# Hubbert peak theory

{{#invoke:Hatnote|hatnote}}Template:Main other

2004 U.S. government predictions for oil production other than in OPEC and the former Soviet Union

The Hubbert peak theory says that for any given geographical area, from an individual oil-producing region to the planet as a whole, the rate of petroleum production tends to follow a bell-shaped curve. It is one of the primary theories on peak oil.

Choosing a particular curve determines a point of maximum production based on discovery rates, production rates and cumulative production. Early in the curve (pre-peak), the production rate increases because of the discovery rate and the addition of infrastructure. Late in the curve (post-peak), production declines because of resource depletion.

The Hubbert peak theory is based on the observation that the amount of oil under the ground in any region is finite, therefore the rate of discovery which initially increases quickly must reach a maximum and decline. In the US, oil extraction followed the discovery curve after a time lag of 32 to 35 years.[1][2] The theory is named after American geophysicist M. King Hubbert, who created a method of modeling the production curve given an assumed ultimate recovery volume.

## Hubbert's peak

"Hubbert's peak" can refer to the peaking of production of a particular area, which has now been observed for many fields and regions.

### Reliability

#### Crude Oil

US oil production (Lower 48 states crude oil only) and Hubbert high estimate for the US.

Hubbert, in his 1956 paper,[3] presented two scenarios for US crude oil production:

• most likely estimate: a logistic curve with a logistic growth rate equal to 6%, an ultimate resource equal to 150 Giga-barrels (Gb) and a peak in 1965. The size of the ultimate resource was taken from a synthesis of estimates by well-known oil geologists and the US Geological Survey, which Hubbert judged to be the most likely case.
• upper-bound estimate: a logistic curve with a logistic growth rate equal to 6% and ultimate resource equal to 200 Giga-barrels and a peak in 1970.

Hubbert's upper-bound estimate, which he regarded as optimistic, accurately predicted that US oil production would peak in 1970. Forty years later, the upper-bound estimate has also proven to be very accurate in terms of cumulative production, less so in terms of annual production. For 2005, the upper-bound Hubbert model predicts 178.2 Gb cumulative and 1.17 Gb current production; actual US production was 176.4 Gb cumulative crude oil + condensate (1% lower than the upper bound estimate), with annual production of 1.55 Gb (32% higher than the upper bound estimate).

Hubbert's 1956 production curves depended on geological estimates of ultimate recoverable oil resources, but he was dissatisfied by the uncertainty this introduced, given the various estimates ranging from 110 billion to 590 billion barrels for the US. Starting in his 1962 publication, he made his calculations, including that of ultimate recovery, based only on mathematical analysis of production rates, proved reserves, and new discoveries, independent of any geological estimates of future discoveries. He concluded that the ultimate recoverable oil resource of the contiguous 48 states was 170 billion barrels, with a production peak in 1966 or 1967. He considered that because his model incorporated past technical advances, that any future advances would occur at the same rate, and were also incorporated.[8] Hubbert continued to defend his calculation of 170 billion barrels in his publications of 1965 and 1967, although by 1967 he had moved the peak forward slightly, to 1968 or 1969.[9][10]

A post-hoc analysis of peaked oil wells, fields, regions and nations found that Hubbert's model was the "most widely useful" (providing the best fit to the data), though many areas studied had a sharper "peak" than predicted.[11]

#### Natural Gas

Hubbert's 1962 prediction of US lower 48-state gas production, versus actual production through 2012

Hubbert also predicted that natural gas production would follow a logistic curve similar to that of oil. At right is his gas production curve for the United States, published in 1962.[12]

## Economics

Oil imports by country Pre-2006

### Energy return on energy investment

The ratio of energy extracted to the energy expended in the process is often referred to as the Energy Return on Energy Investment (EROI or EROEI). As the EROEI drops to one, or equivalently the Net energy gain falls to zero, the oil production is no longer a net energy source. This happens long before the resource is physically exhausted.

