METHANE IN THE ARCTIC

SURFACE WATER OVER THE EASTERN SIBERIAN ARCTIC

The sea surface above the East Siberian Arctic Shelf
is full of ice and bubbles.
Sonar is the only way to detect
the vast clouds of methane bubbles rising from the seafloor.
Igor Semiletov, University of Alaska Fairbanks

 

Dee Finney's blog

Start date July 20, 2011

Today's date December 17, 2011

page 87

 

I listened to Dr. Bill Deagle this afternoon from last Friday's radio show.  He was all freaked out by methane in the Arctic, and he said that the military pulled back 100 miles from the Gulf disaster because they were afraid of a tsunami coming on shore due to a possible methane explosion out to sea. 

 

You can hear the show here; http://www.greatdreams.com/blog/1216113.mp3

 

 

 

Methane

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Methane
Identifiers
CAS number 74-82-8 YesY
PubChem 297
ChemSpider 291 YesY
EC number 200-812-7
UN number 1971
KEGG C01438 N
MeSH Methane
ChEBI CHEBI:16183 YesY
ChEMBL CHEMBL17564 YesY
RTECS number PA1490000
Beilstein Reference 1718732
Gmelin Reference 59
3DMet B01450
Jmol-3D images Image 1
Properties
Molecular formula CH4
Molar mass 16.04 g mol−1
Exact mass 16.031300128 g mol−1
Appearance Colorless gas
Odor Odorless
Density
  • 655.6 mg dm−3 (1 atm)
  • 644.3 mg dm−3 (at 300 K)
Melting point

85.7 K;−187.5 °C; −305.4 °F
Boiling point

111 K;−162 °C; −260 °F
Solubility in water 35 mg dm−3 (at 17 °C)
log P 1.09
Structure
Molecular shape tetrahedral
Thermochemistry
Std enthalpy of
formation ΔfHo298		 −74.87 kJ mol−1
Std enthalpy of
combustion ΔcHo298		 −891.1–−890.3 kJ mol−1
Standard molar
entropy So298		 186.25 J K−1 mol−1
Specific heat capacity, C 35.69 J K−1 mol−1
Hazards[3]
MSDS External MSDS
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H220
GHS precautionary statements P210
EU Index 601-001-00-4
EU classification Flammable F+
R-phrases R12
S-phrases (S2), S16, S33
NFPA 704
4
1
0
Flash point −188 °C
Autoignition
temperature		 537 °C
Explosive limits 5–15%
Related compounds
Related alkanes Ethane
Related compounds
Supplementary data page
Structure and
properties		 n, εr, etc.
Thermodynamic
data		 Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Methane (pronounced /ˈmɛθeɪn/ or /ˈmiːθeɪn/) is a chemical compound with the chemical formula CH4. It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel. However, because it is a gas at normal conditions, methane is difficult to transport from its source.

Methane is a relatively potent greenhouse gas. The concentration of methane in the Earth's atmosphere in 1998, expressed as a mole fraction, was 1745 nmol/mol (parts per billion, ppb), up from 700 nmol/mol in 1750. By 2008, however, global methane levels, which had stayed mostly flat since 1998, had risen to 1,800 nmol/mol.[4]

Properties and bonding

Methane is a tetrahedral molecule with four equivalent C-H bonds. Its electronic structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this level in energy is a triply degenerate set of MOs that involve overlap if the 2p orbitals on carbon with various linear combinations of the 1s orbitals on hydrogen. The resulting "three-over-one" bonding scheme is consistent with photoelectron spectroscopic measurements.

