九大地熱・火山研究報告第 11 号 (2002) 34-43 頁

GEOTHERMAL ENERGY IN MÉXICO AND ITS RELATIONWITH THE ENVIRONMENT
Manuel Herrera-Gutierrez* and Ruth Tapia-Salazar**

ABSTRACTThe Comisión Federal de Electricidad (CFE), is the governmental company in charge of Generation, transmission
and distribution of electricity in almost all country. In 2000, CFE produced 57.3 million of metric tons ofgeothermal steam. A total of 157 wells produced an annual average rate of 41.6 tons of steam per hour per
well, reaching a generation geothermal electricity of 5,901 GWh, which represents 3.1 % of the total electricity
produced in México. The places with geothermal fields are: Cerro Prieto I to IV, in Mexicali, Baja California
Norte (720 MW); Los Azufres, in Hidalgo City, Michoacán (93 MW); Los Humeros in Puebla (42 MW) and Tres
Vírgenes in Santa Rosalía, Baja California Sur (10 MW). Other projects are: In short term, Los Azufres II (100MW); in medium term are La Primavera in Jalisco and Araró in Michoacán. CFE has studied some hydrothermalzones like Punta Banda in Baja California. Agree with its mission, CFE also has put in practice policies about its
environmental behavior, because it knows that sustainability is not an aim, it must be a style life in all companies
and countries in the world.
1. INTRODUCTION

conditions of technology, quantity, quality and price,using different resources of energy. To optimize thephysical, commercial and human infrastructures, withcareful attention to the clients, promoting the social
development and protecting the environment where
the electric power stations are.

The progress of any country can be measured behind
its electrical installed capacity. So, México has
many kinds of electrical power plants using different
resources to produce electricity.

Vision of CFE

Comisión Federal de Electricidad (CFE) is thegovernmental company in charge of generation,transmission and distribution of this kind of energy inalmost all the country. Luz y Fuerza del Centro (LFC),
is the other company who produces less than 1 % of
the electricity sold in the country. Private industry also
generates electricity in co-generation facilities, fortheir own use, or for sale to CFE.

 To keep us like the most important electricity

company of México.
 To operate above the productivity, competitivity andtechnological international indicators.
 To be recognized by our clients like an excelential

company, worrying for the environment and theservice.
 To Promotion high qualification and professional
development of our employers and directive people.

Environmental protection is one of the important aimsin México. The application of renewable resourcesenergy is used for generating electricity.
Following the environmental policies of México, CFE
has decided its mission, vision and environmental
policies.

Environmental Policy of CFE

Agree with its mission, CFE has put in practice six
policies about its environmental behavior: To take in all forms the environmental impacts of
the actions in our company and to evaluate them forassuring the balance between internal and externalcosts and benefits.

Mission of CFE

To assure the electric power supply in appropriate*Jefe del Departamento de Ing. Ambiental, C.T. Manzanillo.
C.P. 28809, Manzanillo, Colima, México; mhg93188@cfe.gob.mx**Jefe del Área de Geoquimica, C.G. Tres Virgenes, B.C.S.
rtsv0182@cfe.gob.mx ; ruth_tapia@yahoo.com
Comisión Federal de Electricidad
MÉXICO34

GEOTHERMAL ENERGY IN MEXICO AND ITS RELATION WITH THE ENVIRONMENT To consider the national laws for environmental

thermoelectric ones that they consume heavy oil, gas
and diesel; 2,600 MW to carboeléctrics; 854.9 MW togeothermoeléctrics; 1,364.9 MW to the nucleoelectricand 2.2 MW to the eoeléctric.

protection and to take them like a minimum value
to take care of it.
 To support the environmental authorities to develop
rules and environmental methodologies.
 To incorporate professional points of view about
our environmental design and activities.
 To take the social people point of view, about theenvironmental development in projects of thecompany.
 To s u p p o r t e d u c a t i o n , i nv e s t i g a t i o n a n dtechnological development in the environmentalarea.

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Throughout the years, the generation has increased
to fulfill the fundamental aim of CFE, that it isto advance to take care of all the necessities of
population, industry, agriculture, the commerce andservices through electricity, in México.

