreational, or religious purposes. Although conflicts over agricultural uses can generally be resolved during the leasing process, conflicts over land for recreational or religious purposes are generally more difficult to overcome. GEA-102 Reed, M.J. & Renner, J.L. (1995). Environmental Compatibility of

Geothermal Energy. In F.S. Sterrett (Ed.), Alternative Fuels and the Environment. (pp. 27). Boca Raton: CRC Press, Inc. ReviewThis article briefly mentions geothermal power plant’s land use, among other environmental issues. It notes that geothermal plants use up far less space than traditional fossil-fired plants. The number the authors give on land use is frequently cited in the geothermal literature. Abstract/IntroductionGeothermal energy is one of the cleaner forms of energy now available in commercial quantities. The use of this alternative energy source, with low atmospheric emissions, has a beneficial effect on our environment by displacing more polluting fossil and nuclear fuels. Rapidly growing energy needs around the world will make geothermal energy exceedingly important in several developing countries. In the production of geothermal energy, wells are used to bring hot water or steam to the surface from underground reservoirs. The thermal energy carried in the produced fluid can be used for direct heating in residential, agricultural, and industrial applications; or the thermal energy of higher temperature systems can be used to produce electricity.

GEA-107 Intman, P.R. (1983). Towards Solving the Conflict Between Geothermal

Resource Uses. Geothermal Resources Council Transactions, 7, 357-360. ReviewThis article specifically discusses the issues that arise from the use of geothermal resources for recreation versus its use for electricity generation. This article looks at the benefits of reinjection for surface geothermal features.

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Abstract/IntroductionThe development of a geothermal resource for energy is often seriously hindered by conflict with the alternative use of the same geothermal resource for recreation. Incompatibility between the development of geothermal energy and the enjoyment of surficial thermal features has constrained development in Japan, New Zealand, Europe, and the United States. Four approaches to the resolution of this problem have been identifies. They are 1) research, 2) new technology, 3) design, and 4) marketing.

GEA-108 Intemann, P. (1981). Land and Resource Use Issues at the Valles Caldera. Geothermal Resources Council Transactions, 5, 599-602. ReviewThis article discusses the conflicting land use issues at Valles Caldera, New Mexico. The author argues that any geothermal development undertaken must respect the various other uses of the land. These include recreational uses, wildlife habitat, and Native American religious sites, among others. To date, no geothermal development has taken place at this location. Abstract/IntroductionThe Valles Caldera possesses a wealth of resources from which various private parties as well as the public at large can benefit. Among the most significant of these are the geothermal energy resource and the natural resource. Wildlife, scenic, and recreational resources can be considered components of the natural resource. In addition, Native Americans in the area value the Valles Caldera as part of their religion. The use of land in the caldera to achieve the full benefits of one resource may adversely affect the value of other resources. Measures can be taken to minimize adverse affects and to maximize the benefits of all the varied resources within the caldera as equitably as possible. An understanding of present and potential land and resource uses in the caldera, and who will benefit from these uses, can lead to the formulation of such measures.

GEA-109 Round, F.O., Jr., Kingery, F.A. & Gardner, R.J. (1979). Impacts of Geothermal Power Transmission on Agriculture Operation. Geothermal Resources Council Transactions, 3, 601-604. ReviewPresents a list of issues and concerns regarding the placement of power transmission lines from Imperial Valley through agricultural lands. Most of the issues raised deal with property rights, easements, and potential interruption of agricultural activity. However, most concerns raised seem to have solutions agreeable to both farmers and geothermal developers.

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Abstract/IntroductionFaced with a rapidly growing technology which will soon transform Imperial Valley’s geothermal resources into electrical energy for local use as well as for export, the County of Imperial and the California Energy Resources Conservation and Development Commission recently funded a study aimed at establishing a recommended network of high voltage electrical transmission line corridors within the Imperial Valley. Major emphasis was placed on identifying potential conflicts between such corridors and the long-term viability of the Valley’s agricultural industry. As anticipated, a number of conflicts – both real and perceived – were identified through close interaction with the agricultural community and local leaders. Concurrently, a series of possible solutions and measures designed to minimize these conflicts were also produced. Thus, while the construction and operation of electrical transmission lines does create certain problems for those involved in agricultural production, it is possible – and highly desirable – to design the system in such a way as to eliminate or significantly reduce the potential for conflict.

GEA-110 Wassinger, C.E. & Koza, D.M. (1979). A Summary of Geothermal Resources and Conflicting Concerns in the Alvord Valley, Oregon. Geothermal Resources Council Transactions, 3, 765-768. ReviewSummarizes the various land-use issues associated with hypothetical geothermal development in the largest KGRA in Oregon. These include lawsuits filed by environmental groups, leasing conflicts, Environmental Impact Statement issues, etc. To date, no geothermal development has taken place at this location. Abstract/IntroductionThe geothermal resource potential of the Alvord Valley is among the highest in Oregon. However, environmental concerns, litigation, and administrative requirements have delayed exploration and development of this resource. Present estimates indicate that deep exploratory drilling may not take place on Federal lands in the Alvord Valley until 1982.

GEA-113 Anderson, S. O. (1975). Environmental Impacts of Geothermal Resource Development on Commercial Agriculture: A Case Study of Land Use Conflict. Second United Nation’s Symposium on Geothermal Energy, 1, 1317-1321. ReviewThis paper briefly outlines the environmental hazards of geothermal development, and discusses these issues in relation to commercial

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agriculture. More specifically the article looks at landowner’s decisions to lease or not. Abstract/IntroductionThe environmental impacts from geothermal exploitation are largely limited to the area immediately surrounding the production facilities. This creates the unique situation where private landowners and associated development companies could conceivably bear the full benefits and costs of development with neither adverse nor beneficial implications to the rest of society. This relationship provides the remarkable opportunity to test the contention that when all costs and benefits are “internalized,” maximum social gain is achieved. Analytically, we shall investigate the changes in resource management which occur as landowners become better informed of financial and environmental implications of geothermal development. This paper reports on the preliminary research. This paper examines the probable impact of actions of increasingly well-informed landowners who negotiate for higher lease returns and stronger environmental protection. First we summarize the environmental implications of geothermal development from the private landowner’s perspective, next we hypothesize the probable influence on lease provisions, finally we explore some of the corporate and social implications of these actions.

