Immedi-ately after World War II, fuel coal use in the United States, representing 78 percent of annual production, was divided into steam raising 29 percent, railway transportation 23 pe
Trang 1presence of which would ordinarily cause decay of the
plant tissue Under such near-stagnant conditions
plant remains are preserved, while the presence of
hy-drogen sulfide discourages the presence of organisms
that feed on dead vegetation Analog environments
under which coal is presently forming are found
within the Atchafalaya swamp of coastal Louisiana
and the many peat-producing regions of Ireland A
layer of peat in excess of 2 meters in thickness and
cov-ering more than 5,000 square kilometers is present in
the Dismal Swamp of coastal North Carolina and
Vir-ginia
The sapropelic class of coal, relatively uncommon
in distribution and composed of fossil algae and
spores, is formed through partial decomposition of
organic matter by organisms within oxygen-deficient
lakes and ponds Sapropelic coals are subdivided into
boghead (algae origin) and cannel (spore origin)
de-posits
The vegetable origin of coal has been accepted
since 1825 and is convincingly evidenced by the
iden-tification of more than three thousand freshwater
plant species in coal beds of Carboniferous (360 to
286 million years ago) age The common association
of root structures and even upright stumps with layers
of coal indicates that the parent plant material grew
and accumulated in place
Detailed geologic studies of rock sequences that lie
immediately above and below coal deposits indicate
that most coals were formed in coastal regions
af-fected by long-term sea-level cycles characterized by
transgressing (advancing) and regressing (retreating)
shorelines Such a sequence of rock deposited during
a single advance and retreat of the shoreline, termed
a “cyclothem,” typically contains nonmarine strata
separated from overlying marine strata by a single
layer of coal In sections of the Interior coal province,
a minimum of fifty cyclothems have been recognized,
some of which can be traced across thousands of
square kilometers Such repetition in a rock sequence
is most advantageous to the economics of a coal
re-gion, creating a situation in which a vertical mine
shaft could penetrate scores of layers of coal
The formation of coal is a long-term geologic
pro-cess Coal cannot therefore be considered a
able resource, even though it is formed from
renew-able resource plant matter Studies have suggested
that 1 meter of low-rank coal requires approximately
ten thousand years of plant growth, accumulation,
bi-ologic reduction, and compaction to develop Using
these time lines, the 3-meter-thick Pittsburgh coal bed, underlying 39,000 square kilometers of Pennsyl-vania, developed over a period of thirty thousand years, while the 26-meter-thick bed of coal found at Adaville, Wyoming, required approximately one-quarter of a million years to develop
Coal formation favors climate conditions under which plant growth is abundant and conditions for or-ganic preservation are favorable Such climates range from subtropical to cold, with the ideal being classed
as temperate Tropical swamps produce an abun-dance of plant matter but very high bacterial activity, resulting in low production of peat Modern peats are developing in temperate to cold climate regions, such
as Canada and Ireland, where abundant precipitation ensures fast plant growth while relatively cool temper-atures diminish the effectiveness of decay-promoting bacteria
The first coal provinces began to form with the evo-lution of cellulose-rich land plants One of the earliest known coal deposits, of Upper Devonian age (approx-imately 365 million years ago), is found on Buren Is-land, Norway Between the Devonian period and to-day every geologic period is represented by at least some coal somewhere in the world Certain periods of time, however, are significant coal-forming ages During the Carboniferous and Permian periods (360 to 245 million years ago) widespread develop-ment of fern and scale tree growth set the stage for the formation of the Appalachian coal province and the coal districts of the United Kingdom, Russia, and Manchuria Coal volumes formed during these pe-riods of geologic time constitute approximately 65 percent of present world reserves The remaining re-serves, developed mainly over the past 200 million years, formed in swamps consisting of angiosperm (flowering) plants The reserves of the Rocky Moun-tain province and those of central Europe are repre-sentative of these younger coals
After dead land-plant matter has accumulated and slowly begun to compact, biochemical decomposi-tion, rising temperature, and rising pressure all con-tribute to the lengthy process of altering visible plant debris into various ranks of coal With the advent of the Industrial Revolution there was a need for a sys-tem of classification defining in detail the various types of coals Up to the beginning of the nineteenth century, coal was divided into three rudimentary classes, determined by appearance: bright coal, black coal, and brown coal Through the decades, other
Trang 2schemes involving various parameters were
intro-duced, including oxygen content, percent of residue
remaining after the burning of coal, ratio of carbon to
volatile matter content, or analysis of fixed carbon
content and calorific value (heat-generating ability)
In 1937, a classification of coal rank using fixed
car-bon and Btu content was adopted by the American
Standards Association Adaptations of this scheme are
still in use, listing the steps of progressive increase in
coal rank as lignite (brown coal), subbituminous,
bi-tuminous (soft coal), subanthracite, and anthracite
(hard coal) Some classification schemes also list peat
as the lowest rank of coal (Technically speaking, peat
is not a coal; rather, it is a fuel and a precursor to coal.)
