Encyclopedia of Global Resources part 124 potx

In 2009, British scientists presented a design for a gravity tractor that would fly close to an asteroid surface and, through gravitational influence alone, over perhaps fifteen years, make changes in the orbital path of such a body. If a near-Earth object or small asteroid were on a collision course with Earth, such a spacecraft placed close to its surface could avert a deadly global catastrophe. A 9-metric-ton gravity tractor, however, could not be used to bring a resource- laden asteroid into Earth proximity for convenient mining operations. Charles W. Rogers and David G. Fisher Further Reading Clarke, Arthur C. The Snows of Olympus: A Garden on Mars. London: Victor Gollancz, 1994. Davidson, Frank Paul, Katinka I. Csigi, and Peter E. Glaser. Solar Power Satellites: A Space Energy System for Earth. New York: Wiley & Sons, 1998. Elbert, Bruce R. Introduction to Satellite Communication. 3d ed. New York: Artech House, 2008. Fogg, Martyn J. Terraforming: Engineering Planetary En- vironments. Warrendale, Pa.: Society of Automotive Engineers, 1995. Handberg, Roger. International Space Commerce: Build- ing from Scratch. Gainesville: University Press of Florida, 2006. Harris, Philip Robert. Space Enterprise: Living and Working Offworld in the Twenty-first Century. New York: Praxis, 2009. Johnson, Richard D., and Charles Holbrow, eds. Space Settlements: A Design Study. Washington, D.C.: Na- tional Aeronautics and Space Administration, 1977. Karl, John. Celestial Navigation in the GPS Age. New York: Paradise Cay, 2007. Kendall, Henry W., and Steven J. Nadis, eds. Energy Strategies—Toward a Solar Future: A Report of the Union of Concerned Scientists. Cambridge, Mass.: Ballinger, 1980. Lewis, John S. Mining the Sky: Untold Riches from the As- teroids, Comets, and Planets. Reading, Mass.: Addi- son-Wesley, 1996. Olla, Phillip, ed. Commerce in Space: Infrastructures, Technologies, and Applications. Hershey, Pa.: Infor- mation Science Reference, 2008. Olsen, R. C. Remote Sensing from Air and Space. New York: SPIE Press, 2007. Pop, Virgiliu. Who Owns the Moon? Extraterrestrial As - pects of Land and Mineral Resources Ownership. Dor - drecht, the Netherlands: Springer, 2009. Ride, Sally K. Mission, Planet Earth: Our World and Its Climate—And How HumansAre Changing Them. New York: Flash Point, 2009. Robinson, Ian S. Measuring the Oceans from Space: The Principles and Methods of Satellite Oceanography. New York: Springer, 2004. Schmitt, Harrison. Return to the Moon: A Practical Plan for Going Back to Stay. New York: Springer, 2005. Web Site National Aeronautics and Space Administration Using Space Resources http://ares.jsc.nasa.gov/HumanExplore/ Exploration/EXLibrary/docs/ISRU/00toc.htm See also: Aerial photography; Greenhouse gases and global climate change; Landsat satellites and satellite technologies; Ozone layerand ozone hole debate;Re- mote sensing; Solar energy; Weather and resources. Spain Categories: Countries; government and resources Spain tends to import more commodities than it exports. It once exported iron but now exports products made from iron and steel. The country is a large and increasingly important exporter of olives and olive oil, sweet oranges, mandarins (especially clementines), wine, and various fruits and vegetables. Most exports go to France, Germany, Portugal, Italy, the United Kingdom, and the United States. The Country Spain is located in the southwest corner of Europe on the Iberian Peninsula between the Atlantic Ocean and the Mediterranean Sea. The dominant physical feature is the Meseta, a vast, somewhat barren table- land that has an average elevation of 600 meters and slopes gentlyto the west. Three majorrivers flowfrom the Meseta to the Atlantic: the Douro, Tagus, and Guadiana. The high and broad Pyrenees are on the northern border with France. The Cantabrian Moun- tains runbehind the northcoast.The Betic Cordillera stretches from the Gibraltar highlands at the penin - sula’s southern tip east to the province of Alicante. Less dramatic sierras punctuate the Meseta. Two ma - 1136 • Spain Global Resources Global Resources Spain • 1137 Spain: Resources at a Glance Official name: Kingdom of Spain Government: Parliamentary monarchy Capital city: Madrid Area: 195,139 mi 2 ; 505,370 km 2 Population (2009 est.): 40,525,002 Languages: Castilian Spanish Monetary unit: euro (EUR) Economic summary: GDP composition by sector (2008 est.): agriculture, 3.4%; industry, 29%; services, 67.6% Natural resources: coal, lignite, iron ore, copper, lead, zinc, uranium, tungsten, mercury, pyrites, magnesite, fluorspar, gypsum, sepiolite, kaolin, potash, hydropower, arable land Land use (2005): arable land, 27.18%; permanent crops, 9.85%; other, 62.97% Industries: textiles and apparel (including footwear), food and beverages, metals and metal manufactures, chemicals, shipbuilding, automobiles, machine tools, tourism, clay and refractory