Tiếng anh 10- Năng lượng tiến hóa

Evolution of Energy Sources The economic and technological development of societies is linked with shifts in sources of energy. The tendency has been the adoption of denser energy sources, as the shift from coal (solid) to oil (liquid) and natural gas (gas) indicates. This shift can be simplified into 5 major phases, one being speculative: From the beginning of history up to the industrial revolution (18th century), mankind's use of energy relied only on muscular and biomass sources. Most work was provided by manual labor and animals, while the biomass (mainly wood) provided for heating and cooking energy needs. Other sources of energy, such as windmills and watermills were present but their overall contribution was marginal. By the mid 19th century, the industrial revolution brought a major shift in energy sources with the usage of coal, mainly for steam engines, but increasingly for power plants. As the 20th century began, the major reliance was on coal, but a gradual shift towards higher energy content sources like oil began. This second major shift inaugurated the era of the internal combustion engine and of oil-powered ships. In the late 20th century, the emphasis on petroleum products as the main provider of energy reached the point where the world economy highly depends on the internal combustion engine and supporting industries. As its level of technical expertise increased, mankind was able to tap on more efficient sources of fossil fuels, mainly natural gas, and energy released by matter itself (nuclear fission). The 21st century will be characterized by major shifts in energy sources with a gradual obsolescence of polluting fossil fuels, like coal and oil, for more efficient fossil fuels such as natural gas (although there may be substantial clean coal technology potential). Advances in biotechnologies let anticipate the growing usage of biofuels. Nuclear energy, if nuclear fusion becomes commercially possible, may also play a significant role. A very important change in energy sources is likely to be the usage of hydrogen, mainly for fuel cells powering vehicles, small energy generators and numerous portable devices. History of Energy James C. Williams, Ph.D. April 25, 2006 Energy plays a fundamental role in shaping the human condition. People's need for energy is essential for survival, so it is not surprising that energy production and consumption are some of the most important activities of human life. Indeed, it has been argued that energy is the key "to the advance of civilization," that the evolution of human societies is dependent on the conversion of energy for human use.1 Few people have questioned the long-held assumption that standard of living and quality of civilization are proportional to the quantity of energy a society uses. However imprecise it may be, most people still accept the steadfast formula: energy=progress=civilization. The widespread belief that energy and civilization are inextricably linked certainly has historical foundation. Throughout history, humans have focused on controlling the energy stores and flows that are part of nature. For tens of thousands of years, people relied solely on the chemical (caloric) energy gained from food that produced the mechanical (kinetic) energy of working muscles. But thanks to human intellect, people were able to unlock and overcome physical limits imposed on their own muscle power "by using tools and harnessing the energies outside their own bodies." The earliest "energy tools" were those used to hunt animals, harvest edible plants, catch fish and fowl, and process and transport foodstuffs. Most of the family structures, societal groupings, and political and economic institutions created over thousands of years focused primarily on the extraction, processing, exchange, and marketing of food, as well as of "fossil and organic energy sources (wood, peat, coal) ... used ... for heating, cooking, lighting, or for firing the kilns and furnaces used in smelting ores." The vast array of unique human cultures absorbed the quest for these basic energy resources into the widest range of human activities—rituals, festivals, taboos, myth, dance, games, religion, language, art, and warfare—all of which embody humanity's cultural values in their most fundamental forms. Quite simply, human existence has been dominated by the age-old necessity for energy. Age of Water Power Before the modern era, people relied for power on their own muscles, on the muscles of domesticated animals, such as horses and oxen, and on water and wind. People used these energy resources to create a variety of significant landscapes, from agricultural fields and grazing land to mining centers and commercial woodlots, and they built the towns and cities and transportation networks of ancient civilizations. The technologies that relied on these energy resources are familiar to us all: axes, picks, plows, harnesses, wagons and carriages, waterwheels, windmills, and sailing ships. Europe, which possessed many areas of water-power potential, particularly benefited from harnessing the energy produced by moving water. The vertical waterwheel, invented perhaps two centuries before the time of Christ, spread across Europe within a few hundred years. By the end of the Roman era, waterwheels powered mills to crush grain, full cloth, tan leather, smelt and shape iron, saw wood, and carry out a variety of other early industrial processes. Productivity increased, dependence on human and animal muscle power gradually declined, and locations with good water-power resources became centers of economic and industrial activity. The historian Terry Reynolds observes: "Water power grew to be a central element in Western technology."6 During the Middle Ages, hydraulic engineers mounted mills on boats and bridges, and from these evolved hydropower dams to store and develop water pressure and to divert water into power canals and thence onto wheels. By the fifteenth century, large milling complexes in France signaled the reality of industrial dependence on water