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Section III:

Water Quality, Brine and Solid Wastes

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Water Quality, Brine and Solid Wastes Article Index

GEA-201 Processing of Spent Geothermal Brines Premuzic, E.T., Lin, M., Bohenek, M., Shelenkova, L., Wilke, R. & Joshi-Tope, G. (1999). Processing of Spent Geothermal Brines. Geothermal Resources Council Transactions, 23, 229-239.

GEA-202 Turning Community Wastes into Sustainable Geothermal Energy: The S.E. Geysers Effluent Pipeline Project

Dellinger, M., Allen, E. (1996). Turning Community Wastes into Sustainable Geothermal Energy: The S.E. Geysers Effluent Pipeline Project. Geothermal Resources Council Transactions, 20, 205-208.

GEA-203 Environmental Compatibility of Geothermal Energy

Reed, M.J. & Renner, J.L. (1995). Environmental Compatibility of Geothermal Energy. In F.S. Sterrett (Ed.), Alternative Fuels and the Environment. (pp. 25-27) Boca Raton: CRC Press, Inc.

GEA-204 Biochemical Processing of Geothermal Brines and Sludges: Adaptability to Multiple Industrial Applications

Premuzic, E. (1994). Biochemical Processing of Geothermal Brines and Sludges: Adaptability to Multiple Industrial Applications. Geothermal Resources Council Transactions, 18, 127-131.

GEA-205 Progress in Geothermal Waste Treatment Biotechnology Premuzic, E.T., Lin. M.S. & Kang, S.K. (1991). Progress in Geothermal Waste Treatment Biotechnology. Geothermal Resources Council Transactions, 15, 149-154.

GEA-206 Hazardous Waste Volume Reduction: A Sulfur Sludge Dewatering

Facility at The Geysers Tso, B. Jr., (1990). Hazardous Waste Volume Reduction: A Sulfur Sludge Dewatering Facility at The Geysers. Geothermal Resources Council Transactions, 14, 1169-1174.

GEA-207 Sulfur Sludge and Its Regulations: A Case Study at the Geysers KGRA,

Lake County, California Crockett, C. (1990). Sulfur Sludge and Its Regulations: A Case Study at

the Geysers KGRA, Lake County, California. Geothermal Resources Council Transactions, 14, 1095-1100.

GEA-208 Environmental Protection and the Chemistry of Geothermal Fluids

Weres, O. (1988). Environmental Protection and the Chemistry of Geothermal Fluids. From Geothermal Science and Technology. (pp. 272-302) Gordon and Breach Science Publishers, Vol. 1.

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GEA-209 Utilization of Geothermal Effluents to Create Waterfowl Wetlands

Kaczynski, V.W., Wert, M.A. & LaBar, D.J. (1981). Utilization of Geothermal Effluents to Create Waterfowl Wetlands. Geothermal Resources Council Transactions, 5, 603-606.

GEA-210 Injection at Raft River – An Environmental Concern?

Spencer, S.G. (1979). Injection at Raft River – An Environmental Concern? Geothermal Resources Council Transactions, 3, 675-678.

GEA-211 Surface Water Issues Facing Geothermal Developers in the Geysers-

Calistoga Known Geothermal Resource Area Bohrer, Z. (1983). Surface Water Issues Facing Geothermal Developers in the Geysers-Calistoga Known Geothermal Resource Area. California Energy Commission EE-39 SWI, 1-34.

GEA-212 An Environmental Overview of Geothermal Development: The Geysers-

Calistoga KGRA, Volume 6, Water Quality Pimentel, K.D. (1978). An Environmental Overview of Geothermal Development: The Geysers-Calistoga KGRA, Volume 6, Water Quality. Lawrence Livermore Laboratory UC-66C, 1-48.

GEA-213 Water Quality Management for Imperial Valley Geothermal

Development Swajian, A., Morris, G.L. & Pimentel, K.D. (1978). Water Quality Management for Imperial Valley Geothermal Development? Geothermal Resources Council Transactions, 2, 631-364.

GEA-214 Disposal of Geothermal Waste Water by Reinjection Einarsson, S.S. & Cuellar, A.V.R.G. (1975, May). Disposal of Geothermal

Waste Water by Reinjection. Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, 1313-1315.

GEA-215 Environmental Impact of a Geothermal Power Plant

Axtmann, R. (1975). Environmental Impact of a Geothermal Power Plant. Science, 187, (4179), 795-803.

GEA-217 Geothermal Hazards: Mercury Emission

Siegel, S.M. & Siegel, B. (1975). Geothermal Hazards: Mercury Emission. Environmental Science & Technology, 9, (5), 473-474.

GEA-216 Reinjection of Geothermal Hot Water at the Otake Geothermal Field

Kubota, K. & Aosaki, K. (1975). Reinjection of Geothermal Hot Water at the Otake Geothermal Field. Second United Nations Symposium on Geothermal Energy, 2, 1379-1383.

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GEA-218 Heavy Metal Contamination from Geothermal Sources Sabadell, J.E. & Axtmann, R. (1975). Heavy Metal Contamination from Geothermal Sources. Environmental Health Perspectives, 12, 1-7.

