Thailand: Resources at a GlanceOfficial name: Kingdom of Thailand Government: Constitutional monarchy Capital city: Bangkok Area: 198,131 mi2; 513,120 km2 Population 2009 est.: 65,905,41
Trang 1Thailand: Resources at a Glance
Official name: Kingdom of Thailand Government: Constitutional monarchy Capital city: Bangkok
Area: 198,131 mi2; 513,120 km2
Population (2009 est.): 65,905,410 Language: Thai
Monetary unit: baht (THB)
Economic summary:
GDP composition by sector (2008 est.): agriculture, 11.6%; industry, 45.1%; services, 43.3%
Natural resources: tin, rubber, natural gas, tungsten, tantalum, timber, lead, fish, gypsum, lignite, fluorite, arable
land
Land use (2005): arable land, 27.54%; permanent crops, 6.93%; other, 65.53%
Industries: tourism, textiles and garments, agricultural processing, beverages, tobacco, cement, light manufacturing
such as jewelry and electric appliances, computers and parts, integrated circuits, furniture, plastics, automobiles and automotive parts; world’s second largest tungsten producer and third largest tin producer
Agricultural products: rice, cassava (tapioca), rubber, corn, sugarcane, coconuts, soybeans
Exports (2008 est.): $174.8 billion
Commodities exported: textiles and footwear, fishery products, rice, rubber, jewelry, automobiles, computers and
electrical appliances
Imports (2008 est.): $157.3 billion
Commodities imported: capital goods, intermediate goods and raw materials, consumer goods, fuels
Labor force (2008 est.): 37.78 million
Labor force by occupation (2005 est.): agriculture, 42.6%; industry, 20.2%; services, 37.1%
Energy resources:
Electricity production (2007 est.): 148.4 billion kWh
Electricity consumption (2007 est.): 138.6 billion kWh
Electricity exports (2007 est.): 731 million kWh
Electricity imports (2007 est.): 4.488 billion kWh
Natural gas production (2007 est.): 25.4 billion m3
Natural gas consumption (2007 est.): 35.3 billion m3
Natural gas exports (2007 est.): 0 m3
Natural gas imports (2007 est.): 9.8 billion m3
Natural gas proved reserves ( Jan 2008 est.): 331.2 billion m3
Oil production (2007 est.): 348,600 bbl/day Oil imports (2005): 832,900 bbl/day Oil proved reserves ( Jan 2008 est.): 176 million bbl Source: Data from The World Factbook 2009 Washington, D.C.: Central Intelligence Agency, 2009.
Notes: Data are the most recent tracked by the CIA Values are given in U.S dollars Abbreviations: bbl/day = barrels per day;
GDP = gross domestic product; km 2 = square kilometers; kWh = kilowatt-hours; m 3 = cubic meters; mi 2 = square miles.
China
Bangkok
Myanmar
Thailand
Cambodia
Vietnam Laos
Malaysia Indonesia
Bay of
Bengal
Andaman
Thailand
S o u t h
C h i n a S e a
I n d i a n
O c e a n
Trang 2increased 60 percent, earning $2.8 billion Three
years later, Thailand produced 2.7 million metric tons
of that resource, and industry representatives expected
yields to expand 2.2 percent annually afterward That
year, Thailand exported 2.5 million metric tons of
nat-ural rubber worth $5.41 billion to the United States,
Japan, China, and other markets
Occasionally, weather changes caused by El Niño
have threatened successful rubber harvests and that
industry’s success in Thailand Synthetic rubber has
competed against natural rubber for markets,
impact-ing Thailand’s rubber industry, which has suffered
declining prices and lost income The Thai
govern-ment has encouraged rubber farmers to continue
cul-tivating rubber plantations during economic crises,
such as the international recession in 2008, which
affected automobile production, reducing demand
for rubber tires
Tin
Thailand has produced the third most tin
internation-ally since 2002, competing with neighboring Malaysia
and Indonesia, both of which have ample tin resources
Tin deposits stretch from Thailand’s peninsula, which
has the largest reserves, to smaller amounts in
north-ern provinces along the Myanmar (Burma) border
Thais have mined tin ore for several centuries In
ad-dition to their location in land sites, tin ore deposits
are often found in sea- and riverbeds Islands near
Phangnga Province have large tin deposits
The retrieval of tin from seabed deposits requires
specialized technology, such as dredges and suction
devices on boats Because of the expenses involved in
extracting tin, mining companies that can afford the
necessary equipment and employ experienced divers
dominate offshore tin mining In addition to Thai
mining businesses, many foreign companies invest
in extracting tin resources located close to Thailand’s
coasts By 1963, Thailand Smelting and Refining
Com-pany Ltd (THAISARCO) operated a tin smelter at
Phuket
During the 1980’s, Thailand produced more than
