Encyclopedia of Global Resources part 101 pptx

Petroleum fuels. See Gasoline and other petroleum fuels Petroleum refining and processing Category: Obtaining and using resources Petroleum is separated into a variety of fuels—gaso- line, kerosene, and diesel fuel—and into feedstocks for the chemical industry. Petroleum is first distilled, then each of the “cuts” is further treated or blended to pro- vide the various marketed products. A significant ef- fort is devoted to gasoline production, in order to ob- tain the quantities needed and the desired engine performance. Background Petroleum, or crude oil, is found in many parts of the world. It is not a chemically pure substance of uni- form properties. Rather, petroleum is a complex mix- ture of hundreds of individual chemical compounds that occur in various proportions, depending on the source and geological history of the particular sam- ple. As a result, various kinds of petroleum range in properties and appearance from lightly colored, free- flowing liquids to black, tarry, odiferous materials. It would beimpractical todesign furnacesor enginesca- pable of efficient, reliable operation on a fuel whose characteristics varied so widely. Therefore, to provide products of predictable quality to the users, petro- leum is separated into specific products that, through treating, blending, and purification, goonthe market as the familiar gasoline, kerosene, and diesel and heating oils. Some petroleum supplies also contain impurities, most notablysulfur compounds, that must be removed for environmental reasons. The sequence of separation, blending, treating, and purification operations all make up the processes of petroleum refining. Distillation The first major step in refining petroleum is distilla- tion, the separation of components based on boiling point. In principle, it would be possible toseparate pe- troleum into each of its component compounds, one by one, producing many hundreds of individual pure compounds. Doing so would be so laborious that the products would be too expensive for widespread use as fuels or synthetic chemicals. Instead, petroleum is separated into boiling ranges, or “cuts,” such that even though a particular distillation cut will still be composed of a large number of compounds, its physi- cal properties and combustion behavior will be rea- sonably constant and predictable. Many crude oils contain dissolved gases, such as propane and butane. These are driven off during dis- tillation and can be captured for sale as liquefied pe- troleum gas (LPG). The first distillation cut (that is, the one with the lowest boiling temperature) that is a liquid is gasoline.Products obtained in higherboiling ranges include, in order of increasing boiling range, naphtha, kerosene, diesel oil, and some heating oils or furnace oils. Some fraction of the crude oil will not distill; this is the residuum, usually informally called the resid. The resid can be treated to separate lubri- cating oils and waxes. If the amount of resid is large, it can be distilled further at reduced pressure (vacuum distillation) to increase the yield of the products with higher boiling ranges and a so-called vacuum resid. Catalytic Cracking The product that usually dominates refinery produc- tion is gasoline. Gasoline produced directly by distilla- tion, called straight-run gasoline, is not sufficient in quantity or in engine performance to meet modern market demand. Substantial effort is devoted to en- hancing the yield and quality of gasoline. The yield of straight-run gasoline from very good quality petro- leum is not more than 20 percent; from poorer quality crudes, it may be less than 10 percent. About 50 per- cent of a barrel ofpetroleum needs to be converted to gasoline to satisfy current needs. Gasolineengine per- formance is measured by octane number, which indi- cates the tendency of the gasoline to “knock” (to deto- nate prematurely in the engine cylinder). Knocking causes poor engine efficiency and can lead to me- chanical problems. Most regular grade gasolines have octane numbers of 87; straight-run gasolines may have octane numbers below 50. Increasing the yield of gasolinerequiresproducing more molecules that boil in the gasoline range. Gen- erally the boiling range of molecules relates to their size; reducing the boiling range is effected by reduc- ing their size, or “cracking” the molecules. Octane number is determined by molecular shape. The com - mon components of most crude oils are the paraffins, or normal alkanes, characterized by straight chains of 928 • Petroleum refining and processing Global Resources carbon atoms. These paraffins have very low octane numbers; heptane, for