At room temperature and standard pressure, methane is a colorless, odorless gas.[5] The familiar smell of natural gas as used in homes is a safety measure achieved by the addition of an odorant, often methanethiol or ethanethiol. Methane has a boiling point of −161 °C (−257.8 °F) at a pressure of one atmosphere.[6] As a gas it is flammable only over a narrow range of concentrations (5–15%) in air. Liquid methane does not burn unless subjected to high pressure (normally 4–5 atmospheres).[7]

[edit] Chemical reactions

Main reactions with methane are: combustion, steam reforming to syngas, and halogenation. In general, methane reactions are difficult to control. Partial oxidation to methanol, for example, is challenging because the reaction typically progresses all the way to carbon dioxide and water even with incomplete amounts of oxygen. The enzymes methane monooxygenase can produce methanol from methane, but they cannot be used for industrial scale reactions.[8]

[edit] Acid-base reactions

Like other hydrocarbons, methane is a very weak acid. Its pKa in DMSO is estimated to be 56.[9] It cannot be deprotonated in solution, but the conjugate base methyl lithium is known. Protonation of methane can be achieved with super acids to give CH5+, sometimes called the methanium ion. Despite the strength of its C-H bonds, there is intense interest in catalysts that facilitate C–H bond activation in methane (and other low alkanes).[10]

[edit] Combustion

In the combustion of methane, several steps are involved. An early intermediate is formaldehyde (HCHO or H2CO). Oxidation of formaldehyde gives the formyl radical (HCO), which then give carbon monoxide (CO):

CH4 + O2 → CO + H2 + H2O

The resulting H2 oxidizes to H2O, releasing heat. This reaction occurs very quickly, usually in significantly less than a millisecond.

2 H2 + O2 → 2 H2O

Finally, the CO oxidizes, forming CO2 and releasing more heat. This process is generally slower than the other chemical steps, and typically requires a few to several milliseconds to occur.

2 CO + O2 → 2 CO2

The result of the above is the following total equation:

CH4 + 2 O2 → CO2 + 2 H2O (ΔH = −891 kJ/mol (at standard conditions))

[edit] Reactions with halogens

Methane reacts with halogens given appropriate conditions as follows:

CH4 + X2 → CH3X + HX

where X is a halogen: fluorine (F), chlorine (Cl), bromine (Br), or iodine (I). This mechanism for this process is called free radical halogenation, beginning with the attach of Cl· radicals on methane to produce CH3·, which combines with a second Cl· to give methyl chloride (CH3Cl). Similar reactions will produce dichloromethane (CH2Cl2), chloroform (CHCl3), and, ultimately, carbon tetrachloride (CCl4). The energy required to start this reaction comes from UV radiation or heating.[11]

[edit] Uses

Methane is used in industrial chemical processes and may be transported as a refrigerated liquid (liquefied natural gas, or LNG). While leaks from a refrigerated liquid container are initially heavier than air due to the increased density of the cold gas, the gas at ambient temperature is lighter than air. Gas pipelines distribute large amounts of natural gas, of which methane is the principal component.

[edit] Fuel

Main article: natural gas

Methane is important for electrical generation by burning it as a fuel in a gas turbine or steam boiler. Compared to other hydrocarbon fuels, burning methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's heat of combustion is lower than any other hydrocarbon but the ratio of the heat of combustion (891 kJ/mol) to the molecular mass (16.0 g/mol, of which 12.0 g/mol is carbon) shows that methane, being the simplest hydrocarbon, produces more heat per mass unit (55.7 kJ/g) than other complex hydrocarbons. In many cities, methane is piped into homes for domestic heating and cooking purposes. In this context it is usually known as natural gas, and is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot.

Methane in the form of compressed natural gas is used as a vehicle fuel and is claimed to be more environmentally friendly than other fossil fuels such as gasoline/petrol and diesel.[12]

Research into adsorption methods of methane storage for this purpose has been conducted.[13]

[edit] Developing technologies

Research is being conducted by NASA on methane's potential as a rocket fuel.[14]

Methane emitted from coal mines has been converted to electricity.[15]

[edit] Chemical feedstock

Although there is great interest in converting methane into useful or more easily liquified compounds, the only practical processes are relatively unselective. In the chemical industry, methane is converted to synthesis gas, a mixture of carbon monoxide and hydrogen, by steam reforming. This endergonic process (requiring energy) utilizes nickel catalysts and requires high temperatures, around 700–1100 °C:

CH4 + 2 H2O → CO2 + 4 H2

Related chemistries are exploited in the Haber-Bosch Synthesis of ammonia from air, which is reduced with natural gas to a mixture of carbon dioxide, water, and ammonia.