products, footwear, pharmaceuticals, medical equipment Agricultural products: grain, vegetables, olives, wine grapes, sugar beets, citrus, beef, pork, poultry, dairy products, fish Exports (2008 est.): $285.4 billion Commodities exported: machinery, motor vehicles, foodstuffs, pharmaceuticals, medicines, other consumer goods Imports (2008 est.): $414.5 billion Commodities imported: machinery and equipment, fuels, chemicals, semifinished goods, foodstuffs, consumer goods, measuring and medical control instruments Labor force (2008 est.): 22.85 million Labor force by occupation (2008 est.): agriculture, 4%; industry, 26.4%; services, 69.5% Energy resources: Electricity production (2008 est.): 294.3 billion kWh Electricity consumption (2008 est.): 276.1 billion kWh Electricity exports (2007 est.): 14.52 billion kWh Electricity imports (2007 est.): 8.773 billion kWh Natural gas production (2007 est.): 88 million m 3 Natural gas consumption (2007 est.): 34.43 billion m 3 Natural gas exports (2007 est.): 0 m 3 Natural gas imports (2007 est.): 34.47 billion m 3 Natural gas proved reserves ( Jan. 2008 est.): 2.548 billion m 3 Oil production (2007 est.): 29,000 bbl/day Oil imports (2005): 1.777 million bbl/day Oil proved reserves ( Jan. 2008 est.): 150 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. Madrid Spain France Portugal Algeria Morocco Mediterranean Sea Atlantic Ocean jor depressions are between the Meseta and the mar - ginal ranges: the Ebro, with its namesake river drain- ing to the Mediterranean, and the Guadalquivir, with its namesake river flowing to the Atlantic. The coastal plains are fewin number and extent. Spain’s territory also includes the Balearic Islandsin the western Medi- terranean; the Canary Islands off the northwest coast of Africa;Ceuta and Melilla, two autonomous port cities along the Mediterranean coast of Morocco; and six small islands off that coast. In 2007, Spain had the world’s eighth largest national economy. Key resources are coal, iron and steel, water, olives and olive oil, citrus fruit,grapevines and wine, andotherminer- als and foodstuffs. Coal Coal is Spain’s most plentiful natural resource. Bitu- minous and anthracite coals are found in the northern provinces of Asturias and León and in the southern provinces of Ciudad Real and Córdoba. Lignite (brown coal) occurs intheregionsof Catalonia and in Galicia. Coal has been important to Spain’s economy since the lasthalf of thenineteenth century.However, importing coal has been necessary because Spain’s deposits tend tobesmall, with narrow seams andimpuri- ties, and domestic anthracite is not suitable for con- version into coke foruseintheiron and steel industry. Because of these disadvantages, Spain’s coal industry demanded government protection from competition with cheaper coal imported from Great Britain. This protection is estimated tohaveraised industrial prices in Spain between 2 and 5 percent until the 1960’s, when the coal industry was largely nationalized. A small amount of domestic black coal is used for local industry and for heating fuel. Brown coal is used for mine-mouth power stations, but imported steam coal is increasingly important for power generation. The main use of coal in Spain is the generation of electric power, especially during times of drought, when hydroelectric power is less available. Spain has reduced its subsidies to the coal industry while investing instructural changethat will limit coal mining and government welfare for coal-mining dis- tricts. The Institute for the Restructuring of Coal Mining and Alternative Development of Mining Dis- tricts supports projects that create jobs and promotes alternative development of mining areas. Since 1998, billions of dollars have been invested in hundreds of mining-district projects, closure of some coal pro - duction units, early retirement of miners, aid to some companies, and investment in some companies to guarantee access to coal reserves for reasons of national security. Iron and Steel The iron and steel industry depends on two main resources: iron and coal. The nineteenth century blast furnaces required about 4 metric tons of coal to process 1 metrictonofiron. This ratio drew iron and steel producers to the coal deposits. Because Spanish coal was not competitive in quality and price with foreign coal, the iron and steel producers finally located in the province of Vizcaya. From there, ships exported Spain’sironoreandpig iron to England and returned with inexpensive Welsh coking coal from Cardiff. By 1901, 90 percent of Spain’s excavated iron ore was exported to Great Britain. Although some of the largest iron-mining companies were subsidiaries of foreign iron manufacturers, most of the profits remained in Spain, helping to develop the iron and steel industry in Vizcaya and also partially underwriting the indus- trialization of the city of Bilbao. In 1902, the three largest iron and steel companies merged to form Altos Hornos de Vizcaya, which became