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Water Quality, Brine and Solid Wastes Abstracts and Reviews

GEOTHERMAL BRINES A number of papers written in the 1970s were critical of geothermal energy. They claimed that geothermal plants contaminated ground and surface water with mercury and other toxic substances. However, modern drilling and casing technology have been effective in protecting groundwater and injection of spent brines has served to maintain reservoir pressures and avoid effects of discharge to surface waters. Current brine research is focused on the extraction of metallic and non-metallic elements and compounds from geothermal brines for industrial use, which is of environmental benefit because it offsets mining of these materials. GEA-201 Premuzic, E.T., Lin, M., Bohenek, M., Shelenkova, L., Wilke, R. & Joshi-

Tope, G. (1999). Processing of Spent Geothermal Brines. Geothermal Resources Council Transactions, 23, 229-239. ReviewThis comprehensive article looks at the work that has been done over the years to enhance the extraction of valuable materials from geothermal brines and discusses recent results in this field. This paper includes a chart which lists common substances found in geothermal water, and lists the environmental effects of each. AbstractStudies of spent geothermal liquids and precipitates aimed at the development of methods for their conversion to non-hazardous, environmentally acceptable “wastes” have shown that they are a potential resource of valuable materials. Isolation of commercially viable products from these resources would offset the overall cost of geothermal power production. Further savings could be accomplished by the development of methods for the prevention of fouling due to the formation of bio-mass in several streams of the processes. Consequently, the current R&D effort is focusing on processes which lead to (1) generation of feedstock amorphous silica for application in the production of fine chemicals, fillers, adsorbents, catalyst carriers and similar materials, (2) recovery of valuable trace metals, such as gold, silver and platinum, and (3) isolation of environmentally friendly anti-fouling agents from naturally occurring sources. Some recent results will be discussed in the present paper.

GEA-203 Reed, M.J. & Renner, J.L. (1995). Environmental Compatibility of

Geothermal Energy. In F.S. Sterrett (Ed.), Alternative Fuels and the Environment. (pp. 25-27) Boca Raton: CRC Press, Inc.

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ReviewThis article discusses the impact of geothermal power plants on water quality, among other environmental issues. It notes that geothermal plants vary widely in the chemical composition of their brines. This makes it difficult to make broad generalizations about water quality issues affecting geothermal plants. The article also notes that current U.S. law requires cooled geothermal fluids to be reinjected into the reservoir to avoid groundwater and surface water contamination. The article offers a good overview of water quality issues relating to geothermal power plants. Abstract/IntroductionGeothermal energy is one of the cleaner forms of energy now available in commercial quantities. The use of this alternative energy source, with low atmospheric emissions, has a beneficial effect on our environment by displacing more polluting fossil and nuclear fuels. Rapidly growing energy needs around the world will make geothermal energy exceedingly important in several developing countries. In the production of geothermal energy, wells are used to bring hot water or steam to the surface from underground reservoirs. The thermal energy carried in the produced fluid can be used for direct heating in residential, agricultural, and industrial applications; or the thermal energy of higher temperature systems can be used to produce electricity.

GEA-204 Premuzic, E. (1994). Biochemical Processing of Geothermal Brines and Sludges: Adaptability to Multiple Industrial Applications. Geothermal Resources Council Transactions, 18, 127-131. ReviewThis dense article discusses the processing of geothermal brines and sludges to extract potentially valuable minerals. The article states that this is an environmentally and economically sound way to deal with geothermal wastes. Abstract/IntroductionExtensive Research and Development effort leading to the identification of low cost environmentally acceptable disposal of geothermal brines and sludges has shown that biochemical processing of the waste streams meets these requirements. Further exploration of the process variables has also indicated that biochemical treatment of waste streams is a versatile technology, adaptable to several applications beyond that of rendering hazardous and/or mixed wastes to non-hazardous by-products which meet regulatory requirements. Such advanced biochemical technologies may be used for arsenic and mercury to the isolation of many metals, including radionuclides. Spin-offs from this technology have also applications in the treatment of crude oils, oil wastes and the recovery of valuable metals and salts. In the metal recovery mode the aqueous phase can be reinjected

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or treated further so that the end products meet the environmental drinking water standards. In this paper, recent studies dealing with the multiple industrial applications potential of biochemical processes will be discussed.

GEA-208 Weres, O. (1988). Environmental Protection and the Chemistry of

Geothermal Fluids. From Geothermal Science and Technology. (pp. 272-302) Gordon and Breach Science Publishers, Vol. 1. Review This article discusses the composition of geothermal brines and displays this information in a chart that breaks down brine composition based on different geothermal locations. The article also talks about disposal of geothermal brines, how reinjection can be of help in disposal, and the challenges silica poses in geothermal brines.

Abstract/IntroductionNone provided.

GEA-209 Kaczynski, V.W., Wert, M.A. & LaBar, D.J. (1981). Utilization of Geothermal Effluents to Create Waterfowl Wetlands. Geothermal Resources Council Transactions, 5, 603-606. Review This article discusses one method of cleaning geothermal effluents through disposal into wetlands. The authors mention that this method is cheaper than reinjection, and can effectively clean geothermal effluents. Although the benefits and risks of using such methods are still debated today, the authors present a unique idea for cleaning geothermal effluent. Abstract/IntroductionA generic research study was performed to determine the feasibility of using spent geothermal fluids to create waterfowl wetlands. Aspects studied included water quality, biology, ecology, toxicology, ground-water hydrology, geology and soils, wastewater treatment, economic, socioeconomic, and legal constraints. Results indicate that some geothermal effluents can be used directly with no treatment to create waterfowl wetlands. Many geothermal effluents can be used to create wetlands with relatively minimal pretreatment; this category is economically more attractive than injection. The wetlands themselves will effectively further cleanse the effluents for possible cascading resource use (such as irrigation water or surface water enhancement). Finally, some effluents require extensive pretreatment before wetland use. Economics in this latter category favor injection.

