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Oswego Career Ladders - Introduction to the Energy Field

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Introduction to the Energy Field

(from the US Department of Energy Education Project)

Energy is essential to life. Living creatures draw on energy flowing through the environment and convert it to forms they can use. The most fundamental energy flow for living creatures is the energy of sunlight, and the most important conversion is the act of biological primary production in which plants and sea-dwelling phytoplankton convert sunlight into biomass by photosynthesis. The Earth's web of life, including human beings, rests on this foundation.

Over millenia, humans have found ways to extend and expand their energy harvest, first by harnessing draft animals and later by inventing machines to tap the power of wind and water. Industrialization, the watershed social and economic development of the modern world, was enabled by the widespread and intensive use of fossil fuels. This development freed human society from the limitation of natural energy flows by unlocking the Earth's vast stores of coal, oil, and natural gas. Tapping these ancient concentrated deposits of solar energy enormously multiplied the rate at which energy could be poured into the human economy.

The result was one of the most profound social transformations in history. The new river of energy wrought astonishing changes and did so with unprecedented speed. The energy transformations experienced by traditional societies--from human labor alone to animal muscle power and later windmills and watermills--were very slow and their consequences were equally slow to take effect. In contrast, industrialization and its associated socioeconomic changes took place in the space of a few generations.

The history of energy use in the United States reflects these general themes. Wood energy, for example, has been a significant part of the U.S. energy mix since colonial times. In fact, fuelwood was overwhelmingly the dominant energy source from the founding of the earliest colonies until late in the last century. But thereafter, the modern era is notable for the accelerated appearance of new sources of energy, in contrast to the imperceptible pace of change in earlier times. Coal ended the long dominance of fuelwood in the United States about 1852, only itseft to be surpassed in 1951 by petroleum and then by natural gas a few years later. Hydroelectric power and nuclear electric power appeared about 1890 and 1957, respectively. Solar photovoltaic, advanced solar thermal, and geothermal technologies represent further recent developments in energy sources. The most striking of these entrances, however, is that of petroleum and natural gas. Annual consumption of petroleum and naturanl gas exceeded that of coal in 1947 and then qualdrupled in a single generation. Neither before nor since has any souirce of energy become so dominant so quickly.

No doubt we have not seen the end of evolution in energy sources. The paragraphs that follow briefly discuss the major energy sources now in use in the United States, including a bit of history, trends, and snapshots of consumption and production patterns as of 2000. The story they tell is one of diversity and transformation, driven by change, the play of economic forces, and human ingenuity. Whatever energy future awaits us, that part of the story seems unlikely to change.

Until te 1950s the United States produced nearly all the petroleum it needed. But by the end of the decade the gap between production and consumption began to widen and imported petroleum became a major component of the U.S. petroleum supply. Beginning in 1994, the Nation imported more petroleum than it produced.

Natural gas
Natural gas is most likely a mixture of methane, ethane, and propane with methane making up 73 to 93 percent of the total. The United States had large natural-gas reserves and was essentially self-sufficient in natural gas until the late 1980, when consumption began to significantly outpace production. Imports rose to make up the difference, nearly all coming by pipeline from Canada, although small volumes were brought by tanker in liquefied form from Algeria and, in recent years, from a few other countries as well.

From 1885 through 1951, coal was the leading source of energy produced in the United States. Crude oil and natural gas then vied for that role until 1982. Coal regained the position of the top resource that year and again in 1984, and has retained it since. At 23 quadrillion Btu in 2000, coal accounted for nearly a third of all energy produced in the country.

Electricity generation accounted for nearly 92 percent of all coal consumed in the United States in 2000. Over the past several decades, coal production shifted from primarily underground mines to surface mines. In addition, the coal resources of Wyoming and other area west of the Mississippi River underwent tremendous development. Since 19502, the United States has produced more coal than it has consumed. The excess production allowed the United States to become a significant exporter of coal to other nations. In 2000, coal exports totaled 58 Million short tons, which accounted for 37 percent of all U.S. energy exports.

Of all the major forms of energy now in use, only nuclear power has truly modern roots. In 1951 an experimental reactor sponsored by the U.S. Atomic Energy Commission generated the first electricity from nuclear power. The British completed the first operable commercial reactor, at Calder Hall, in 1956. The U.S. Shippingport unit, a design based on power plants used in nuclear submarines, followed a year later. In cooperation with the U.S. electric utility industry, reactor manufacturers then built several demonstration plants and made commitments to build additional plants at fixed prices. This commitment helped launch commercial nuclear power in the United States.