example, has an octane num- ber of 0. A related family of compounds, isoparaffins, have chains of carbon atoms with one or more side branches; these have very high octane numbers. The compound familiarly referred to as iso-octane (2,2,4- trimethylpentane) has an octane number of 100. In- creasing the yield and engine performance of gas- oline requires both cracking and rearranging the molecular structures. Both of these processes can be performed in a sin- gle step, using catalysts such as zeolites. For this rea- son, the overall process is known as catalytic cracking. The feedstock to a catalytic cracking unit is a high- boiling cut material of low value. Different refineries may choose to use different feeds, but a typical choice would be a vacuum gas oil, which is produced in the vacuum distillation step. Much effort has gone into the development of catalysts and into evaluating ap- propriate choices of temperature, pressure, and reac- tion time. Catalytic cracking is second only to distilla- tion in importance in most refineries. It can produce gasolines with octane numbers above 90 and in- creases the yield of gasoline in a refinery to about 45 percent. Catalytic Reforming Straight-run gasoline and naphthas have acceptable boiling ranges but suffer in octane number. Treating these streams does not require cracking, only altering Global Resources Petroleum refining and processing • 929 Separation and Uses of Petroleum CRUDE OIL IN PETROLEUM REFINERY SEPARATING PURIFICATION CONVERSION ASPHALT INDUSTRIAL FUEL OIL DE-WAXING LUBRICANTS AND GREASES DIESEL OILS FUEL OIL GASOLINE BOTTLED GAS CRACKING ROOFING PAINTS PLASTICS PHOTOGRAPHIC FILM SYNTHETIC RUBBER WEED-KILLERS AND FERTILIZERS MEDICINES DETERGENTS ENAMEL SYNTHETIC FIBERS CANDLES WAXED PAPER POLISH OINTMENTS AND CREAMS JET FUEL SOLVENTS INSECTICIDES the shapes of molecules—re-forming them—to en - hance octane number.This processalsorelies on cata- lysts, though ofdifferent types thanthose used in cata- lytic cracking. Reforming catalysts usually include a metal, such as nickel or platinum. Catalytic reforming can produce gasolines with octane numbers close to 100. Hydrotreating Other distillation cuts, such as kerosene and diesel fuel, require less refining. Two processes of impor- tance for environmental reasons are the removal of sulfur and removal of aromatic compounds. Since both involve the use of hydrogen, they are referred to as hydrotreating. Sulfur removal—hydrodesulfurization—is done to reduce the amount of sulfur oxide emissions that would have been produced when the fuel is burned. Additionally, sulfur compounds are corrosive and can have noxious odors. Hydrodesulfurization is per- formed by treating the feedstock, such as kerosene, with hydrogen using catalysts containing cobalt or nickel and molybdenum. As environmental regula- tions become more stringent, hydrodesulfurization will become increasingly important. Aromatic compounds also have several undesir- able characteristics. Some compounds, such as ben- zene, are carcinogens. Larger aromatic molecules, which might be found in kerosene or diesel oil, con- tribute to the formation of smoke and soot when these fuels are burned. Soot formation is unpleasant in its own right, but in addition, some soot compo- nents are also carcinogens. Aromatic compounds are reacted with hydrogen to form new compounds— naphthenes or cycloalkanes—of more desirable prop- erties. Resid Treating Resids can be treated with solvents to extract lubricat- ing oils (these oils can also be made during the vac- uum distillation of resid), waxes, and asphalts. Al- though lubricating oils are produced only in low yield (about 2 percent of a barrel of crude may wind up as lubricating oil), they are commercially valuable prod- ucts. Asphalts are of great importance for road pav- ing. Resid is also converted by heating into petroleum coke, a solid material high in carbon content. High- quality petroleum cokes are used to manufacture syn - thetic graphite, which has a range of uses, the most important of which is for electrodes for the metallur - gical industry. Poorer quality petroleum cokes can be used as solid fuels. Petrochemicals Petroleum is the source not only of liquid fuels but also of most synthetic chemicals and polymers. Some products having low value as fuels, such as naphtha or even waxes, can be decomposed to produce ethylene, the most important feedstock for the chemical indus- try. Ethylene is converted to polyethylene, polyvinyl chloride, polyvinyl acetate, and polystyrene, which to- gether make up a large share of the total market for plastics. Another petroleum product of great use in the chemical industry is propylene, the starting mate- rial for making polypropylene and polyacrylonitrile. Harold H. Schobert Further Reading Berger, Bill D., and Kenneth E. Anderson. Modern Pe- troleum: A Basic Primer of the Industry. 