Methane is also subjected to free-radical chlorination in the production of chloromethanes, although methanol is a more typical precursor.[11]

[edit] Production

[edit] Biological routes

Main article: methanogenesis

Naturally occurring methane is mainly produced by the process of methanogenesis. This multistep process is used by microorganisms as an energy source. The net reaction is:

CO2 + 8 H+ + 8 e- → CH4 + 2 H2O

The final step in the process is catalysed by the enzyme methyl-coenzyme M reductase. Methanogenesis is a form of anaerobic respiration used by organisms that occupy landfill, ruminants (e.g., cattle), and the guts of termites.

It is uncertain if plants are a source of methane emissions.[16][17][18]

[edit] Industrial routes

Natural gas is so abundant that the intentional production of methane would be unusual. Methane can be produced by hydrogenation carbon dioxide through the Sabatier process. It is also a side product of the hydrogenation of carbon monoxide in the Fischer-Tropsch process. This technology is practiced on a large scale to produce longer chain molecules than methane.

[edit] Occurrence

Methane was discovered and isolated by Alessandro Volta between 1776 and 1778 when studying marsh gas from Lake Maggiore. It is the major component of natural gas, about 87% by volume. The major source of methane is extraction from geological deposits known as natural gas fields, with coal seam gas extraction becoming a major source (see Coal bed methane extraction, a method for extracting methane from a coal deposit, while enhanced coal bed methane recovery is a method of recovering methane from an non-minable coal seams). It is associated with other hydrocarbon fuels, and sometimes accompanied by helium and nitrogen. The gas at shallow levels (low pressure) forms by anaerobic decay of organic matter and reworked methane from deep under the Earth's surface. In general, sediments buried deeper and at higher temperatures than those that contain oil generate natural gas.

It is generally transported in bulk by pipeline in its natural gas form, or LNG carriers in its liquefied form; few countries transport it by truck.

[edit] Alternative sources

Apart from gas fields, an alternative method of obtaining methane is via biogas generated by the fermentation of organic matter including manure, wastewater sludge, municipal solid waste (including landfills), or any other biodegradable feedstock, under anaerobic conditions. Rice fields also generate large amounts of methane during plant growth. Methane hydrates/clathrates (ice-like combinations of methane and water on the sea floor, found in vast quantities) are a potential future source of methane. Cattle belch methane accounts for 16% of the world's annual methane emissions to the atmosphere.[19] One study reported that the livestock sector in general (primarily cattle, chickens, and pigs) produces 37% of all human-induced methane.[20] Early research has found a number of medical treatments and dietary adjustments that help slightly limit the production of methane in ruminants.[21] [22] A more recent study, in 2009, found that at a conservative estimate, at least 51% of global greenhouse gas emissions were attributable to the life cycle and supply chain of livestock products, meaning all meat, dairy, and by-products, and their transportation.[23]

[edit] Atmospheric methane

Main article: Atmospheric methane
2006–2009 methane concentration in the upper troposphere

Methane is created near the Earth's surface, primarily by microorganisms by the process of methanogenesis. It is carried into the stratosphere by rising air in the tropics. Uncontrolled build-up of methane in the atmosphere is naturally checked — although human influence can upset this natural regulation — by methane's reaction with hydroxyl radicals formed from singlet oxygen atoms and with water vapor. It has a net lifetime of about 10 years,[24] and is primarily removed by conversion to carbon dioxide and water

Methane also affects the degradation of the ozone layer.[25][26]

In addition, there is a large (but unknown) amount of methane in methane clathrates in the ocean floors as well as the Earth's crust. Most methane is the result of biological process called methanogenesis.

In 2010, methane levels in the Arctic were measured at 1850 nmol/mol, a level over twice as high as at any time in the previous 400,000 years. Historically, methane concentrations in the world's atmosphere have ranged between 300 and 400 nmol/mol during glacial periods commonly known as ice ages, and between 600 to 700 nmol/mol during the warm interglacial periods. It has a high global warming potential: 72 times that of carbon dioxide over 20 years, and 25 times over 100 years,[27] and the levels are rising.