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2. GEOTHERMAL SITUATION IN MÉXICO����Comisión Federal de Electricidad has worried
to develop power plants to generate electricity,
alternating to fossil fuels, hydroelectric plants and thenuclear power stations. Considering the geographic
and geologic location of México, more reasonableof the alternating sources of energy are geothermal
and the eolic energy. México has one long history ofadvantage of geothermal to generate electricity; samethat begins in the decade of fifties when it settled in
Pathé, Hidalgo, the first geothermoeléctric plant in theAmerican continent.

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The generation in México is constituted by 153
generating power stations of electrical energy, divided
in 64 hydroelectric power stations, 81 thermoelectric,
6 geothermoelé ctric and 2 eoelé ctric ones with an
installed capacity of 35,869 MW all together, to theclosing of December of 2000.

The geothermoel é ctric capacity of México is of
865 megawatts (MW); it was generated 3,1% of the191,197 GWh generated during year 2000. Cerro
Prieto geothermal field is the second greatest one of
the world and produces 60% of the electricity that is
distributed in the network of Baja California, that is
an isolated system of the Mexican National Electrical
System.

The generation of electricity in CFE is made it
by modern available technology in hydroel é ctric,
thermoelectric, geothermal, eólical and nuclear kinds.
In the year 2000, CFE counted with an effective
capacity installed to generate electricity of 35,869
megawatts (MW), of which 9,389.8 MW are ofhydroelectric, 21,657.1 MW correspond to the35Manuel Herrera-Gutierrez and Ruth Tapia-Salazar����� ������ �����
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Cerro Prieto

The Alfa reservoir in the west part of the field is theshallowest and was the first to be exploited. It is foundat depths between 1000 and 1500 m. the deeper Beta
reservoir extends underneath the entire area of the
Cerro Prieto (about 15 km2) at depths between 1500
and 2700 m. with temperatures higher than thosein Alfa reservoir. The deep Gamma reservoir is not
exploited yet.

The Cerro Prieto Geothermal field, Located in thestate of Baja California, 20 miles to border with theUnited States of America, is the largest known water
dominated geothermal field in the world and one of
the more thoroughly studied. It is contained mostly insandstone's and shale's of the Colorado River Delta.
Cerro Prieto Power Plant has an installed capacity of
720 MW. At present, there are 13 units in operation
housed in four power plants (Table No.1).

Tectonically, The Salton Trough-Gulf of California
area is a zone of transition between the divergent
boundary of the East Pacific Rise and the transformboundary of the San Andr é s Fault System. The
sediments at Cerro Prieto were deposited during
Pliocene to middle Pliocene times (Halfman et. al.,There are three reservoirs developed in sandstoneand sandy shale units that are fed from depth byfluids rising from fractures, (Lippmann et. Al., 1991).
36

GEOTHERMAL ENERGY IN MEXICO AND ITS RELATION WITH THE ENVIRONMENT

1984), classified like granodioritic basement.

include cleanout of the orifice plate, workover wells
or drill new wells. In Cerro Prieto field are using
new tools like chemistry, water isotope analysis, andelectronic instruments (TPS), to understand the latest
reservoir changes (Jesús de León V., Juán de Dios O.
And Andres P., 2001).

Hydrothermally talking, minerals identified in Cerro
Prieto are in equilibrium with hot fluids of the sodium
chloride type with pH from neutral to basic. Several
mineral assemblages have been defined. From themcan be concluded that the temperature in the samples
studied is close to 250 ° C; it ends to increase as
minerals like amphibole, biotite and muscovite form
(Georgina I., Enrique P., Alfonso A., Ignacio T. And
Julio A., 2001).

The total electricity generated in 2000 was 5,103.67
GWh (Subdirecci ó n de Distribuci ó n, 2001). This
amount is the highest in the history in Cerro Prieto; it
is 9 % higher than what was produced in 1999 (4,670
GWh; Quijano-Leó n and Gutié rrez-Negrí n, 2000),
because four additional units were placed on line in
July 2000.

In 2000, on average there were 125 production and 9
injection well in service at Cerro Prieto; The number
varied from 119 production and 8 injection wells
in January and February, to 133 production and 10
injection wells in December (Residencia de Estudios,
2001).