27,000 tons of tin yearly in addition to unreported tin
exports shipped clandestinely to markets in an
at-tempt to avoid paying taxes and royalties to the
gov-ernment During the following decades, tin exports
consistently generated foreign income for Thailand,
with only a small portion of that resource being used
domestically By 2000, approximately 70 percent of
Thai tin and related materials, such as slag and
tanta-lum, were that country’s leading global exports Thai-land exported tin worth 6 billion baht (roughly $162 million) in 2006 In 2007, tin prices reached $15,000 per metric ton; the rate of government royalties and the willingness of the Department of Mineral Re-sources to adjust percentages the government re-ceived affected the interest of mining companies and investors in that resource
Tantalum Tantalum represents Thailand’s most controversial resource Thais have resisted tantalum refinery meth-ods, which they consider detrimental to environmen-tal and economic quality Tanenvironmen-talum is often used in computing, electronics, and aerospace technology In
1985, the Thailand Tantalum Industry Corporation, with a desire to profit from this tin by-product, started construction of a $46 million tantalum refinery near
A worker in a Thai rubber factory holds a container of latex Rubber
is a major natural resource for Thailand (Sukree Sukplang/
Reuters/Landov)
Trang 3houses and hotels on Phuket, a popular Thai island
that generates income from tourism and fisheries
Many people in Phuket were already angry that tin
mining and related industrial processes had
detri-mentally impacted their community, particularly in
terms of the environment, which was crucial to
at-tracting tourists and maintaining fish health (fishing
provides many residents funds) They voiced their
worries about disposal of hydrofluoric acid
incorpo-rated in Thailand Tantalum Industry Corporation’s
procedures
On June 1, 1986, fifty thousand citizens,
represent-ing the Committee to Coordinate Action Against
Pol-lution, protested publicly and signed petitions,
de-manding the Thai government intervene to stop the
refinery Thai industry minister Chirayu Isarangkun
na Ayutthaya traveled to Phuket on June 23 but left
quickly, frightened by the enraged crowd, which
burned the refinery and kept firefighters away
Re-sponding to this action, the Thai government passed
the National Environmental Quality Act to fund
regu-lating industries, particularly those refining tantalum,
and to remove industrial materials contaminating the
environment By August, 1992, the Thailand
Tanta-lum Industry Corporation had built another
tanta-lum refinery at Map Tha Phut, an industrial site, and
stated hydrofluoric acid would not be released
out-side the factory Achieving rates of 272,000 kilograms
annually, that company often produced 40 percent of
tantalum globally, the most in the world Thailand
hosted the World Tantalum Conference in 1992
Rice
In the first decade of the twenty-first century,
Thai-land exported more rice than any other country in
the world Prior to the 2008 economic crisis, Thailand
exported more than 5.9 million metric tons of rice
ev-ery year Encouraged by King Bhumibol Adulyadej,
who promotes agriculture, Thai farmers cultivate this
lucrative crop on large areas (28 percent of the
coun-try) of Thailand’s arable land Thailand’s unique
jas-mine rice attracts foreign buyers willing to pay higher
prices for this delicacy
The Thai government started emphasizing jasmine
rice in the 1980’s in an attempt to surpass other
ex-porting nations Thai exports of jasmine rice
accumu-lated $48 million dollars during 1988 Prices for Thai
jasmine rice exports rose 44.4 percent within two
decades, with yields increasing approximately 2.5
per-cent annually Competitors attempt to grow and
market jasmine rice but have been unable to achieve the quality and quantity Thai rice producers have achieved Thailand’s greatest challengers for rice-exporting leadership include U.S long-grain rice and Pakistan’s basmati rice Vietnam poses regional com-petition for rice production
In 2004, Thailand produced 9.18 million metric tons of rice worth $2.73 billion A 2005 drought low-ered rice exports, with jasmine rice selling for about
$400 per metric ton and pathumthani rice receiving
$275 to $450 per metric ton The global economic cri-sis in 2008 impacted Thailand’s rice exports despite food shortages increasing demand Rice production
in Nakhon Sawan Province decreased by 25 percent
In 2009, the Bangkok Post reported Thailand’s rice
ex-ports had decreased by 15.9 percent, with the country exporting only 666,688 metric tons of rice, worth