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GEA-213 Swajian, A., Morris, G.L. & Pimentel, K.D. (1978). Water Quality Management for Imperial Valley Geothermal Development? Geothermal Resources Council Transactions, 2, 631-364. Review This study examined the composition of brine effluents from geothermal plants in the Imperial Valley with that of ground and surface water in the region. Although it admitted that further monitoring was necessary, the study concluded that waste water from the local geothermal power plant was possibly contaminating groundwater with high amounts of Boron, Lithium, Manganese, Strontium, Zinc, and Lead, among other things. Since this study was published in 1978 several technological advances have been made that make the results of this study out-of-date. A new study would certainly be necessary to either confirm or disprove the results presented in this article. Abstract/IntroductionThe development of geothermal resources in the Imperial Valley of California poses the possibility of geothermal brine pollution of surface and subsurface waters. Control of pollution of Imperial Valley waters comes under the jurisdiction of the California Regional Water Quality Control Board, Colorado River Basin Region. Division 7 of the California Water Code requires that “Each regional board shall establish such water quality control plans as in its judgment will insure the reasonable protection of beneficial uses and the prevention of nuisance.” The “Water Quality Control Plan, West Colorado River Basin (7A), April 1975” establishes the following beneficial uses of Imperial Valley water supply canals:

1. Municipal and Domestic Water Supply 2. Noncontact Water Recreation 3. Industrial Water Service Supply 4. Agricultural Water Supply 5. Warm Freshwater Aquatic Habitat 6. Wildlife Habitat 7. Hydropower Generation

In order to protect the beneficial uses of Imperial Valley waters, it is essential that the characteristics of geothermal water quality pollution be understood and closely monitored by the Regional Water Quality Control Board.

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GEA-215 Axtmann, R. (1975). Environmental Impact of a Geothermal Power Plant. Science, 187, (4179), 795-803. ReviewThis article focuses specifically on the geothermal power plant at Wairakei, New Zealand, and examines its environmental impacts. Among other things, it looks at the waste water effluents leaving the plant and being dumped directly into a nearby river. The author examines the impact of the geothermal plant on the ecosystem of the river, and concludes that the power plant has a negative impact on the river. Since this study was published in 1975, the United States has mandated the use of reinjection technology to prevent the contamination of waterways by geothermal plants. The environmental situation at Wairakei is not representative of the geothermal industry in the United States. Abstract/IntroductionTo supply urgent energy needs, many nations are initiating or expanding ventures in geothermal technology. Although geothermal power enjoys a reputation for “cleanness,” relevant environmental data are sparse; as far as I know, no detailed impact analysis of a mature installation has heretofore appeared.

GEA-217 Siegel, S.M. & Siegel, B. (1975). Geothermal Hazards: Mercury Emission.

Environmental Science & Technology, 9, (5), 473-474. ReviewIn this study, the authors measured the levels of mercury emitted from thermal and volcanic sites, and noted that the levels were quite high. The authors cautioned that geothermal development should take this into consideration before development of resources. Abstract/IntroductionEnthusiasm for intensified geothermal exploration may induce many participants to overlook a long-term potential toxicity hazard possibly associated with the tapping of magmatic steam. The association of high atmospheric Hg levels with geothermal activity has been established both in Hawaii and Iceland, and it has been shown that mercury can be introduced into the atmosphere from fumaroles, hot springs, and magmatic sources. These arguments, extended to thallium, selenium, and other hazardous elements, underscore the need for environmental monitoring in conjunction with the delivery of magmatic steam to the surface.

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GEA-218 Sabadell, J.E. & Axtmann, R. (1975). Heavy Metal Contamination from Geothermal Sources. Environmental Health Perspectives, 12, 1-7. ReviewThis article discusses the chemical and heavy metal content of geothermal fluids. The authors provide numbers from Imperial Valley and Cerro Prieto among other places. They pay special attention to the case of Wairakei and the mercury contamination of the river there. Most importantly, the authors provide numbers which show that geothermal plants put out only about 1% of the mercury produced by coal-fired plants. Since this study was published in 1975, the United States has mandated the use of reinjection technology to prevent the contamination of waterways by geothermal plants. Therefore, some of the information presented in this paper may be out-of-date. Abstract/IntroductionLiquid-dominated hydrothermal reservoirs, which contain saline fluids at high temperatures and pressures, have a significant potential for contamination of the environment by heavy metals. The design of the power conversion cycle in a liquid-dominated geothermal plants is a key factor in determining the impact of the installation. Reinjection of the fluid into the reservoir minimizes heavy metal effluents but is routinely practiced at few installations. Binary power cycles with reinjection would provide even cleaner systems but are not yet ready for commercial application. Vapor-dominated systems, which contain superheated steam, have less potential for contamination but are relatively uncommon. Field data on heavy metal effluents from geothermal plants are sparse and confounded by contributions from “natural” sources such as geysers and hot springs which often exist nearby. Insofar as geothermal power supplies are destined to multiply, much work is required on their environmental effects including those caused by heavy metals.

GEOTHERMAL SLUDGE Geothermal power plants that utilize cooling towers accumulate sludge during normal operation. This sludge, commonly comprised of sulfur, has to be dealt with as a hazardous waste and properly disposed of. Current studies have focused on how to more efficiently and cost-effectively dispose of the sludge. GEA-204 Premuzic, E. (1994). Biochemical Processing of Geothermal Brines and

Sludges: Adaptability to Multiple Industrial Applications. Geothermal Resources Council Transactions, 18, 127-131.

