036is5442/80/0?01411 l/w2.w/o zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Printed in Great Britain zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Vol Em-&-v S pp Ill-16s tb Pergamon Pres I.ld 1980 GEOTHERMAL ENERGY AND THE ENVIRONMENT: THE GLOBAL EXPERIENCE Department of Geography, M J zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML PASQUALETTI State University, Tempe, AZ 85281 U.S.A zyxwvutsrqponmlkjihgfedcbaZ Arizona (Receked 29 May 1979) Abstract-The conflict between energy supply and the environment is one of the critical issues of our time and geothermal energy, often touted as plentiful and environmentally benign, has received a measure of attention as one possible answer to the problem Some environmental issues, however, have been encountered during the development of the world’s geothermal resources and these have had an impact on the speed of development The environmental problems at each of the world’s geothermal generating stations are discussed in this paper The significant environmental impacts include conflicts in land use, air pollution, subsidence water pollution, induced seismicity, blowouts, and noise, and every country has encountered some difficulty with one or more of these problems Development plans have been slowed by environmental concerns in tome countries In the U.S.A., this problem has been the emission of hydrogen sulfide: in Japan, land use in national parks plus waste-water disposal; in El Salvador, waste-water disposal Other environmental impacts which have not had an appreciable effect on development plans include: waste-water disposal and subsidence in New Zealand, land use and air pollution in Mexico Italy has encountered no particular environmental barriers yet but this may be a function of minimal monitoring Collectively, the environmental difficulties at the operating power stations around the world have been minor compared to the actual disasters that have befallen other processes of generating electricity Even the polenlial environmental hazard of geothermal energy development is much less It cannot be compared to a massive oil spill, a strip mine, or a radiation leak Nevertheless, geothermal development faces an array of rules and regulations which, in view of world-wide environmental experience, need not be so strict Regulation i\ particularly tight in the United States, a country which would, with appropriately relaxed controls, stimulate a global acceleration in development Instead, the U.S lies smothered in rules, and electrical geothermal development everywhere remains mired in a role of insignificant contribution INTRODUCTION Within the past ten years we have become most clearly aware of the finite nature of two commodities, energy resources and environmental quality During that time it has become increasingly apparent that not only is there an “energy crisis” but there is also an “energy and environment crises” No step in the development of energy zyxwvutsrqponmlkjihgfedcbaZY resources is free of environmental impact, and no action on behalf of the environment is without energy implications Individually each topic touches our daily lives Collectively there may be no more central theme in the broad spectrum of relationships between man and his world One hope for the future is an energy source which is at once plentiful and environmentally benign, one which removes us from the painful position of choosing in favor of one need at the expense of the other In the search for such a source of power geothermal energy has received a share of attention Although geothermal resources have been known and utilized in various forms for thousands of years, their use for the generation of electricity or even for large-scale direct applications such as space conditioning has been small and little noted Rising costs of fossil fuels and the claim of a relatively small environmental impact from geothermal development have lately stimulated interest in reversing this situation Ironically, environmental regulations have often played an important part in slowing the development and use of the resource, especially in the United States With new developments being proposed, the need for a global sharing of environmental experience and solutions becomes apparent and meaningful Such exchange can allay apprehensions while sensitizing responses in areas of appropriate concern In theory, at least, this should render the decision-making process everywhere speedier and more commensurate with the facts Applicable data have been accumulating rapidly and we are now at a point where the worldwide body of experience is large enough to allow beneficial analysis but not quite too compendious for brief summary and study In such light the aim of this paper is to summarize III EGY Vol S No 2-A M zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHG J PASQUALETTI 112 and evaluate the actual operational environmental experience of the world’s geothermal power plants (Table 1) (Fig 1) This will be done in terms of what the problems have been and what is being done about them Environmental impacts may vary with differences in local environmental sensitivities, reservoir characteristics, bureaucratic procedures, and long-term cultural heritage, but it appears that most countries face similar environmental problems in developing their geothermal resources Clearly, these problems are not mutually exclusive, but ‘for purposes of presentation they have been categorized as follows: land use, air pollution, subsidence, water pollution, induced seismicity, blowouts, and noise The order of presentation of course has been largely subjective The topic of land use is placed first because, in one way or another, most of the problems can be reduced to the considerations of land use An early discussion of land use is also a convenient way to introduce each geothermal area The subsequent placement of air pollution is a function of the emphasis it has received Subsidence, water pollution, and induced seismicity are tied together by considerations of reinjection Blowouts and noise are generally lesser problems One will note that issues of societal impact are not mentioned This should not be construed as a deletion for lack of significance but rather a reflection of sparse data Partially filling this void a new bookt on geothermal development in California considers many socio-economic issues Table Summary of operating geothermal power plant installed capacity Source: Ronald DiPippo, “A summary of the technical specifications of the geothermal power plants in the world” U.S Dept of Energy Contract EY-76-S-02-4051.AOO1, Report No CATMEC/ZI, Brown University, Draft,Revision1 Year of Start-up Country/Plant Site Capacity/ MW Totals El Salvador Ahuachapan, Unit Ahuachapan, Unit 1975 1976 30.0 30.0 1969 3.0 60 Mw Iceland Namafjall Waciferous region) Larderello (5 units) Larderello (6 units) Gabbro Castelnuovo V.C (4 units) Serrazzano (5 units) Lag0 (3 units) Sass0 Pisano (2 units) Monterotondo Sant'Ippolito-Vallonsordo Lagoni Rossi Lagoni Rossi Sass0 Capriola Molinetto Travale (Monte Pmiata region) Bagnore Bagnore Piancastagnaio Matsukawa Otake Onuna Onikobe Hatchobaru Takinoue (Kakkonda) Binary (pilot) 1969 1969 -_ -_ lG2 1962 -_ -_ 69.0 120.0 15.0 50.0 47.0 33.5 15.7 12.5 0.9 3.5 3.0 7.0 3.0 lG3 1::: 1959 1969 1::; 1966 1967 1973 1975 1977 1977 1978 20.0 10.0 10.0 25.0 50.0 50.0 1.0 1973 1973 1979 1979 37.5 37.5 37.5 37.5 3.0 Mw 420.6 N 3.5 166 Mw Mexico Cerro Cerro Cerro Cerro Prieto Prieto Prieto Prieto I, I, I, I Unit Unit Unit Unit Wahrl Fdmunds and Adam Rose (Fds.), Praeger, New York (1979) 3* 4* 150 Mvl Geothermal Energy and Regional Development: The Case of Imperial County Geothermal energy and the environment: II3 the global experience Table zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA I (C’ontd) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK of Capaci tyl Total s Start-up MW zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Year Country/Plant New Site Zealand Kawerau Wairakei, Station A: Unit (HP) Unit (HP) Unit (HP) Unit (HP) Unit (IP) Unit (IP) Unit (LP) Unit (LP) Unit (LP) Unit (LP) Wairakei, Station B: Unit JMP) Unit (MP) Unit IMP) 1961 10.0 1958 1959 1962 1962 1959 1959 1959 1959 1960 1960 6.5 6.5 11.2 11.2 11.2 11.2 11.2 11.2 11.2 11.2 1962 1963 1963 30.0 30.0 30.0 Philippines Leyte, Portable Power Unit Los Banes, Wellhead Unit 1917 1977 3.0 1.2 4.2 Mw Indonesia Kampojang, West Java 1978 0.25 0.25 Mw Turkev Kizildere, Wellhead Unit 1975 0.5 