$406 million to international markets Payment of European Union tariffs, approximately $160 per met-ric ton, which many Asian countries are not required
to pay, reduced Thailand’s profits
Lignite Since the 1960’s, the Electricity Generating Authority
of Thailand (EGAT) has extracted lignite, a form of coal, from the Mae Moh Lignite Mine in the country’s northern Lampang Province as an energy resource to fuel the country’s biggest power plant Geologists stated the coal deposits beneath the Mae Moh mine, which encompasses 32 square kilometers, total 630 million metric tons, placing it among the region’s big-gest mines This mine annually produced 2.5 million metric tons of lignite at its peak Wanting to reduce Thailand’s reliance on imported oil, government of-ficials planned additional development of Thai re-sources to generate energy The Second Mae Moh Lignite Project resulted in more lignite extraction
at that mine, attaining 4.5 million metric tons pro-duced yearly Thailand’s second lignite mine, in Krabi Province on Thailand’s peninsula, produces about 250,000 metric tons of lignite annually
Lignite mining in Thailand has caused problems Approximately thirty thousand citizens were removed from lands in the Mae Moh valley in order to facilitate construction and operation of the Mae Moh mine and power plant The mining process released pollut-ants, especially dust and sulfur dioxide emissions, into the environment, contaminating water and air sources and damaging people’s health Agricultural resources, including soil and crops, were severely damaged
Trang 4In the early twenty-first century, the Mae Moh
power plant provided Thailand with electricity but
had the undesirable distinction of being Southeast
Asia’s largest producer of sulfur gas Villagers pursued
litigation against EGAT In March, 2009, a Chiang
Mai court demanded that EGAT provide $7,000 per
Thai whom lignite mining and power generation had
harmed physically and economically EGAT also was
required to pay for villagers to move to land located at
a safe distance from the power plant and to improve
the mine’s environment by planting trees
Natural Gas
Thailand has sought to develop such indigenous
en-ergy resources as natural gas because the country did
not produce sufficient oil to meet domestic demand
and was consistently among the top oil importers in
Southeast Asia During the 1970’s, Thailand
identi-fied several Gulf of Thailand natural gas fields The
field near Sattahip contained 40 billion cubic meters
of known natural gas reserves and possibly another
6.2 billion cubic meters Another field, located 170
ki-lometers south of Sattahip, held 3 billion cubic meters
of natural gas with potentially 127 billion cubic meters
more Other fields contributed to more than 300
bil-lion cubic meters of Thai natural gas reserves
In the early 1980’s, the Petroleum Authority of
Thailand (PTT) and the Ministry of Industry oversaw
pipeline construction near Map Tha Phut,
extend-ing south 425 kilometers in the gulf to a natural gas
field Other pipelines on land transported natural
gas to thermal power plants and industries in
Bang-kok and Bang Pakong The Erawan field provided
natural gas through pipelines to several gas and
power plant sites, including ones in Rayong, Samut
Prakan Province, and the Khanom district in Nakhon
Si Thammarat Province The Bongkot natural gas
field became Thailand’s biggest source of that
re-source, attracting such international companies as
Chevron That company extracts natural gas from
twenty-two Thai fields, producing 70 percent of that
resource in Thailand
In 2008, the Gulf of Thailand’s Arthit and Block
A-18 fields began contributing 20 million cubic meters
of natural gas daily to boost yields Oil and Gas Journal
projected that extraction from more Gulf of Thailand
natural gas fields will enable Thailand to acquire
suffi-cient amounts of that resource to exceed demand
Officials urged Thai motorists to use natural gas as a
fuel instead of oil
Other Resources Thailand has numerous mineral resources with vary-ing production levels and contributions to the global economy Exports of Thai feldspar have ranked high internationally, behind Italy and Turkey, with one mil-lion metric tons produced in 2006, approximately 7.5 percent of the global exports A zinc deposit located
in Tak Province at Mae Sot held 3.2 million metric tons Thailand ranked eighth in the world for gypsum exports in 2001, producing 8.6 million metric tons of gypsum in 2007 Finally, Thailand’s Ministry of En-ergy has encouraged companies such as Solartron to manufacture sufficient amounts of photovoltaic cells
to export that commodity