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Review This dense article discusses the processing of geothermal brines and sludges to extract potentially valuable minerals. The article states that this is an environmentally and economically sound way to deal with geothermal wastes. AbstractExtensive Research and Development effort leading to the identification of low cost environmentally acceptable disposal of geothermal brines and sludges has shown that biochemical processing of the waste streams meets these requirements. Further exploration of the process variables has also indicated that biochemical treatment of waste streams is a versatile technology, adaptable to several applications beyond that of rendering hazardous and/or mixed wastes to non-hazardous by-products which meet regulatory requirements. Such advanced biochemical technologies may be used for arsenic and mercury to the isolation of many metals, including radionuclides. Spin-offs from this technology have also applications in the treatment of crude oils, oil wastes and the recovery of valuable metals and salts. In the metal recovery mode the aqueous phase can be reinjected or treated further so that the end products meet the environmental drinking water standards. In this paper, recent studies dealing with the multiple industrial applications potential of biochemical processes will be discussed.

GEA-205 Premuzic, E.T., Lin. M.S. & Kang, S.K. (1991). Progress in Geothermal Waste Treatment Biotechnology. Geothermal Resources Council Transactions, 15, 149-154.

ReviewThis article discusses the treatment of toxic geothermal sludges. The authors explain that they have recently developed technology which is an economically and technically feasible method for disposing of geothermal sludge. Abstract/IntroductionStudies directed at the development of an environmentally acceptable technology for the treatment and disposal of geothermal sludges have shown that a biotechnology based on microbial bio-chemical processes is technically and economically feasible. Process designs for the emerging bio-technology have to take several variables into consideration. In the present paper some of these variables will be discussed in terms of their effect on the cost and efficiency of potential processes.

GEA-206 Tso, B. Jr., (1990). Hazardous Waste Volume Reduction: A Sulfur Sludge Dewatering Facility at The Geysers. Geothermal Resources Council Transactions, 14, 1169-1174.

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Review

This article describes a system developed by PG&E which reduces the volume of geothermal sludge from The Geysers by two-thirds. The system developed dries and compacts the sludge so that PG&E’s shipping cost of hazardous waste could be reduced. Abstract/Introduction

Sulfur sludge accumulates in geothermal power plant cooling tower basins during normal operation. Installing a permanent automatic vertical chamber filter press at the Geysers to dewater this sludge has reduced hazardous waste quantities and associated operating costs by two-thirds. After passing through a separator tank, filtrate from the filter press is clean enough to be reinjected into the steam reservoir. This paper presents the details of the design, installation, and operation of filter press facility.

GEA-207 Crockett, C. (1990). Sulfur Sludge and Its Regulations: A Case Study at the Geysers KGRA, Lake County, California. Geothermal Resources Council Transactions, 14, 1095-1100.

Review

This article summarizes the issues surrounding the disposal of sludge as a hazardous waste from geothermal developments. A comprehensive article that gives a good overview of California regulations regarding the disposal of sludge. Includes a table which shows breakdown of minerals found in sludge.

Abstract/Introduction

The use of geothermal energy to produce electricity is environmentally benign in comparison to the use of fossil fuels. However, at The Geysers in Northern California, the resource contains hydrogen sulfide gas which is regulated by the local Air Pollution Control District and may not be emitted to the atmosphere without abatement. The abatement of H2S results in the production of a sulfur sludge which is sometimes hazardous. Federal and State regulations, administered by the Environmental Protection Agency and Department of Health Services respectively, regulate the treatment, storage and disposal of this sludge. The Department of Transportation regulates its transport from the site of generation to its disposal point. Regulations covering sulfur sludge and analysis of the options available for its disposal are discussed.

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REINJECTION TECHNOLOGY The development of reinjection technology has greatly helped geothermal plants with the disposal of brine in a safe and effective way. The papers in this section examine the development of this technology and its environmental benefits. GEA-208 Weres, O. (1988). Environmental Protection and the Chemistry of

Geothermal Fluids. From Geothermal Science and Technology. (pp. 272-302) Gordon and Breach Science Publishers, Vol. 1. Review This article discusses the composition of geothermal brines and displays this information in a chart that breaks down brine composition based on different geothermal locations. The article also talks about disposal of geothermal brines, how reinjection can be of help in disposal, and the challenges silica poses in geothermal brines. Abstract/IntroductionNone provided.

GEA-210 Spencer, S.G. (1979). Injection at Raft River – An Environmental Concern? Geothermal Resources Council Transactions, 3, 675-678. Review In this study, the author shows that geothermal fluid reinjected back into the reservoir can leach into shallow aquifers surrounding the geothermal system. Given the chemical makeup of the geothermal fluids in the Raft River geothermal system, such leaching is probably of environmental concern. This is a very old source, and technological advances have been made since this time that inhibit the leaching of geothermal brines during reinjection. Abstract/IntroductionInjection is an acceptable disposal method for geothermal fluid; however, use of injection can be limited by environmental considerations. This is the case in Raft River. The primary concern is that injection will affect either the quality or quantity or irrigation water in the closed groundwater basin. Data indicate that there is a natural migration of geothermal fluids into shallower aquifers to intermediate-depth injection. Several of these monitor wells have shown marked pressure response to injection in RRGI-4 and RRGI-6. These data will be used to evaluate both current injection practices and fluid disposal alternatives in Raft River.

GEA-214 Einarsson, S.S. & Cuellar, A.V.R.G. (1975, May). Disposal of Geothermal Waste Water by Reinjection. Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, 1313-1315.

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ReviewThis article summarizes the results of an experiment with reinjection done in El Salvador in the 1970s. A comprehensive article that gives an example of a successful reinjection program at one high-temperature geothermal system in Central America.

Abstract/Introduction Highly mineralized waters represented a major problem for the

exploitation of the Ahuachapán geothermal field. Large-scale reinjection experiments were successfully carried out in 1970 and 1971, during which time almost 2,000,000 cu m of water at 150°C were reinjected at the rates of 91 and 164 liters/sec by using a combination of gravity and vapor pressure as the driving force. The water was injected into the high-temperature aquifer at depth, and the resulting cooling effect was observed. No technical difficulties from scaling or of any other nature were experienced.