Methane in the Earth's atmosphere is an important greenhouse gas with a global warming potential of 25 compared to CO2 over a 100-year period (although accepted figures probably represents an underestimate[28]). This means that a methane emission will have 25 times the effect on temperature of a carbon dioxide emission of the same mass over the following 100 years. Methane has a large effect for a brief period (a net lifetime of 8.4 years in the atmosphere), whereas carbon dioxide has a small effect for a long period (over 100 years). Because of this difference in effect and time period, the global warming potential of methane over a 20 year time period is 72. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases (these gases don't include water vapour which is by far the largest component of the greenhouse effect).[29] Usually, excess methane from landfills and other natural producers of methane is burned so CO2 is released into the atmosphere instead of methane, because methane is a more effective greenhouse gas. Recently, methane emitted from coal mines has been successfully utilized to generate electricity.

[edit] Clathrates

Arctic methane release from permafrost and methane clathrates is an expected consequence of global warming.[30] [31]

[edit] Safety

Methane is not toxic; however, it is extremely flammable and may form explosive mixtures with air. Methane is violently reactive with oxidizers, halogens, and some halogen-containing compounds. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia may result if the oxygen concentration is reduced to below about 16% by displacement, as most people can tolerate a reduction from 21% to 16% without ill effects. The concentration of methane at which asphyxiation risk becomes significant is much higher than the 5–15% concentration in a flammable or explosive mixture. Methane off-gas can penetrate the interiors of buildings near landfills and expose occupants to significant levels of methane. Some buildings have specially engineered recovery systems below their basements to actively capture this gas and vent it away from the building.