Fish comprise 10 percent of Thailand’s exports, especially prawns and tuna Thailand has regularly ranked third in deep-sea fishing yields among Asian countries Thailand’s agricultural resources, rang-ing from crops—includrang-ing sugarcane, coconuts, and pineapples—to forestry, have consistently earned land global rankings near the top ten for exports Thai-land also exports cassava, sold as tapioca, globally Thailand has gained income from luxury resources
In 2006, Thailand earned $14.5 million from silk exports Although India and China dominate interna-tional silk trade, many consumers prefer Thai silk, produced from silkworms cultivated on mulberry groves in Isan Thailand exports orchids to global markets Consistent consumer demand, despite eco-nomic recessions, enables Thailand to acquire more than $100 billion yearly from orchid exports Gem-stones contribute to Thailand’s export gains, with sap-phires mined from Kanchanaburi Province and ru-bies extracted from Chanthaburi and Trat provinces Mines in Lamphun and Chiang Mai provinces extract minerals, including some uranium, from sizable fluo-rite deposits
Elizabeth D Schafer
Further Reading
“Amanta Revives Thai Tungsten.” Mining Journal
(June, 2008): 7
Douangngeune, Bounlouane, Yujiro Hayami, and Yo-shihisa Godo “Education and Natural Resources
in Economic Development: Thailand Compared
with Japan and Korea.” Journal of Asian Economics
16, no 2 (April, 2005): 179-204
Hirsch, Philip, ed Seeing Forests for Trees: Environment and Environmentalism in Thailand Chiang Mai,
Thailand: Silkworm Books, 1998
Trang 5Keeratipipatpong, Walailak “Thai Orchid Exports
Remain Resilient.” Bangkok Post, June 17, 2009.
Rahman, Sanzidur, Aree Wiboonpongse, Songsak
Sriboonchitta, and Yaovarate Chaovanapoonphol
“Production Efficiency of Jasmine Rice Producers
in Northern and Northeastern Thailand.” Journal
of Agricultural Economics 60, no 2 (2009): 419-435.
Web Sites
Amanta Resources Ltd
http://www.amantaresources.com
Thailand Ministry of Natural Resources and
Environment
Department of Mineral Resources
http://www.dmr.go.th/dmr_data/eng/
indexeng.htm
Thailand Smelting and Refining Company Ltd
http://www.thaisarco.com
See also: Agricultural products; Agriculture
indus-try; El Niño and La Niña; Oil and natural gas
distribu-tion; Rice; Rubber, natural; Tin; Tungsten
Thallium
Category: Mineral and other nonliving resources
Where Found
Thallium is widely distributed in the Earth’s crust in
small amounts A few minerals exist that contain up to
60 percent thallium, but these are extremely rare The
most important sources of thallium are zinc and lead
ores
Primary Uses
Thallium compounds are used in very small amounts
for special applications in electronics and
glass-making Thallium was used previously in pesticides
Technical Definition
Thallium (abbreviated Tl), atomic number 81,
be-longs to Group IIIA of the periodic table of the
ele-ments and resembles lead in its chemical and physical
properties It has two naturally occurring isotopes and
an average atomic weight of 204.37 Pure thallium is a
soft, dense, shiny metal that dulls to a blue-gray tinge
when exposed to air Its density is 11.85 grams per
cu-bic centimeter; it has a melting point of 303.5° Celsius and a boiling point of 1,457° Celsius
Description, Distribution, and Forms Thallium is a fairly rare element resembling lead It is mostly obtained as a by-product of the extraction of lead or zinc from sulfide ores or from copper smelting Most of this production takes place in the United States (recovery from flue dust and smelters), Canada, and Europe Once used in pesticides, thallium is now used
to a limited extent in manufacturing photoelectric de-vices and in making special kinds of optical equipment
History Thallium was discovered in 1861 by the British chem-ist and physicchem-ist Sir William Crookes Its first impor-tant industrial use was as a rat poison and insecticide
in the form of thallium sulfate, first used in Germany
in the 1920’s In the 1960’s, thallium compounds fell out of use for this purpose
Obtaining Thallium Thallium is usually obtained from the sulfide ores
of zinc and lead When these ores are heated to ex-tract the zinc or lead, dust and gas that contain thal-lium compounds, as well as compounds of elements such as cadmium, indium, selenium, and tellurium, are released Thallium compounds are separated from the other compounds by a variety of chemical pro-cesses In general, these methods involve forming compounds of thallium that have higher or lower sol-ubilities in certain liquids than the equivalent com-pounds of the other elements Crystallization removes the least soluble compound