It was concluded that reinjection should be carried out within the high-temperature system, which means recycling the water with the residual heat after flashing to the reservoir, thus practically eliminating any danger of insufficient water for heat extraction even with limited natural recharge, and possibly at the same time effecting significant conservation of energy.

The local cooling effect around the point of injection, which should be a minimum of 1.5 km away from the production area, was estimated and found to be of minor significance in relation to the expected benefits.

The cost of reinjection was estimated to be approximately 1 US mill/kWh, and the reinjection of the waste water is considered a technically and economically feasible disposal method.

GEA-216 Kubota, K. & Aosaki, K. (1975). Reinjection of Geothermal Hot Water at the Otake Geothermal Field. Second United Nations Symposium on Geothermal Energy, 2, 1379-1383. Review This paper mainly discusses reinjection technology, which at the time the paper was written, was a relatively new concept. It mentions that in the researcher’s experiments, no sign of leakage in the reinjection wells was noticed. This is important as it indicated that reinjection in sealed wells does not cause ground or surface water contamination. Abstract/IntroductionAt the Otake geothermal field, geothermal hot water has been reinjected under the ground since March, 1972 for the purposes of an artificial

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supply of hot water to the geothermal resources and of the disposal of hot water separated from the mixture of the production wells. The total hot water reinjected by three reinjection wells is 8 million tons to date. A tendency of increased steam discharge from each production well was observed. So far we have seen no influence of reinjection on ground water and surrounding hot springs, and have no indication of leakage of the reinjected water to the surface. In addition, earthquakes which might be caused by reinjection have not occurred. This paper presents the purpose of reinjection, the place and the specification of reinjection wells, and the conditions and results of reinjection.

WATER RIGHTS AND COMPETING USES There was a limited amount of information found on the subjects of water rights and competing uses. However, from the available literature it appears that water-rights issues were of much greater concern during the 1970s, before the widespread and successful use of reinjection technology. However, since reinjection of spent fluid in to the reservoir has become standard practice, water rights and geothermal developments impacts on other water users have not been major problem. In addition, recent developments have shown that treated wastewater from local communities can be injected into geothermal reservoirs to help preserve the life of the field. Please see the “Reinjection Technology” subsection for more information on the issue of reinjection. GEA-202 Dellinger, M., Allen, E. (1996). Turning Community Wastes into

Sustainable Geothermal Energy: The S.E. Geysers Effluent Pipeline Project. Geothermal Resources Council Transactions, 20, 205-208. Review This article summarizes the plans and progress for the effluent pipeline project at The Geysers. This project brings treated waste water from Lake County to The Geysers for injection. The paper discusses some of the permits and agreements needed to complete the project and gives a brief history of the development process of the project. Abstract/IntroductionA unique public/private partnership of local, state, federal, and corporate stakeholders are constructing the world's first wastewater-to-electricity system at The Geysers. A rare example of a genuinely "sustainable" energy system, three Lake County communities will recycle their treated wastewater effluent through the southeast portion of The Geysers steamfield to produce approximately 625,000 MWh annually from six existing geothermal power plants. In effect, the communities' effluent will

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produce enough power to indefinitely sustain their electric needs, along with enough extra power for thousands of other California consumers. Because of the project's unique sponsorship, function, and environmental impacts, its implementation has required: 1) preparation of a consolidated state environmental impact report (EIR) and federal environmental impact statement (EIS), and seven related environmental agreements and management plans; 2) acquisition of 25 local, state, and federal permits; 3) negotiation of six participant agreements on construction, operation, and financing of the project; and 5) acquisition of 163 easements from private land owners for pipeline construction access and ongoing maintenance. The project's success in efficiently and economically completing these requirements is a model for geothermal innovation and partnering throughout the Pacific Rim and elsewhere internationally.

GEA-211 Bohrer, Z. (1983). Surface Water Issues Facing Geothermal Developers in the Geysers-Calistoga Known Geothermal Resource Area. California Energy Commission EE-39 SWI, 1-34.

ReviewDiscusses water-rights issues encountered by geothermal developers in the Geysers-Calistoga KGRA. The author gives an overview of water rights issues that injection may raise, and claims that geothermal development at The Geysers has “led to adverse impacts on local water quality and increased use for industrial purposes.” The article also briefly discusses surface water contamination geothermal development may cause during construction. While this report provides a basic overview of water-rights issues, many of the concerns the author raises are outdated due to the advent of reinjection technology. Abstract/Introduction During 1982-83 the California Energy Commission (CEC) conducted a water use investigation within the Geysers-Calistoga Known Geothermal Resource Area (KGRA). The purpose of the investigation was to determine the extent of competition between local water users and steam field developers for existing water supplies and the need for additional water resource development. To determine current and future needs CEC canvassed local water users, reviewed water rights records and investigated plans for proposed water supply projects. The evaluation focused on the Big Sulphur, Putah and Kelsey Creek basins and provided a perspective from which steam field developers, power producers, local residents and public agencies can evaluate existing water uses, future demands and the need for additional water supply projects.

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Because streamflow and water use data is fragmentary the report focuses subjectively on the following:

• Current and potential competition for local water supplies; • A qualitative assessment of the effects of steam field development

on local water supplies, in-stream flow rates and water quality degradation;

• Opportunities for the use of existing water supplies for geothermal developments; and

• Need for additional water supply projects capable of meeting the needs of local users and geothermal developers.

GEA-212 Pimentel, K.D. (1978). An Environmental Overview of Geothermal

Development: The Geysers-Calistoga KGRA, Volume 6, Water Quality. Lawrence Livermore Laboratory UC-66C, 1-48.