Coalification is the geologic process whereby plant
material is altered into differing ranks of coal by
geo-chemical and diagenetic change With an increase in
rank, chemical changes involve an increase in carbon
content accompanied by a decrease in hydrogen and
oxygen Correspondingly, diagenesis involves an
in-crease in density and calorific value, and a progressive
decrease in moisture At all ranks, common
impuri-ties include sulfur, silt and clay particles, and silica
U.S reserves are found mainly in eleven
northeast-ern counties in Pennsylvania Subanthracite coal has
characteristics intermediate between bituminous and
anthracite
Bedded and compacted coal layers are geologically
considered to be rocks Lignite and bituminous ranks
are classed as organic sedimentary rocks Anthracite,
formed when bituminous beds of coal are subjected
to the folding and regional deformation affiliated
with mountain building processes, is listed as a
meta-morphic rock Because peat is not consolidated or
compacted, it is classed as an organic sediment
Graph-ite, a naturally occurring crystalline form of almost
pure carbon, is occasionally associated with
anthra-cite While it can occur as the result of
high-tempera-ture alteration of anthracite, its chemical purity and
common association with crystalline rock causes it to
be listed as a mineral
History
Considering the importance of coal to modern
soci-ety, it is somewhat surprising that the production
of this commodity played only a minor role in
pre-Industrial Revolution (that is, prior to the middle
eighteenth century) history The origins of coal use
date back at least several thousands of years, as
evi-denced by the discovery of flint axes embedded in
layered coal in central England These primitive tools have been attributed to Neolithic (New Stone Age, c 6000-2000 b.c.e.) open-pit mining The Chi-nese were acquainted early with the value of coal, us-ing it in the makus-ing of porcelain Coal cinders found
in Roman-era walls in association with implements
of similar age suggest the use of coal for heating purposes prior to the colonization of England by the Saxons
The philosopher Theophrastus (c 372-287 b.c.e.), noted as the academic successor to Aristotle and the
author of many studies on plants, called coal anthrax,
a Greek word later used in the naming of anthracite
coal Later, the Anglo-Saxon term col, probably de-rived from the Latin caulis, meaning plant stalk,
evolved into “cole” prior to the emergence of the modern spelling some three centuries ago
With the decline of forests in England by the thir-teenth century, coal began to assume a significant role The first coal-mining charter was granted the freemen of Newcastle in 1239 This early burning of coal, however, because of its propensity to befoul the atmosphere, was banned in 1306 by King Edward I King Edward III reversed this ban and again granted the Newcastle freemen a coal-mining license, whereby this town soon became the center of the first impor-tant coal-mining district
Coal mining was initiated in North America near Richmond, Virginia, in 1748 A decade later, coal-mining activities had moved to the rich deposits around Pittsburgh, Pennsylvania The spread of the Industrial Revolution, invention of the iron-smelting process, and improvement of the steam engine guar-anteed the classification of coal as an industrial staple With the development of the steam-driven electric generator in the last decade of the nineteenth cen-tury, coal became the dominant fuel A century later, world coal production exceeded 4.5 billion metric tons and constituted some 26 percent of world energy production on a Btu basis In the early twenty-first cen-tury, with the rapid growth of the Chinese economy, China passed the United States as the top producer of coal
Obtaining Coal Coal has been produced by two common methods: underground (or deep) mining and surface (or strip) mining Underground mining requires the digging of extensive systems of tunnels and passages within and along the coal layers These openings are connected
Trang 3to the surface so the coal can be removed Prior to the
development of the gigantic machinery necessary to
open-pit mining, deep mining was the industry norm
This early period was characterized by labor-intensive
pick-and-shovel work in cramped mine passages
Con-stant dangers included the collapse of ceilings and
methane gas explosions
Today, augers and drilling machinery supplement
manpower to a large extent, and mine safety and
health regulations have greatly reduced the annual
death toll The common method of underground
ex-traction involves initial removal of about 50 percent of
the coal, leaving a series of pillars to support the mine
roof As reserves are exhausted, the mine is gradually
abandoned after removal of some or all of the pillars
Another modern underground-mining technique,
with a coal removal rate approaching 100 percent,
in-volves the use of an integrated rotary cutting machine
and conveyer belt
Surface mining of coal, accounting for about 40
percent of global production, is a multiple-step
pro-cess First, the overburden material must be removed,
allowing exposure of the coal The coal is then mined