3d ed. Tulsa, Okla.: PennWell Books, 1992. Gary, James H., Glenn E. Handwerk, and Mark J. Kai- ser. Petroleum Refining: Technology and Economics. 5th ed. Boca Raton, Fla.: CRC Press, 2007. Jones, D. S. J. Elements of Petroleum Processing. Chich- ester, England: John Wiley & Sons, 1995. Leffler, William L. Petroleum Refining in Nontechnical Language. 4th ed. Tulsa, Okla.: PennWell, 2008. Meyers, Robert A., ed. Handbook of Petroleum Refining Processes. 3d ed. New York: McGraw-Hill, 2004. Royal Dutch/Shell Group of Companies, comp. The Petroleum Handbook. 6th ed. New York: Elsevier, 1983. Speight, James G. The Chemistry and Technology of Petro- leum. 4th ed. Boca Raton, Fla.: CRC Press/Taylor & Francis, 2007. Szmant, H. Harry. Organic Building Blocks of the Chemi- cal Industry. New York: Wiley, 1989. Web Site U.S. Department of Energy, Energy Information Administration Refining http://www.eia.doe.gov/pub/oil_gas/petroleum/ analysis_publications/oil_market_basics/ refining_text.htm See also: Gasoline and other petroleum fuels; Oil and natural gas chemistry; Oil industry; Petrochemi - cal products; Propane. 930 • Petroleum refining and processing Global Resources Phosphate Category: Mineral and other nonliving resources Where Found Phosphate rock ore is mined in Florida and North Carolina (more than 85 percent of U.S. output), as well as Idaho and Utah. Major world producers in - clude China, followed by the United States, Morocco and the western Sahara, Russia, Tunisia, and Brazil. Primary Uses Phosphate rock is used primarily in the production of fertilizers. In the United States, more than 95 percent is used in the manufacture of phosphoric acids, which Global Resources Phosphate • 931 Data from the U.S. Geological Survey, . U.S. Government Printing Office, 2009.Source: Mineral Commodity Summaries, 2009 28,000,000 11,000,000 600,000 2,400,000 3,700,000 800,000 7,800,000 30,900,000 10,800,000 Metric Tons 60,000,00050,000,00040,000,00030,000,00020,000,00010,000,000 United States Syria South Africa Senegal Russia Morocco and western Sahara Togo Tunisia Other countries 2,300,000 6,000,000 800,000 50,000,000 3,000,000 3,100,000 5,500,000 Egypt China Canada Brazil Australia Israel Jordan Phosphate Rock: World Mine Production, 2008 in turn are usedto make ammoniumphosphate fertil - izers and feed supplements for animals. Technical Definition Phosphate rock is a general term for any earth mate- rial from which phosphorus can be extracted at a profit. The principal phosphorus-bearing mineral in these deposits is a hydrated calcium phosphate called apatite, Ca 5 (PO 4 ) 3 (OH). Apatite can also accommo- date variable amounts of fluorine (F) and carbonate ion (CO 3 ) and contains from 18.0 to 18.7 percent phosphorus. Description, Distribution, and Forms In its organic form, apatite occurs as the main compo- nent of bones and teeth, and it makes up the shells of some marine invertebrates. Some phosphate depos- its, particularly those in Florida, also contain certain aluminum phosphate minerals. Commercial phos- phate deposits occur in two major forms: (1) marine sedimentary deposits, in which phosphate-rich beds are associated with carbonate rocks (limestones, dolostones) and mudstones or shales deposited on the floor of an ocean or shallow sea, and (2) igneous deposits, in which apatite has crystallized from for- merly molten plutons (molten magma that solidifies below ground). The sedimentary deposits are by far the most im- portant phosphate producers. In the United States these areas are located in the eastern states of Florida, Tennessee, and North Carolina, and the western states (the “western field”) of Wyoming, Montana, Idaho, Utah, and Nevada. The most widespread, con- tinuous deposits of phosphate rock in the United States occur in the Phosphoria formation of Utah, Wy- oming, Idaho, Montana, and Nevada. By far the most important phosphate localities worldwide are in North Africa and Russia. Elsewhere in the world, significant deposits are found in North Africa, specifically Algeria, Tunisia, Morocco, and Egypt. The principal igneous deposits occur in Russia (the Kola Peninsula) and in Ontario, Canada. History Production started in the United States in 1867, with mining of the extensive Florida deposits beginning in 1888. Over time, the price of phosphate rock jumped—with a notable spike in 2007—as agricul - tural demand increased worldwide. The mining of phosphate rock has also spiked in China, as that na - tion’s development escalates. Interest in the