Note that it is important to understand the distinction between a barrel of oil, which is a measure of oil, and a barrel of oil equivalent (BOE), which is a measure of energy. Many sources of energy, such as fission, solar, wind, and coal, are not subject to the same near-term supply restrictions that oil is. Accordingly, even an oil source with an EROEI of 0.5 can be usefully exploited if the energy required to produce that oil comes from a cheap and plentiful energy source. Availability of cheap, but hard to transport, natural gas in some oil fields has led to using natural gas to fuel enhanced oil recovery. Similarly, natural gas in huge amounts is used to power most Athabasca Tar Sands plants. Cheap natural gas has also led to Ethanol fuel produced with a net EROEI of less than 1, although figures in this area are controversial because methods to measure EROEI are in debate.

Advances in technology or experience can lead to greater productivity. The US Energy Information Administration has reported that drilling for shale gas and light tight oil in the United States became much more efficient throughout the period 2007-2014. In terms of oil produced per day of rig drilling time, Bakken wells drilled in January 2014 produced 2.4 times as much oil as those drilled five years earlier, in January 2009. In the Marcellus Gas Trend, wells drilled in January 2014 produced more than nine times as much gas per day of drilling rig time as those drilled five years previously, in January 2009.[13][14]

### Growth-based economic models

World energy consumption & predictions, 2005-2035. Source: International Energy Outlook 2011.

Insofar as economic growth is driven by oil consumption growth, post-peak societies must adapt. Hubbert believed:[15]

Some economists describe the problem as uneconomic growth or a false economy. At the political right, Fred Ikle has warned about "conservatives addicted to the Utopia of Perpetual Growth".[16] Brief oil interruptions in 1973 and 1979 markedly slowed—but did not stop—the growth of world GDP.[17]

Between 1950 and 1984, as the Green Revolution transformed agriculture around the globe, world grain production increased by 250%. The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon fueled irrigation.[18]

David Pimentel, professor of ecology and agriculture at Cornell University, and Mario Giampietro, senior researcher at the National Research Institute on Food and Nutrition (INRAN), place in their study Food, Land, Population and the U.S. Economy the maximum U.S. population for a sustainable economy at 200 million. To achieve a sustainable economy world population will have to be reduced by two-thirds, says the study.[19] Without population reduction, this study predicts an agricultural crisis beginning in 2020, becoming critical c. 2050. The peaking of global oil along with the decline in regional natural gas production may precipitate this agricultural crisis sooner than generally expected. Dale Allen Pfeiffer claims that coming decades could see spiraling food prices without relief and massive starvation on a global level such as never experienced before.[20][21]

## Hubbert peaks

Although Hubbert peak theory receives most attention in relation to peak oil production, it has also been applied to other natural resources.

### Natural gas

{{#invoke:main|main}} Doug Reynolds predicted in 2005 that the North American peak would occur in 2007.[22] Bentley predicted a world "decline in conventional gas production from about 2020".[23]

### Coal

{{#invoke:main|main}} Although observers believe that peak coal is significantly further out than peak oil, Hubbert studied the specific example of anthracite in the USA, a high grade coal, whose production peaked in the 1920s. Hubbert found that anthracite matches a curve closely.[24] Pennsylvania's coal production also matches Hubbert's curve closely, but this does not mean that coal in Pennsylvania is exhausted—far from it.{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }} Hubbert had recoverable coal reserves worldwide at 2500 × 109 metric tons and peaking around 2150 (depending on usage). More recent estimates suggest an earlier peak. Coal: Resources and Future Production (PDF 630KB[25]), published on April 5, 2007 by the Energy Watch Group (EWG), which reports to the German Parliament, found that global coal production could peak in as few as 15 years.[26] Reporting on this, Richard Heinberg also notes that the date of peak annual energetic extraction from coal is likely to come earlier than the date of peak in quantity of coal (tons per year) extracted as the most energy-dense types of coal have been mined most extensively.[27] A second study, The Future of Coal by B. Kavalov and S. D. Peteves of the Institute for Energy (IFE), prepared for European Commission Joint Research Centre, reaches similar conclusions and states that ""coal might not be so abundant, widely available and reliable as an energy source in the future".[26] Work by David Rutledge of Caltech predicts that the total of world coal production will amount to only about 450 gigatonnes.[28] This implies that coal is running out faster than usually assumed. Finally, insofar as global peak oil and peak in natural gas are expected anywhere from imminently to within decades at most, any increase in coal production (mining) per annum to compensate for declines in oil or natural gas production, would necessarily translate to an earlier date of peak as compared with peak coal under a scenario in which annual production remains constant.{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }}