by means of various types of surface machinery,
rang-ing from bulldozers to gigantic power shovels Finally,
after removal of all the coal, the overburden is used to
fill in the excavated trench and the area is restored to
its natural topography and vegetation Economics
usually determine whether underground or open-pit
techniques are preferable in a given situation
Gen-erally, if the ratio of overburden to coal thickness does
not exceed twenty to one, surface mining is more
profitable
In the Appalachian coal province, coal-mining
tech-nique is closely related to geology In tightly folded
re-gions of West Virginia, the steeply dipping coal beds
are mostly mined underground To the northwest,
folds become gentler, and both deep- and
surface-mining methods are used In the Interior province,
strip mining is the most common process In the
Rocky Mountain area, where many thick coal beds lie
close to the surface, strip mining again predominates,
although a few underground mines are present
With increased concern regarding the state of the
natural Earth environment, and with federal passage
of the Coal Mine Health and Safety Act (1969) and
the Clean Air Acts (U.S.), the mining of coal in the
United States has undergone both geographic and
extraction-technology changes Because the Rocky
Mountain province coals, while lower grade than
east-ern coals, contain lower percentages of sulfur, the center of U.S production has gradually shifted west-ward The burning of high-sulfur coals releases sulfur dioxide into the atmosphere; it is a significant contrib-utor to acid rain
Western coals are often contained within layers thicker than those found in the east, are shallow in depth, and can be found under large areas—all con-ditions amenable to surface mining As a result, the state of Wyoming, with a 1995 production of 240 mil-lion metric tons of low-sulfur coal that is burned in more than twenty-four states in the generation of elec-tricity, became the leading U.S coal producer Coal mining has played an integral role in the de-velopment of the industrialized world, and this role should continue well into the future Reserve addi-tions continue to closely equal losses due to mining, and at current levels of production estimates indicate that there is enough recoverable coal globally for some 130 to 150 years of future production
Uses of Coal Historically, coal has been industry’s fuel of choice Those countries in possession of sufficient coal reserves have risen commercially, while those less endowed with this resource—or lacking it altogether—have turned to agriculture or stagnated in development The top exporters of coal are Australia, Indonesia, Russia, Colombia, South Africa, China, and the United States The top importers are Japan, South Korea, Taiwan, India, the United Kingdom, China, and Ger-many
Different ranks of coal are employed for different purposes In the middle of the twentieth century, it was common to see separate listings of coking, gas, steam, fuel, and domestic coals Each had its specific uses Domestic coal could not yield excessive smoke, while coal for locomotives had to raise steam quickly and not produce too high an ash content Immedi-ately after World War II, fuel coal use in the United States, representing 78 percent of annual production, was divided into steam raising (29 percent), railway transportation (23 percent), domestic consumption (17 percent), electric generation (6 percent), and bunker coal (3 percent) The remaining 22 percent was employed in the production of pig iron (10 per-cent), steel (7 perper-cent), and gas (5 percent) Fifty years later, more than 80 percent of the approxi-mately 900 million metric tons of coal produced an-nually in the United States was used in the generation
Trang 4of electricity Industrial consumption
of coal, particularly in the
produc-tion of coke for the steel and iron
manufacturing industry, is the
sec-ond most important use Globally, 13
percent of hard coal production is
used by the steel industry Some 70
percent of global steel production
depends on coal Additional
indus-trial groups that use coal include
food processing, paper, glass,
ce-ment, and stone Coal produces
more energy than any other fuel,
more than natural gas, crude oil,
nu-clear, and renewable fuels
The drying of malted barley by
peat fires has long been important in
giving Scotch whiskey its smoky
fla-vor Peat has also been increasingly
employed as a soil conditioner While
expensive to produce, the
conver-sion of intermediate ranks of coal
into liquid (coal oil) and gaseous
(coal gas) forms of hydrocarbon
fu-els will become more economically
viable, especially during times of
in-crease in the value of crude oil and
natural gas reserves
New uses of coal are constantly
be-ing explored and tested Two
prom-ising techniques are the mixing of
water with powdered coal to make
a slurry that can be burned as a
liq-uid fuel and the underground extraction of coal-bed
methane (firedamp) Interest in the latter by-product
as an accessible and clean-burning fuel is especially
high in Appalachian province localities distant from
conventional gas resources
Albert B Dickas
Further Reading
Berkowitz, Norbert An Introduction to Coal Technology.