lU.5Mw Union of Soviet Socialist Republics 1967 Pauzhetka 5.0 5.0 Mw 1.0 1.0 MN 202.6 Mw People's Republic of China Tibet United States The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit The Geysers, Unit 10 11 12* 13* World total instal?ed capacity 1960 1963 1967 1968 1971 1971 1972 1972 1973 1973 1976 1979 1979 11.0 13.0 27.0 27.0 53.0 53.0 53.0 53.0 53.0 53.0 106.0 667 Mw zyxwvutsrqponmlkjihgfedcbaZYXWVUT 110.0 55.0 _ *Units added too late for complete reworking of the text Unless specifically refer to the situation priorto the commercialization of the new units 1680.15 Mw noted, all calculations and comments The present paper should not be considered as a guide to everything which may happen or even a methodology for policy makers; other problems may still arise Events suspected but not evidenced have received little attention I am not deliberately trying to predict future events The parameters for the study have been as follows: (1) Those aspects which have effects on environmental quality In other words, little notice has been paid to problems which generally not threaten the environment directly, e.g scaling, corrosion, and cavitation; (2) topics dealing with normal construction and operations, as well as accidental occurrences; (3) those operations which have had an appreciable effect or at least have been studied The topics discussed are not unique to geothermal sites but usually may be found in some phase of conventional energy development Nevertheless, no concerted effort is being made here for a point by point comparison between geothermal operations and more conventional power plants The approach taken has been to present the geothermal data and to allow the reader the opportunity to compare it with any specific conventional power plant It should be mentioned that it has not been possible to visit each site personally, but available public and in-house material has been complemented by correspondence with experts within each country, conversations with persons in the U.S who have had recent first-hand field experience, and discussions with foreign experts who have visited the U.S I would welcome additional data on any site 114 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA M J PASQUALETTI Geothermal energy and the environment: LAND the global experience II5 USE Two inherent characteristics of geothermal energy are fundamental to all considerations of land use: (I) site specificity, and (2) the lack of many aspects of conventional fuel extraction, processing, and transportation The site specific nature of the resource is directly related to the desire to maintain heat quality: the greater the distance the steam or hot water is piped the more the original temperature will drop Such decreased heat content affects plant efficiency and ultimately energy price With the power plant effectively constrained to the site of the reservoir, field development must give close consideration to the nature of the land surface and its present use, whether it be wasteland or scenic wonder, flat or mountainous agricultural field or metropolis Competitive land use, actual or foreseen, can slow and even halt development unless all parties are satisfied Even if the area is unpopulated and scenically commonplace, a hilly, inaccessible location will present problems of extra expense and slope stability which would be absent in a flat area well serviced by a preexisting road network Potential effects on land use reach beyond the actual site of the power plant Noise, roadway construction and use, odors, climatic effects, and alteration of wildlife habits and habitats may all be noticeable some distance from the center of activities and influence land use there The absence of several traditional steps in the generation of electricity from geothermal resources has been offered as an environmental argument in favor of its development.’ It is contended, correctly, that this absence reduces the collective negative impact on land use By the same token, however, impacts from the remaining steps are unalterably found in a single area and can influence substantial land locally Significantly, the degree of disturbance, though over a wide area, is comparatively light, and farming, for example, can continue between pipelines and power plants This is not possible within the perimeter fence of other types of generating stations Two criteria are primarily responsible for the scattered location of facilities at geothermal generating sites First, geothermal developments require extra spacing between individual turbine houses This is a direct function of the short distance the steam/water can be piped and the need to maintain reservoir temperature and pressure: if the entire well field were in one area, the resource would be depleted more rapidly Second, extra area is needed for injection wells These must be positioned at a distance close enough to recharge the production zone but far enough away to avoid quenching A generalized scheme of land needs has been worked out The drill site commonly occupies an area of approx 250 km2 The entire pad generally involves an area of less than half a hectare which must be cleared and graded Adjacent to the actual drill rig are the mud pumps, mud tanks, generators, drill pipe rack, tool house, etc., normal to many types of drilling Other facilities not usually on the drill pad include storage tanks for water and fuel A sump sometimes lies adjacent to the drill pad and may be a pit about 95 m*and 1.8 to 2.4 m deep into which waste fluids and cuttings are dumped during drilling operations In addition to all these land requirements drilling presupposes access, and often geothermal fields are quite isolated and road construction is required It is during construction of the power plant and the transmission pipes and lines that land disruption is more noticeable and probably most significant The pipes themselves are, at present always on the surface although there has been some consideration of underground pipes in the Imperial Valley of California In a discussion of land area and impacts definitions are important If we define the entire geothermal development in terms of the outermost wells, then geothermal developments affect a substantial amount of land, in some cases more than other forms of generation A distinction must be made, however, between land removed from current or potential use and land which lies within the perimeter marked by such wells The land actually removed from other use includes that needed for wells (production and injection), piping, the turbine house, cooling apparatus, transmission facilities and perhaps access roads All this equipment might be spotted within an area substantially larger than that needed for a more conventional development but, in terms of land actually displaced, the area is smaller The existence of transmission pipes at geothermal sites need not constrain land use appreciably If the site was previously gridded with a network of roadways along which pipes may be placed (e.g in a flat agricultural area), indeed there may be virtually no change due to piping requirements Thus, the land actually within a 116 M J PASQUALERI perimeter delimited by the farthest wells could make geothermal development appear landconsumptive In actuality much of the land within geothermal field development remains useable even after full operational status is achieved.* Once the wells have been drilled and the construction phase completed, the effects on the land begin to diminish Of course there may be changes brought about by faulty practices or faulty construction which are greater than immediately realized but it is unlikely that they would present disruption to the land at a level comparable to the construction phase The environmental effects decline as the field comes into full-scale production There is, for example, no continuing mining, fuel processing or transportation or ash disposal as there is at a coal-burning power plant It is at this point that active multiple land use may be started In terms of the overall change, assuming the power generation capacity is large enough, the area may change from essentially one land use to an industrial one.’ Directional drilling is a common method of reducing the impact on the land The additional cost which results from this type of drilling is partially offset by the consolidation of wellhead equipment Up to six wellheads can be accommodated in an area only slightly larger than that previously needed for one wellhead In order to limit heat degradation in the steam the pipelines are never very long Usually they not exceed km This also serves to reduce the effects of construction and the rights-of-way needed to move the steam from the wellheads to the units U.S.A The hilly Geysers Known Geothermal Resource Area (KGRA) was discovered by the white man in the mid-1800s After that time the area zyxwvutsrqponmlkjihgfed wa s use d for watershed, hunting, balneology, and the extraction of mercury The mercury mines remained in production until the mid-l%Os, and many of the shafts are still visible High mercury concentration is still common in surface waters As the field has been developed, odor and noise have increased They have attracted serious attention by those who live immediately downwind, over Cobb Mountain to the east (Fig 2) Much of the income in this part of Lake County is derived from the tourist industry, and the expressed concern regarding the impact of odors and noise on tourists has been added to complaints by local residents These complaints have occurred even though natural emissions must have periodically exceeded the current allowable concentration Such competition in land use continues to plague geothermal development at The Geysers, and prodigious amounts of money are being expended to reduce emissions Fig Geysers geothermal field Geothermal energy Fig Typical and the environment: drilling site for multiple the global experience II7 wells at The Geysers In addition to problems of noise and odor, several detailed surveys have been made to gather data on habitat disturbance Each 110MW(e) power plant at The Geysers requires from 14 to 20 wells to provide the approx 909,000 kg/hr of required steam supply Each well typically requires from 8-16 ha,4 but this is bottom-hole spacing Most wells are now directionally drilled, meaning that a site of less than one hectare can accommodate wells (Fig 3) In the earlier days of development at The Geysers about half a hectare was required for each well Of course, there are other land use requirements such as the power plant itself, pipes, and roads (Fig 4; Table 2) Conservatively estimated, the amount of land actually disturbed per magawatt at The Geysers ranges from 0.19 to 0.32 ha.’ This contrasts to about ha/MW for the Navajo coal-fired power plant at Page, Arizona (including 30 years of strip mining at Black Mesa) The land use impacts at a geothermal development located on flat land (e.g the Imperial Valley) would be even less than at The Geysers6 The most visible biological change at The Geysers is the removal of vegetation, and the most serious consequence of such removal is the loss of animal habitat In speaking of biological impact, Suter cautions that the “Appearance of minimal habitat loss is only real if critical habitat components are preserved”.’ Site preparation in this hilly area has required the removal of more vegetation than would be removed in a flatter landscape A recent wildlife study showed that, in one area, the Big Sulphur Creek watershed, only 410 of the total of 10,364ha has been developed for roads, well pads, pipeline easements and power plants as of February 1976.This amounted to less than 4% of the entire watershed study area The habitat loss within the Kelsey and Putah Creek watersheds was 3.7 and 2.4%, respectively This factors to a bit more than 0.8 ha/MW, or more than twice the figure for the development as a whole.” This figure was revised downward to the 0.19-0.32 ha/MW after more detained photogrammetric analysis The concern that the removal of habitat will have deleterious effects on native fauna has i I :ig Typical Geysers power plant qite M J zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJI PASQUALE~I 118 Table Habitatlossat The Geysers Source: Weinberg, Ref Total Hectares Percent of Leasehold Hectares/Mw 28 zyxwvutsrqponmlkjihgfedcbaZYXWVUT Units - Leasehold 53 3.4 Unit 11 Leasehold 35 3.6 32 Unit 16 Leasehold 21 2.5 19 Unit 17 Leasehold 26 3.4 24 Unit Percent of Leasehold Land Use 1_6 1.9 16 1.0 17 1.3 Well Pads 97 Power Plant 2a 61 32 Roads B9 B5 65 Pipelines 16 I6 12 40 Transmission Lines 52 _- 20 _- Replacement Wells 24 32 44 oa _- Office Buildings 3.4 3.6 2.5 24 1.1 3.4 received more support than claims that the animals are affected by the increased commotion within the KGRA.9 Regardless, both domestic and wild animals have been seen feeding immediately adjacent to geothermal equipment In addition to the impact that habitat removal has on animals, it has been considered a cause for observed changes in vegetation surrounding the cleared area Species usually associated with early successional plant communities appear to increase in density near developed areas However, species more dependent upon a climax or stable plant community decrease in density in developed areas In general, “the areas adjacent to geothermal development show a series of shifts in individual species abundance rather than a uniform increase or decrease of all wildlife species”.” The cause for this is considered to be only partly a response to geothermal development Weinberg indicates that “it appears that several habitat parameters other than the extent of geothermal development may be more significant in explaining the differences observed in population density”,” although he does not mention what those other factors might be Removal of vegetation increases slope instability at The Geysers The entire area is prone to mass wasting, and the development activities have periodically resulted in some movement Sensitivity of the land in this regard is responsible for an isolation of construction activities to the dry summer months On a related matter, the trouble which has been experienced with wild wells has been largely a result of unknowing placement of the well sites atop old, camouflaged landslips zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA New Zealand Wairakei is located on New Zealand’s North Island within an extensive thermal area about 50 km wide and 250 km long The land devoted to the Wairakei operations was formerly scrub and pine lands, much as the surrounding land is today It was occupied by Maori and other settlers The burough of Taupo catered to tourists visiting the site of the famous natural vents Except for the natural geothermal activity, these lands are not unique in their timber resources and the loss of some area of them has not affected the economy Bolton” has called the region “a small area of wasteland of little aesthetic value”, and Axtmann13 has indicated that the present existence of the geothermal facilities has actually improved the aesthetic value of the area Natural emissions have been reduced by the development of the field, but the greater Geothermal energy and the environment: the global experience II9 publicity the generation facility has produced is largely responsible for the 100,000visitors who yearly Aside from changes in roadways and facilities which have been necessitated by construction and the additional influx of tourists and scientists, the field development has required some very noticeable changes in the use of the land The most noticeable change in land use is in the bore field where all the vegetation has been removed The wells are up to 1.6 km away from the power station, and vegetation has also been removed in corridors along which the pipes pass Land was also required for the construction of the power houses and electrical transmission facilities Had the site not been developed for geothermal energy, it would now probably be in use for pastoral farming.14 Many of the present farmers have found it necessary to travel longer routes during their activities because of the addition of obstacles associated with geothermal development visit Wairakei Mexico Cerro Prieto lies a few meters above sea level on the delta sediments of the Colorado River It is possible to farm this land with excellent yields all year when good water is available Originally, the site was primarily barren, clayey, and saline, partly devoted to therapeutic hot baths Some agricultural fields were nearby Since geothermal development began, both farming and spa activities have halted, and the land now within the well field is barren and devoted only to generating electricity Eighteen wells atop this land are needed to generate the first 75 MW connected to each 37.5 MW unit; the remainder of the 41 wells drilled through 1974(Figs and 6) were on standby and are now used in Units and There