ReviewThis is a rather outdated overview of water quality issues pertaining to geothermal development in the Geysers-Calistoga region. The report covers three main topics within water quality: erosion, cooling tower drift, and accidental spills. The authors state that erosion and sedimentation of streams after construction presents the biggest water quality concern for geothermal developers and that too little is known about cooling tower drift to make any definitive statements. Abstract/IntroductionThe report identifies key issues, assesses available information, and recommends research related to water quality degradation resulting from geothermal development in The Geysers-Calistoga Known Geothermal Resource Area. Data necessary for making decisions to minimize damage while allowing development is lacking in three areas:

• For the whole KGRA, there is insufficient information on the relation of industry-related construction to erosion, with its resulting increase in sediment and silt in area streams.

• The effects of cooling tower drift on soils and vegetation near power plants should be studied as precursors of potential effects on water quality.

• For the hot-water resource area in the eastern portion of the KGRA, a long-range program of water quality monitoring is needed to establish a baseline.

We recommend that future funding for water quality research be concentrated in these three areas of inquiry.

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Section IV: Noise Pollution

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Noise Pollution Article Index GEA-301 Impacts on the Physical Environment

Brown, K. (1995). Impacts on the Physical Environment. Pre-Courses of the World Geothermal Congress, C4, 39-55.

GEA-302 Environmental Noise Need Not Hinder Geothermal Development

Norris, T. (1982). Environmental Noise Need Not Hinder Geothermal Development. Geothermal Resources Council Transactions, 6, 509-512.

GEA-303 Simulated Geothermal Drilling Noise Study

Hass, W., Norris, T. & Carey, D. (1981). Simulated Geothermal Drilling Noise Study. Geothermal Resources Council Transactions, 5, 239-242.

GEA-304 Northern California Power Association-Shell Oil Company Geothermal

Project No. 2: Noise Effects Lamson, K.C. (1979). Northern California Power Association-Shell Oil Company Geothermal Project No. 2: Noise Effects. Lawrence Livermore Laboratory, UC-66e, 1-26.

GEA-305 An Environmental Overview of Geothermal Development: The Geysers-

Calistoga KGRA, Volume 3, Noise Leitner, P. (1978). An Environmental Overview of Geothermal Development: The Geysers-Calistoga KGRA, Volume 3, Noise. Lawrence Livermore Laboratory UC 66c, 1-8.

GEA-306 Resource, Technology, and Environment at The Geysers

Weres, O., Tsao, K. & Wood, B. (1977). Resource, Technology, and Environment at The Geysers. Lawrence Berkeley Laboratory, LBL-5231, V-17-V-20.

GEA-307 Environmental Impacts of Geothermal Resource Development on

Commercial Agriculture Anderson, S.O. (1975). Environmental Impacts of Geothermal Resource Development on Commercial Agriculture. Second United Nations Symposium on Geothermal Energy, 2, 1317-1321.

GEA-308 Environmental Noise and Vibration Control at Geothermal Sites

Jhaveri, A.G. (1975, May). Environmental Noise and Vibration Control at Geothermal Sites. Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, 1313-1315.

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Noise Pollution Abstracts and Reviews Geothermal development is a somewhat noisy process, and mitigating noise pollution should be taken into consideration, especially when developing geothermal resources near residential areas. However, how serious a problem noise pollution is for the industry is not clear from the published literature. Most of the information that is available on the matter is outdated and doesn't comport with current practices of the geothermal industry. Technological developments have allowed modern geothermal developers to muffle noise to acceptable levels for residential areas, and yet these technological advances are generally not reflected in the literature. In fact, it appears that most of the data sited on geothermal noise pollution can be traced back to a report done by the Department of Interior in 1973. There is a clear need for updated published information in this subject area. GEA-301 Brown, K. (1995). Impacts on the Physical Environment. Pre-Courses of

the World Geothermal Congress, C4, 39-55. ReviewThis article discusses the noise created by geothermal developments, among other things. The article gives a table showing decibel noise levels for several common sounds that geothermal development would produce in comparison to “everyday” sound levels. The decibel noise levels listed for geothermal sounds appear high in comparison to other published information on the subject. Abstract/IntroductionExploration, development and utilization of a geothermal area can have a significant impact on the physical environment surrounding the resource. During the initial exploration stages, the impact will be slight, due mainly to the construction of access tracks for geochemical and geophysical measurements. If the decision is made to move on to exploration drilling, then the consequences for the physical environment become more pronounced. At this stage, access roads and drill pads need to be constructed with their attendant problems for the landscape, noise is emitted from the drilling operations, and cooling water may be required. As development proceeds, the effect on the landscape reaches a maximum when more land is required for further drilling operations, pipeline routes and the power station. Also during these construction phases, noise pollution increases, local waterways become affected by construction run-off and the appearance of the landscape can be drastically altered with large earthworks. With the exploitation phase, a number of new impacts on the physical environment become important. Natural geothermal features may decrease or increase in activity, the local climate may be affected, large volumes of cooling water may contribute to thermal pollution of local waterways and some areas of land may be subject to

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subsidence. It is these effects that the paper suggests need further investigation.

GEA-302 Norris, T. (1982). Environmental Noise Need Not Hinder Geothermal

Development. Geothermal Resources Council Transactions, 6, 509-512. Review In this article the author explains and assess the available technology to muffle noise from geothermal power plants. The author claims that the use of such technology makes it possible to develop geothermal resources close to residential communities. Abstract/IntroductionEnvironmental noise issues have hindered some geothermal power developments located near residents by delaying necessary regulatory approvals. However, with full use of demonstrated noise control technology, noise can be reduced to levels acceptable to most quiet rural communities at a distance of about 1000 feet. Thus, it may be feasible to drill closer to residences than is often presumed.