the largest and most profitable industrial enterprise in Spain. However, at that time, Spain’s outputs of pig iron and steel were small compared to those of Great Britain and Germany. The domestic industry’s growth resulted largely from tariffs protecting an oligopoly led by Altos Hornos de Vizcaya. When demand for iron and steel rose, the oligopoly raised prices before attempting to increase supply. Until 1960, the iron and steel industry retarded Spain’s economic development. In 1959, Spain adopted an economic stabilization plan and embarked on an industrial revolution in which the industrial sector grew at a faster rate than the gross domestic product (GDP). Much of the dynamic growth in iron and steel production resulted from the derived demand of a rapidly growing Span- ish automobile industry. By the 1970’s, the iron and steel industry, mademore competitive bythe creation in 1956 and gradual expansion of the state-owned Empresa Nacional Siderúrgica Sociedad Anónima (ENSIDESA), began to export production. Spain was required to lower its iron and steel out- put upon joining the European Union and the Euro- pean Coal and Steel Community in 1986. Neverthe - less, the industry remains dynamic. In 2006, Spain produced 17.8 million metric tons of crude steel, and 1138 • Spain Global Resources iron and steel accounted for almost $7 billion in ex - ports andwere the seventhleading export group. The industry also supports exports of machinery, ships, and other articlesofironandsteel, not to mention the export of vehicles, Spain’s greatest export by value ($44 billion in 2006). Water The most industrialized regions of Spain—the Basque Country and Catalonia—are relatively well endowed with water.However, water isa scarce resource in most of Spain, large regions of which receive less than 500 millimeters average annual precipitation. These regions are dry in the summer months, whentheirrivers carry less water for irrigation, processing raw materi- als for industry, and hydropower. Only 8 percent of Spain’s hydrologic resources are available for use with- outartificially altering thenaturalregimen; in the rest of Europe the comparable figureis40 percent. As a result, Spain has about twelve hundred large dams and reservoirs and many canals to alter the natural water regimen so that an estimated 37 to 47 percent of the water is available for use. Water management in Spain focuses on the river basin or watershed. Each autonomous community manages watersheds entirely within its boundaries. A Hydrographic Confederationoversees watersheds that spread over more than one autonomous community. Spain’s dams and reservoirs generate hydroelectric power, provide irrigation water for farming, supply potable water, support recreation, regulate down- stream flow, and make water available for interbasin transfers. Thelarge reservoirs havea waterstorage ca- pacity of about 52 cubic kilometers; about 79 percent is for agriculture, 15 percentisfor potable water inthe urban supply network, and 6 percent is for industry. The transfers of water from one basin to another (trasvases) began in 1980 with the Tagus-Segura aque- duct, which stretches 300 kilometers from the upper Tagus River tothe Segura River basin in the provinces of Albacete and Murcia; most of that water has been used for irrigating citrus orchards. The National Hy- drological Plan of 2001 called for transfer of water from the Ebro River to basins along the Mediterra- nean coast, but public outcry led to its replacement with Programa AGUA (2004), a program to build twenty-one desalinization plants in six provinces along the Mediterranean. Spain is forging additional poli- cies that support sustainable water management. Olives and Olive Oil Spain has 2.4 million hectares in olive cultivation—as much as in Italy and Greece, the next largest olive growers in Europe, combined. Olivetrees prefer thin, Global Resources Spain • 1139 Olive trees in Andalusia, Spain. Spain is a leading producer of olives and olive oil. (©Anton Moiseenko/Dreamstime.com) stony soils with little water and long, hot summers. The olive tree is intolerant to temperatures less than −5° Celsius. Most of the olive cultivation is in Anda- lusia, where 58 percent of the total cultivated area is dedicated to olive trees. The province of Jaén is home to more than one-half of Andalusia’s olive groves, followed in importance by the provinces of Córdoba, Sevilla, Badajoz, and Granada. Almost all of this cultivation isfor oil; only 6 percent is fortable olives.Span- iards consume about 0.4 liter of olive oil per person per week, andolive oil provides most ofthe fat intheir diets. Spain is the world’s largest exporterofoliveoil. In recent years, olive oil production has risen in response to world demand, which grew 4 percent per year in the1990’s.Although the traditional form of olive cultivation has been on small farms of less than 20 hectares, the growing demand has led to more farms larger than 100 