are main steam gathering lines which run to the first power house The total length of gathering pipelines of diameter greater than 406 mm is over 12 km (for units).” The vacant land in between pipes in the well field goes unused at Cerro Prieto Although agriculture is practiced within other geothermal well fields zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM (e.g in Italy), it would be very difficult and inefficient at Cerro Prieto because of the need for careful cultivation and irrigation in its arid environment and because the pipe network has been layed out without agriculture in mind In its present condition the land at Cerro Prieto is also unable to support lifestock El Salvador The Ahuachapan power plant lies at an elevation of about 800 m on gently sloping, agricultural land along a small tributary of the Rio Paz The Rio Paz in turn is part of the TO SAN L km Evaporation Pond Fig Well location at Cerro Prieto LUIS- M J PASQUALETTI zyxwvutsrqponmlkjihgfedcbaZYXWVUTSR 120 Ml1 (Afte r Re f 15) Fig Well location and steam pipeline gathering system for units No I and at Cerro Prieto international border with Guatemala The Ahuachapan thermal area is situated on the western (nonactive) margin of a volcanic complex which includes Santa Ana and Izelco volcanoes In their arrangements of facilities and their care during construction and operation the developers have been notably successful in minimizing the impact on the land Twenty-eight wells have been completed, 10 of which operate the turbines (5 to each) (Fig 7) The separation between the wells is not less than about 150m The average spacing over the entire field is roughly 23 per well, although near the central portion of the field the wells are spaced at 11 per we11.‘6 The natural vegetation reflects seasonal stress brought about by a distinct dry season which ends about May of each year The volcanic soil provides the basis for surrounding plantations (notably coffee), parts of which have been removed during development of the field Besides agriculture, cattle grazing is common around the geothermal development, even within the bore field zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Ztaly The Boraciferous Region includes power plants at 12 locations and covers a surface of approx 170km2 This region is found within a basin known as Larderello, an area believed to cover about 25,000 (250 km*).” In addition, the Travale region, about 13 km to the southeast of the Larderello basin, is sometimes included in the Boraciferous Region The Travale field is very small, and it has been impossible to maintain fluid output at 1960 levels.‘* Through March 1975, 511 wells had been drilled in the Boraciferous Region (excluding Travale), at an average density of drilling of 2.7 wells per km* One hundred and ninety of these were productive and 181 were branched onto the pipeline network Nine were under observation for reservoir engineering study I9 The well pipelines in the Boraciferous Region totaled 94 km in length and extended over the 170 km* with a density of 533 m/km2 The Mt Amiata Region, located about 70 km southeast of Iarderello, is characterized by productive features which individually never exceed a surface area of more than 10 km2 Drilling has been concentrated on small separated plots which cover an aggregate area of 40 km2 By March 1975, 60 wells had been drilled, with a density of 1.5 wells per km2.20At that Geothermal energy and the environment: the global experience 151 caution: ” the probability of triggering earthquakes as a consequence of geothermal development is far greater than might be inferred from a review of the literature on injection technology”.223 Whiting stated: “Although, thus far, no seismic effects have been attributed to geothermal resources exploitation, seismic effects can be anticipated if large pressure differences are developed vertically and/or laterally in the reservoir”.224 Ridley and Taylor believe the greatest potential for induced seismicity will not be associated with any of the operating geothermal developments but rather during the development of hot dry rock resources.“’ Some authorities believe reinjection may reduce the threat of earthquakes Ward and Bjornsson have asserted that geothermal activity might relieve strain by lubricating the faults and thereby result in small earthquakes rather than large ones.226Furthermore, even in an area of short-term microearthquake activity reinjection “is not necessarily positively correlated with long-term activity and with earthquake hazard, and in some areas the relationship may be inverse”.“’ Raleigh et al., suggested that earthquakes can be controlled when fluid pressure in a fault zone can be controlled.*** The best way to clarify this issue is by actual test Such testing requires baseline data for later comparison Crow identified two criteria useful in such comparisons: (1) a change in the frequency and magnitude in the vicinity of the geothermal field; and (2) a shift in the location (particularly depth) of seismic events coincident with geothermal production.z29 zyxwvutsrqponmlkjihgfedcbaZYXW U.S.A The Geysers field is located within 48 km of the San Andreas fault and 16 km of the Healdsburg-Rogers Creek fault It has been postulated that the damaging Santa Rosa earthquake of October 1%9 was caused at depth along the latter break, although active faulting has not been demonstrated within the immediate Geysers area Because of the inherent slope instability at The Geysers and the low population density, the most immediate concern with regard to earthquakes is the effect they would have on stimulating or reactivating landslides For a three-week period in 1971, Hamilton and Muffler conducted a study of microearthquakes at The Geysers site 230Fifthy-three micro-earthquakes were recorded along a cone km long and km wide All shocks registered below 1.5 on the Richter scale, and it was concluded that these earthquakes were the result of natural causes and not steam extraction or reinjection A recent study, however, indicates a likelihood that “much of the present seismicity at The Geysers is induced by steam withdrawal and/or injection of condensate”.23’ Japan Gravity feed is used during reinjection at all but one power plant in Japan, primarily out of fear of induced seismicity Six seismometers have been installed to monitor both Otake and Hatchobaru The signals are telemetered to a central data processing system for interpretation and evaluation Between 1972 and 1975 no earthquakes were caused by reinjection.232 Similar networks are in place around the other power plants Monitoring is especially important at Takinoue where reinjection is conducted under pressure (and at about 150°C to prevent scaling) If such reinjection produces no seismic activity, the pressurized reinjection system may be retrofitted at existing plants, where possible No evidence of such seismicity has yet been observed at this newly operational plant.233 Mexico Cerro Prieto is in one of the most seismically active areas of the world Several faults including the San Andreas pass close to the area So far injection has not been practiced at Cerro Prieto and there are no known studies of micro-seismicity as it relates to man-made causes New Zealand Like Cerro Prieto, Wairakei lies on the boundary between two active crustal plates In addition it is located in the southern part of the Taupo Volcanic zone The area is within a zone of potentially strong ground shaking:” but there has been relatively little experience with reinjection and no reported seismic consequences M J PASQUALETTI 152 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Italy Although no seismic studies ar known for the developed areas, reinjection experiments conducted in the area of Cura de Vetralla were specifically designed to detect seismic effects.23’ One of the technical difficulties reported in these experiments was the high background noise from human activity, especially during the day These were filtered out as their regularity made them identifiable, and the net result of the experiments was to rule out “any possibility” of increased seismic background or microshocks resulting from reinjection BLOWOUTS AND OTHER SURFACE LEAKS All blowouts are undesirable, and virtually all oil, gas, and geothermal well drilling incorporates the use of blowout preventers as standard equipment Preventers are also standard on completed wells, and under most circumstances these devices, complemented by properly trained personnel, can handle situations which would otherwise result in a loss of control Nevertheless, blowouts occur and they can produce water and air pollution, noise, damage to plants and animals, and can create unfavorable publicity In addition, they decrease reservoir pressure and waste the resource They can also be dangerous; a recent blowout at a geothermal well in Java killed three people.