In 2000, the average capacity factor for Cerro Prieto
was 88 % as compared 86 % in 1999.
Los Azufres

The wells produced 46.7 millions metric tons of steam
during the 2000, at annual average rate of 5,332 ton/h.
This is 4 % higher than in 1999, when 44.8 million
tons were produced. Steam production well averaged
42.7 ton/h, slightly better than in previous year (40.7
ton/h)(Quijano-Leó n and Gutié rrez-Negrí n, 2000).
In addition 68.4 million tons of geothermal brine
were produced, which were disposed by injection andevaporation (Residencia de Estudios, 2000).

Los Azufres is the second of the four geothermal
fields of México in commercial development, and it
is located in central México, in the Michoacán State,
within the Mexican volcanic Belt. The main featuresof the conceptual model are as follows.
Geothermal electric generation began in 1982. At thistime there 11 power units: one 50 MW condensing
unit, eight 5 MW back pressure units and two 1.5
MW binary cycle units, which totals 93 MW. Another
5 MW backpressure unit, formerly operating in Los
Azufres, has been installed in the Amatitlan geothermal
field, Guatemala.

The annual average specific steam consumption was
8.8 ton/h. This number considers only the steam
available to the plants. That is, the actual steam
arriving at the power plants facilities, and excludes thesteam losses in the pipeline and valve system. During
2000, the available steam was of 44.9 million tons
(Residencia de Estudios, 2001).

The subsurface lithology can be grouped into two
main units, the Mil Cumbres andesites and the Agua
Fria rhyolites (L ó pez, 1991). Andesites containthe geothermal reservoir, while rhyolites act as asealing cap in the south and middle parts of the field.
The superficial limits of the reservoir were definedaccording to geophysical and reservoir engineering
data. For the north zone, in 24.5 km2 (Pérez-Esquivias,
2001), and the volume of the reservoir was calculated
in 42.9 km3. For the south zone the area was estimatedin 12.3 km2 and volume of 14.7 km3.

The exploitation for 27 years has been causing
thermodynamic and chemical changes in the reservoir
conditions, such us boiling, dilution and scaling
and phase segregation. These processes affect the
productivity capacity of the wells (Trhuesdell, et. al.,
1995, 1997).
The steam production decline at Cerro Prieto has
been attributed to five main causes: reservoir pressure
drawdown, scaling in the bottom hole or main feedzones, scaling in the upper production casing, or
scaling in the orifice plates on the surface piping andentalphy decrement (Arellano et. al., 1998). To recover
lost steam production routine maintenance procedures

On average, 20 production well and 6 injection
wells were in operation during 2000. The number of
production wells varied during the year, between 16 in
September-November and 23 in August (Residencia
de Los Azufres, 2001). Their depths range from 800 to2500 meters.
37

Manuel Herrera-Gutierrez and Ruth Tapia-Salazar

Total steam production in 2000 increased to 7.6
million tons (i.e., annual average of 864 ton/h), in thisis the highest recorded in Los Azufres since 1994.

supply the additional steam that the units will require.
Three exploration wells will be repaired also tocomplete the steam.

Production of separated geothermal brine reached4.51 million metric tons, which was reinjected into thereservoir using 6 wells. In 2000 it was almost 0.6 tonsof brine per ton of steam.

Los Humeros

Los Humeros is another geothermal field systemhosted in volcanic rocks. It is located in the centraleastern part of México, also within the Mexican
Volcanic Belt.

Generation of electricity in Los Azufres amounted
586.1 GWh during 2000 (Subdireccion de Distribución, 2001). That year, the annual average capacity factor
was 73.5%. The total available steam at Los Azufres
was 6.9 million tons. (Residencia de Los Azufres,2001). The average annual specific steam consumption
for the entire field was 11.8 ton/MWh.

The first power unit came on line in 1990. By
December 2000 seven 5 MW backpressure units had
been installed in the field. All units have been operated
at 6 MW level for more than 4 years (1997-2000),
increasing the total installed capacity at Los Humeros
to 42 MW (Quijano-Le ó n and Guti é rrez-Negr í n,2000).

Reservoir volumetric analysis and numericalsimulation were used to investigate the potential forfurther development of the field (CFE, 1991; CFE,
1993); results are shown in next table.