hectares. The large groves tend to be located in flatter areas, use drip irrigation to increase tree density, and adopt mechanical harvesting. The large groves not only enjoy lower costs of production per kilogramof olives thansmall groves butalso bene- fit from European Unionsubsidiesthatare correlated positively with the amount of production. The traditional groves onsteeper slopes also can receive aid, but only if they minimize tillage, keep walls and terraces, maintain at least 50 percent green cover on the land, and do not use chemicals. The more mountainous traditional groves try to compensate for their lower productivity by forming Designation of Origin (DO) areas. The DOs have regulatory councils to ensure quality, andsome of their farms have adoptedorganic cultivation. As Spain hasmore than 260 olive cultivars, there is much room for market differentiation. Olive groves create a distinct landscape. In parts of Andalusia there are little more than olive trees for as far as the eye can see. Olive mills are located on or near farms, so the harvested olives can be pressed quickly to prevent an increase in acidity. Virgin oil is bottled at the mill. Pomace oil is made in refineries from olive pomace and pits and is often mixed with virgin olive oil; it is used in commercial cooking. Lampante oil is refined in cities andisusedinindustry. Citrus Fruit Spain’s citrus crops are, inorder of importance, sweet oranges, mandarins (especially clementines), lemons, grapefruit, and bitter (Seville) oranges. They are grown mainly inMediterranean coast provinces,from Castellón to Málaga. The center of sweet orange or - chards has been the province of Valencia; clemen - tines are raised especially in Castellón; lemons and grapefruit prefer the hotter province ofMurcia. How- ever, citrus production is increasing rapidly in the region of Andalusia. Everywhere the trees are irrigated, either through flood irrigation or, in newer orchards, through drip irrigation. The sweet orange accounts for about one-half of Spain’s citrus production. The sweet oranges come in many varieties and are typically raised on small farms belonging tocooperatives that supplypackinghouses. Barring water-supply problems and unusually cold temperature spells, their production is gradually increasing. Clementines, a crossbetween the sweetorangeand the Chinese mandarin, are small, seedlesscitrus of different varieties. The small clementine tree (around 3 meters tall) istrimmedannually, and thefruit mustbe clipped by hand; a job for whichthe cooperatives usually recruit migrant labor. Clementine cultivation has expanded significantly, with most new orchards located in the Guadalquivir Valley and averaging more than 100 hectares. Spain is the world’s largest exporter of clementines, and U.S. imports of the fruit have risen dramatically in recent years. Spain supplies nearly one-half of all the world’s exports of oranges and clementines, which gener- ates about $3 billion per year. More than 80 percent of these exports go to Europe, especially Germany, France, the Netherlands, and the United Kingdom. Grapevines and Wine Grapevines require a dry, well-drained soil, summer temperatures neither too cold nor too hot, and an au- tumn without heavy rain. The vines grow in every province of Spain, but most vineyards are located along the Mediterranean coast from near the French border to the province of Almería. However, the largest wine region is La Mancha (in the provinces of Albacete, Ciudad Real, Cuenca, and Toledo). Spain has more land devoted to the wine grape than does any other country, with 1.2 million hectares under vine cultivation. However, the country produces less wine than France and Italy because of its aridity and rainfall variability. Spain’s vineyards traditionally were planted in wide rows, with drought-resistant vines kept low and bushy to minimizeevaporation. The resulting wine was ordi - nary to good, with some exceptional wines in the re - gions of Jerez, La Rioja, andPriorat.However,growers 1140 • Spain Global Resources have been replacing vines with new grape varieties, adding drip irrigation, and pursuing new methods of wine making. Spain’s sixty-nine Qualified Designation of Origin (DOCA) and DO areas produce distinct quality wines crafted from 146 varieties of grapes. OnlyLaRiojaand Priorat havethe DOCAdesignation. Vino de laTierra (VdlT) wines come from regions with no special DO status but have a distinctive character. Vino Comarcal (VC) wines come from areas without any claim to quality. Finally, Vino de Mesa (VdM) table wines are a blend of wines from different regions and from any vintage. The VC and VdM wines are for domestic consumption, which is considerable, as wine is typically imbibed with afternoon and evening meals. Wine is integral to the Spanish culture; it has been made in the country since the fourth millennium before Christ. Today, a number of Spaniards in rural areas make their own wines and have