[edit] See also

Sustainable development.svg Sustainable development portal

[edit] References

  1. ^ a b "methane (CHEBI:16183)". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute. 17 October 2009. Main. https://www.ebi.ac.uk/chebi/searchId.do?chebiId=16183. Retrieved 10 October 2011.
  2. ^ a b Linstrom, P.J.; Mallard, W.G., eds (2011). "Methane". NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology. http://webbook.nist.gov/cgi/inchi/InChI%3D1S/CH4/h1H4. Retrieved 4 December 2011.
  3. ^ "Safety Datasheet, Material Name: Methane" (PDF). USA: Metheson Tri-Gas Incorporated. 4 December 2009. http://www.chemadvisor.com/Matheson/database/msds/00244226000800003.PDF. Retrieved 4 December 2011.
  4. ^ Carbon Dioxide, Methane Rise Sharply in 2007
  5. ^ David A. Hensher, Kenneth J. Button (2003). Handbook of transport and the environment. Emerald Group Publishing. p. 168. ISBN 0080441033. http://books.google.com/books?id=yp3qEgHrsJ4C&pg=PA168.
  6. ^ NIST Chemistry Webbook
  7. ^ Ayhan Demirbas (2010). Methane Gas Hydrate. Springer. p. 102. ISBN 1848828713. http://books.google.com/books?id=WFefWAq1Sh0C&pg=PA102.
  8. ^ Mu-Hyun Baik, Martin Newcomb, Richard A. Friesner, and Stephen J. Lippard "Mechanistic Studies on the Hydroxylation of Methane by Methane Monooxygenase" Chem. Rev., 2003, vol. 103, pp 2385–2420. doi:10.1021/cr950244f
  9. ^ Equilibrium acidities in dimethyl sulfoxide solution Frederick G. Bordwell Acc. Chem. Res.; 1988; 21(12) pp 456 – 463; doi:10.1021/ar00156a004
  10. ^ Wesley H. Bernskoetter, Cynthia K. Schauer, Karen I. Goldberg and Maurice Brookhart "Characterization of a Rhodium(I) σ-Methane Complex in Solution" Science 2009, Vol. 326, pp. 553–556. doi:10.1126/science.1177485
  11. ^ a b M. Rossberg et al. “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_233.pub2
  12. ^ Clayton B. Cornell (April 29, 2008). "Natural Gas Cars: CNG Fuel Almost Free in Some Parts of the Country". http://www.gas2.org/2008/04/29/natural-gas-cars-cng-fuel-almost-free-in-some-parts-of-the-country/. "Compressed natural gas is touted as the 'cleanest burning' alternative fuel available, since the simplicity of the methane molecule reduces tailpipe emissions of different pollutants by 35 to 97%. Not quite as dramatic is the reduction in net greenhouse-gas emissions, which is about the same as corn-grain ethanol at about a 20% reduction over gasoline"
  13. ^ Düren, Tina; Sarkisov, Lev; Yaghi, Omar M.; Snurr, Randall Q. (2004). "Design of New Materials for Methane Storage". Langmuir 20 (7): 2683–9. doi:10.1021/la0355500. PMID 15835137.
  14. ^ Lunar Engines, Aviation Week & Space Technology, 171, 2 (13 July 2009), p. 16: "Aerojet has completed assembly of a 5,500-pound-thrust liquid oxygen/liquid methane rocket engine—a propulsion technology under consideration as the way off the Moon for human explorers" One advantage of methane is that it is abundant in many parts of the solar system and it could potentially be harvested in situ (i.e. on the surface of another solar-system body), providing fuel for a return journey.Methane Blast, NASA, May 4, 2007. Current methane engines in development produce a thrust of 7,500 pounds-force (33 kN), which is far from the 7,000,000 lbf (31 MN) needed to launch the Space Shuttle. Instead, such engines will most likely propel voyages from the Moon or send robotic expeditions to other planets in the solar system.Green, V. (September). Hit the Gas: NASA's methane rocket could make long distance space travel possible, on the cheap. 271. Popular Science magazine. pp. 16–17. ISSN 0161-7370. http://books.google.com/?id=3AClY8pMg-EC&pg=PA16&lpg=PA16.
  15. ^ A Global First: Coal Mine Turns Greenhouse Gas into Green Energy
  16. ^ Hamilton JT, McRoberts WC, Keppler F, Kalin RM, Harper DB (July 2003). "Chloride methylation by plant pectin: an efficient environmentally significant process". Science 301 (5630): 206–9. Bibcode 2003Sci...301..206H. doi:10.1126/science.1085036. PMID 12855805.
  17. ^ "Methane Emissions? Don't Blame Plants", ScienceNOW, 14 January 2009
  18. ^ "Plants do emit methane after all". New Scientist. 2 December 2007. http://environment.newscientist.com/article/mg19626322.900-plants-do-emit-methane-after-all.html.
  19. ^ Miller, G. Tyler. Sustaining the Earth: An Integrated Approach. U.S.A.: Thomson Advantage Books, 2007. 160.
  20. ^ FAO (2006). Livestock’s Long Shadow–Environmental Issues and Options. Rome: Food and Agriculture Organization of the United Nations (FAO). http://www.fao.org/docrep/010/a0701e/a0701e00.HTM. Retrieved 2009-10-27.
  21. ^ John Roach (2002-05-13). "New Zealand Tries to Cap Gaseous Sheep Burps". National Geographic. http://news.nationalgeographic.com/news/2002/05/0509_020509_belch.html. Retrieved 2011-03-02.
  22. ^ Research on use of bacteria from the stomach lining of kangaroos (who don't emit methane) to reduce methane in cattle
  23. ^ Goodland, Robert, and Anhang, Jeff. (November/ December 2009), Livestock and Climate Change., Washington, D.C.: World Watch, www.worldwatch.org, http://en.wikipedia.org/wiki/Worldwatch_institute, http://www.worldwatch.org/files/pdf/Livestock%20and%20Climate%20Change.pdf
  24. ^ Boucher, Olivier; Friedlingstein, Pierre; Collins, Bill; Shine, Keith P (2009). "The indirect global warming potential and global temperature change potential due to methane oxidation". Environmental Research Letters 4 (4): 044007. Bibcode 2009ERL.....4d4007B. doi:10.1088/1748-9326/4/4/044007.
  25. ^ Ozon – wpływ na życie człowieka, Ozonowanie/Ewa Sroka, Group: Freony i inne związki, Reakcje rozkładu ozonu.
  26. ^ Twenty Questions And Answers About The Ozone Layer, UNEP/D.W. Fahey 2002, pp. 12, 34, 38
  27. ^ IPCC Fourth Assessment Report, Working Group 1, Chapter 2
  28. ^ Shindell, D. T.; Faluvegi, G.; Koch, D. M.; Schmidt, G. A.; Unger, N.; Bauer, S. E. (2009). "Improved Attribution of Climate Forcing to Emissions". Science 326 (5953): 716–8. Bibcode 2009Sci...326..716S. doi:10.1126/science.1174760. PMID 19900930.
  29. ^ "Technical summary". Climate Change 2001. United Nations Environment Programme. http://www.grida.no/climate/ipcc_tar/wg1/017.htm.
  30. ^ "Methane Releases From Arctic Shelf May Be Much Larger and Faster Than Anticipated". Press Release. National Science Foundation. http://www.nsf.gov/news/news_summ.jsp?cntn_id=116532&org=NSF&from=news.
  31. ^ "Methane discovery stokes new global warming fears Shock as retreat of Arctic releases greenhouse gas". Steve Connor. www.independent.co.uk. http://www.independent.co.uk/news/science/methane-discovery-stokes-new-global-warming-fears-shock-as-retreat-of-arctic-releases-greenhouse-gas-6276278.html.