Free thallium may be obtained from the com-pound by electrolysis, resulting in a powder It may then be transformed into metallic form by compress-ing it, heatcompress-ing it in the absence of oxygen, and castcompress-ing
it into molds
Uses of Thallium Thallium is not a major resource in manufacturing, but it has a few special uses Thallium sulfide may be used to make photoelectric cells that are highly sensi-tive to infrared light Thallium bromide and thallium iodide can be used to produce crystals that transmit infrared light These crystals may then be used to make lenses, windows, and prisms for use in infrared optical systems Thallium oxide may be used to make special kinds of glass or to add color to artificial gems
Trang 6Thallium-barium-calcium-copper oxide
high-temperature superconductors are used in wireless
communication devices Sodium iodide crystals doped
with thallium are used in scintillometers for the
detec-tion of gamma rays Thallium increases the refractive
index and density of glass; it is employed as a catalyst
for the synthesis of organic compounds; it is used
in high-density liquids that are employed in
mineral-separation methods; it is also alloyed with mercury to
measure low temperature Finally, thallium 201, a
ra-dioactive isotope, is used in cardiovascular imaging
Thallium compounds are often toxic, as shown by
their former use in pesticides Thallium poisoning is
rare but can be fatal Symptoms of thallium toxicity
in-clude rapid hair loss and disorders of the digestive
and nervous systems
Rose Secrest
Web Site
WebElements
Thallium: the Essentials
http://www.webelements.com/thallium/
See also: Lead; Metals and metallurgy; Pesticides and
pest control; Zinc
Thermal pollution and thermal
pollution control
Category: Pollution and waste disposal
Thermoelectric power plants remove large quantities of
water from the environment, use it to condense steam
exiting a turbine, and return warmer water Although
the water is heated only slightly, there are
environmen-tal consequences.
Definition
Thermal pollution is waste heat that has been dumped
into an aquatic environment The main sources of
thermal pollution are fossil-fuel and nuclear power
plants
Overview
The oxygen content of the heated water, critical for
most marine life, decreases as the temperature
in-creases, while concurrently plankton multiply more
rapidly, putting a further demand on the available oxygen Since fish are cold-blooded and cannot main-tain a constant body temperature, their metabolic rate increases with temperature: More oxygen is needed, and less is available
Also, the toxicity of chemical pollutants present in
a lake or river increases with temperature Extra heat
in the water can also raise the temperature beyond the lethal temperature for fish Cold-water species such as salmon and trout die quickly when the water tempera-ture reaches 26° Celsius Although fish can adapt to warmer water if the change occurs slowly, the rapid changes that occur when power plants shut down for maintenance are usually fatal Furthermore, warm water can block cold-water species from reaching their spawning areas, and entire food chains can be disrupted when higher temperatures alter a local eco-logical balance
Thermal pollution can be controlled either by us-ing the waste heat or by alleviatus-ing it through other means when it cannot be used Waste heat could be utilized to irrigate fields in cold, dry climates so as to extend the growing season Waste heat can preheat salt water for distillation in coastal regions where fresh water is scarce, such as in Southern California A large pond could be used to contain the heat, and the pond could be stocked with catfish, a source of food, which thrive in 34° Celsius water Combining a sewage treat-ment plant with an electric power plant, the waste heat could be employed to help evaporate water from treated sewage In winter, waste heat could be used to heat factories located near the power plant Finally, rivers such as the St Lawrence that often freeze in win-ter perhaps could, with a sufficient number of power plants along its bank, be kept open for navigation There are two methods for alleviating thermal pol-lution when no useful means of using the heat can be found The simpler method is a cooling pond The warmed water flows into a large artificial pond, where
it releases its heat into the atmosphere After cooling, the water may be reused or flow back into a river Al-though relatively inexpensive to construct and main-tain, this method requires a large amount of land— approximately 800 hectares for a typical small power plant producing 1,000 megawatts Obviously this is not feasible in a densely populated region