‘” The particular environmental damage which is actually produced from such occurrences is of course site specific, both in terms of environmental surroundings and discharged constituents For example, a blowout of relatively clean steam in an isolated vapor-dominated field presents a smaller potential hazard than a blowout of caustic liquids within a populated area valued for its agricultural products Although there are several differences between geothermal wells and wells for the extraction of fossil fuels, the techniques of drilling all these wells are basically the same Blowouts in oil fields appear relatively rare Between l%O and 1970 only 100 incidents occurred, and these were mostly gas wellst3’ of the 14,000 offshore wells drilled through 1970, only about 25 had blown out of contro1.238 Of course, this relative infrequency does not diminish local environmental significance or industry desire to reduce their number The substantial negative publicity afforded such events as the Santa Barbara blowout of 1%9 have piqued public awareness and have been responsible for the expressions of environmental concern during the drilling of all new wells Sensitive to the issue, the drilling industry has been working together with the U.S Geological Survey to reduce blowouts.239 Blowouts can occur during any phase of field development As Farrara et al have stated:240 “One of the most striking consequences of the thermal and hydraulic changes occurring in an exploited field is the spontaneous blowout of originally nonproductive wells, some time after drilling”, even at abandoned or suspended operations At Beowawe, Nevada in 1971 a shut-in well was dynamited and emissions continued for over a year.“’ Nevertheless, it is during drilling that the developer fills in most rapidly the gaps in his knowledge of subsurface geologic and thermal conditions His incomplete knowledge is a primary reason the possibility of a blowout is somewhat higher during the drilling stage than in the following stages Surface leakage of water can be as damaging as a blowout and is certainly more common A stuck valve or an overflowing cooling tower basin, for example, can send large amounts of toxic water through vegetated areas and into stream channels Because there are so many potential sources of surface leaks it is difficult to prevent them all, and operators at some geothermal fields have taken the approach of accepting the inevitability of such leaks and have worked toward containing the fluid itself U.S.A In September, 1957 “Thermal 4” at The Geysers blew out during the drilling phase All attempts at control have failed, and it is still discharging 80,000 kglhr of steam to the atmosphere This has caused noise, pollution, and embarrassment Two wells at The Geysers have blown out during production “Thermal 5” blew out in January, 1970 and “Happy Jack 7” blew out in January, 1973 Injection of cement slurry into the casing controlled the first blowout in 10 days, but it was not until November, 1974 that the second one was controlled Until then, 90,000 kglhr were vented to the atmosphere.%* On the evening of 31 March 1975 “G.D.C Geothermal energy and the environment: the global experience IS3 65-28” blew out The well had been on standby since its completion in September 1968 and was located in a remote area of the Mayacamas Mountains, 6.4 km southeast of the main Geysers area A crater 30 by 36 m and about 7.5 m deep formed by the day after the blowout A large depression had to be excavated around the well to a depth of about 25 m New segments of casing were welded on to replace those removed during excavation and the well was quenched by pumping in large volumes of cold water A cement plug was also installed.“3 “Thermal 4” was a very early well at The Geysers and was positioned on an old land slip The other blowouts also seem to have been located on camouflaged slips, and Pacific Gas and Electric has conducted extensive aerial reconnaissance to try to spot and avoid future siting problem areas They are also discussing the possibility of utilizing the escaping steam from Thermal 4, the so-called “wild well” in a small, perhaps binary, power plant This procedure would have the multiple benefits of stopping the waste as well as the noise and air pollution It has been estimated that the well wastage has amounted to $125,000 per year, and that the emissions, between 1957 and 1972, amounted to 8.1 million tons of steam, 3600 tons of HS, 4500 tons of ammonia, and 5400 tons of methane.‘” PC&E has decided it is practically impossible to prevent all surface leaks Thus, they have decided to construct berms around those parts of the equipment which are most likely to produce accidental discharge, e.g.cooling towers These berms are designed to contain any leak which occurs and thus prevent pollution of the land surface and streams.245 For their part, Union Oil Company (owner of the latest were to blow out) has revised their procedures and now investigate all potential new well sites before acceptance for drilling They have also initiated a program to inspect and rework all old wells.2h zyxwvutsrqponmlkjihgfedcbaZYX M exico There have been two blowouts at Cerro Prieto One occurred in l%l during the production testing of one of the earliest completed wells The blowout was caused by mechanical failure due to vibrations in the wellhead equipment The well was brought under control by Christmas tree repositioning and cement injection Following the blowout, modifications of the well-head layout were made, and this type of mishap has been “eliminated”.247 A producing well (M-13) blew out in April 1972 and continued to flow wild for four months The well had been completed and tested a few years earlier and was ready to go on line as one of 17 producing wells for the first 75 MW of the power piant The cause of the blowout was a fractured casing at 200 m A steam-water mixture reached the surface about 100 m from the well Within 36 hr a 10 m diameter crater was formed around the Christmas tree, and this crater later enlarged to a diameter of 18 m It was controlled by injecting bentonitic mud with barite When the mud reached the surface all the valves were closed while the pumps continued Cement plugs were installed and the well was later repaired.2a Relative environmental effect on the previously barren landscape at Cerro Prieto was negligible This failure has been attributed to improper casing cementation and wellhead construction.249 New Zealand Two blowouts have been reported from Wairakei, “one due to failure of a well casing after some years in service, the other during the course of drilling a well”.2s0At Bore 26, the casing broke about 180m below the ground in January l%O A “violently steaming crater formed with several smaller steam jets and active mud pools Hot mud blocked the access to the site for the rig All hands were able to get clear, and there were only minor injuries Shortly afterwards another explosion occurred, covering the bore site (1.8 m) deep in rock and mud”.