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Sustainable Society:  A society that balances the environment, other life forms, and human interactions over an indefinite time period.

Introduction
    Figure 1. Energy Consumption by Source, 1635-2000
Total Energy
    Figure 2. Energy Production by Source for 2000
    Figure 3. Energy Overview
    Figure 4. Energy Overview, 2000
    Figure 5. Petroleum Imports, 1960-2000
    Figure 6. Energy Consumption by End Use
    Figure 7. Residential and Commercial Energy Consumption
    Figure 8. Industrial Energy Consumption
    Figure 9. Transportation Energy Consumption
    Figure 10. Motor Vehicle Indicators

 

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 millennia, 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 limitations 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 (Figure 1). 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 1885, only itself 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. The curves depicting their consumption remain shallow for several decades following the success of Edwin Drake's drilling rig in 1859, but begin to rise more steeply in the 1920s. Then, interrupted only by the Depression, the curves climb at increasingly alpine angles until 1973. Annual consumption of petroleum and natural gas exceeded that of coal in 1947 and then quadrupled in a single generation. Neither before nor since has any source of energy become so dominant so quickly.

As for the social, economic, and ecological consequences of evolving energy sources, they are too deep and numerous to do more than give suggestive examples. One of the most significant is the shift between muscle- and machine power. Horses, mules, and other draft animals were invaluable prime movers well into the first half of the 20th century, and despite increasing reliance on fossil fuels and the engines they powered, the number of draft animals in the United States continued to rise until about 1920. As late as 1870, draft animals accounted for more than half of the total horsepower of all prime movers. Their displacement by fossil-fuel engines meant, eventually, the disappearance from city and farm alike of millions of animals, along with the vast stables that housed the city-based animals, the mountains of dung they left on city streets, and many of the English sparrows that fed on the grain therein.

As fossil fuels and the machines that ran on them proliferated, the nature of work itself was transformed along with the fundamental social, political, and geopolitical circumstances of the Nation. In the middle of the 19th century, most Americans lived in the countryside and worked on farms. The country ran mainly on wood fuel and was relatively unimportant in global affairs. A hundred years later, after the Nation had become the world's largest producer and consumer of fossil fuels, most Americans were city-dwellers and only a relative handful were agricultural workers. The United States had roughly tripled its per-capita consumption of energy and become a global superpower.

Although coal, oil, and natural gas are the world's most important energy sources, their dominance does not extend to all corners of the globe. In most places and times diversity and evolution in energy supplies has been the rule. In many areas muscle power and biomass energy remain indispensable or even primary. The shifting emphasis over time is clear not only in the long sweep of history but also in the short term, especially in the industrialized world. Electricity, for example, was essentially unavailable until the 1880s; now it is ubiquitous. And in the span of a few decades nuclear electric power in the United States was born, peaked, and began to decline in its contribution to total energy production. 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 chance, the play of economic forces, and human ingenuity. Whatever energy future awaits us, that part of the story seems unlikely to change.

The United States has always been a resource-rich nation, but in 1776, the year the Nation declared its independence from Great Britain, nearly all energy was still supplied by muscle power and fuelwood. America's vast deposits of coal and petroleum lay untapped and mostly undiscovered, although small amounts of coal were used to make coke, vital for casting the cannon that helped win the war. Mills made use of waterpower, and of course the wind enabled transport by ship. Fuelwood use continued to expand in parallel with the Nation's economic growth, but chronic shortages of energy in general encouraged the search for other sources.

During the first 30 years or so of the 19th century, coal began to be used in blast furnaces and in making coal-gas for illumination. Natural gas also found limited application in lighting during the period. Even electricity sought a niche; for example, experiments were conducted with battery-powered electric trains in the 1840s and 1850s. Still, muscle power remained an important source of energy for decades. Although a number of mechanical innovations appeared, including the cotton gin and the mechanical reaper, they had the effect of multiplying the productivity of human and animal muscle power rather than spurring the development of machine power. It was not until well after mid-century that the total work output from all types of engines exceeded that of work animals. The westward expansion helped change that. As railroads drove west to the plains and the mountains, they left behind the fuelwood so abundant along the eastern seaboard.