2d ed San Diego, Calif.: Academic Press, 1994
Freese, Barbara Coal: A Human History Cambridge,
Mass.: Perseus, 2003
Goodell, Jeff Big Coal: The Dirty Secret Behind America’s
Energy Future Boston: Houghton Mifflin, 2006.
Schobert, Harold H Coal: The Energy Source of the Past
and Future Washington, D.C.: American Chemical
Society, 1987
Speight, James G The Chemistry and Technology of Coal.
2d ed., rev and expanded New York: M Dekker, 1994
Thomas, Larry Coal Geology Hoboken, N.J.: Wiley,
2002
_ Handbook of Practical Coal Geology New York:
Wiley, 1992
Web Sites American Coal Foundation All About Coal
http://www.teachcoal.org/aboutcoal/index.html Natural Resources Canada
About Coal http://www.nrcan.gc.ca/eneene/sources/coacha-eng.php
History: U.S Energy Information Administration (EIA),
(June-December, 2008) Projections: EIA, World Energy Projections Plus (2009).
Energy Annual, 2006
2025
2010 2005 2000 1995 1990
2015 2020
2030
1985 1980
89.2
88.5
93.6
121.7
140.6
150.7
161.7
175.2
190.2
82.4 70.0
Quadrillion British Thermal Units (Btus)
200 150
100 50
World Coal Consumption and Projections
Trang 5U.S Department of Energy
Coal
http://www.energy.gov/energysources/coal.htm
U.S Geological Survey
Coal Resources: Over One Hundred Years of USGS
Research
http://energy.usgs.gov/coal.html
World Coal Institute
Gas and Liquids
http://www.worldcoal.org/
See also: American Mining Congress; Asbestos;
Car-bon; Coal gasification and liquefaction;
Environmen-tal degradation, resource exploitation and; Industrial
Revolution and industrialization; Mining safety and
health issues; Mining wastes and mine reclamation;
Open-pit mining; Peat; Strip mining; Surface Mining
Control and Reclamation Act; Underground mining
Coal gasification and liquefaction
Categories: Energy resources; obtaining and using
resources
Synthetic fuels offer alternatives for systems, such as
vehicles, designed to operate on liquid or gaseous fuels.
Historically, these fuels have been used when imports
of petroleum or natural gas are restricted by boycotts or
warfare The conversion of coal to synthetic fuels can
reduce the amounts of sulfur and ash released into the
environment, providing a cleaner fuel.
Background
Coal is one of the most abundant fossil fuel resources
in the world The worldwide reserves of coal are likely
to last substantially longer than reserves of petroleum
and natural gas Several factors can create shortages
of liquid or gaseous fuels, including international
trade embargoes (as occurred during the 1970’s),
wars, and, in the long run, the depletion of petroleum
and gas reserves Gaseous or liquid fuels are easier to
handle and transport than are solids, and they are
eas-ier to treat for removal of potential pollutants, such as
sulfur Worldwide there is an immense investment in
combustion devices of many kinds designed to
oper-ate on liquids or gases A large-scale replacement of all
these units, or retrofitting them to burn solid coal, is
not practically or economically feasible Solid coal
is not a practical alternative for many applications
of liquid or gaseous fuels, such as automobile en-gines Conversion of coal to synthetic gaseous or liq-uid fuels offers opportunities for providing alterna-tive fuel supplies, for removing sulfur and ash from the fuel before combustion, and for providing strate-gic security against the possible interruption of im-ports
Coal Gasification The simplest approach to producing gaseous fuel from coal is heating in closed vessels under conditions that would not allow combustion to occur In such a process, the coal decomposes to a variety of products, including gases, liquids (coal tar), and a solid residue Depending on the quality of the coal used, the gas can have excellent fuel qualities, because it is rich in hy-drogen and methane and has a calorific value of about two-thirds that of natural gas The product has a variety of names: town gas, illuminating gas, or coal gas The process itself also has various names, includ-ing pyrolysis, destructive distillation, and carboniza-tion