power. The development of the camshaft and crankshaft allowed water power to be applied to tasks that required a reciprocating motion (e.g., operating trip hammers and blast furnace bellows), which revolutionized the iron industry. The number of watermills in Europe increased steadily. Larger and larger water-powered industrial complexes emerged, culminating in large water-powered cotton mills operated during the 1770s by William Strutt and Richard Arkwright in England. Meanwhile, the harnessing of wind power to propel sailing ships across wide ocean expanses opened up the Americas to Europe. Colonists brought with them water-powered mills, which appeared from Latin America to Canada. By 1800, citizens of the newly established United States were importing English style textile factories, and within two decades expansive water-powered industrial cities emerged in Lowell, Massachusetts and other New England locations. By the time of the Industrial Revolution, Euro-American industry depended for energy almost entirely on water power. Age of Steam The modern era began with the eighteenth century introduction of steam power to English coal mines by Thomas Savery and Thomas Newcomen. Their steam engines and those of James Watt supplanted less geographically flexible water-powered mine pumps. Synergistic relationships between coal mining, the iron industry, and steam power led to advances in steam technology, and by 1800 steam engines joined waterwheels in powering English textile mills. Entrepreneurs found that steam power overcame water power's geographic inflexibility, the limitation that any one stream could only support so many mills, and waterwheel stoppages and slow downs caused by drought, flooding, and ice. Although water power continued to be the dominant energy resource for manufacturing through much of the nineteenth century, particularly in France and the United States, steam power ultimately proved more flexible and economically efficient. During the nineteenth century, steam engines improved enormously. American businessmen imported steam power from England, and by the 1840s it began competing successfully with water-powered manufactures. Philadelphia inventor Oliver Evans, famously known for automating water-powered flour milling, patented one of the first successful high-pressure steam engines. His engine and others modeled on it soon drove the riverboats and railroads that characterized America's nineteenth century transportation revolution. In Philadelphia in 1876, an enormous iconic Corliss steam engine towered over the main exhibition hall and powered the hundreds of machines on display at the Centennial Exhibition.7 The steam engine permanently established the link between fossil energy resources and industrialization.8 England and European countries turned to coal for steam fuel before 1800, and by the mid-nineteenth century Appalachian coal succeeded wood as steam fuel in the eastern United States. On the Pacific Coast, manufacturers and transporters continued to use wood, but they preferred coal and imported it at great cost from as far away as Australia. The scarcity and high cost of good coal on the Pacific Coast combined with discoveries of petroleum in southern California resulted in the development of oil as steam fuel, which unseated coal as steam fuel during the first half of the twentieth century.9 The Electrical Age Among the technological challenges in using inanimate energy resources is the transmission of power. Toward the end of the eighteenth century, fascination with the phenomenon of electricity captured many people.10 The production of electricity with primary batteries and eventually with electromagnetic induction, the transmission of electricity through copper wires, and the development of electric motors ultimately revolutionized the transmission of power. By the end of the nineteenth century, restrictive and inflexible direct connection of manufacturing machines to waterwheels, windmills, and steam engines by gears, drive shafts, and belts gave way to electrically powered machinery getting its power through wires strung from far away hydroelectric and steam-turbine power plants. The shape and character of factories changed dramatically during the twentieth century, as machines powered by electric motors could be sited almost anywhere.11 Additionally, electric power supplanted horse-drawn and steam-powered street railways with the electric "trolley," it replaced gas for outdoor lighting, and it replaced kerosene lights and wood and coal stoves and heaters in homes.12 Thomas Edison was especially important in the development of electricity. As noted in these Franklin Institute case studies, "Edison's innovative approach to invention propelled the development of the electric light plus the generation and distribution system to make it work." In the 1880s, his incandescent lamp made possible widespread, reliable, commercial indoor lighting, and his Pearl Street central station generating system in Manhattan became the archetype for electric power generation and distribution. Equally significant, Edison mentored a number of other important contributors to electric power technology, among them Frank Sprague, who constructed the first commercially successful electric street railway system in Richmond, Virginia in 1887, and Nicola Tesla, who developed alternating current (AC) power generation. Edison's direct current (DC) power system became the initial standard for distributed electricity, powering electric railways and manufacturing motors as well as lighting. Unfortunately, it could not be easily transmitted over long distances, which Tesla's AC power system achieved. Implemented by Edison's competitor in electric power, the Westinghouse Company, AC power superseded DC power and made possible the development of large electrical generating plants sited long distances from customers. Although Westinghouse's harnessing of hydropower at Niagara Falls with Tesla's polyphase system is perhaps better remembered, developments in AC power transmission from distant Sierra Nevada