Coal became more attractive, both because deposits were often found near the new railroad rights of way and because its higher energy content increased the range and load of steam trains. Demand for coal also rose because the railroads were laying thousands of miles of new track and the metals industry needed an economical source of coke to make iron and steel for the rails and spikes. The transportation and industrial sectors in general began to grow rapidly during the latter half of the century, and coal helped fuel their growth.

Petroleum got its start as an illuminant and ingredient in patent medicines and did not catch on as a fuel for some time. At the end of World War I, coal still accounted for about 75 percent of U.S. total energy use. About the same time, the horse and mule population reached 26 million and then went into permanent decline. The beginning of the transition from muscle power was over. America's appetite for energy as it industrialized was prodigious, roughly quadrupling between 1880 and 1918. Coal fed much of this growth, while electricity expanded in applications and total use alike. Petroleum got major boosts with the discovery of Texas's vast Spindletop Oil Field in 1901 and with the advent of mass-produced automobiles, several million of which had been built by 1918.

In the years after World War II, "Old King Coal" relinquished its place as the premier fuel in the United States. The railroads lost business to trucks that ran on gasoline and diesel fuel, and also began switching to diesel locomotives themselves. Labor troubles and safety standards drove up coal production costs. The declining demand for natural gas as an illuminant forced that industry to look for other markets, and because heating applications had obvious potential, natural gas replaced coal in many household ranges and furnaces. The coal industry survived, however, mainly because nationwide electrification created new demand for coal among electric utilities despite regional competition from hydroelectric and petroleum-fired generation. Most energy produced today in the United States, as in the rest of the industrialized world, comes from fossil fuels —coal, natural gas, crude oil, and natural gas plant liquids (Figure 2). Although U.S. energy production takes many forms, fossil fuels together far exceed all other sources of energy. In 2000 they accounted for 80 percent of total energy production and were valued at an estimated $148 billion (nominal dollars).

For much of its history, the United States was mostly self-sufficient in energy, although small amounts of coal were imported from Britain in colonial times. Through the late 1950s, production and consumption of energy were nearly in balance. Over the following decade, however, consumption slightly outpaced domestic production and by the early 1970s a more significant gap had developed (Figure 3).

In 2000 the United States produced just under 72 quadrillion British thermal units (Btu) of energy and exported roughly 4 quadrillion Btu. Consumption totaled about 98 quadrillion Btu, requiring imports of almost 29 quadrillion Btu (Figure 4), 19 times the 1949 level.

This appetite for imported energy is driven by petroleum consumption. U.S. petroleum imports in 1973 totaled 6.3 million barrels per day (3.2 million barrels per day of crude oil and 3.0 million barrels per day of petroleum products). In October 1973, however, the Arab members of the Organization of Petroleum Exporting Countries (OPEC) embargoed the sale of oil to the United States, prices rose sharply, and petroleum imports fell for two years (Figure 5). They increased again until the price of crude oil rose dramatically (roughly 1979 through 1981) and suppressed imports. The rising-import trend resumed by 1986 and, except for slight dips in 1990, 1991, and 1995, has continued ever since. In 2000 U.S. petroleum imports reached an annual record level of 11 million barrels per day.

The efficiency with which Americans use energy has improved over the years. One such measure is the amount of energy consumed to produce a (constant) dollar's worth of gross domestic product (GDP). By that yardstick, efficiency improved 49 percent between 1949 and 2000, as the amount of energy required to generate a dollar of output (chained 1996 dollars) fell from 20.6 thousand Btu to 10.6 thousand Btu.