*” To control this blowout another well was spudded in about 60 m away and drilled to 450 m, intercepting Bore 26 Massive amounts of cement grout were then pumped in, and the well was sealed Later, two wells were drilled in the same area, and one is used today Environmental effects from the discharge were substantial, though the denuded hillside has been terraced and replanted In 1960, a blowout also occurred at Bore 204 and for 15 years the emissions did not diminish Eventually a large crater was formed in which surface water collected to create a boiling pool Considerable efforts were made to control this well at the time it happened, but they were unsuccessful The site of the well was not considered to be one of great environmental 154 M J.PASQUALETTI sensitivity and, as it turned out, the well provided substantial tourist attraction In 1975the bore sealed itself zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Italy There have been no reported blowouts at Larderello, Travale, or Monte Amiata; however, one occurred in early 1975 during development of the Cesano field, 20 km north-northwest of Rome During the drilling of the Cesano-1 well it was decided to lower the hydrostatic head by replacing mud with water, but, after introducing about 1OOOmof drilling stems, short geysertype eruptions of mud began which suggested extracting the rods introduced without replacing mud with water “During the extraction of drilling steam, the well blew out Eruption was initially accompanied by a rather modest flow (of water mixed with mud) which did not prevent continuation of rod extraction After a few hours, however, the flow rate rose progressively and with it, the temperature, the rate of flashed steam, and salt deposition”.2s2 After three to four hours of production the incrustations covered the entire drilling rig and after ten hours’ production the well had to be closed The low overall incidence of blowouts in Italy can be attributed to the requirement of blowout preventers at each wellhead The preventer is designed to close off the central bore in case of emergencies, even when equipment happens to be in the well.253Mechanically or hydraulically actuated valves are fitted with appropriate jaws to clamp around anything that happens to be in the well For steam-well drilling, high-temperature gaskets are required.254 Japan At Matsukawa, well MR-4, drilled between March and August 1%5, blew out The 21.9 cm casing collapsed at 35 m depth Complete cementing was imperfect so that cement slurry had not risen to the surface Accordingly “additional cemment slurry was poured from the surface through the tubing As a result of this a water pocket seemed to be caused between the two cementings, and the water located there expanded promptly when the high temperature steam was produced, resulting in increase in external pressure and co1lapse”.2s5No ecological damage was reported El Salvador There have been no blowouts at El Salvador, although Goldsmith has reported that surface leaks have damaged coffee plants 256Two wells at Ahuachapan collapsed and erupted, AH-24 in November 1976 and AH-20 in April 1978.257Both wells are back in production NOISE Noise contributes to hearing loss, reduced worker efficiency, increased anxiety, and annoyance (Table 21) It has gained increasing attention in areas of geothermal development because of the periodic high decibel readings, especially as it compares with pre-development conditions Control of this noise is important to geothermal programs because citizen complaints can directly affect development plans Noise can also have an adverse impact on animals The EPA suspects that noise can cause increase in heart rate, modified weaning, aldosteronism and water and sodium retention, no milk production, and even increased litter sizes.258 Noise for geothermal operations may be produced during drilling and well cleaning, flashing of waste water, periodic venting to control pressures and flows, blowouts, turbine operation, and several other activities Sound pressures at geothermal operations vary according to many factors: (1) The “noise” must be perceived as such; many geothermal sites are distant from populated areas On site, construction workers and operators can take protective measures as necessary (2) Noise varies as a function of the type of geothermal resource being exploited A vapor-dominated field, for instance, requires drilling with air rather than mud, and such drilling is generally noisier (3) Noise varies according to the phase of development For example, noise levels are higher during drilling, especially in a dry-steam field Testing and cleaning of a vapor-dominated well requires that the well be vented freely to clean out particles and this produces noise If the well Geothermal energy and the environment: the global experience 155 Table 21 Some typical sound levels Source: Donald F Anthrop, Noise zyxwvutsrqponmlkjihgfedcbaZYXWVUTS Po llutio n, D C Heath and Co (Lexington Books), Lexington, Mass (1973) Familiar Sounds dB(A) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 130 takeoff (60 m ) 125 Jet 120 Threshold frequency of pain at 2000-4000 (cycleslsec.) Unmuffled diesel 110 100 Loud 95 motorcycle truck (15 m (15 m ) 90 85 USAF-recommended maximum 80 Street corner in a large 65 Normal speech c.3 m 60 Accounting 75 city 70 ) Office 55 50 45 40 Residential area at night 35 30 25 Broadcasting studio 20 15 10 Threshold of hearing is closed in for a few days it must be vented to the atmosphere After longer periods, the well must be vented to the atmosphere for three to five days to clean out rock particles.2s9 (4) Its perception varies according to tonal frequency, the lower tones being more perceptible (if less painful) because they not “compete” as much with more natural, higher frequency sounds (5) The distance sound will travel depends on acoustical characteristics of terrain, wind, temperature, humidity, and ground cover Little has been published on actual measured noise levels al geothermal plants Perhaps this is because loud noises are relatively infrequent Most of the time, muffling equipment is used Nishiwaki et ~1.‘~ described a muffler that reduced 100-130 dB(A) sound to 60-90 dB(A), and silencers of various types and effectiveness are standard at most geothermal fields U.S.A The Geysers is in a vapor-dominated field, and air is used in drilling Sound levels of 90-122 dB(A) (Table 22) “were once common” during this phase but these levels have been reduced to 75-90 dB(A) by the use of “wet cyclonic separator/mufflers at the end of the blooie line expander tube”.%’ Venting is necessary subsequent to drilling and shutdowns Sound levels from commercial mufflers in full vent service ranged from 90 to 110dB(A).262Air compressors, diesel motors, electrical generators, and pumps also contribute to the noise levels, although major sources at 156 M J PASQUALETTI The Geysers are the cooling tower, steam jet gas ejector, and the turbine generator building Rock mufflers had been used for several years to reduce noise from small bleeds, and recently they have been adapted to plant stacks with a high level of success Sound levels of a well in full vent (450-500 tons per hour) have been attenuated to a range of 70-85 dB(A) Rock mufflers are being retrofitted on operating units where required.263 As drilling and production operations at The Geysers have moved closer to the nearby and quiet inhabited areas, complaints have increased about noise, especially when it has had a disturbing effect on sleep 264The low tonal frequencies are especially to blame in this matter According to Illingworth part of the problem of measurement at The Geysers has been the use of the “A” weighted sound pressure level 265The “A” weighting puts emphasis on higher frequencies, and under such measurement increases in low frequency energy result in little or no change in the “A” weighted scale Under such a circumstance noise which is readily perceptible and perhaps annoying often does not measure as a significant increase over the pre-development ambient levels The use of the flat or “C” weighted scale would register a more accurate reading of real changes in noise levels as geothermal development progressed With regard to the effects of noises on animals, recent studies completed at The Geysers by Lietner indicate that noise appears to be a “non-problem”.266 Leitner indicated that the opinion is quite firm for nonpredators, but even for predators there is as yet no evidence to indicate any change in habits This is explainable in part as a function of the type of noises which geothermal operations produce Broadband noises common with geothermal developments not affect animals like sudden, threatening noises As evidence of this relationship wild animals are seen regularly grazing within 20 m of a venting well Several measures would further reduce noise problems at The Geysers Illingworth, and Lukas, both advocate continued improvement of muffling equipment, especially in the lower tonal frequencies (e.g below ~OOOHZ).