their own bodegas (wine cellars), preferably in caves dug into hills near their homes. Although wine production accounts for only 2 percent of Spain’s total agricultural production by value, it enjoys the fastest growth in net sales of any agrifood industry. About one-half of Spanish wine exports is bulk, going mainly to France, Italy, and Portugal where it is used to blend with domestic wines before bottling. Spain’s bottled exports go mainly to Ger- many, the United Kingdom, the United States, and the Netherlands, in that order. Other Resources In the dry interior of the tablelands, wheat and barley are important crops grown for domestic consumption. Both are grown largely in the same areas and usually secano (without irrigation). Although barley is hardier, both crops can suffer significantly reduced yields from droughts and spring storms. Other crops grown mainly for the export market include Spanish melons, eggplants, tomatoes, lettuce, strawberries, peppers, and tomatoes. They are often grown under huge sheets of plastic and harvestedbymigrantsliving in nearby encampments. Spain is highly mineralized, and its metal ores other than iron include alumina, copper, gold, lead, mercury, nickel, pyrites, silver, tungsten, uranium, and zinc. Industrial minerals include barite, clays, fluorspar, and potash. Energy resources also include small amounts of petroleum and natural gas. Steven L. Driever Further Reading Harrison, Joseph. “The Economic History of Spain Since 1800.” Economic History Review 43, no. 1 (1990): 79-89. Sommers, Brian J. The Geography of Wine: How Land- scapes, Cultures, Terroir, and the Weather Make a Good Drop. New York: Penguin Group, 2008. Tortella, Gabriel The Development of Modern Spain: An Economic History of the Nineteenth and Twentieth Cen- turies. Translated by Valerie J. Herr. Cambridge, Mass.: Harvard University Press, 2000. Viladomiu, Lourdes, and Jordi Rosell. “Olive Oil Pro- duction and the Rural Economy of Spain.” In Sus- taining Agriculture and the Rural Environment: Gover- nance, Policy and Multifunctionality, edited by Floor Brouwer. Northhampton, Mass.: Edward Elgar, 2004. See also: Agricultural products; Agriculture industry; Coal; Resources as a medium of economic ex- change; Steel; Steel industry. Species loss Category: Environment, conservation, and resource management Species loss, particularly the extinction of speciesthatis caused by human activities, has increasingly concerned scientists in a number of fields. The Endan- gered Species Act (1973) is the central piece of legislation concerned with preventing species loss in the United States. Background Public and scientific concern about species loss stems from several factors andencompassesavarietyof view- points. Ethically, many people believe that species have value in and of themselves and that humankind does not have the right to cause the extinction of any species. A species may also have an unknown po- tential to enrich human life and health. The latter argument is important in that many synthetic medicines and commercial products were first produced by plants and animals. The loss of species could mean the loss of beneficial new products for human soci - ety. Species that exist today are the result of millions of years of evolutionary success, and to lose species Global Resources Species loss • 1141 is to lose that evolutionary history. From a resource management point of view, ecologists and land man- agers alike are concerned about the effects that species loss may have on the function and stability of bi- otic communities. The ramifications of species loss are not easily pre- dictable. The food-web relationships among species in a community may or may not be known and, if known, may not have been measured. Relationships such as predation, competition, and parasitism link species into complex community relationships. One way species are linked is by trophic levels within the community food chain, which is more accurately de- scribed as a food web. Starting with plants at the base of the web, trophic levels begin with producers, followed byseveral successivelevels ofconsumers: herbi- vore, first-level carnivore, second-level carnivore, and so on, up to top carnivore. Omnivores feed both as herbivores and as carnivores and thus feed at more than one trophic level. Finally decomposers feed on dead organisms and their waste products from all trophic levels. Species-Removal Studies Species-removal studies provide some indication of what may occur when a species becomes extinct. In more than 90 percent of predator-removal studies, population densities of prey species in the trophic level immediately below the predator have shown a significant increase or decrease. In many cases, the change in density was twofold. Rarely has the removal of predator species had no effect on the population density of itsprey. However, notall studies have shown the expected increase in prey density; many have shown an