Nevertheless, a growing population and economy drove total energy use up. As the U.S. population expanded from 149 million people in 1949 to 281 million in 2000 (an increase of 89 percent), total energy consumption grew from 32 quadrillion Btu to 98 quadrillion Btu (up 208 percent). Per-capita energy consumption rose 63 percent, from 215 million Btu in 1949 to 350 million Btu in 2000. Energy plays a central role in the operation of the industrialized U.S. economy, and energy spending is commensurately large. In recent years, American consumers have spent over half a trillion dollars a year on energy. That energy is consumed in four broad sectors: residential, commercial, industrial, and transportation. Industry is historically the largest consuming sector of the economy. In contrast to the relatively smooth trends in the other sectors, industrial energy use has fluctuated sharply (Figure 6).

Sectoral energy sources have changed dramatically over time. In the residential and commercial sectors, for example, coal was the leading source as late as 1951 but then disappeared rapidly (Figure 7). Petroleum usage grew slowly to its peak in 1972 and then subsided. Natural gas became an important resource, growing strongly until 1972, when its growth essentially stalled. Electricity, only an incidental source in 1949, expanded in almost every year since then, as did the energy losses associated with producing and distributing the electricity. (See "Electricity" section below for an explanation of these losses.)

The expansion of electricity use reflects the increased electrification of U.S. households, which typically rely on a wide variety of electrical appliances and systems. In 1997, 99 percent of U.S. households had a color television and 47 percent had central air conditioning. Eighty-five percent of all households had one refrigerator; the remaining 15 percent had two or more. New products continued to penetrate the market; for example, in 1978 only 8 percent of U.S. households had a microwave oven, but by 1997 microwaves could be found in 83 percent.

The Energy Information Administration (EIA) first collected household survey data on personal computers in 1990, when 16 percent of households owned one or more. By 1997 that share had more than doubled to 35 percent. U.S. home heating also underwent a big change. Over a third of all U.S. housing units were warmed by coal in 1950, but by 1999 that share was only 0.2 percent. Distillate fuel oil lost more than half its share of the home-heating market during the same period, falling from 22 percent to 10 percent. Natural gas and electricity gained as home-heating sources: the share of natural gas rose from about a quarter of all homes to over half, while electricity's share shot up from only 0.6 percent in 1950 to 30 percent in 1999. In recent times, electricity and natural gas have been the most common sources of energy used by commercial buildings as well. In the industrial sector, the consumption of both natural gas and petroleum rose steadily and in tandem until the oil embargo in 1973, after which their use fluctuated (Figure 8). Consumption of coal, once the leading source in the sector, shrank. Electricity and its associated losses grew steadily.

About three-fifths of the energy consumed in the industrial sector is used for manufacturing. The remainder goes to mining, construction, agriculture, fisheries, and forestry. Within manufacturing, large consumers of energy are the petroleum and coal products, chemicals and allied products, paper and allied products, and primary metal industries. Natural gas is the most commonly consumed energy source in manufacturing. The predominant end-use activity is process heating, followed by machine drive and then facility heating, ventilation, and air conditioning combined. About 7 percent of all energy consumed in the United States is used for nonfuel purposes, such as asphalt and road oil for roofing products and road building and conditioning; liquefied petroleum gases for feedstocks at petrochemical plants; waxes for packaging, cosmetics, pharmaceuticals, inks, and adhesives; and still gas for chemical and rubber manufacture. While variety and change in energy sources are the hallmarks of the industrial, residential, and commercial sectors, transportation has relied almost totally on petroleum since 1949 (Figure 9).

Compared with trends just prior to the oil embargo of 1973, fuel consumption per motor vehicle fell in the two decades that followed, miles traveled per vehicle generally fell until the early 1980s and then resumed a pattern of increase, and the fuel rate (i.e., miles per gallon) improved greatly before essentially leveling off in the 1990s (Figure 10).

_____
* Annual Energy Review 2003
Energy Information Administration
Report No. DOE/EIA-0384(2003), September 7, 2004
See original at  < http://www.eia.doe.gov/emeu/aer/eh/frame.html > and
at < http://www.eia.doe.gov/emeu/aer/eh/frame.html >.

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