GEA-303 Hass, W., Norris, T. & Carey, D. (1981). Simulated Geothermal Drilling

Noise Study. Geothermal Resources Council Transactions, 5, 239-242. ReviewThis paper presents the results of a study carried out by Republic Geothermal, Inc. to determine noise levels in geothermal production areas. Their study measured a peak noise pollution of 52 dBA. Abstract/IntroductionGeothermal drilling noise was simulated at potential well sites located in Republic Geothermal, Inc.’s Robbins-Perini Hill Project area in Lake County, California. The noise levels at selected receptor sites located in the project’s vicinity were recorded and compared with worst case noise impacts predicted by spherical spreading and molecular absorption modeling calculations. The results indicate that noise attenuation was greater than predicted at receptor sites in close proximity due to the shielding ridges, and was generally less than predicted at other receptor sites due apparently to unique atmospheric conditions present at the time of testing. Reduction of the emanating noise source produced a less-than-equal reduction in the measured noise at the receptor sites.

GEA-304 Lamson, K.C. (1979). Northern California Power Association-Shell Oil Company Geothermal Project No. 2: Noise Effects. Lawrence Livermore Laboratory, UC-66e, 1-26.

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Review This article gives an overview of noise pollution associated with a geothermal power plant in the Geysers-Calistoga region. The article provides charts with dBA levels from common noises and from geothermal power plants. The report notes that well venting is typically the loudest geothermal noise, which is normally about 125 dBA at a distance of 50ft. The decibel noise levels listed for geothermal sounds appear high in comparison to other published information on the subject. AbstractThis report evaluates occupational and environmental noise impacts from the construction and operation of the Northern California Power Association-Shell Oil Company 110-MW geothermal power plant and associated steam wells located in The Geysers-Calistoga Known Geothermal Resource Area. Available data and measurements indicate that the nearby populated noise-sensitive areas will not be significantly affected by the construction or operation of this facility.

GEA-305 Leitner, P. (1978). An Environmental Overview of Geothermal

Development: The Geysers-Calistoga KGRA, Volume 3, Noise. Lawrence Livermore Laboratory UC 66c, 1-8.

ReviewThe first part of this report lists and analyses useful resources on various aspects of noise from geothermal developments. The second part of the report focuses on methodologies used when studying geothermal noise. The third and final part discusses technologies to muffle geothermal noise, which by now may be outdated. AbstractNoise from geothermal resource development at The Geysers-Calistoga Known Geothermal Resource Area (KGRA) will cause community annoyance unless noise-level standards are set and adhered to. Venting of steam is the loudest source of noise and can reach 100 to 125 dBA at 20 to 100 ft; most of the other noise sources fall below 100 dBA and are those usually associated with construction and industrial projects. Enough data exist for assessment and decision making, but it is scattered and must be compiled. In addition, communities must decide on their criteria for noise levels. Residential areas in The Geysers-Calistoga KGRA will require more stringent controls on noise than will the open space of which the KGRA is primarily composed. Existing technology can reduce noise levels somewhat, but more effective silencing devices are needed, particularly on steam venting systems.

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GEA-306 Weres, O., Tsao, K. & Wood, B. (1977). Resource, Technology, and Environment at The Geysers. Lawrence Berkeley Laboratory, LBL-5231, V-17-V-20.

Review One section of this paper covers noise and noise control technology used in geothermal development. The authors provide a helpful table that shows dBA levels for various geothermal noises. The section on noise within this paper is quite brief. Abstract/IntroductionNone available

GEA-307 Anderson, S.O. (1975). Environmental Impacts of Geothermal Resource

Development on Commercial Agriculture. Second United Nations Symposium on Geothermal Energy, 2, 1317-1321. Review This paper has a short section on geothermal noise pollution, and it primarily discusses its effects on livestock. The article references a chart that shows decibel levels of common geothermal production noises. Abstract/Introduction The environmental impacts from geothermal exploitation are largely limited to the area immediately surrounding the production facilities. This creates the unique situation where private landowners and associated development companies could conceivably bear the full benefits and costs of development with neither adverse nor beneficial implications to the rest of society. This relationship provides the remarkable opportunity to test the contention that when all costs and benefits are “internalized,” maximum social gain is achieved. Analytically, we shall investigate the changes in resource management which occur as landowners become better informed of financial and environmental implications of geothermal development. This paper reports on the preliminary research. This paper examines the probable impact of actions of increasingly well-informed landowners who negotiate for higher lease returns and stronger environmental protection. First it summarizes the environmental implications of geothermal development from the private landowner’s perspective, next it hypothesizes the probable influence on lease provisions, finally it explores some of the corporate and social implications of these actions.

GEA-308 Jhaveri, A.G. (1975, May). Environmental Noise and Vibration Control at

Geothermal Sites. Second United Nations Symposium on the Development and Use of Geothermal Resources, 2, 1313-1315.

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Review This article appears to be one of the first ever written specifically on geothermal noise pollution. It discusses human health impacts on noise and vibration coming from geothermal developments. Although this article is only a proposal for further research, it highlights the need for such research in this area, and addresses the lack of substantive information regarding geothermal energy and noise pollution. Abstract/Introduction Environmental effects of withdrawing steam from the earth are several. Air pollution, thermal pollution, water pollution, land subsidence, ground-water contamination, and possible earth tremors constitute a formidable array of unanswered environmental questions. The more pressing environmental issues generally relate to local effects. Land use, aesthetics, effect on recreation, damage to resources and wildlife, local physical pollutants, geographic changes, and destruction of wilderness areas have environmental effects that immediately affect people and their surroundings. Such effects must—and generally can—be reduced, made beneficial, or offset by responsible and dedicated utility planning. It suffices to say that geothermal power is not environmentally free. Although the economics of geothermal energy appear to be promising, the environmental hazards seem manifold. The effects and control of excessive noise and ground-born vibrations within the framework of a comprehensive geothermal Environmental Impact Statement (EIS) will be the main objective of this paper.

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