If the primary objective is to produce a gaseous fuel, then simple carbonization is very wasteful of the coal, because only about 20 percent is converted to gas Much of the original coal still remains a solid, and some converts to a liquid However, if the gas is col-lected as a by-product, for example from the conver-sion of coal to metallurgical coke, then sale of the gas can provide extra revenue; it can also be used as a fuel inside the plant Carbonization is not useful when the intent is to convert the maximum amount of coal to a gaseous fuel
The principal method for converting coal com-pletely to a gaseous fuel is the reaction of coal with steam When steam is passed over a bed of red-hot coal, the product is water gas, which consists mainly
of hydrogen and carbon monoxide The reaction of steam with coal is endothermic (it requires a source of heat in order to proceed) Consequently, some por-tion of the coal must be burned to provide the heat to
“drive” the reaction of coal with steam This is usually accomplished by allowing the combustion reaction and the reaction with steam to proceed simultaneously
in the same vessel Initially this was accomplished by feeding coal, air, and steam together into a reactor The heat-releasing combustion reaction effectively balances the heat-consuming reaction with steam,
Trang 6and the process can operate continuously.
When air is used for the combustion reaction,
the product gas will inevitably be diluted with large
amounts of nitrogen Consequently, its calorific value
will be very low, about 10 to 20 percent of the value of
natural gas For this reason, modern approaches to
coal gasification use coal, steam, and oxygen as the
feedstocks Though this adds to the cost and
complex-ity of separating oxygen from air for the gasification
process, it is more than recompensed by a much
higher quality product
Gasifier Designs
Early designs of gasifiers were so-called moving bed
gasifiers, in which a bed of solid coal slowly descended
through a tall cylindrical vessel to react with a
steam-oxygen (or steam-air) mixture at the bottom Such
gasifiers, such as the Lurgi gasifier, developed in
Ger-many in the 1930’s, have a disadvantage in that the
heating drives out any moisture that may be in the
coal and generates some liquids or tars Some of
the compounds driven out of the coal will dissolve
in the water, producing a wastewater that must be
treated before discharge into the environment The
tars represent a by-product for which uses must be
found or which must be disposed of in
environmen-tally acceptable ways Despite these apparent
disad-vantages, the Lurgi is one of the most successful
gasifier designs in the world: The gasifier is used in the
synthetic fuels plants in South Africa as well as in the
Dakota gasification plant in Beulah, North Dakota,
the primary coal gasification facility in the United
States
Alternative approaches to gasification rely on the
so-called entrained flow method, in which finely
pul-verized coal is blown into the gasifier or injected as a
coal-water slurry In these gasifiers, the coal is heated
and reacted so rapidly that the formation of by-product
tars is avoided One such gasifier is the
Koppers-Totzek, which is used in many places around the
world, mainly to produce hydrogen for ammonia
syn-thesis (for eventual production of fertilizers) The
Koppers-Totzek unit uses pulverized solid coal The
Texaco gasifier injects coal in the form of a slurry
Synthesis Gas
The composition of the gas depends on the specific
gasification process used Generally, the main
compo-nents are hydrogen and carbon monoxide, the
mix-ture of which makes synthesis gas One application of
synthesis gas is the production of methane, which can then be sold as substitute for natural gas Synthesis gas can be converted to liquid fuels, as discussed below The gas can also be burned, particularly in gas tur-bines that are part of combined-cycle plants for elec-tricity generation Other uses include production of methanol as a liquid fuel, acetic anhydride for chemi-cals production, or hydrogen (by removing the car-bon monoxide)
Coal Liquefaction There are two major routes for production of syn-thetic liquid fuels from coal The first is called indirect liquefaction, because the coal itself is actually con-verted to synthesis gas by gasification In a subsequent step, the synthesis gas is converted to liquid fuels The dominant technology for this process was developed
by Franz Fischer and Hans Tropsch in Germany in the 1920’s Synthesis gas is reacted over a catalyst at high temperatures and pressures Depending on the spe-cific choice of catalyst, the pressure and temperature