unexpected decrease. For species that possibly compete with one another, more than 90 percent of competitor-removal studies have shown an increase in the “remaining competitor” population density. Several factors may influence the strength of community response in species-removal experiments. For example, a predator may prey more heavily on a large, aggressive prey species and thus allow the coexistence of a less aggressive, competitor prey species. If the predator is removed, the aggressive prey may increase in density while the less aggressive one may actually decrease. Studies in aquatic communities indicate that the higher the trophic level in which species removal oc - curs, the greater the effect on population densities at lower trophic levels. The ramifications of species loss can be only par - tially predicted with knowledge of community food webs. The size and direction of population density change within a community may or may not be as expected. It is safe to predict, however, that species loss will cause changes in most instances. Wildlife Protection and Endangered-Species Legislation Concern about species loss in North America can be traced back at least as far as 1872, when legislation offering limited protection to the buffalo was passed by Congress. This legislation was passed at the height of buffalo exploitation by market hunters and during the U.S. Army’s policy of fighting American In- dian tribes by cutting off their food supply. However, President Ulysses S. Grant vetoed the legislation, and the buffalo was almost lost. Only a few hundred remained by 1900. The first National Wildlife Refuge was set asideby President Theodore Rooseveltin 1902 to protect egrets from extinction by feather hunters. Three years later, the Wichita Mountain National Wildlife Refuge was set aside to protect one of the small remnant herds of buffalo. Several North Ameri- can species and subspecies are now extinct because of similar exploitations: The passenger pigeon, Caro- lina parakeet, heath hen, Merriam’s elk, and Bad- lands bighorn sheep are some of the best-known ex- amples. During the 1960’s increasing concern about an ac- celerated species extinctionrateattributable to human exploitation and disturbance of the environment cul- minated in the first federal protective legislation for endangered species, the Endangered Species Preser- vation Act of 1966. This act was limited to listing endangered birds and mammals and funding research on their population ecology and habitat acquisition. This legislation was expanded in 1969 to include all vertebrate animal species and some invertebrates. The definitive protection legislation is the 1973 En- dangered Species Act. This act set procedures for listing threatened and endangered species, called for designation of critical habitats for each threatened or endangered species, and mandated the development of recovery plans for these species. The act pro- hibits the use of federal funds for projects that would harm threatened or endangered species. The cover- age of the 1973 act was also expanded to include plants and invertebrate animals (except pest insects), subspecies, and distinct vertebrate populations. 1142 • Species loss Global Resources Beginning in 1966, the United States Fish and Wildlife Service(USFWS) assumed thelegalresponsi- bility of compiling and maintaining an official threatened and endangered species list. There are formal petitioning processes for placing additional species on the list and for removing them from the list. Peti- tions may be initiated by the USFWS or by private organizations. Petitions are reviewed byscientificpan- els using all available information on the species. If sufficient information is available to support the petition, a proposed addition to the list is published in the Federal Register and other appropriate places to solicit public comment. Final decisions about listing, “down-listing” (for example, changing a species designation from “endangered” to “threatened”), or “delisting” are made by the USFWS. The ultimate goal of the listing process and the implementation of a recovery plan is to increase the abundance and distribution of a species to the point of being able to remove it from the threatened and endangered species list. James F. Fowler Further Reading Ellis, Richard. The Empty Ocean: Plundering the World’s Marine Life. Washington, D.C.: Island Press/Shear- water Books, 2003. Garbutt, Nick, and Mike Unwin. One Hundred Animals to See Before They Die. Chalfont St. Peter, England: Bradt, 2007. Goodall, Jane, Thane Maynard, and Gail Hudson. Hope for Animals and Their World: How Endangered Species Are Being Rescued from the Brink. New York: Grand Central, 2009. McGavin, George. Endangered: Wildlife on the Brink of Extinction. Buffalo, N.Y.: Firefly Books, 2006. Maclaurin, James, and Kim Sterelny. What Is Biodiver- sity? Chicago: University of Chicago Press, 2008. Pimm, Stuart L. The Balance of