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Oct. 17 marks the 40th anniversary of the start of the 1973 Arab Oil Embargo - an event that arguably launched the U.S.' ongoing pursuit of a national energy policy.

The embargo was a response by the Arab oil exporting nations to the U.S.' support of Israel during the Yom Kippur War. The resulting oil price increases and reductions in supply prompted then-President Richard Nixon to launch an effort he termed "Project Independence," which outlined a series of government initiatives to reduce energy use, increase domestic energy supplies and diversify the nation's energy mix. That, in turn, laid the foundation for a still-ongoing debate among policymakers, businesses and advocates on what the shape of the nation's energy policy should be.

Forty years ago, the U.S. economy was dominated by fossil fuels, accounting for 93% of the nation's energy consumption. Petroleum - more than 30% of which was imported - accounted for almost half of fossil fuel consumption, with roughly half used in the transportation sector and 17% burned to generate electricity.

In 1973, conventional hydropower generated almost 15% of the nation's electricity and provided 3.8% of its total energy consumption. Biomass claimed a 2% share of the nation's energy use but, like geothermal, provided less than 1/10th of a percent of the country's electrical generation. Energy produced by solar, wind and biofuels was essentially non-existent.

The 42 nuclear reactors operating in 1973 provided 4.5% of U.S. electrical generation and satisfied just over 1% of the nation's total energy demand.

Four decades later, U.S. energy use in some areas appears to have changed only modestly. Fossil fuels, for example, still dominate and, in 2013, will account for roughly 82% of total energy consumption.

However, other energy technologies have experienced significant growth.

Nuclear power has increased nine-fold and now provides over 19% of U.S. electrical generation - roughly 8.2% of total U.S. energy use.

The mix of renewable energy technologies (biofuels, biomass, geothermal, hydropower, solar, wind) now accounts for 10% of energy consumption, 12% of domestic energy production and 14% of net electrical generation.

Perhaps most significantly, major gains in energy efficiency mean that the energy intensity of the American economy today - measured as energy use per unit of GDP - is less than half of what it was 40 years ago.


Over the past four decades, U.S. energy use has increased by 28% from 75.6 quads in 1973 to about 97 quads in 2013. However, during that same period, the nation's population has grown by 50% (from ~210 million in 1973 to ~315 million in 2013) and the nation's GDP (constant prices) grew from less than $6 trillion in 1973 to about $16 trillion in 2013.

Thus, energy intensity, measured as energy used (thousand Btu)/real dollar of GDP (2009 chained dollar), dropped by more than half from 13.97 in 1973 to 6.15 in 2012 due to a combination of energy efficiency legislation, agency regulations, price signals, technological advances and changes in consuming habits.

Had energy growth continued at the rates experienced after World War II until 1973, energy use in the U.S. today would be at least 40% higher than it actually is, making energy efficiency, in effect, the nation's largest "energy resource."

Yet, study-after-study suggests that the U.S. has still not picked all of the low-hanging fruit, much less implemented the more complex structural changes that could secure far greater gains in energy efficiency. Some analysts argue that energy intensity of the U.S. economy could be further reduced in the near term by 30% or more using cost-effective, currently available technologies.

For example, a complete shift in the lighting market to compact fluorescents and LEDs could theoretically cut energy use in that sector by 75% or more. New buildings can be economically constructed that use 30% less energy (some would argue 50% or more) while existing buildings can often be upgraded to achieve gains almost as large.

Far greater use of cogeneration and waste heat recovery, as well as smart grid and new transmission line technologies, could greatly reduce energy losses in electrical generation, which typically wastes nearly two-thirds of the fuel consumed.   


In 1973, renewable energy sources (biofuels, biomass, geothermal, hydropower, solar, wind) accounted for 6.9% of domestic energy production comprising hydropower (65%) and biomass (35%) with a trace contribution from geothermal. There was essentially no contribution from biofuels, solar or wind. In the electricity sector, hydropower accounted for 99.2% of all power generated by renewable sources.

By 2013, renewables accounted for almost 12% of domestic energy production with a mix of hydropower (29.7%), biomass (25.4%), biofuels (20.0%), wind (19.3%), solar (3.2%) and geothermal (2.4%). By mid-2013, renewables accounted for 14.2% of U.S. net electrical generation, with almost half coming from non-hydro renewables.