[edit] Appendix: extraterrestrial methane

Methane has been detected or is believed to exist in several locations of the solar system. In most cases, it is believed to have been created by abiotic processes. Possible exceptions are Mars and Titan.

[edit] References

  1. ^ Stern, S.A. (1999). "The Lunar atmosphere: History, status, current problems, and context". Rev. Geophys. 37 (4): 453–491. Bibcode 1999RvGeo..37..453S. doi:10.1029/1999RG900005.
  2. ^ Mars Vents Methane in What Could Be Sign of Life, Washington Post, January 16, 2009
  3. ^ Niemann, HB; Atreya, SK; Bauer, SJ; Carignan, GR; Demick, JE; Frost, RL; Gautier, D; Haberman, JA et al. (2005). "The abundances of constituents of Titan’s atmosphere from the GCMS instrument on the Huygens probe". Nature 438 (7069): 779–784. Bibcode 2005Natur.438..779N. doi:10.1038/nature04122. PMID 16319830.
  4. ^ Chris Mckay (2010). "Have We Discovered Evidence For Life On Titan". SpaceDaily. http://www.spacedaily.com/reports/Have_We_Discovered_Evidence_For_Life_On_Titan_999.html. Retrieved 2010-06-10. Space.com. March 23, 2010.
  5. ^ Waite, J. H.; et al.; (2006); Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure, Science, Vol. 311, No. 5766, pp. 1419–1422
  6. ^ Shemansky, DF; Yelle, RV; Linick; Lunine (December 15, 1989). "Ultraviolet Spectrometer Observations of Neptune and Triton". Science 246 (4936): 1459–1466. Bibcode 1989Sci...246.1459B. doi:10.1126/science.246.4936.1459. PMID 17756000.
  7. ^ Ron Miller; William K. Hartmann (2005). The Grand Tour: A Traveler's Guide to the Solar System (3rd ed.). Thailand: Workman Publishing. pp. 172–73. ISBN 0-7611-3547-2.
  8. ^ Tobias C. Owen, Ted L. Roush et al. (6 August 1993). "Surface Ices and the Atmospheric Composition of Pluto". Science 261 (5122): 745–748. Bibcode 1993Sci...261..745O. doi:10.1126/science.261.5122.745. PMID 17757212. http://www.sciencemag.org/cgi/content/abstract/261/5122/745. Retrieved 2007-03-29.
  9. ^ "Pluto". SolStation. 2006. http://www.solstation.com/stars/pluto.htm. Retrieved 2007-03-28.
  10. ^ Sicardy, B; Bellucci, A; Gendron, E; Lacombe, F; Lacour, S; Lecacheux, J; Lellouch, E; Renner, S et al. (2006). "Charon’s size and an upper limit on its atmosphere from a stellar occultation". Nature 439 (7072): 52–4. Bibcode 2006Natur.439...52S. doi:10.1038/nature04351. PMID 16397493. http://www.nature.com/nature/journal/v439/n7072/abs/nature04351.html.
  11. ^ Mumma, M.J.; Disanti, M.A., dello Russo, N., Fomenkova, M., Magee-Sauer, K., Kaminski, C.D., and D.X. Xie (1996). "Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin". Science 272 (5266): 1310–4. Bibcode 1996Sci...272.1310M. doi:10.1126/science.272.5266.1310. PMID 8650540.
  12. ^ Stephen Battersby (2008-02-11). "Organic molecules found on alien world for first time". http://space.newscientist.com/article/dn13303-organic-molecules-found-on-alien-world-for-first-time.html. Retrieved 2008-02-12.
  13. ^ J. H. Lacy, J. S. Carr, N. J. Evans, II, F. Baas, J. M. Achtermann, J. F. Arens (1991). "Discovery of interstellar methane — Observations of gaseous and solid CH4 absorption toward young stars in molecular clouds". Astrophysical Journal 376: 556–560. Bibcode 1991ApJ...376..556L. doi:10.1086/170304.