In 2000, an average of 12 production wells werein operation at los Humeros, ranging between 21
in January and 8 in December (Residencia de Los
Humeros, 2001). Two injection wells were usedthroughout the year.

Based upon those studies, the Comisión Federal���� �� ����������
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The total steam produced in 2000 was 3 million metrictons, at annual average rate of 342 ton/h (Residencia
de Los Humeros, 2001). This number is quite lower
than in 1999 (4.8 million metric ton; Quijano-Leó
n and Gutiérrez-Negrín, 2000). The reduction wascaused because units 4 and 5 were taken out of line tobe repaired in May and units 3 and 7 in June. Thesefour units did not go back on line during 2000, as
repairs were not completed yet.

de Electricidad decided to install 100 more MW of
Geothermal generation in this field, which represent
only the third of the total potential, assessed by thenumerical modeling. This is the project known as Los
Azufres II, consisting of four units of 25 MW (Units
13, 14, 15 and 16).

The average steam production per well was 29.5 ton/h,and it is the highest rate since 1994.

Because most of the power is installed at the southzone of the field, it was decided to install three of
those power units in the north zone, and one at thesouth zone. With this, the total capacity in Los Azufres
will increase of 93 MW to 193 MW.

During 2000, the total available steam at Los Humeros
was 2.52 million tons; the annual average specificsteam consumption for the operating units was 11.9
ton/MWh, equal to 1999. That indicates that the field
was very well operated, in spite of the problems withthe power units.

Work started in December 2000, and was launchedunder a Build-Lease-Transfer contract, and should
be finished by January 2003. The first one, Unit 13 isscheduled to be commissioned in October 2002, thesecond one, Unit 14, in November 2002, the third one,
Unit 15, in December 2002, and the fourth, Unit 16,
in January 2003. The typical steam required for thoseunits are 7.65 ton/h, at 170 °C and 8.0 bar of absolutepressure, per MW. Eight wells are being drilled to

Because most units were undergoing repair, theelectricity generation during 2000 was only 211.5
GWh (Subdirección de Distribución, 2001), which is
the lowest since 1994. The capacity factor was also
low (57.5 %).
Las Tres Vírgenes
38GEOTHERMAL ENERGY IN MEXICO AND ITS RELATION WITH THE ENVIRONMENT

Las Tres Virgenes field, is located in the central partof Baja California Peninsula, about 46 kilometers
northwest of Santa Rosalia.

and wells is CO2 is the predominant gas (>95%) thatis expected in a geothermal environment. H2 and H2S
are found in significant amounts.

Several exploitation studies as geological, resistivity,geophysical and geochemical studies had been carriedout between 1982 and 1994, to confirm the existenceof a geothermal system in the zone, in order to install
geothermal power plants and satisfy the electricalrequirements of the State of Baja California Sur.
Las Tres Virgenes is situated inside of El Vizcaino
Biosphere Reserve, and has an extension of 57 km2
approximately.

At present the most important problem in Las Tres
Virgenes is the silica and calcite scale in pipelines
and wells. There is a highly saturation calcite index
in the produce mixture, and, because the relatively
low temperature of the resource there is deposition of
calcite inside the well casing in the saturation point of
the fluid.
This prorogues declination of the flow rate and total
blockage of the well with time.

This field is located in an isolated area of the
distribution net, and at the moment the electric poweris generated by means of diesel plants, that implies avery high cost for fuel and transportation.

Besides at surface temperature, the silica deposits
in the injection lines, increasing the frequency andcost of maintenance and in the worst place, scaling in
the injector wells. We are focussing in solving these
problems.

Two condensing power plants of 5 MW each are
already installed, giving 10 MW more to the total
electrical capacity in México. It entered in operation
last May 23rd and it is already providing energy to theelectrical system.

The studies of numerical simulation indicate thefeasibility of operating without further problems
during 25 years, with 20 MW in the southern area, but
this expansion will require exploration toward othergeologic structures such as Cerro Blanco fault andsoutheastern sector where evidence of high seismic
activity is found.