produc - tion of phosphate has prompted exploration of new resources, particularly sources off the coasts of Mex- ico and Namibia. Obtaining Phosphate Phosphate rock is the ore of the element phosphorus (P). It occurs mostly as marine (saltwater) sedimen- tary deposits in which the predominant phosphorus- bearing mineral is apatite, a hydrated calcium phos- phate. Phosphate rock is mined from sedimentary marine phosphorites both on land and on continen- tal shelves and seamountsand is available via aprocess in which sea organisms die and settle to the bottom of a given water body. Through mining, inorganic phos- phates are obtained and can be separated from other chemicals. Uses of Phosphate Most of the mined phosphate rock is turned into wet- process phosphoric acid, which is used for fertilizers and supplements in animal feed. It is also used in many industrial processes, including the manufac- ture of phosphoric acids and other chemicals used in the fields of metallurgy, photography, and medicine and in sugar refining, soft drinks, preserved foods, ce- ramics, textiles, matches, and both military and com- mercial pyrotechnics (munitions and fireworks). John L. Berkley Web Site Florida Institute of Phosphate Research http://www.fipr.state.fl.us/index.html See also: Eutrophication; Fertilizers; Mohs hardness scale; Phosphorus cycle; Sedimentary processes, rocks, and mineral deposits. Phosphorus cycle Category: Geological processes and formations Phosphorus stimulates rapid growth of algae in water and is the maincause of eutrophication. Fertilizers, de - tergents, and animal waste are major sources of phos - phorus. 932 • Phosphorus cycle Global Resources Definition The phosphorus cycle describes the continuous move- ment of organic and inorganic phosphorus from the Earth’s crust and living organisms to water bodies and the atmosphere. Overview The element phosphorus (abbreviated P) exists pri- marily in its highest oxidized state—that is, the phos- phate ion (PO 4 ). Phosphorus can be found ina variety of inorganic and organic compounds. Geochemical phosphorus occurs mainly as calcium phosphate (apa - tite),Ca 3 (PO 4 ) 2 , and as hydroxyapatite, Ca 5 (PO 4 ) 3 (OH), and is relatively insoluble. Even when phosphorus is leached into solution through weathering, it readily reacts with other elements to form calcium, alumi- num, manganese, and iron phosphates or binds to clay minerals, resulting in other insoluble phases. Phosphorus has no stable gaseous compounds. There- fore, phosphorus is transported mainly in particulate form by means of overland and riverine runoff and to a lesser extent by atmospheric precipitation. Phosphorus is essential to all life processes. Along with carbon and nitrogen, phosphorus is a highly im - Global Resources Phosphorus cycle • 933 Assimilation by plant cells Weathering of rock Incorporation into sedimentary rock; geologic uplift moves this rock into terrestrial environments Phosphates in solution Loss in drainage Phosphates in soil Decomposition by fungi and bacteria Urine Animal tissues and feces Plant tissues The Phosphorus Cycle The biogeochemical phosphorus cycle is the movement of the essential element phosphorus through the earth’s ecosystems. Released largely from eroding rocks, as well as from dead plant and animal tissues by decomposers such as bacteria and fungi, phosphorus migrates into the soil, where it is picked up by plant cells and is assimilated into plant tissues. The plant tissues are then eaten by animals and released back into the soil via urination, defecation, and decomposition of dead animals. In marine and freshwater aquatic environments, phosphorus is a large component of shells, from which it sediments back into rock and can return to the land environment as a result of seismic uplift. portant nutrient of freshwater bodies. Carbon and ni - trogen are more readily available than phosphorus, and the short supply of phosphorus can control the growth of aquatic vegetation and other microorgan- isms. Thus, phosphorus can act as a limiting factor. An abundance of phosphorus can lead to excessive growth of filamentous algae, a condition called eutro- phication, which can create odor and taste problems and can cause biofouling of the filters, pipes, and in- strumentation that are crucial parts of water supply systems. Much phosphorus input is anthropogenic—in other words, human activities contribute to phospho- rus input at a much greater rate than natural pro- cesses do. Human waste and detergents in domestic and industrial sewage, along with leaching and runoff of fertilizers andanimal waste from agricultural lands, are the major sources of phosphorus. Inorganic phosphorus is taken