The success of the demonstration plants and the growing awareness of U.S. dependency on imported crude oil led to a wave of enthusiasm or nuclear electric power that sent orders for reactor untis soaring between 1966 and 1974. The number of operable units increased in turn, as ordered units were constructed, tested, licensed for full power operation, and connected to the electricity grid. However, the curve of operable units lagged behind the curve of ordered units somewhat because of the long construction times required for the large, complex plants. The total number of U.S. operable reactor units peaked in 1990 at 112.

Orders for new units fell off sharply after 1974. Of the total of 259 units ordered to date, none was ordered after 1978. Although safety concerns, especially after the accident at Three Mile Island in 1979, reinforced a growing wariness of nuclear power, the chief reason for its declining momentum in the United States was economic. The promise of nuclear electric power had been that it would, in the now-famour phrase, make energy "too cheap to meter." In reality, nuclear power plants have always been costly to build and, for several reasons, became radically more costly between mid-1960s and the mid-1970s. The trends disillusioned many utilities and investors. Interest in further orders subsided and many ordered units were canceled before they were built. By the end of 2000, 124 units had been canceled, 48 percent of all ordered units.

Renewable Energy
For all but the most recent fraction of humanity's time on Earth, virtually all energy was renewable energy. Before the widespread use of fossil fuels and nuclear power, which arrived only a relative eyeblink ago, our ancestors warmed themselved directly in the sun, burned brush and fuelwood fashioned by photosynthesis from sunlight and nutrients, harnessed the power of wind and water created mainly by sun-driven atmospheric and hydrologic cycles, and of course used their own muscle power and that of animals.

Modern renewable sources in the United States contribute about as much to total energy consumpation as does nuclear power. Hydroelectric power generation, which uses dam-impounded water to drive turbine generators, generally accounts for a large share of U.S. renewable energy output. In 2000 (a relatively bad year for U.S. hyrdopower) that share was 46 percent of the total renewable energy consumption. The American hyrdropower infrastructure includes the great dams of the intermountain West, the Columbia basin, and the Tennessee River valley, as well as hundreds of other smaller installations nationwide.

Much of U.S. renewable energy comes from wood and waste, a diverse category that accounted for almost half of the total in 2000. It includes not ony the obvious candidates (such as wood, methanol, and ethanol) but also peat, wood liquors, wood sludge, railroad ties, pitch, municipal solid waste, agricultural waste, straw, tires, landfill gas, fish oil, and other things. Wood and wood byproducts are the most heavily used form of biomass and are an important source of energy for such industries as paper manufacturing and lumber, which have ready access to them. Georthermal, which began supplying a measurable amount of energy on 1960, accounted for 5 percent of U.S. renewable energy in 2000. Despite their cachet, solar energy (photovoltaic and thermal) and wind energy contribute reltively little to the renewable total. The peak year for U.S manufactures; shipments of salor thermal collectors was 1981, when 21 million square deek were shipped. DUring the 1990s, shipments averaged less than half that level through the 1999 total of 8.6 million square feel was the highest since 1990. Ninety-one percent of the 1999 total went to the residential sector, and 95 percent of the newly shipped collectors were used to heat swimming pools. Four percent were used to heat water. Inflation-adjusted prices for photovoltaic cells have generally declined in recent years and the volume of shipments (expressed as peak kilowatts) has risen steadily since 1985. Over 70 percent of U.S. production went for export in 1999. Wind energy production rose 113 percent between 1989 and 2000 but remains a small factor in the U.S. renewable energy picture.

Future of Energy
Future patterns of energy production, use, and consequences in the United State are, of course, purely speculative. But educated guesses can be made by means of sophisticated computer models such as the Energy Information Administration's National Energy Modeling System (NEMS). The projections in AEO2001, which assume known trends in technology and demographics and current laws, regulations, and policies, suggest that our near-term energy future will be one of more: more consumption, more production, more imports, and higher emissions.

What of our long-term energy future? That is even more speculative. Many would argue that the world is destined to move beyond fossil fuels eventually; if the threat of global climate change does not compel it, then exhausted supplies and rising prices might. The far future seems likly to beliong to renewable sources of energy. Although the form they take may be radically different than in the past--solar hydrogen and advanced photovoltaics, perhaps, rather than fuelwood and dung--humakind's sources of engery this will have come full circle.

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