The field is related to a quaternary volcanic complex,
composed of three volcanoes aligned north south.
During the last years Comisión Federal de Electricidad(CFE) has carried out geochemical and isotopic
studies to characterize the thermal springs and thewater produced by the wells.

3. DEVELOPMENT PERSPECTIVESAt present, Comisión Federal de electricidad
is interested to re-initiate the exploration anddevelopment of different areas in México toincrease the geothermal production. Three projects
are activated to continue the friendly energy withenvironment.

Nine wells have been drilled, 6 are producers and 3
reinjectors, their depths range between 1290 and 2500
meters.
Water produced by the wells has a sodium-chloride
composition, characteristic of geothermal brine,
completely equilibrated at a temperature of 280°C;
this temperature is in agreement with the temperature
estimated by geothermometry of gases. The low
Cl/B molar ratio (approximately 12), and the low
magnesium concentrations suggest that the water-rockinteraction took place at high temperatures, and a deep
circulation.

La Primavera

La Primavera geothermal field is located in thewestern of México, in the state of Jalisco. It is about
11 kilometers west from Guadalajara City, and lies
within a quaternary volcanic caldera at an averageheight of 1800 meters above sea level.
The Comisión Federal de Electricidad (CFE) started
the prospecting works in the early 60 ´ s. Four
exploratory wells were drilled between January 1980
and August 1982, and seven more wells were drilled
between January 1984 and January 1988, and in 1989
the activities in this field were stopped and since thenLas Tres Virgenes geothermal system is a dominantliquid reservoir.
The chemical composition of gases from fumaroles
39

Manuel Herrera-Gutierrez and Ruth Tapia-Salazar

The total heat discharge in the Arar ó surface isestimated as 19.7 MWe by García y Tovar (1989),
which is in the rank suggested by Hochestein (1993).

most of the production wells were kept closed orunder flowing confition through 1⁄4" pipes.
Taking into account the abruptness of the local
topography, it would be expected to install 5 MW
backpressure turbo gerator units. Preliminary reservoir
assessment studies (JICA, 1989) have indicated thepossibility to install at least 75 MWe for a 20 year
period. Nowadays, CFE is interested to reinitiate thisproject to install 2 x 25 MWe turbo-generator units inthe near feature.

So, CFE is studying this zone to be sure about ageothermal potential of electricity.
Punta Banda

Deep submarine energy is related to the existence ofhydrotermal vents emerging in many places along theoceanic spreading centers between tectonic plates.
These systems have a total length of about 65,000-km
in the earth's oceanic crust. Shallow submarine heat is
related to faults and fractures in the sea bottom close
to some coasts. Hydrotermal submarine reservoirs
contain an essentially infinite energy potential.

CFE has carried out a complete and comprehensive
program to restore the environmental impacts causedby the prior work.
Other programs are about to estimate the production
parameter variation caused by the modification tothe original pipe completion of the production wells,
using Wellsim as the official wellbore simulator.
As it knows, it internally incorporates five different
two-phase flow correlations (Aziz, Duns, Hagedorn,Orkiszewski and Wellsim) for well simulations.

This type of shallow subsea system was foundoffshore at Punta Banda in Ensenada, Baja California.
The 3He detected in the Wagner Depression, is ofmagmatic origin and comes directly from the sea
bottom carried by vertical submarine streams.

According to the results obtained through thesimulation work done, the total mass flow rate is not
drastically affected with respect to the modification
studied. In this way, the drilled wells can be repairedwith no substantive changes in their original
production rates. However, it seems to be necessarythat all wells would have to be opened before any
further decision be taken (Sánchez-Upton, 2001).

Natural chimneys photographed by Mercado (1990)
at 2600 m depth in the Gulf of California, discharge
spouts of waters at 350 °C. These plumes of warm
water generate conditions in adjacent water to produce
suspended materials as source of nourishment fooddifferent living organisms.

Araró

Comisión Federal de Electricidad In order to transform
into facts the environmental commitment andpolicies, an Institutional Program of Environmental
Protection settled down that contains actions relative
to the quality protection of the air, water, ground andto the conservation of the flora and fauna in all thestages of each electrical project. Comisión Federal
de Electricidad counts on the necessary infrastructure
for the protection to the atmosphere that surrounds it
and with specialized departments by Environmental
engineering, ordered of the measurement of all theenvironmental aspects, supervising the fulfillment of
the parameters marked in the effective rules and laws,
in environmental protection matters.