up by living cells and becomes a major constituent of nucleic acids, phospholipids, and different phosphorylated com- pounds. In nature, organic phosphorus is derived from dead and living cells through excretion and de- composition respectively. Generally, both inorganic and organic phosphates are transformed into dissolved inorganic orthophos- phate. The orthophosphate either precipitates or is consumed or released by phytoplankton or bacteria. Through these lower forms of life, phosphorus is first assimilated by zooplankton and subsequently by higher order organisms. Precipitated phosphorus is utilized by aquatic plants and is diffused into the am- bient water or is buried in deep sediments. In eutro- phic (nutrient-rich, particularly phosphorus-rich) lakes the amount of phosphorus precipitated from the atmosphere is relatively insignificant in compari- son to the amount present in water and sediments. On the other hand, atmospheric phosphorus may be a significant source of phosphorus for oligotrophic (oxygen-rich) lakes. In stratified lakes during the spring season under well-mixed oxidized conditions phosphorus may bond to the bottom sediments. However, in winter, under anoxic (oxygen-deficient) conditions, phosphorus is released from the sediments into the water column. Therefore, phosphorus-laden sediments can serve as internal sources of phosphorus and can continue to promote eutrophication long after the external sources have ceased to exist. Panagiotis D. Scarlatos See also: Agriculture industry;Clean WaterAct; Envi - ronmental engineering; Eutrophication; Fertilizers; Food chain; Lakes; Phosphate; Soil; Water pollution and water pollution control. Photovoltaic cells Categories: Energy resources; obtaining and using resources Photovoltaic cells convert the abundant, free, and clean energy of the Sun directly into electricity. Already widely used in satellites, many consumer products, and residential or commercial electrical systems throughout the world, photovoltaic technology is one of the most promising alternative, renewable energy re- sources. Background Since ancient times, people have used energy from the Sun. In the seventh century b.c.e., mirrors and glass were used to concentrate heat tolight fires. Solar energy can also be converted into electricity. Photo- voltaic (PV) cells, also called solar cells, convert sun- light directly intoelectricity at the atomic level through the process called photovoltaics. A PV cell is made of a special semiconductor mate- rial, so that when photons, or small light particles, strike the cell, some of them are absorbed within the photoelectric material. The energy of the absorbed light loosens electrons (negatively charged compo- nents of an atom) and causes them to flow freely, pro- ducing an electric current. French physicist Alexandre-Edmond Becquerel discovered the photovoltaic effect in 1839. He no- ticed that when exposedto light,certain metals or ma- terials produced small quantities of electric current. In 1883, Charles Fritts built the first working solar cell by coating the semiconductor material selenium with a thin, almost transparent layer of gold. The early so- lar cells had low energy conversion efficiencies, trans- forming less than 1 percent of the absorbed solar en- ergy into electricity. In 1905, Albert Einstein published his theories about the nature of light and the PV effect, which laid the foundation for photovoltaic technology. The first silicon photovoltaic cell was developed by Daryl M. Chapin, Calvin Fuller, andGerald Pearsonat Bell Lab - 934 • Photovoltaic cells Global Resources oratories in 1954. With an efficiency of 6 percent, it was the first solar cell that could convert enough en- ergy to power ordinary electrical equipment. After sil- icon was adopted for many kinds of electronic cir- cuitry in the 1960’s, silicon production increased exponentially, resulting in lower prices. Silicon be- came the standard semiconductor material for PV cells. At first, the crystalline form of silicon was more common, but the amorphous form eventually be- came widespread. Applications The first practical application of photovoltaics oc- curred in 1958, when the U.S. satellite Vanguard 1 used a radio transmitter powered by solar cells. Un- like the battery-powered transmitter on board, which broadcast for less than one month, the solar battery sent signals for years. This breakthrough demon- strated the reliability of PV for electric power genera- tion in space, and solar cells became indispensable in subsequent satellites. In 2000, solar panels were intro- duced at the International Space Station, which held the largest solar power array in space. During the energy