power sites in California to the coastal cities of San Francisco and Los Angeles established the standard in long-distance polyphase electric-power transmission.13 By the early twentieth century, electricity had become the favored method for transmitting energy, but applying it for human uses depended on many scientists and technicians working together. Perhaps Edison's most important invention was the industrial research laboratory, and by the beginning of the twentieth century, the General Electric Research Laboratory had emerged as a model for advancing science and technology. There, researchers steadily improved the ways in which humankind could apply electricity, and among them William Coolidge stood out. His development of the tungsten filament for Edison's incandescent lamp and later the X-ray tube earned him a most respected place in the ranks of twentieth century scientists and engineers. The Nuclear Age As electricity use became ubiquitous during the twentieth century, the exploitation of energy resources increased enormously. Hydroelectricity continued to play an important role in the modern energy matrix, but accessible water power sites were soon tapped. Engineers steadily improved steam-turbine technology so that more electricity could be generated by smaller quantities of fuel. As the size and efficiency of power plants increased, the cost of electric power dropped dramatically, which stimulated even more consumption of electricity. Fossil fuels—first coal, then oil—became the essential energy resources for electric-power generation. Unfortunately, during the 1960s, increased efficiencies in electric-power generation leveled off, the cost of electricity began to climb. Moreover, a growing environmental movement attributed acid raid and other negative environmental impacts to the heavy use of fossil fuels. A search for an alternative to fossil-fuel electric-power generation led many people to the atom. Well back into the nineteenth century, research in physics had led to the discovery of nuclear radiation. Most prominent in this discovery was Marie Curie, whose work "on the spontaneous radiation emitted by uranium compounds" set the stage for subsequent discoveries on atomic structure and the intrinsic power of the atom. The early decades of the twentieth century brought sustained scientific research in atomic physics, particularly in Europe. Italian physicist Enrico Fermi at the University of Rome was prominent among scientists working in this exciting field, and during the 1930s he focused on producing artificial radiation by bombarding uranium atoms with neutrons. As the European world became more and more unstable with the rise of Nazi Germany, its alliance with Italian fascists, and increasing anti-Semitism, Fermi and other nuclear physicists began leaving their universities and research laboratories for North America. Fermi's particular circumstance was quite remarkable, for he was awarded the Nobel Prize in 1938 and received permission from Italy's fascist government to go to Stockholm to receive the award. Instead of returning to Italy, however, he and his Jewish wife and children traveled to the United States, where Fermi took a professorship at Columbia University in New York City. As the world went to war in the 1940s, Fermi and other physicists in Europe and America came to understand that a uranium atom split by a neutron would cause a self-perpetuating chain reaction of atom splitting that would release enormous energy. This process, called nuclear fission, suggested possible military applications, and Fermi and his colleagues at Columbia University joined with Albert Einstein to persuade the U.S. Government to study the idea. Meanwhile, at Columbia, Fermi sought to develop a controlled nuclear fission chain reaction. In 1942, when President Franklin Roosevelt authorized the "Manhattan Project," Fermi's work was relocated to the University of Chicago, where in December of that year, he and his team achieved the first controlled nuclear chain reaction. The work of Fermi and other nuclear physicists led directly to development of the atomic bomb, which the United States twice used against Japan in 1945. In the wake of World War II, the United States created an Atomic Energy Commission (AEC) to oversee nuclear weapons development as well as to bring nuclear power to peaceful applications. During the 1950s, the AEC worked with public utilities such as Pacific Gas and Electric Company in California to develop electric power generation using nuclear fission. Nuclear energy soon emerged as one of the most touted solutions to the electrical world's energy problem. Industrialized nations everywhere constructed plants to meet ever-multiplying demands for electric power, but nuclear power was not without its drawbacks. But by the end of the 1970s, seismic safety became a substantial enough issue for Californians that a moratorium was placed on building new nuclear power plants and the 1979 Three Mile Island nuclear plant accident in Pennsylvania galvanized nuclear power opponents. These incidents combined with the unresolved solution to the disposal of radioactive nuclear waste and extended construction times to effectively end new nuclear power plant construction in the United States. In 1986 the meltdown at the Chernobyl nuclear power plant in the Ukraine and subsequent widespread radiation poisoning, put Italy, Germany, and other countries on the path toward ending reliance on nuclear power. While nuclear energy has not gone away and is still seen by many people as one of the best solutions to human energy needs, other energy resources such as solar, wind, and biomass also offer promise. No matter where people find the energy to support their cultures and societies, it is plain that human life has been dominated by the age-old necessity for energy. The Energy Case Studies presented here celebrate the unique ingenuity underscoring humankind's scientific and technological quest to harness inanimate energy to its use. Imagine, if you can, just what the next steps in our energy history will be.