The main way that thermal pollution is alleviated is
by means of the cooling tower, essentially a very large radiator The heated water flows through finned tubes, transferring its heat to the atmosphere If the system Global Resources Thermal pollution and thermal pollution control • 1221
Trang 7is closed, no water is lost through evaporation For a
typical small, 1,000-megawatt plant, at least one tower
76 meters in diameter and 98 meters high is required
Although not much land area is covered, the towers
are much more expensive than cooling ponds Each
tower adds approximately 10 percent to the cost of
constructing the power plant, which causes electricity
rates to be about 5 percent higher
George R Plitnik
See also: Coal; Cogeneration; Nuclear energy; Water
pollution and water pollution control
Third World countries See
Developing countries
Thorium
Category: Mineral and other nonliving resources
Where Found
Thorium occurs in various minerals that contain
ura-nium or rare earth elements The most important
source of thorium is monazite, which is usually found
in sand Sand containing monazite is found in India,
Brazil, Australia, Madagascar, Sri Lanka, South Africa,
and Canada In the United States, thorium is found
in Idaho, Florida, Michigan, California, Colorado,
North Carolina, and South Carolina
Primary Uses
Thorium is mostly used in the form of thorium 232
This can be used to produce uranium 233 for nuclear
reactors
Technical Definition
Thorium (abbreviated Th), atomic number 90,
be-longs to the actinide series of the periodic table of the
elements and resembles uranium in its chemical and
physical properties All thorium isotopes are
radio-active; thorium 232 dominates because it has a
half-life of about fourteen billion years Thorium has an
atomic weight of 232.038 Pure thorium is a
silver-white metal that turns gray or black when exposed to
air Its density is 11.7 grams per cubic centimeter; it
has a melting point of about 1,700° Celsius and a
boil-ing point of about 4,000° Celsius (Exact figures
can-not be given because these values are greatly changed
by impurities.)
Description, Distribution, and Forms Thorium is a fairly rare radioactive element resem-bling uranium It is mostly obtained along with rare earth elements in the processing of monazite Tho-rium serves as an indirect source of nuclear power be-cause it can be changed into uranium
History Thorium was discovered in 1828 by the Swedish chem-ist Jöns Jacob Berzelius Its radioactive nature was dis-covered in 1898 In the late nineteenth century and early twentieth century, thorium was mostly used in mantles for incandescent gaslights because it gave off
a bright white light when heated
Obtaining Thorium Thorium is usually obtained from monazite First the monazite is finely ground and mixed with hot sulfuric acid or hot sodium hydroxide to separate thorium and rare earth elements from the other substances found in monazite Thorium compounds are then obtained from this mixture by a variety of chemical re-actions In general, these methods depend on the fact that certain thorium compounds have different solu-bilities from similar compounds of the rare earth ele-ments in certain solvents
Free thorium may be obtained by treating thorium oxide with calcium at about 950° Celsius It may also
be obtained by the electrolysis of thorium chloride The thorium powder obtained by these methods may
be transformed into thorium metal by compressing it and heating it in a vacuum
Uses of Thorium
In a nuclear reactor thorium 232 can be transformed into uranium 233, which can undergo fission to re-lease nuclear energy Thorium is also used to strengthen magnesium alloys, to make photoelectric cells, as a catalyst, in welding electrodes, and in high-temperature ceramics
Because thorium is radioactive, it poses a health hazard Although thorium 232 is not particularly dan-gerous on its own, one of the substances it changes into as it decays, radon 220, is hazardous because it is a gas and may enter the lungs Because of its radioactiv-ity, the use of thorium products has decreased
Rose Secrest
Trang 8Web Site
U.S Geological Survey
Mineral Information: Thorium Statistics and
Information
http://minerals.usgs.gov/minerals/pubs/
commodity/thorium/
See also: Metals and metallurgy; Nuclear energy;
Rare earth elements; Uranium
Three Gorges Dam
Category: Obtaining and using resources
The Three Gorges Dam, in addition to being one of the
largest dams ever built, is perhaps the most public
example of the conflict between resource
manage-ment benefits and the environmanage-mental and societal
costs.