Nature? Ecological Issues in the Conservation of Species and Communities. Chi- cago: University of Chicago Press, 1991. Ricklefs, Robert E., andDolphSchluter,eds.SpeciesDi- versity in Ecological Communities: Historical and Geo- graphical Perspectives. Chicago: University of Chi- cago Press, 1993. Strong, Donald R., Jr., et al., eds. Ecological Commu- nities: Conceptual Issues and the Evidence. Princeton, N.J.: Princeton University Press, 1984. Wilson, Edward O. The Future of Life. New York: Alfred A. Knopf, 2002. Web Sites Environment Canada: Canadian Wildlife Service Species at Risk http://www.cws-scf.ec.gc.ca/ theme.cfm?lang=e&category=12 U.S. Fish and Wildlife Service Endangered Species Program http://www.fws.gov/endangered See also: Biodiversity; Conservation; Conservation biology; Endangered species; Endangered Species Act; Fish and Wildlife Service, U.S.; Nature Conservancy; Plants as a medical resource. Steam and steam turbines Categories: Energy resources; obtaining and using resources A steam boiler converts the chemical energy in fuel into the thermal energy of steam. A steam turbine converts this thermal energy into the mechanical energy of a rotating shaft. This shaft can drive an electric generator or other device. Background Fossil fuels such as oil and coal contain chemical energy. Uranium contains nuclear energy. Either of these forms of energy can be converted into thermal energy (heat), and this thermal energy can be used to make steam ina boiler. Asteam turbine canbeused to convert thethermal energy of steaminto the mechanical energy of a rotating shaft. When the turbine shaft is used to drive an electric generator, electricity ispro- duced. Although electric generators can be driven by diesel engines, gas turbines, and other devices, most electricity is generated using steam turbines. Principles of Turbine Operation High-pressure, high-temperature steam enters a steam turbine through a throttle valve. Inside the turbine the steam flows through a series of nozzles and rotating blades. As it flows through a nozzle, the pressure and temperature of the steam decrease, and its speed increases. The fast-moving steam is directed against rotating blades, whichwork something likethe blades Global Resources Steam and steam turbines • 1143 on a pinwheel. The steam is deflected as it passes over the rotating blades, and in response the steam pushes against the blades and makes them rotate. As the steam flows over the rotating blades its speed de- creases. Large turbines are composed of many stages. Each stage has a ring of nozzles followed by a ring of rotating blades. The slow-moving steam leaving the rotating blades of one stage enters the nozzles of the next stage, where it speeds up again. This arrangement is called pressure compounding. The energy of the steam is converted to mechanical work in small steps. Less of thesteam’sthermal energyis wasted orlost if it is converted in small steps. The amount of power produced by a turbine depends on the amount of steam flowing through it and on the inlet and outlet steam pressures. Steam flow is constantly regulated by the throttle valve, but the steam pressures are fixed by the design of the system. Inlet steam pressure is determined by the operating pressure of the boiler that supplies it. Outlet pressure is determined by where the steam goes when it leaves the turbine. If the steam simply es- capes into the atmosphere, the outlet pressure is atmosphere. If the outlet steam pressure is made lower than atmospheric pressure, the turbine produces more power. This is accomplished by having the steam leaving the turbine flow into a condenser. Cooling water passing through tubes inside the condenser removes heat from the steam flowing around the tubes and causes it to condense and become liquid water. Since water occupies a much smaller volumeas a liquid than as steam, condensing cre- ates a vacuum. When a turbine is connected to a condenser, the outlet steam pressure can be far below one atmosphere. Details of Turbine Construction Inside the steel turbine casing, sta - tionary partitions called diaphragms separate one turbine stage from the next. Each diaphragm has a hole at the center for the rotor shaft to pass through. Nozzle passages are cut through the diaphragms near their outer rims, and the steam is forced to pass through these nozzles to get to the next stage. The rotor of aturbineismade up of solidsteeldisks that are firmly attached to a shaft. Rotating blades are mounted around the rims of the disks. Where the shaft extends from the casing at each end, it is supported by journal bearings and a thrust bearing. The journal bearings are stationary hollow cylinders of soft metal that support the weight of the rotor. A thrust bearing consists of a small disk on the shaft of the turbine that is trapped between two stationary disks supported by the casing. If the rotor tries to move forward or back along its own axis, the rotating disk presses