[edit] External links

Wikimedia Commons has media related to: Methane
Look up methane in Wiktionary, the free dictionary.


Arctic methane warming danger

By Marmian Grimes
University of Alaska, Fairbanks

Part of the Arctic Ocean seafloor that holds vast stores of frozen methane is showing signs of instability and widespread venting of the powerful greenhouse gas, according to new research findings.

The study, published this month in the journal Science, shows that the frozen seabed under the East Siberian Arctic Shelf, long thought to be an impermeable barrier sealing in methane, is perforated and leaking large amounts of the gas into the atmosphere.

The Shelf is a very methane-rich area encompassing more than two million square kilometres of seafloor in the Arctic - more than three times as large as the nearby Siberian wetlands, which have long been considered the primary source of atmospheric methane in the Northern Hemisphere.

With methane a potent greenhouse gas - with 25 times the warming potential of carbon dioxide - release of even a fraction of the Shelf's stores could trigger abrupt climate warming, according to lead researchers Natalia Shakhova and Igor Semiletov, from the University of Alaska in Fairbanks.

"The amount of methane currently coming out of the East Siberian Arctic Shelf is comparable to the amount coming out of the entire world's oceans," Shakhova said. "Subsea permafrost is losing its ability to be an impermeable cap."

Her team's research shows that the Shelf is already releasing around seven million tonnes of methane each year, about equal to tthe amount of methane coming from the rest of the ocean.

Our concern is that the subsea permafrost has been showing signs of destabilisation already," she said. "If it further destabilises, the methane emissions may not be in [millions of tonnes], it would be significantly larger."

Also of concern, she said, is that in addition to holding large stores of frozen methane, the Shelf area is also very shallow. In deep water, methane gas can be converted into the less potent carbon dioxide before it reaches the surface and enters the atmosphere. In the shallows, there isn't enough time for this conversion to occur. That, combined with the sheer amount of methane in the region, could add a previously uncalculated variable to climate models.

"The release to the atmosphere of only one per cent of the methane assumed to be stored in shallow...deposits might alter the current atmospheric burden of methane up to three to four times," Shakhova said. "The climatic consequences of this are hard to predict."

Shakhova also noted that the Earth's geological record indicates that atmospheric methane concentrations have varied between about 0.3 to 0.4 parts per million during cold periods to 0.6 to 0.7 parts per million during warm periods. Current average methane concentrations in the Arctic average about 1.85 parts per million, the highest in 400,000 years, she said. Concentrations above the East Siberian Arctic Shelf are even higher.

FROM:  http://www.gmagazine.com.au/news/1863/warming-danger-arctic-methane-vents

Tundra dangers

May 24, 2008

in Canada,Law,Politics,Science,The environment

 

One of the biggest climatic dangers out there is that warming in the Arctic will melt the permafrost. The tundra is heavily laden with methane – a potent greenhouse gas. In total, the ten million square kilometres contain about 1,000 gigatonnes of carbon (3,670 gigatonnes of carbon dioxide). The permafrost contains more carbon dioxide equivalent than the entire atmosphere at present.