4. ENVIRONMENTAL PROTECTION

The Arar ó geothermal zone is located in thenortheastern part of the state of Michoacán, 40
kilometers south of Morelia city, within the Mexican
Volcanic Belt. The main zone of hydrothermal
manifestation is 6 km north of the Zinapecuaro town.
In the Araró geothermal zone, CFE has carried out
several exploratory studies and drilled five shallow
gradient wells as well as two deep exploratory
wells. The reinterpretation of these results will givethe conditions to define some characteristics ofthe subsurface geothermal system. It seems to be afracture zone reservoir of a stock work type and fluid
flow appears to be limited to a throttle, or narrowconduit, probably linked to the Araró Zimirao fault at
more than 2000 m depth.



In Air Matter

Network of measurement of quality of the air

For more than 10 years it has been having installed40

GEOTHERMAL ENERGY IN MEXICO AND ITS RELATION WITH THE ENVIRONMENTin the country, networks of measurement in several
power stations to know the quality air in thesurroundings of the same ones. During the period of
operation of the measurement network.


substance to the atmosphere.
Grounds Matter・ Studies to verify if impacts exist that could besignificant to the environmental surroundings of thepower stations.

In the Matter of Water

CFE has made works to mitigate the environmental
impact through several actions, as follows.

Special Projects

・Voluntary environmental audits, under the terms of・Construction of separating graves of oil and waterreference of the PROFEPA, obtaining itself thus
Certified from "Clean Industry" for 8 power stations
and 22 more in process, Included Cerro Prieto and
Los Azufres.
・Certification in the international Norm of Quality
ISO 9002 for than 30 power stations, hoping morethat for the 2003, all the institution is left registeredletter in this norm.
・ C e r t i fi c a t i o n i n t h e i n t e r n a t i o n a l N o r m o fenvironmental Administration ISO 14001 of 16
power stations, 2 corporate areas and a laboratory oftests, being in process other 10 power stations.

in each one of the pluvial water unloading, which
operate in order to assure that by no reason fats andoils unload that by some contingency could arrive atthese unloading.
・Black water plants to treat the sanitary unloading
about CFE.
・Graves of neutralization that allows the appropriate
processing of process waters, previous to its
unloading. In these graves arrive the unloading fromthe plants of water processing, chemical washingsof regenerative air preheaters and other effluents thatby their composition could cause pollution risks.
・Brigade of fire-fighting emergency and for attentionof spills of dangerous substances or oils, in caseof a contingency that could affect the ecologicalsurroundings.
Legal Aspect

Comisión Federal de Electricidad has worried to counton the Permissions, Registries and Information thatare due to obtain and/or to present/display before theNormative Dependencies. Between the most important
permissions it is counted on the following ones:

Residual Water Discharges

The residual water discharges are registered by the
Comisión Nacional del Agua (CNA); same that fulfill
the limits established in the Mexican Official RuleNOM-001-ECOL-1996. Inclusively, CNA has freed to
CFE in several power stations of the accomplishmentof the metal analyses of its discharges, by virtue of tohave demonstrated through analysis, that it does not
add in his unloading any of the polluting agents of thattype established by the mentioned Official Rule.

・License of Operation and/or Unique Environmental

License.
・ Permission of generating company of dangerous

remainders.
・Certificate of annual operation.
・Title of deep Well concession.
・Title of Allocation of residual water unloading.
・Permission of burns to sky opened for practices fire

protective.
Remainders matter

・ Procedures of control of the remainders that are

Flora Preservation and Ecological Restoration at

generated by the activities of production andmaintenance. In these procedures one settles
down as remainders are the nondangerous anddangerous ones, and as it is the strategy of handling,
segregation, temporary and final disposition, as wellas the control necessary to fulfill the rules in theremainders matter.
・ Temporary warehouses of storage of dangerous
remainders.
・Zones of mud evaporation to wash the nondangerous
materials that are impregnated by some dangerous