### Fissionable materials

{{#invoke:main|main}} In a paper in 1956,[29] after a review of US fissionable reserves, Hubbert notes of nuclear power:

Technologies such as the thorium fuel cycle, reprocessing and fast breeders can, in theory, considerably extend the life of uranium reserves. Roscoe Bartlett claims[30]

Caltech physics professor David Goodstein has stated[31] that

### Helium

Almost all helium on Earth is a result of radioactive decay of uranium and thorium. Helium is extracted by fractional distillation from natural gas, which contains up to 7% helium. The world's largest helium-rich natural gas fields are found in the United States, especially in the Hugoton and nearby gas fields in Kansas, Oklahoma, and Texas. The extracted helium is stored underground in the National Helium Reserve near Amarillo, Texas, the self-proclaimed "Helium Capital of the World". Helium production is expected to decline along with natural gas production in these areas.

Helium is the second-lightest chemical element in the Universe, causing it to rise to the upper layers of Earth's atmosphere. Helium atoms are so light that the Earth's gravity field is simply not strong enough to trap helium in the atmosphere and it dissipates slowly into space and is lost forever.[32]

### Transition metals

{{#invoke:main|main}} Hubbert applied his theory to "rock containing an abnormally high concentration of a given metal"[33] and reasoned that the peak production for metals such as copper, tin, lead, zinc and others would occur in the time frame of decades and iron in the time frame of two centuries like coal. The price of copper rose 500% between 2003 and 2007[34] and was attributed by someTemplate:Who to peak copper.[35][36] Copper prices later fell, along with many other commodities and stock prices, as demand shrank from fear of a global recession.[37] Lithium availability is a concern for a fleet of Li-ion battery using cars but a paper published in 1996 estimated that world reserves are adequate for at least 50 years.[38] A similar prediction[39] for platinum use in fuel cells notes that the metal could be easily recycled.

### Precious metals

In 2009, Aaron Regent president of the Canadian gold giant Barrik Gold said that global output has been falling by roughly one million ounces a year since the start of the decade. The total global mine supply has dropped by 10pc as ore quality erodes, implying that the roaring bull market of the last eight years may have further to run. "There is a strong case to be made that we are already at 'peak gold'," he told The Daily Telegraph at the RBC's annual gold conference in London. "Production peaked around 2000 and it has been in decline ever since, and we forecast that decline to continue. It is increasingly difficult to find ore," he said.[40]

Ore grades have fallen from around 12 grams per tonne in 1950 to nearer 3 grams in the US, Canada, and Australia. South Africa's output has halved since peaking in 1970. Output fell a further 14 percent in South Africa in 2008 as companies were forced to dig ever deeper - at greater cost - to replace depleted reserves.

### Phosphorus

{{#invoke:main|main}} Phosphorus supplies are essential to farming and depletion of reserves is estimated at somewhere from 60 to 130 years.[41] According to a 2008 study, the total reserves of phosphorus are estimated to be approximately 3,200 MT, with a peak production at 28 MT/year in 2034.[42] Individual countries' supplies vary widely; without a recycling initiative America's supply[43] is estimated around 30 years.[44] Phosphorus supplies affect agricultural output which in turn limits alternative fuels such as biodiesel and ethanol. Its increasing price and scarcity (global price of rock phosphate rose 8-fold in the 2 years to mid 2008) could change global agricultural patterns. Lands, perceived as marginal because of remoteness, but with very high phosphorus content, such as the Gran Chaco[45] may get more agricultural development, while other farming areas, where nutrients are a constraint, may drop below the line of profitability.