Definition
The Three Gorges Dam lies on the Chang River
(also known as the Yangtze River) in China It is
designed primarily to provide flood control,
electricity, and reliable water resources In
pro-viding these resource benefits, however,
con-struction of the dam also damaged the existing
ecology, forced people be relocated, and flooded
cultural sites
Overview
The Three Gorges Dam was proposed by Sun
Yat-sen in 1919 and later supported by Mao
Zedong Plans for the dam were approved in
1992, and construction began in 1994 In 2006,
the 185-meter-tall and 2.3-kilometer-long dam
was completed The reservoir behind the dam
extends 660 kilometers to Chongqing and
cov-ers an area of approximately 1,050 square
kilo-meters The dam cost approximately $30 billion,
with an additional $22 billion spent to relocate
people living in the flooded area of the
voir, $2 billion to stabilize slopes near the
reser-voir, and $5 billion to improve water quality in
the reservoir
A benefit of the Three Gorges Dam is flood
control The Chang River has flooded
approxi-mately one thousand times in the last two
thou-sand years, including five major floods in the twenti-eth century that killed thousands to millions of people The Three Gorges Dam is designed to dramatically re-duce the possibility of floods The dam also prore-duces more electricity than any other dam in the world At full capacity, the dam is expected to generate more than 80 terrawatt-hours per year in electricity This en-ergy will help fuel growth and development in China, while contributing to China’s goal of meeting up to 15 percent of its energy needs from renewable sources by
2020 The large volume of water stored in the reser-voir, approximately 40 cubic kilometers, will provide reliable water resources for nearby industry, agricul-ture, and municipalities Finally, because the reser-voir widens and deepens the Chang River for such a long distance, large vessel navigation is now possible from Shanghai to Chongqing
As of 2010, the controversial Three Gorges Dam in China was the largest hydropower station in the world (Zheng Jiayu/Xinhua/Landov)
Trang 9These benefits do not come without significant
costs Approximately 1.2 million people had to be
re-located, which is the largest population resettlement
in peacetime history In addition, it was announced
that between 4 and 16 million additional people living
in the area might need to be relocated in the future
The decreased freshwater outflow from the dam
re-sults in more saline conditions farther downstream,
which has impacts on wildlife and on diseases, such as
schistosomiasis The heavily fished Chang River has
seen a steep decline in its total catch since the
reser-voir started filling, although it is uncertain how much
of this decline is because of the dam Also, it is possible
that the Three Gorges Dam will result in the
extinc-tion of the river dolphin (baiji) and the finless
por-poise (jiangzhu) Finally, it is uncertain how quickly
sediment will build up behind the dam and how this
loss of sediment from downstream will erode the
im-portant Chang Delta islands With the dam in place,
China has spent billions of dollars to monitor its
envi-ronmental impact
Thomas R MacDonald
See also: Central Arizona Project; China; Dams;
Deltas; Energy politics; Floods and flood control;
Hydroenergy; Irrigation; Los Angeles Aqueduct;
Streams and rivers; Water; Water supply systems
Three Mile Island nuclear accident
Category: Historical events and movements
On March 28, 1979, a serious accident at Three Mile
Island nuclear reactor number two resulted in the
re-lease of a relatively small amount of radioactivity into
the surrounding area Fearing that the accident might
be worse, 100,000 residents fled The legacy of Three
Mile Island was to stop the expansion of nuclear power
generation in the United States.
Background
Near Middletown, Pennsylvania, there is an island in
the Susquehanna River that is almost exactly 3 miles
(4.8 kilometers) long A consortium of electric power
companies built two pressurized-water nuclear power
plants on this island Safety precautions included
en-closing the reactor core in a steel containment vessel
22 centimeters thick This vessel and the reactor
cool-ing system were then enclosed inside a large contain-ment building having walls of heavily reinforced con-crete 1.2 meters thick When an accident occurred in March of 1979, the safety precautions worked The accident was caused by a combination of hu-man error and mechanical failure As a result, the core overheated and released radioactivity into the cooling water Subsequently, many thousands of liters
of contaminated water flowed into the containment building and into an auxiliary building A large hydro-gen gas bubble formed at the top of the core contain-ment vessel Fearing that the bubble might explode and breach the containment vessel, authorities con-sidered evacuation
Reaction and Evacuation
As news of the accident was broadcast, the local citi-zens were understandably apprehensive Although no evacuation was ordered, Richard Thornburg, gover-nor of Pennsylvania, prudently advised a limited evac-uation of those who were most susceptible to harm
by radiation: preschool-aged children and pregnant women Out of prudence or fear, more than 100,000 people evacuated For a brief period the area near Three Mile Island became a ghost town inhabited mainly by monitoring teams and news reporters Over the next several days, there were both planned and unplanned releases of radioactivity into the atmo-sphere as the reactor core was cooled and the hydro-gen bubble removed These releases were carefully monitored Background radiation near Three Mile Is-land temporarily increased by 10 percent, which sta-tistically translates into a possible increase in cancer fatalities of 0.01 percent, a rate sufficiently small that
it is likely that no one was harmed (The probability of someone in the United States dying of cancer ranges between 15 and 20 percent Ignoring the body’s abil-ity to repair itself and assuming that small radiation doses are harmful in the same proportion as large doses are known to be, background radiation from natural sources might increase cancer fatalities by 0.1 percent.)