~~’ People can also be conditioned to Table 22 Sound levels associated with geothermal development at The Geysers (SPL at 15.2m) Source: Weinberg, see Ref zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQP SOUND ACTIVITY 60 NSTRUCTION BACKHOES COMPACTORS SCRAPERS TRACTORS TRUCKS ILLING MUD AIR AIR AIR AIR (NO STEAM) (BLOOIE LINE (BLOOIE LINE (~~001~ LINE LL CLEANOUT VENT VENT AND W/O MUFFLER W/COMMERCIAL EXPANDER TUBE) W/DRY MUFFLER) W/WET MUFFLER) TESTING MUFFLER ANT STACKING PIPELINE COMMISSIONING COMMERCIAL MUFFLER DRAG VALVE ROCK MUFFLER :SCELLANEOUS POWER PLANT BLEEDS UNMUFFLED BLEEDS COMMERCIAL MUFFLER BLEEDS ROCK MUFFLER BLEEDS INTO VENT GATHERING SYSTEM PRESSURE 70 80 LEVEL 90 @ 15.2M 100 110 dB(A) 120 Geothermal energy and the environment: the global experience IS7 ignore changes in ambient noise level Noise sources tend to gain higher perception when sources are visible, and it has been suggested that power companies should reforest areas affected by development operations.268 Such camouflage is particularly important in reducing complaints of noise from cooling towers which are not as easily muflled as wells Cerro zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Prieto The sources of noise at Cerro Prieto are generally the same as are found at other water-dominated sites with the exception of the nozzle of the pipe disposing of waste water to the evaporation pond Although measured readings were not available, personal experience indicated that communication immediately adjacent to the well is very difficult The noise drops off quickly with distance and there are no residences near enough to be affected by this source Future reinjection would reduce the problem The flow-regulating system was provided with silencers and located as far as possible from the plant (200 m) These measures have produced “good results”.‘h9 In addition each well is equipped with its own vertical silencer of concrete with a wooden stack They have given satisfactory results.*” zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH New Zealand Noise is also quite noticeable at New Zealand Personal protective equipment i\ necessary near an unsilenced well, but vertical discharge of the wells is usually for only a short period after which it is diverted to silencers which bring the noise to acceptable levels.*” Even though some noise is still apparent at the near Wairakei tourist hotel (a few hundred meters from the bores and vent valves), guests not seem annoyed.“* The noise is said to resemble that of a waterfall, and Armstead suggested that the noise has a “soporific rather than a distressing effect”.273 Japan Silencers are installed at all the Japanese power plants At Hatchobaru each wellhead includes sets of twin cyclone silencers The environmental restrictions placed on noise at Hatchobaru are extremely tight and are in accordance with the generally high environmental standards that govern all operations there Permitted noise can not exceed 5OdB(A) under normal operating conditions at the plant boundary, or 70dB(A) under emergency conditions when the safety valves are open (In the U.S the requirements are 65 dB(A) at the plant boundary or at 0.8 km from the sound source, whichever is greater.) Owing to the high standards, every effort has been made to take advantage of the natural muffling afforded by the terrain.274 As at all vapor-dominated fields, there is a high likelihood of air drilling and commensurate high noise levels at Matsukawa and Onikobe At Matsukawa air-drilling was initiated for the new No well Mud was used to a depth of 815 m while air was used from there down to 1170m.275At Kakkonda, once the well reaches depths at which steam is expected, air drilling replaces mud drilling to avoid problems associated with the loss of circulating mud.27nNoise levels should approximate The Geysers’ experience SUMMARY AND CONCLUSIONS Whereas individual geothermal sites clearly may differ in many characteristics such as fluid constituents and enthalpy as well as local environmental makeup and sensitivities, general similarities in environmental problems and concerns are apparent In this light a sharing of experiences is possible and can help identify potential developmental impediments and solutions at any location This should stimulate a speedier increase in generating capacity by reducing unwarranted effort and allowing a focus of attention on locally important issues It is apparent that the cost for environmental protection can be expressed in terms of money, efficiency, or time Usually all three costs are intertwined: pollution control technology takes time to develop and install and results in a lowered efficiency This, in turn, is translated into a higher per-unit cost for the electricity produced Although there are several potential problems associated with geothermal development actual experience has indicated that each site usually faces a challenge from only one or two At The Geysers, concern for air pollution has created the most difficulty although concern has also been expressed with regard to water pollution, blowouts, noise, land alteration, and habitat 158 M I PASQUALEITI zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA removal At Wairakei, the most notable environmental effects have been subsidence and water pollution Little concern has been expressed with regard to noise, air pollution, or changes in the biota The impacts at Cerro Prieto have been mostly in terms of changes in land use Noted impacts in Japan and Italy have thus far been largely limited to water pollution, but land use effects have lately become important, especially in Japan Environmental concern in El Salvador has also centered on waste water disposal All countries have indicated an interest and concern for environmental impacts as caused by their geothermal operations, and all have endorsed support of plans to mitigate undesirable effects With regard to air pollution, no site has received more attention than The Geysers Results from tests of the several devices which have been suggested for use at the site (iron catalyst, EIC upstream, Stretford scrubber) indicate an ability to reduce air pollution to a small fraction of possible emission rates The problem of waste water disposal seems solvable through several technologies including forced evaporation and distillation, membrane filtration, and ion exchange, but reinjection holds the most promise for economic and technical feasibility It has the added benefits of reducing subsidence potential as well as retarding the loss of heat and hydraulic pressure Reinjection for waste water disposal is being utilized operationally at The Geysers, El Salvador, and most of the Japanese sites, and experimentally at Wairakei and Larderello Pretreatment of such waste water, however, may be required to prevent subsurfact problems of well sealing and groundwater contamination The only certainty at this point regarding seismicity is its high correlation with the occurrence of geothermal activity Seismicity induced from geothermal development has not been observed at operating power plants, and its occurrence in association with injection in general is rare The few examples which exist seem limited to high pressure efforts, and Kakkonda is being monitored closely in this regard Objectionable or dangerous noise, either periodic or constant, attributable to geothermal operations is generally limited to periods of drilling and/or venting In addition to continuing successful use of mufflers, barriers, and planning and design techniques, many of the noisier components are being manufactured to emit reduced noise levels In most phases of geothermal operation noise is routinely mitigated at all sites Subsidence has not been a great problem in part because most experience has been at the less subsidence-prone vapor-dominated fields Even where it has been reported (Wairakei and The Geysers), the physical damage has been minor or nonexistent Subsidence experience at oil fields as well as preliminary experimentation at Wairakei, indicate that injection can slow and usually prevent the problem The effects of geothermal developments on biota are largely in terms of habitat removal Human activity tends to keep some of the wild animals away although noise by itself seems to little bother any animals Domestic animals generally pay small attention to geothermal activities, and wild animals, if not hunted or harrassed, will usually find enough refuge within geothermal areas to return after their initial skittishness Effects on land use and aesthetics are inevitable, but to some degree they can be mitigated Flat land requires less scarring than hilly land, but as the widespread impacts at Cerro Prieto show, level topography affords no automatic protection The hilly Geysers site has been changed appreciably from pre-development days This has been exacerbated by the fact that the slopes are inherently unstable In New Zealand the Wairakei development has resulted in vegetation removal, especially in the bore field, but this is not an unusual occurrence Larderello has been offered as an illustration that a productive agricultural landscape can coexist with large-scale geothermal development The most serious impact related to land use may be the limits it places on development and/or expansion as in Japan and at The Geysers The environmental experiences outlined in this article lead us to several conclusions: (1) There are three types of environmental problems: (a) operational, (b) human, and (c) biotic The longer the environmental interest and monitoring (and the more concern that is expressed) the more the emphasis moves from (a) to (c) (2) Environmental concern is quite recent Of Italy, Cataldi wrote: “This is a recent field of investigation at our geothermal sites and no systematic publication of the data has been made “.