of the reaction, and the relative amounts of hydrogen and carbon monoxide, it is possible to produce a vari-ety of liquid fuels, ranging from gasoline to heating oils The Fischer-Tropsch process, coupled with coal gasification, produced about 757 million liters per year of synthetic liquid fuels used by Germany during World War II Subsequently, it was commercialized on
a large scale in South Africa, which was barred from international trade in oil during the apartheid years but possesses large reserves of coal
The alternative approach is direct liquefaction Di-rect liquefaction is based on the observation that most desirable petroleum products contain about two at-oms of hydrogen per atom of carbon Coal has on av-erage less than one hydrogen atom per carbon atom The direct conversion of coal to synthetic petroleum-like liquids therefore requires adding hydrogen chemically to the coal Direct liquefaction is some-times also called coal hydrogenation The methods for performing direct liquefaction were developed by Friedrich Bergius, who received the Nobel Prize in Chemistry in 1931 The Bergius process requires ex-tremely high temperatures (500° Celsius) and pres-sures (up to 4,500 kilograms per six square centime-ters), a situation which poses difficult engineering challenges for large-scale operation Nevertheless, the Bergius process provided three billion liters of synthetic fuels per year to the German war effort in World War II A metric ton of coal will yield
Trang 7mately 150 to 170 liters of gasoline, 200 liters of diesel
fuel, and 130 liters of fuel oil
During the 1970’s and 1980’s, much ingenious
re-search in chemistry and process engineering was
di-rected toward reducing the severe conditions of the
Bergius process in order to make the eventual
prod-uct more economically competitive with petroleum
Despite substantial progress, a synthetic crude oil
from coal is likely to cost about $30 to $40 per barrel
There are no direct liquefaction plants operating in
the world, though China had plans to open one by
2007, which did not happen
Harold H Schobert
Further Reading
Berkowitz, Norbert An Introduction to Coal Technology.
2d ed San Diego, Calif.: Academic Press, 1994
Freese, Barbara Coal: A Human History Cambridge,
Mass.: Perseus, 2003
Goodell, Jeff Big Coal: The Dirty Secret Behind America’s
Energy Future Boston: Houghton Mifflin, 2006.
Higman, Chris, and Maarten van der Burgt
Gasifica-tion 2d ed Boston: Elsevier/Gulf Professional,
2008
Probstein, Ronald F., and R Edwin Hicks Synthetic
Fuels New York: McGraw-Hill, 1982.
Schobert, Harold H Coal: The Energy Source of the Past
and Future Washington, D.C.: American Chemical
Society, 1987
Speight, James G The Chemistry and Technology of Coal.
2d ed., rev and expanded New York: M Dekker,
1994
Thomas, Larry Coal Geology Hoboken, N.J.: Wiley,
2002
_ Handbook of Practical Coal Geology New York:
Wiley, 1992
Williams, A., M Pourkashanian, J M Jones, and
N Skorupska Combustion and Gasification of Coal.
New York: Taylor & Francis, 2000
Web Sites
American Coal Foundation
All About Coal
http://www.teachcoal.org/aboutcoal/index.html
Natural Resources Canada
About Coal
http://www.nrcan.gc.ca/eneene/sources/coacha-eng.php
U.S Department of Energy Coal
http://www.energy.gov/energysources/coal.htm U.S Department of Energy
Gasification Technology R&D (Research and Development)
http://www.fossil.energy.gov/programs/
powersystems/gasification/index.html U.S Geological Survey
Coal Resources: Over One Hundred Years of USGS Research
http://energy.usgs.gov/coal.html World Coal Institute
Gas and Liquids http://www.worldcoal.org/pages/content/
index.asp?PageID=415 See also: Carbon; Coal; Electrical power; energy poli-tics; Synthetic Fuels Corporation
Coast and Geodetic Survey, U.S.
Category: Organizations, agencies, and programs Date: Established as Coast Survey in 1807;
reestablished in 1832; renamed Coast and Geodetic Survey in 1878; abolished in early 1970’s
The Coast and Geodetic Survey, moving far beyond its original assignment of making coastal navigation charts, was a research agency that became a world leader in geodesy It developed and refined navigation and measurement techniques and did research in hy-drography and coastal geology.
