Petroleum use
Shrinking Net Energy from Fossil Fuels
| "The key to understanding energy issues is to look at the 'energy price' of energy. Energy resources that consume more energy than they produce are worthless as sources of energy. This thermodynamic law applies no matter how high the 'money price' of energy goes. For example, if it takes more energy to search for and mine a barrel of oil than the energy recovered, then it makes no energy sense look for that barrel—no matter how high the money price of oil goes." --Jay Hanson, 1998, Titanic Sinks |
(Note: The following material, slightly revised and updated, is drawn from "Energy, Environment and Social Change," by Thomas Detwyler, 1979, pp. 42-76 in Current Issues V: The Yearbook of Environmental Education and Environmental Studies, ed. by Arthur B. Sacks and C.B. Davis, publ. by ERIC, Columbus, Ohio.)
In the past, energy-intensive practices generally were successful in solving at least temporarily the problems to which they were applied. But yesterday's solution has become today's problem. Without cheap, safe, and abundant energy, most of the proposed technological solutions to the problems of growth evaporate.
Resource scarcity, together with factors inherent in corporate capitalism, will increase energy prices; and increased environmental stress, associated with high energy use, has reduced both environmental tolerance and the amount of work that Nature does for "free" (Odum and Odum, 1976). An example of the latter is the reduction (by the early 1970s) of forest productivity in New England by 10 percent, because of acid rain resulting from combustion of vast amounts of sulfurous fuels upwind from the region (Woodwell, 1974). Thus, energy-intensive "solutions" become more costly both economically and environmentally.
Now, early in 2001, crude oil prices range between about $26 and $35 per barrel. Prices have tripled in less than two years. (Record-low oil prices in 1998-99 were a temporary aberration, due primarily to an economic slump in Asia, which reduced petroleum consumption there, and hence world demand).
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From: The Sunday Times (London), 10 Sept. 2000 |
The temporary low prices stimulated Americans to buy gas-guzzlers such as SUVs, which now must be fed higher-cost gasoline.
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| Sports utility madness |
The use of high energy subsidies to "solve" our many problems has had its day. Tomorrow it becomes even less tenable. Finite is finite. Because of the net energy concept at work, our stock of nonrenewable energy is even less than commonly supposed.
Shrinking net energy-- The useful energy to be obtained from nonrenewable resources, such as fossil fuels (mainly crude oil, coal and natural gas) and uranium, is subject to diminishing returns through time. It takes energy to get energy. And because we exploit the easiest-to-get energy resources first, each subsequent unit of gross energy (e.g., oil in the ground) requires greater energy subsidy to obtain than did the previous unit, thus leaving less net energy:
| gross energy | - | energy subsidy | = | net energy |
in situ energy contained in resource |
energy expended for exploration, extraction, processing, transportation, make-up from environmental losses, etc. |
energy in useful form and place |
Historical growth of energy subsidies--The tremendous growth of energy subsidy (per unit of either gross or net energy) is suggested by the historical trend in the average depth of oil wells in the United States: 300 feet in 1870, 1,000 feet in 1900, 3,000 feet in the 1920s and more than 6,000 feet by 1980. The cost of drilling oil and gas wells (which is largely a function of energy subsidy) rises exponentially with increasing depth (Cook, 1976, p. 121). By the mid-1970s, about half the petroleum produced in Texas was also consumed there as production-related subsidies, so that at best net energy was only half of gross energy (Ophuls, 1977, p. 114).
The dynamic of shrinking net energy means that the usefulness of gross energy reserves may be vastly overrated. In fact, a large portion of any given gross reserve will be energetically unexploitable, though perhaps technically extractable. The following diagram illustrates this consequence. Beyond the resource cutoff line, the system is an energy sink requiring more energy as subsidy than is returned as net energy.
Net Energy Delivery from a Finite Energy Resource. The difference between the gross energy delivery rate and the net energy delivery rate is the energy subsidy that is expended to develop the resource.
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| Paradise cheap! |
Optional online reading
"The Peak of World Oil Production and the Road to the Olduvai Gorge," Richard C. Duncan, Pardee Keynote Symposia, Geological Society of America, Summit 2000, Reno, Nevada, November 13, 2000-- "World energy production per capita from 1945 to 1973 grew at a breakneck speed of 3.45 %/year. Next from 1973 to the all-time peak in 1979, it slowed to a sluggish 0.64 %/year. Then suddenly�and for the first time in history� energy production per capita took a long-term decline of 0.33 %/year from 1979 to 1999. The Olduvai theory explains the 1979 peak and the subsequent decline. More to the point, it says that energy production per capita will fall to its 1930 value by 2030, thus giving Industrial Civilization a lifetime of less than or equal to 100 years."
Thomas Detwyler maintains this page (tdetwyle@uwsp.edu)
Last updated 3 January 2001
� Copyright 2000-2001 by Thomas Detwyler