Impact of the Accident
As a result of the accident, changes were made For ex-ample, within minutes of the initial coolant failure, a confusing array of more than one hundred lights and alarms clamored for attention with no obvious order
of priority This situation was rectified Furthermore, reactor operators were subsequently given proper
Trang 10training in emergency procedures Safety oversight
procedures also were strengthened
Spurred on by several political figures, antinuclear
rallies exploded across the country Antinuclear
senti-ment became so strong in the United States that
no new nuclear plants were ordered after the
acci-dent, and fifty-nine reactors that had been previously
ordered were canceled Unit two of Three Mile Island
was not repaired It underwent an eleven-year cleanup
process and was shut down The current owner of the
facility continues to maintain Unit two in this
shut-down state It will not be decommissioned until Unit
one is decommissioned In 2009, the Nuclear
Regula-tory Commission extended that date to 2034
Charles W Rogers
See also: Chernobyl nuclear accident; Isotopes,
ra-dioactive; Nuclear energy; Nuclear Regulatory
Com-mission
Tidal energy
Category: Energy resources
Tidal energy utilizes the tides to create electricity by
trapping seawater at the extremes of high and low tide
and then releasing it through turbines Although a
po-tentially large source of power, it is most economically
feasible where the tides average at least 4.5 meters and
a narrow inlet encloses a large bay The world’s first
tidal electric generating station, built at the Rance
es-tuary off the northwest coast of France, began
operat-ing in 1966.
Background
The ebb and flow of the tides have long captured the
imagination of poets, while the possibility of
har-nessing this energy has been equally intriguing to
technically inclined people Mills powered by tidal
motion were used almost continuously from the
twelfth through the nineteenth centuries in England
In the seventeenth century, this technology was
im-ported to New England A tidal water pump installed
under the London Bridge in 1580 operated
success-fully for two and one-half centuries, and a
tidal-pow-ered sewage pump was used in Hamburg, Germany,
until 1880 These systems were eventually superseded
by more convenient electric pumps Not until the
1950’s did a renewed interest in tidal power develop as
an offshoot of the search for environmentally benign sources of electric power
Extent of Tidal Power There are two high and two low tides every day Thus, water may be trapped on one side or the other of a dam four times a day The water released after the tide changes may be used to turn a turbine connected to
a generator, thus producing electricity If, for exam-ple, a tidal lake 3.2 kilometers by 16 kilometers is dammed, and the trapped water has a height of 1.5 meters (the average height of the tides), a maximum
of 8 megawatts of electricity can be generated By way
of comparison, an average fossil-fuel plant generates
at least 1,000 megawatts In many regions of the world, however, the tides are considerably higher—for ex-ample, in the Bay of Fundy, Canada, where the tides average 12 meters
Over the entire globe, the total energy dissipated
in tidal flow is about 3 million megawatts Assuming that approximately one-third of this is potentially available power, and further assuming that the con-version efficiency to electricity is about 20 percent, the maximum power available is 200,000 megawatts, about one-fifth the present world power demand If one limits the consideration of tidal power generating stations to the places with convenient natural bays and/or abnormally high tides, the world total drops
to 15,000 megawatts
The Rance Estuary Project Although many nations had an interest in developing tidal power plants, France solved the technical prob-lems to construct the world’s first large-scale tidal gen-erating station Located at the mouth of Brittany’s Rance River estuary, this 240-megawatt plant was structed at a cost considerably less than that of a con-ventional hydroelectric plant of comparable power The location was chosen for two reasons: The average fluctuation of the tides is 8.8 meters, and, by damming the narrow inlet, a large volume of water could be trapped in the 14.5-square-kilometer estuary
To trap the water at the extremes of high and low tide, a dam 731 meters long was constructed across the Rance River, 3.2 kilometers upstream from where the river separates the towns of Dinard and St Malo The power-producing turbines are located under the central half of the dam All tidal power-generating plants must contend with two problems: First, the