Background The U.S Congress created the Coast and Geodetic Survey, initially known as the Coast Survey, early in the nineteenth century to survey the Atlantic coast of the United States and develop accurate charts for naviga-tion and shipping Legislanaviga-tion in 1807, the Coast Sur-vey Act, first provided for surSur-veying and mapping the nation’s coastline, but Congress failed to allocate ade-quate funding As a result, little progress was made In
1832, Congress authorized reestablishment of the Coast Survey Lawmakers at the time intended for the Coast Survey to be a temporary agency: Funding
Trang 8would be provided only until the charts needed for
safe navigation were completed, and then the Coast
Survey would be dissolved Under the leadership of its
early superintendents, however, the Coast Survey
ex-panded its mission to include basic research into
hydrography, topography, cartography, meteorology,
coastal geology, and a wide range of other topics
relat-ing to the physics of the Earth By the time the Coast
Survey completed charts of the Atlantic and, after the
acquisition of Western territories, Pacific coastlines,
the organization was so thoroughly established as a
scientific agency that it became difficult for legislators
to argue against continued funding In 1878, the
agency’s name was changed to the Coast and
Geo-detic Survey
Impact on Resource Use
Over the course of the more than 150 years of the
Coast and Geodetic Survey’s existence, the agency
achieved numerous scientific and technical
break-throughs In the process of completing its original
mission of creating navigation charts, the
organiza-tion evolved into a scientific research agency that
be-came a world leader in geodesy It developed methods
for use in triangulation, arc measurement, geodetic
astronomy, determining longitude and latitude, and
other aspects of measuring the Earth The Coast and
Geodetic Survey improved instruments used in
sur-veying and navigation for determining position,
dis-tance, angles, directions, and elevations, and it
investi-gated the best methods to be used in reproducing
maps As part of its research in geodesy, the survey
conducted methodical observations of solar eclipses
For the solar eclipse of August 7, 1869, for example,
the survey stationed observation teams in Tennessee,
Kentucky, Illinois, Iowa, and Alaska Other
astronomi-cal observations made at various times included
study-ing the transit of the planets Mercury and Venus
Mea-surements of the great arcs of the thirty-ninth parallel
and the ninety-eighth meridian both provided a basis
for the government surveys of the interior of the
United States and suggested a more refined model of
the shape of the Earth
In addition, the Coast and Geodetic Survey
pio-neered research in tidal flows, hydrography, and
oceanography The organization determined the best
sites for lighthouses and navigation buoys and
re-searched the history of names of prominent
geo-graphic features for use on maps and charts Minor
functions of the Coast and Geodetic Survey included
serving as the keeper of the nation’s standard weights and measures
Though the Coast and Geodetic Survey was even-tually dismantled, its research traditions continued
in other agencies, such as the National Oceanic and Atmospheric Administration (NOAA), a scientific agency created as part of President Richard Nixon’s reorganization of the Department of Commerce in
1970 NOAA’s National Ocean Service, for example, prepares charts and monitors tidal activity
Nancy Farm Männikkö
Web Sites U.S Coast and Geodetic Survey National Geodetic Survey
http://www.ngs.noaa.gov/
U.S Coast and Geodetic Survey Office of Coast Survey
http://www.nauticalcharts.noaa.gov/
See also: Landsat satellites and satellite technologies; National Oceanic and Atmospheric Administration; U.S Geological Survey
Coastal engineering
Category: Environment, conservation, and resource management
Coastal engineering is the discipline that studies the natural and human-induced changes of the geomor-phology of the coastal zone It also develops methods and techniques for protecting and enhancing the coastal environment.
Definition Coastal engineering focuses on the special engineer-ing needs of the coastal environment The discipline studies both natural and anthropogenic effects (those caused by human activity) on the geometry and other physical characteristics of the coastal zone, which in-cludes riverine deltas, inlets, estuaries, bays, and la-goons In the offshore direction, the activities of the coastal engineer are limited to the relatively shallow waters of the continental shelf
Trang 9Since the coastline serves as the boundary between
the land and the ocean, the coastal engineer must
un-derstand the dynamic interaction between water and
sediments Water dynamics involves the action of
as-tronomical tides, tsunamis, storm surges, wind waves,
and longshore currents Water forces continuously
change the shape of the coastline through sediment
erosion and deposition Episodic events such as
hurri-canes may have a significant effect on the stability and
integrity of a coastal system Coastal engineers are
mostly interested in sandy or muddy beaches, which
are readily subject to sediment erosion The
weather-ing of rocky beaches to wave action is a slow process
and is not of direct interest to coastal engineers
The coastline is an extremely dynamic system,
sub-ject to short-term and long-term changes Spatially
these changes may be localized or may extend for
great distances Generally, if left undisturbed, the coast tends to develop its own defense systems against wave action through barrier islands and sand dunes Any attempts by humans to regulate the shape of the coastline at a particular site may have adverse ef-fects on another site on the same coastline Coastal engineers investigate wave and current forces and their impact on the shape of the coastline For that purpose, coastal engineers collect and analyze field data and use physical models (applying determinis-tic or probabilisdeterminis-tic analydeterminis-tical techniques) and com-puter models to simulate the wave and current cli-mate These procedures can lead to predictions of the amount and fate of the transported sediments that cause accretion or erosion of the coastline
Coastal engineers also investigate techniques for protecting residential and industrial developments along the coast, maintaining recreational facilities
One aspect of coastal engineering is the development and protection of coastal environments like this beach at Point Lobos, California.