Renewables have now emerged as a major contributor to the nation's overall energy supply. However, it can be argued they are still well short of their real potential. For example, in 1980, a lengthy, inter-agency analysis conducted by the Carter Administration concluded that renewables could meet 20% of the nation's energy needs by the year 2000 (and some members of the task force argued a goal of 25% was doable). Yet, 33 years later, renewables have only reached the halfway point of the 2000 goal.

Recent growth rates and price drops do suggest, though, that the use of renewables could greatly accelerate in the near-term. Between 2003 and 2012, for example, energy produced from wind increased by a factor of 12, biofuels output grew more than five-fold and solar generation quadrupled. Geothermal also expanded by more than 30%. Only hydropower and biomass (other than biofuels) remained essentially unchanged.

Solar photovoltaic (PV) cell costs today are 1% of what they were in 1973. Wind energy costs have declined by as much as 50% in just the past four years. Combined with recent developments in a number of energy storage technologies, wind and solar are now either at, or close to, "grid parity" with fossil fuels - and, in some instances, actually cheaper. Moreover, the first significant amounts of cellulosic biofuels have been produced in just the past two years with production levels expected to ramp up significantly in the near term.


In 1973, the U.S. had 42 operating nuclear reactors that generated 4.5% of the nation's electricity. In response to the oil embargo, then-President Nixon called for the construction of 1,000 nuclear reactors. The resulting expansion in the 1970s came to a screeching halt with the 1979 Three Mile Island nuclear accident and subsequently resumed at a far-slower pace. By 2010, nuclear power had peaked when 104 reactors provided 11.3% of domestic energy production and 19.6% of the nation's electricity.

Nuclear generation has dropped each year since then and is likely to see further decline - at least for the next several years - in light of the recently announced closures of five reactors (Crystal River, Kewaunee, San Onofre-2, San Onofre-3 and Vermont Yankee). While five new reactors are now under construction, their eventual contribution to the nation's electricity supply (assuming they are completed) may well be offset by retirements of other older reactors.


The total amount of oil used in 1973 (34.8 quads) has changed little over the past four decades (34.7 quads used in 2012), but its share of the nation's energy mix has declined from 46% to 36%. Notably, oil use for electrical generation has changed from 17% in 1973 to less than 1% in 2013. Roughly half the oil used in 1973 was for transportation; it is over 70% today.

Net oil imports (imports minus exports) rose from roughly 30% in 1973 to a high of over 60% in 2005 and have since been declining; the U.S. relied on net imports for about 40% of the petroleum (crude oil and petroleum products) that was consumed in 2012. Contributors to this decline include increased domestic oil production, more biofuels and improvements in motor vehicle fuel economy.


Domestic consumption of natural gas has increased by 26% over the past four decades but remained at about 29% of the total energy mix. Its use in the electricity-generating sector has tripled since 1973, and its share of net electrical generation has increased from 18.3% in 1973 to 26.2% in 2013. (By comparison, electrical generation more than doubled between 1973 and 2013.)


Domestic production of coal has increased by over 40% over the past four decades (13.99 quads in 1973 to 19.79 quads in 2013), but its share of the nation's overall energy consumption has remained relatively unchanged (17.1% in 1973 vs. 17.6% in 2012). Further, its role in electrical generation has dipped in recent years from about 45% in 1973 to about 39% in 2013, reflecting increased competition from both natural gas and renewables.


Carbon dioxide (CO2) emissions from energy consumption today are about 15% higher than they were in 1973. The 2013 figure actually represents a drop of 11% from the peak level recorded in 2007 with the decline attributable to the economic recession, some displacement of coal by natural gas, increased use of renewables, and improving energy efficiency.

The recent downward trend, however, is almost certainly not large enough or fast enough to counter global increases in CO2 emissions or to substantially reduce the risks posed by climate change.

Coal accounted for about 25% of CO2 emissions from energy consumption in 1973, but its share had risen to almost 30% by 2012 with actual CO2 emissions from coal rising 37.3% over the past four decades. By comparison, petroleum was responsible for ~40% of CO2 emissions in 2012, natural gas for ~24% and biofuels/biomass for ~5%.

Ken Bossong is executive director of the SUN DAY Campaign, a non-profit research and educational organization founded in 1993 to promote sustainable energy technologies.

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