History of Energy in the United States: 1635-2000
	The U.S. Energy Outlook as of 2001
	Future patterns of energy production, use, and consequences in the United States are, of course, purely speculative. But educated guesses can be made by means of sophisticated computer models, such as the U.S. Energy Information Administration's National Energy Modeling System (NEMS). At this writing, EIA's current projections are published in its Annual Energy Outlook 2001 (AEO2001) and extend through 2020. Although emphatically not to be taken as predictions--no model pretends to be able to foresee critical but unexpected events, such as the 1973 oil embargo--EIA's projections can sketch a plausible general picture of future developments.
	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: greater consumption, production, and imports, and higher emissions. Real energy prices are expected either to increase slowly (petroleum and natural gas) or to decline (coal and electricity). These circumstances will encourage greater consumption (Figure 33), and AEO2001 projects U.S. total consumption to reach 127 quadrillion Btu in 2020, 29 percent higher than in 2000. Consumption rises in all sectors, but growth is especially strong in transportation because of more travel and greater freight requirements.
	Figure 33. Energy Consumption History and Outlook, 1949-2020
	Despite gains in energy efficiency, higher demand for energy services is expected to raise per-capita energy use slightly over the forecast period. Energy intensity, expressed as energy use per dollar of gross domestic product, has declined since 1970 and is expected to continue falling.
	More energy consumption, of course, means more energy production--somewhere. Because the output of aging U.S. oil fields will continue to drop, rising demand for petroleum will have to be met by imports. The share of U.S. petroleum consumption met by net imports is projected to rise from 52 percent in 2000 to 64 percent in 2020. Domestic natural gas production increases 2.1 percent per year on average, but demand rises enough to require a significant boost in natural gas imports. Output from the Nation's vast coalfields likewise increases to meet rising domestic demand. Growth in production of energy from renewable sources is expected to average about 1.1 percent per year, while output from nuclear power facilities declines at the same rate.
	Unless measures to reduce emissions of carbon dioxide are adopted, greater use of fossil fuels, slow market penetration by renewable energy sources, and less use of nuclear power will inevitably lead to higher emissions. AEO2001 projects U.S. energy-related carbon dioxide emissions to exceed 2 billion metric tons of carbon (7.5 billion tons of gas) in 2020, 33 percent more than in 2000.
	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 likely to belong 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--humankind's sources of energy thus will have come full circle.