(©Joseph Salonis/Dreamstime.com)
Trang 10and beaches, and providing safe navigation through
inlets and coastal waterways Therefore, constructing
structures such as jetties, breakwaters, groins,
bulk-heads, marinas, and harbors falls within the domain
of the coastal engineer Beach nourishment and inlet
dredging are also projects undertaken by coastal
engi-neers
In order to assess the prevailing hydrodynamic and
sedimentological conditions of the coastal zone
effi-ciently and effectively, engineers develop equipment
and instrumentation for data collection of wave and
current characteristics, suspended and bottom
sedi-ments, and other supplementary information such as
salinity and temperature of the ambient water Coastal
engineers are also involved in the environmental
as-pects of coastal waters Estimation of the spread of an
oil spill; the flashing capacity of a lagoon, finger
ca-nals, or any other protected water body; dissolved
con-taminant advection and dispersion; and sediment
contamination are all topics of interest to the coastal
engineer
Panagiotis D Scarlatos
See also: Coastal Zone Management Act; Deltas;
Ocean current energy; Ocean wave energy; Oceans;
Salt; Sand and gravel; Tidal energy
Coastal Zone Management Act
Categories: Laws and conventions; government
and resources
Date: Enacted October 27, 1972
The Coastal Zone Management Act provides a
frame-work for protecting and developing the U.S coastal
zones Achieving both protection and development
de-pends on land management accompanied by land-use
planning and land-use regulation and control.
Background
The Coastal Zone Management Act of 1972 was passed
by Congress in order to establish “a national policy
and develop a national program for the management,
beneficial use, protection, and development of the
land and water resources of the nation’s coastal zones,
and for other purposes.” The coastal zones included
in the act are those of the Atlantic and Pacific Oceans,
the Gulf of Mexico, and the Great Lakes The length
of coastline involved is about 153,000 kilometers The extensive nature of the coastal area of the United States means that thirty states and four territories— Puerto Rico, the Virgin Islands, Guam, and American Samoa—are eligible for coastal zone management as-sistance
The Coastal Zone Management Act was passed as a result of concern for the vulnerable nature of the coastal zones and their exposure to intensive develop-ment pressures These pressures include recreation, fishing, agriculture, housing, transportation, and in-dustrial development With more than half of the U.S population living within eighty kilometers of a coastal area, the pressures are considerable The act is admin-istered by the National Oceanic and Atmospheric Ad-ministration’s Office of Coastal Zone Management The federal role consists of providing assistance to states as they develop programs to manage the coast in
a manner sufficient to deal with the problems arising from competing land uses
Provisions Federal assistance takes the form of both financial and technical aid Paragraph (h) of section 302 of the act emphasizes the importance of a state’s role in ex-ercising its authority over the land and water re-sources of the coastal zone Especially important in this exercise of authority is the encouragement of citizen involvement in the overall planning process From the state perspective, such citizen participation has helped in the development of land-use planning guidelines relating to designation of the coastal zone areas, determination of land uses within the coastal zone, the identification of areas of particular con-cern, the identification of the ways by which the state will control land and water uses, and guidelines for es-tablishing the priority of uses
Impact on Resource Use Over the years, the Coastal Zone Management Act has been amended several times In 1976, the states were given additional time and money for program devel-opment Energy-related coastal development, provi-sions for access to public beaches, and increased agency cooperation were also part of the 1976
amend-ments According to the Congressional Quarterly Alma-nac (1985), the reauthorization of the Coastal Zone
Management Act in 1985 lowered the federal share
of costs to be paid Changes in 1990 gave the states more say over federal activities in offshore areas,