### Peak water

{{#invoke:main|main}} Hubbert's original analysis did not apply to renewable resources. However, over-exploitation often results in a Hubbert peak nonetheless. A modified Hubbert curve applies to any resource that can be harvested faster than it can be replaced.[46]

For example, a reserve such as the Ogallala Aquifer can be mined at a rate that far exceeds replenishment. This turns much of the world's underground water[47] and lakes[48] into finite resources with peak usage debates similar to oil. These debates usually center around agriculture and suburban water usage but generation of electricity[49] from nuclear energy or coal and tar sands mining mentioned above is also water resource intensive. The term fossil water is sometimes used to describe aquifers whose water is not being recharged.

### Renewable resources

• Fisheries: At least one researcher has attempted to perform Hubbert linearization (Hubbert curve) on the whaling industry, as well as charting the transparently dependent price of caviar on sturgeon depletion.[50] The Atlantic northwest cod fishery was a renewable resource, but the numbers of fish taken exceeded the fish's rate of recovery. The end of the cod fishery does match the exponential drop of the Hubbert bell curve. Another example is the cod of the North Sea.[51]
• Birds: The Passenger Pigeon was a renewable food resource but went extinct following the exponential drop of the Hubbert bell curve.{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }} • Herbivore: The Bubal hartebeest was a renewable food resource but went extinct following the exponential drop of the Hubbert bell curve.{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B=

{{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }}

• Wood: The trees on Easter Island were a renewable resource but all were cut down in the 17th century, following the Hubbert bell curve, but could be restored.{{ safesubst:#invoke:Unsubst||date=__DATE__ |\$B=

{{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }}

• Air/oxygen: Half the world's oxygen is produced by phytoplankton. The numbers of plankton have dropped by 40% since the 1950s.[52]

## Criticisms of peak oil

Economist Michael Lynch[53] argues that the theory behind the Hubbert curve is too simplistic and relies on an overly Malthusian point of view.[54] Lynch claims that Campbell's predictions for world oil production are strongly biased towards underestimates, and that Campbell has repeatedly pushed back the date.[55][56]

Leonardo Maugeri, vice president of the Italian energy company Eni, argues that nearly all of peak estimates do not take into account unconventional oil even though the availability of these resources is significant and the costs of extraction and processing, while still very high, are falling because of improved technology. He also notes that the recovery rate from existing world oil fields has increased from about 22% in 1980 to 35% today because of new technology and predicts this trend will continue. The ratio between proven oil reserves and current production has constantly improved, passing from 20 years in 1948 to 35 years in 1972 and reaching about 40 years in 2003.[57] These improvements occurred even with low investment in new exploration and upgrading technology because of the low oil prices during the last 20 years. However, Maugeri feels that encouraging more exploration will require relatively high oil prices.[58]

Edward Luttwak, an economist and historian, claims that unrest in countries such as Russia, Iran and Iraq has led to a massive underestimate of oil reserves.[59] The Association for the Study of Peak Oil and Gas (ASPO) responds by claiming neither Russia nor Iran are troubled by unrest currently, but Iraq is.[60]

Cambridge Energy Research Associates authored a report that is critical of Hubbert-influenced predictions:[61]

CERA does not believe there will be an endless abundance of oil, but instead believes that global production will eventually follow an “undulating plateau” for one or more decades before declining slowly,[62] and that production will reach 40 Mb/d by 2015.[63]

Alfred J. Cavallo, while predicting a conventional oil supply shortage by no later than 2015, does not think Hubbert's peak is the correct theory to apply to world production.[64]

## Criticisms of peak element scenarios

Although M. King Hubbert himself made major distinctions between decline in petroleum production versus depletion (or relative lack of it) for elements such as fissionable uranium and thorium,[65] some others have predicted peaks like peak uranium and peak phosphorus soon on the basis of published reserve figures compared to present and future production. According to some economists, though, the amount of proved reserves inventoried at a time may be considered "a poor indicator of the total future supply of a mineral resource."[66]