crisis in the 1970’s, interest in PV technology for applications other than those for space and commerce grew. By 1978, the first commer- cial solar-powered calculators and wristwatches were introduced. Stand-alone PV systems have become a major source of energy for remote areas far from conven- tional power lines. PV technology provides the neces- sary amount of reliable energy most economically. Applications of PV cells include ocean navigational buoys and lighthouses, remote scientific research and weather stations, telecommunications systems such as mountain-top radio transceivers, and emergency call boxes or road signs. In industrialized nations, PV technology is used in grid-connected electrical systems to supplement con- ventional energy generation. Centralized PV power stations and PV systems in buildings are the two kinds of grid-connected installations. PV power stations, Global Resources Photovoltaic cells • 935 This jail in Germany is fueled by the photovoltaic cells installed on the roof. (AP/Wide World Photos) which send power instantaneously into the grid or dis - tribution network through transformers and invert- ers, are especially cost-effective during hours of peak demand. A PV system in a building is a decentralized system with distributed generation in grid-connected PV arrays or in solar panels on the roofs of residential, commercial, or industrial buildings. More than 70 percent of thepeople in the world do not have electricity. In developing countries andrural areas that do not have access to conventional electri- cal supplies, PV technology is playing an increasingly significant role. Domestic PV systems supply the power for lighting, refrigeration, and basic appliances in many villages and island communities. PV water pumps are also used worldwide for village water sup- plies and irrigation. Advantages and Disadvantages Photovoltaic technology has significant advantages over conventional and other alternative energy tech- nologies. First, because PV systems make electricity di- rectly from sunlight without gaseous or liquid fuel combustion, there is minimal impact on the environ- ment. PV production is clean andquiet, producing no greenhouse gases or hazardous waste by-products. Ranging from microwatts to megawatts, PV energy is also flexible and can be used for a wide range of appli- cations. PV technology is also cost-effective over the life of the system. Sunlight is free and ubiquitous,so PVhasa free, abundant fuel supply. PV systems are also inex- pensive to construct and easy to operate and maintain for long periods of time, because there are no huge generators, complicated wiring, transmission lines, transformers, or moving parts that require frequent servicing or replacement. Because of this high reli- ability and ability to operate unattended, PV technol- ogy has been the choice for space satellites and re- mote areas, where power disruptions and repairs would be costly. Another significant advantage of PV systems is that they are modular, so the systems can be configuredin a variety of sizes and moved as needed. PV technology is more expensive than producing electricity from a grid, but it can provide energy dur- ing peak demand times, such as the hours when air conditioners are turned on during the summer. Dur- ing these times, a grid-connected PV array can be used to meet the peak demand, rather than relying on ex - tremely expensive peaking power plants or other lim - ited energy resources. Thus, PV systems can prevent power outages such as brownouts and blackouts. Solar panels connected to a grid can also produce surplus electricity when the Sun is shining, and this excess is credited against electricity used, resulting in an aver- age 70 to 100 percent savings on electric bills. Other limitations include efficiency and perfor- mance. Because PV technology depends on sunlight, weather conditions affect output. However, even on extremely cloudy days, a PV system can generate up to 80 percent of its maximum output. The Future of Photovoltaics Although sunlight is free, PV hardware manufactur- ing has been too expensive to compete with utilities. Hence, PV technology has been most cost-effective in remote or rural areas without conventional sources of electricity, rather than in urban areas with traditional grid power. However, as more research is done on less expensive materials, the technology improves, and costs decline, PV has thepotentialto become the lead- ing alternative energy resource. It is estimated that in- stalling PV systems in only 4 percent of the area of the world’s deserts would be enough to supply electricity for the whole world. During the 1990’s, research into other materialsin- creased