againstone of thestationary disks.Thrust and journal bearings must be lubricated by a constant 1144 • Steam and steam turbines Global Resources Steam fieldsin Sonoma County, California, feed the McCabe power plant, churning tur - bines that create steam-powered electricity. (AP/Wide World Photos) flow of oil that forms a thin film between the rotating and stationary parts of the bearingand prevents them from making direct contact. Without this film of oil, the bearing would wear out in a few seconds. A seal must be provided where the shaft of the turbine passes through the casing. At one end of the casing the steam pressure inside is high. Outside the casing the air pressure is only one atmosphere. If there were no seal, steam would rush out through the space between the casing and the shaft. At the other end of the turbine, the pressure inside may be below atmospheric. Here air would rush in if there were no seal around the shaft. Electric Power Generation Most electric power is produced by steam turbines driving electric generators. This is true whether the source of the steam is a nuclear reactor or a boiler burning fossil fuel. The turbines in power stations are extremely large. In nuclear plants the turbines may produce as much as 1,300 megawatts of power. Power stations are often located near rivers so that water from theriver can be used as cooling water in the con- densers that receive steam from the large turbines. Edwin G. Wiggins Further Reading Avallone, Eugene A., Theodore Baumeister III, and Ali M. Sadegh. “Steam Turbines.” In Marks’ Stan- dard Handbook for Mechanical Engineers. 11th ed. New York: McGraw-Hill, 2007. Blank, DavidA., Arthur E.Bock, andDavid J. Richard- son. Introduction to Naval Engineering. 2ded. Annap- olis, Md.: Naval Institute Press, 1985. Bloch, Heinz P. Steam Turbines: Design, Applications, and Rerating. 2d ed. New York: McGraw-Hill, 2009. McBirnie, S. C. Marine Steam Engines and Turbines. 4th ed. Boston: Butterworths, 1980. Peng, William W. “Steam Turbines.” In Fundamentals of Turbomachinery. Hoboken, N.J.: J. Wiley, 2008. Termuehlen, Heinz. One Hundred Years of Power Plant Development: Focus on Steam and GasTurbines asPrime Movers. New York: ASME Press, 2001. Web Site How Stuff Works How Steam Technology Works http://science.howstuffworks.com/steam- technology.htm See also: Coal; Electrical power; Metals and metal - lurgy; Nuclear energy; Oil industry; Steam engine; Steel; Uranium. Steam engine Category: Obtaining and using resources A steam boiler converts the chemical energy in fuel into the thermal energy of steam. A steam engine converts this thermal energy into the mechanical energy of a rotating shaft. This shaft can drive an electric generator or pump. Background The chemicalenergy that iscontained within fossil fuels such as oil and coal can be converted into thermal energy (heat) by burning the fuel. This thermal energy can be used to create steam in a boiler. A steam engine converts the thermal energy of steam into the mechanical energy of a rotating shaft, and this shaft can drive a pump, a ventilating fan, a ship’s propeller, and many other devices. History Although there were attempts to use steam to drive mechanical devices as early as 60 c.e. by Hero of Alex- andria, the first real steam engine was designed and built by Thomas Newcomen in 1712. That year New- comen successfully used a steam engine to pump water from a coal mine near Dudley Castle, England. In 1765,as hewalked across Glasgow Green in the city of Glasgow, Scotland, James Watt conceived the idea of connecting the steam engine to a separate condenser. The first full-size engines based on this con- cept were built in 1776: one at John Wilkinson’s blast furnace near Broseley, England, and the other at Bloomfield coal mine near Tipton, England. New- comen’s design andWatt’s earlydesigns used steam at constant pressure. Over the course of his life, Watt in- vented many improvements to the steam engine, including rotary engines, a deviceformeasuring engine performance, and engines in which the steam expanded during the piston stroke. Expanding steam engines soon drove the earliertype offthe market, because the fuel consumption associated with the boiler of an expanding steam engine is far less than that of a constant pressure engine. While modern steam en - Global Resources Steam engine • 1145 . province of Alicante. Less dramatic sierras punctuate the Meseta. Two ma - 1136 • Spain Global Resources Global Resources Spain • 1137 Spain: Resources at a Glance Official name: Kingdom of Spain Government:. loss of species could mean the loss of beneficial new products for human soci - ety. Species that exist today are the result of millions of years of evolutionary success, and to lose species Global. composed of many stages. Each stage has a ring of nozzles followed by a ring of rotating blades. The slow-moving steam leaving the rotating blades of one stage enters the nozzles of the next stage,