Las Tres Virgenes Geothermal Field

Comisión Federal de electricidad developed andcarried out an environmental program at Las Tres
Virgenes geothermal field, Baja California, México, tomitigate and compensate for impacts associated withthe exploration, development and exploitation of thearea.
The field is located within the buffer zone of "El
Vizcaino Biosphere Reserve", which extends overapproximately 25,500 km2. It is the largest ecological41

Manuel Herrera-Gutierrez and Ruth Tapia-Salazar

reserve in México and one of the biggest in Latin
America, and includes the "Vizcaino Desert" andthe "ojo de Liebre" and "Guerrero Negro" marine
lagoon systems. The Mexican Government createdthis reserve to protect this unique area, which includes
major breeding and calving lagoons for gray andhumpback whales. The on land reserve is a refuge forendangered mammals, as well as for several species of
migratory and resident birds (Ortega Varela, 1996).

is also a BLT (Built, Lease and Transfer) contract,which was won by the French Company Alstom.
Construction activities started in November 2000, andshould be finished by January 2003 (Cornejo-Castro,
2001). The project includes 4 x 25 MW condensed
units in four different houses. This project will double
the present capacity at Los Azufres.
Development of Las Tres Virgenes I geothermal
project is finished right now, with a capacity of 10
MW, in 2 x 5 MW. With this, the total installed
geothermal electrical capacity in México is 865 MW.

The program, which consisted mainly of floratransplantation and ecological restoration activities, isas follows.

Comisión Federal de Electricidad CFE has madeyearly an Institutional Program of Environmental
Protection settled down that contains actions relative
to the quality protection of the air, water, ground andto the conservation of the flora and fauna in all thestages of each electrical project.

After many actions and activities in the zone, a totalof 2,430 plants of 16 species were saved from possible
destruction and transplanted. Approximately one year
later, 1815 plants were still alive in the restored sites,
which means a rather high rate of survival (75 %), therest were mostly small plants.

CFE is making voluntary environmental audits, under
the terms of reference of the PROFEPA, obtaining
itself thus Certified from "Clean Industry" for 8 power
stations and 22 more in process, Included Cerro
Prieto and Los Azufres. Also, has made programs forcertification in the international norm of quality ISO
9002 for 30 power stations, hoping more that for the
2003, all the institution is left registered letter in thisnorm, and Certification in the international Norm ofenvironmental Administration ISO 14001 of 16 power
stations, 2 corporate areas and a laboratory of tests,
being in process other 10 power stations.
C e r r o P r i e t o i s t h e fi r s t g e o t h e r m a l fi e l d i n

The plants were removed from construction areas (wellplatforms and roads) covering a total of about 29,225
m2. They were successfully transplanted and used in
the ecological restoration of a 30,000 m2 area near thegeothermal project (Ortega-Varela, et. al., 2001).
5. SUMMARY AND CONCLUSIONS

Year 2000 comparing with four years before for all
operating geothermal fields in México is combined asfollows.
Though during 2000, the number of production wells
in service was the lowest since 1993, the amount of
produced steam was the highest, as well as the annual
average rate of production. This apparent paradox
is due to a larger average production per well (41.6
ton/h), highest since 1993. This increase is the resultof improved productivity attributable to a better
operation of all the geothermal fields during 2000,
in spite of problems with some of the units at Los
Humeros.

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Geothermal electrical generation in 2000 was thehighest in México`s geothermal history. This can be
explained by the commissioning of Cerro Prieto IV
power plant in July 2000.
Another important 2000 highlight was the completionof the international bid for the construction andinstallation of Los Azufres II geothermal project. It

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LatinAmerica to get such certificate ISO 9001.
42

GEOTHERMAL ENERGY IN MEXICO AND ITS RELATION WITH THE ENVIRONMENTREFERENCES

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Hector Perez-Esquivias. Current Conceptual of theLos Azufres, México, Geothermal Field. Geothermal
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Georgina Izquierdo, Enrique Portugal, AlfonsoA r a g o n , I g n a c i o To r r e s a n d J u l i o A l va r e z .
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Magaly Flores-Armenta and Guillermo JaimesM a l d o n a d o . T h e L a s Tr e s Vi rg e n e s M éx i c o
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Roberto Ramirez Ramirez. Characteristics of the43