efficiency to more than 10 percent. In 1992, the University of South Florida developed a 15.89 per- cent thin-film cell. In 1994, the National Renewable Energy Laboratory (NREL) fabricated a solar cell made of gallium indium phosphide and gallium arse- nide, which exceeded 30 percent efficiency. In 1999, the NREL and Spectrolab combined three layers of PV materials into a single 32.3 percent efficient solar cell. In the twenty-first century, PV power generation has expanded to meet global energy needs. In 2008, the world PV market reached a record high of 5.95 gigawatts, up 110 percent from 2007. The global mar- ket consisted of eighty-one countries. Spain, Ger- many, the United States, Italy, and Japan were the top five markets. Global revenues for the PV industry to- taled $37.1 billion. Thin-film production grew 123 percent to 0.89 gigawatt. World solar cell production was 6.85 gigawatts, up from 3.44gigawatts in the previ- ous year. China and Taiwan increased their share of solar-cell production from 35 percent in 2007 to 44 percent in 2008. In 2008, huge multimegawatt PV plants were built in Germany and Portugal. In the United States, the growing PV industry helps gener - ate jobs, reduce dependence on foreign oil, and pro - tect the environment. 936 • Photovoltaic cells Global Resources By 2009, China had made a commitment to reach - ing 2-gigawatt solar capacity by 2011 and become a leader in the PV industry, especially in the production of source parts and components. China has estab- lished installation incentives and built assembly the plants in the United States. The Chinese company Suntech Power Holdings increased sales in the United States by reducing prices on its solar panels. In 2009, the American company Evolution Solar Corporation announced it was moving its physical location to China to take advantage of opportunities there. Alice Myers Further Reading Davidson, Joel, and Fran Orner. The New Solar Electric Home: The Complete Guide to Photovoltaics for Your Home. Ann Arbor, Mich.: Aatec, 2008. Goetzberger, A., and Volker U. Hoffmann. Photovol- taic Solar Energy Generation. New York: Springer, 2005. Nelson, Jenny. The Physics of Solar Cells. London: Impe- rial College Press, 2003. Perlin, John. From Space to Earth: The Story of Solar Elec- tricity. Ann Arbor, Mich.: Aatec, 1999. Wengenmayr, Roland. Renewable Energy: Sustainable Energy Concepts for the Future. Weinheim, Germany: Wiley-VCH, 2008. Wenham, Stuart R., et al., eds. Applied Photovoltaics. London: Earthscan, 2007. Wÿrfel, Peter. Physics of Solar Cells: From Basic Principles to Advanced Concepts. Weinheim, Germany: Wiley- VCH, 2009. See also: Buildings and appliances, energy-efficient; Department of Energy, U.S.; Energy storage; Fuel cells; Solar chimneys; Solar energy. Pinchot, Gifford Category: People Born: August 11, 1865; Simsbury, Connecticut Died: October 4, 1946; New York, New York A leading figure in the conservation movement of the late nineteenth century, Pinchot advocated the scien - tific management of the nation’s forests to assure a con - tinuing supply of wood for future growth. Biographical Background In 1889, Gifford Pinchotgraduated from the Yale For- est School (now the Yale School of Forestry and Envi- ronmental Studies), which his father had helped to found, and then studied forestry in Europe, the first American to do so. When a federal Bureau of Forestry was established, Pinchot was appointed as its head. The bureau became the United States Forest Service in 1905, and Pinchot continued as its leader until 1910, at which time he became president of the Na- tional Conservation Committee. He also taught for- estry at Yale University from 1903 to 1906. Impact on Resource Use Pinchot established the basic principles of American forest policy. In contrast to later environmentalists, Pinchot viewed wooded lands principally in terms of their economic value and was concerned with opti - Global Resources Pinchot, Gifford • 937 From 1905 to 1910, Gifford Pinchot served as the first head of the United States Forest Service. (Library of Congress) . produc - tion of phosphate has prompted exploration of new resources, particularly sources off the coasts of Mex- ico and Namibia. Obtaining Phosphate Phosphate rock is the ore of the element. crude oil, is found in many parts of the world. It is not a chemically pure substance of uni- form properties. Rather, petroleum is a complex mix- ture of hundreds of individual chemical compounds that. rapid growth of algae in water and is the maincause of eutrophication. Fertilizers, de - tergents, and animal waste are major sources of phos - phorus. 932 • Phosphorus cycle Global Resources Definition The