As some illustrations, tin, copper, iron, lead, and zinc all had both production from 1950 to 2000 and reserves in 2000 much exceed world reserves in 1950, which would be impossible except for how "proved reserves are like an inventory of cars to an auto dealer" at a time, having little relationship to the actual total affordable to extract in the future.[66] In the example of peak phosphorus, additional concentrations exist intermediate between 71,000 Mt of identified reserves (USGS)[67] and the approximately 30,000,000,000 Mt of other phosphorus in Earth's crust, with the average rock being 0.1% phosphorus, so showing decline in human phosphorus production will occur soon would require far more than comparing the former figure to the 190 Mt/year of phosphorus extracted in mines (2011 figure).[66][67][68][69]

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Resource peaks

## Notes

1. Jean Laherrere, "Forecasting production from discovery", ASPO Lisbon May 19–20, 2005 [1]
2. Template:Cite web
3. Nuclear Energy and the Fossil Fuels,M.K. Hubbert, Presented before the Spring Meeting of the Southern District, American Petroleum Institute, Plaza Hotel, San Antonio, Texas, March 7–8-9, 1956 [2]
4. Template:Cite web
5. Bartlett A.A 1999 ,"An Analysis of U.S. and World Oil Production Patterns Using Hubbert-Style Curves." Mathematical Geology.
6. Hubbert’s Petroleum Production Model: An Evaluation and Implications for World Oil Production Forecasts, Alfred J. Cavallo, Natural Resources Research,Vol. 13,No. 4, December 2004 [3]
7. Template:Cite web
8. M. King Hubbert, 1962, "Energy Resources," National Academy of Sciences, Publication 1000-D, p.60.
9. M. King Hubbert, "National Academy of Sciences Report on Energy Resources: reply," AAPG Bulletin, Oct. 1965, v.49 n.10 p.1720-1727.
10. M. King Hubbert, "Degree of advancement of petroleum exploration in United States," AAPG Bulletin, Nov. 1967, v.51 n.11 p.2207-2227.
11. {{#invoke:Citation/CS1|citation |CitationClass=journal }}
12. M. King Hubbert, 1962, "Energy Resources," National Academy of Sciences, Publication 1000-D, p.81-83.
13. US EIA, Drilling efficiency is a key driver of oil and natural gas production, Today in Energy, 4 Nov. 3013.
14. US EIA, Drilling productivity report, Excel spreadsheet linked to web page, 8 December 2014.
15. Template:Cite web
16. Template:Cite web
17. http://www.imf.org/external/np/speeches/2006/pdf/050206.pdf
18. Template:Cite web
19. Template:Cite web
20. Template:Cite news
21. {{#invoke:Citation/CS1|citation |CitationClass=journal }}
22. Template:Cite web
23. Template:Cite web
24. Template:Cite web
25. "Coal: Bleak outlook for the black stuff", by David Strahan, New Scientist, January 19, 2008, pp. 38-41.
26. Template:Cite web
27. Template:Cite web
28. {{#invoke:Citation/CS1|citation |CitationClass=journal }}
29. Template:Cite web
30. Template:Cite web
31. Template:Cite web
32. Template:Cite web
33. Template:Cite web
34. Template:Cite web
35. Template:Cite web
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37. Template:Cite web
38. Template:Cite web
39. Template:Cite news
40. Template:Cite web
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43. Template:Cite web
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47. {{#invoke:citation/CS1|citation |CitationClass=book }}
48. {{#invoke:Citation/CS1|citation |CitationClass=journal }}
49. Template:Cite news
50. Template:Cite web
51. Template:Cite web
52. Template:Cite web
53. Template:Cite web
54. Template:Cite web
55. Template:Cite web
56. James D. Gwartney, Richard L. Stroup, Russell S. Sobel, David MacPherson. Economics: Private and Public Choice, 12th Edition. South-Western Cengage Learning, page 730. extract, accessed 5-20-2012
57. Template:Cite web
58. American Geophysical Union, Fall Meeting 2007, abstract #V33A-1161. Mass and Composition of the Continental Crust
59. Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

## References

• Hubbert, M.K. (1982). Techniques of Prediction as Applied to Production of Oil and Gas, US Department of Commerce, NBS Special Publication 631, May 1982