*” Subsidence at Wairakei was not considered during initial design Even at The IS9 Geothermal energy zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA and the environment: the global experience Geysers most of the recent environmental attention was absent when commercial operation began Thus, it is not that some countries are necessarily lagging behind in the environmental sphere, but often that the emphasis has turned only recently to environmental questions (3) Certain positive and negative environmental circumstances are inherent in geothermal energy development: (a) Positive: no fuel mining, transport or preparation of fuel; the fuel is nonfossil and nonnuclear; modular size reduces potential for environmental problems; (b) Negative: large fluid volumes are needed; there are often harmful constituents in the water: such ingredients lead to air and water pollution; heat degrades quickly with distance and therefore a site specificity results which can lead to concentration of environmental effects (4) All the recognized environmental problems appear technically controllable now, if the price (efficiency, time, but usually money) is paid Solutions are also available through direct application, especially with regard to waste heat discharge (5) Whereas most of the potential problems from air and water pollution, noise, and land use may be largely determined prior to actual development, it is probably impossible to model or predict the environmental ramifications related to reinjection, induced seismicity, or subsidence before the initiation of commercial-sized operation (6) There is an unavoidable need for baseline studies, especially for the monitoring of seismicity, subsidence, and air pollution Comparisons with post-operational data are otherwise useless (7) The Geysers operation is the apparent leader in terms of environmental control, and transfer of technologies perfected there should be possible It could be strongly argued that if The Geysers development can operate within the myriad of environmental regulations it must satisfy, environmentally compatible geothermal operations should be possible just about anywhere It is not clear whether such regulations are fully justified (8) Several countries are advancing the technology of some environmental problems; in Japan it is noise and aesthetics: in the U.S it is air; in New Zealand it is subsidence; in El Salvador it is waste water disposal (9) In many countries environmental concern is an inverse function of that country’s perceived need for energy Mexico, for example, has a population which is doubling every 23 years Thus, because environmental protection takes extra time, power, and money the Mexican government has much smaller demonstrated concern for the environment than for energy development (10) Public awareness has kept the world-wide geothermal industry responsive The Geysers is the best example, but a general brightening of public visibility and awareness has stimulated changes in environmental policy in Mexico, New Zealand, Italy, Japan, El Salvador and elsewhere (11) Impact of geothermal operation has been as slight as it has been so far partly because sites are at some distance from human habitats Where geothermal developments and human activities are in close proximity, as they are at The Geysers, the environmental effects has been more quickly noted (12) For several reasons environmental care at geothermal developments should continue Even though the aggregate environmental costs of geothermal development may be less that for other types of power generation, the potential local impact in some cases can be substantial Just because there is no traditional extraction, processing or transport of fuel does not mean all developments will be environmentally benign or even nearly so Each site is different and one must be wary of being caught in the trap of automatically believing that there are no real problems or that all problems can be solved acceptably in all cases (13) Nevertheless, the scale of the problems which have occurred or seem likely to occur appears orders of magnitude less than those which have befallen other generation types We are not talking about the concern for plutonium storage or the prospect of evacuating large numbers of people near a nuclear generating station such as Three Mile Island, Pennsylvania And we are not speaking of strip mines in farming country or an oil well blowout off a scenic beach at Santa Barbara, California And we’are not talking of a million barrel oil spill from an Amoco Cadiz We are considering, at worst, a localized problem, made even smaller by the modular size of geothermal power plants and the usually isolated location of the resource (14) With all this in mind, we should focus our attention on five considerations; (a) there is an EGY Vol No 2-D 160 M J PASQUALETTI ever persistent call for greater supply of affordable and environmentally acceptable sources of energy;(b) the hope for salvation is increasingly being placed upon so-called “alternative” sources, of which geothermal is one example; (c) the United States appears to be the world leader in errecting environmentally-based encumbrances to geothermal development; (d) although high environmental quality must be maintained, it does not seem that the level of regulation necessary for other forms of generation is mandatory with regard to geothermal energy; and (e) the United States, with its vast technological resources and equally enormous geothermal potential could, by more rapidly developing its own resources, be the leader of the sixty or so countries with active interest in developing their own potential Instead, the U.S ties smothered in rules, and geothermal energy development everywhere remains mired in a role of insignificant contribution zyxwvutsrqponm Acknowledgements-1 wish to thank the following for offering suggestions and data: Carl Weinberg, PG&E; Michael Tolmasoff, North Sonoma APCD; Sergio Mercado, Instituto de Investigaciones Electricas, Mexico; Hideo Iga, Japan Geothermal Energy Association; Richard Bolton, Ministry of Works and Development, New Zealand; R Cataldi ENEL, Italy; Patrick Muffler, U.S Geological Survey; Paul Gudiksen, Lawrence Livermore Laboratory; Philip Leitner, St Mary’s College; James Kuwada, Rogers Engineering: Care1Otte and Joel Robinson, Union Oil Co.: and especially Ronald DiPippo of Southeastern Massachusetts University for draft copies of his compendium on geothermal energy and for his constant availability for discussions This paper would not have been possible without their help REFERENCES Note: The following three references are cited several times: zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK Proc of the United Nations Conf on new Sources of EneQy: zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK Sola r Energy, W ind Power and Geothermal Energy, 21-31 zyxwvutsrqponm Aug., 1%1, Rome, Italy, Vol and 3, “Geothermal Energy”; United Nations, New York, 1964.(Referred to as Rome, hereafter.) 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Fdmunds and Adam Rose (Fds.), Praeger, New York (1979) 3* 4* 150 Mvl Geothermal Energy and Regional Development: The Case of Imperial County Geothermal energy and the environment: II3 the global experience. .. aesthetic value of the area Natural emissions have been reduced by the development of the field, but the greater Geothermal energy and the environment: the global experience II9 publicity the generation... of the effect of the Wairakei geothermal power project on the environment both natural and human”, published in the record of the hearings on geothermal energy before the Committee on Science and