If even a fraction of a percent of that gets released every year, it would blow our carbon budget. Even with enormous cuts in human emissions, the planet would keep on warming. Right now, humanity is emitting about 8 gigatonnes of carbon a year, on track to hit 11 gigatonnes by 2020. If we were to stabilize at that level, emitting 11 gigatonnes a year until 2100, the concentration of greenhouse gasses in the atmosphere will surpass 1,000 parts per million, creating the certainty of a vastly transformed world and a very strong possibility of the end of human civilization.

As such, it is vital to stop climate change before the planet warms sufficiently to start melting permafrost. This is especially challenging given that warming in the Arctic is more pronounced than warming elsewhere. There is also the additional challenge of the sea-ice feedback loop, wherein the replacement of reflective ice with absorptive water increases warming.

The actions necessary to prevent that are eminently possible. Unfortunately, people have not yet developed the will to implement them to anything like the degree necessary. Hopefully, the ongoing UNFCCC process for producing a Kyoto successor will help set us along that path before it becomes fantastically more difficult and expensive to act.

[Update: 4 February 2009] Here is a post on the danger of self-amplifying, runaway climate change: Is runaway climate change possible? Hansen’s take.

[Update: 19 February 2010] See also: The threat from methane in the North.

The threat from methane in the North

by Milan on February 18, 2010

in Climate change,Climate science,Wildlife

If catastrophic climate change is to be avoided, it is critical that the massive stock of greenhouse gas held in the Arctic permafrost and in undersea deposits called methane clathrates not be allowed to enter the atmosphere. The permafrost and clathrates contain methane: a gas that is about 25 times more powerful than carbon dioxide, when it comes to preventing infrared radiation from escaping into space, keeping it within the Earth system and warming the planet. As the planet heats up from human greenhouse gas emissions, the threat of all this methane getting released increases.

Right now, there is even more methane on Earth than there was before the Paleocene-Eocene Thermal Maximum (PETM), a period about 56 million years ago when the methane bound up in the north got released over the course of several thousand years. Back then, those emissions made the planet’s temperature rise between 5°C and 9°C – far beyond the level which would be dangerous for human beings. And remember that this warming is on top of whatever warming arises directly from human emissions. According to the modeling conducted by the Met Office in the United Kingdom, if our emissions continue on a business-as-usual course, they will generate 5.5 – 6.1°C of warming by 2100. Just imagine what impact melting clathrates and permafrost could have in addition.

The PETM happened fairly slowly, but was nonetheless accompanied by the extinction of about half the planet’s marine life. Other species migrated hundreds or thousands of kilometres, as the climate in different regions changed. There were no ice sheets during the PETM, whereas Earth currently has enough ice in Greenland and Antarctica to raise sea levels by more than sixty metres. Human-induced climate change is happening far faster than what happened during the PETM. That makes it even harder for plants and animals to adapt. It also means there is less time for negative feedbacks (like increased weathering of rocks) to blunt the edge of the warming.

In addition to the vanishing multi-year sea ice, we are already seeing worrisome degradation of the Arctic permafrost. For instance, researchers in Quebec have found that the edge of where permafrost is found in one region has moved 130 km in just 50 years. The threat of kicking off a PETM-type event is one major reason why the warming caused by human beings must be limited. Because the amount of warming we produce is directly related to how many fossil fuels we burn, it is critical that humanity make the conscious choice to limit our fossil fuel usage. For the sake of protecting a planet that provides the foundation for human prosperity and survival, we need to leave fossil fuels underground and move to a clean and renewable global energy system that can keep operating forever.

 

FROM:  http://burycoal.com/blog/2010/02/18/the-threat-from-methane-in-the-north/

 

The Storegga Landslides: Catastrophic Underwater Natural Methane Explosions

Biot Report #301: November 26, 2005 Printer Printer Friendly

Methane is a small molecule made up of a single carbon atom surrounded by four hydrogen atoms, which exists in an ice-like form variously called “methane hydrate”, “methane ice” or “methane clathrate”. Clathrate means “cage”, which describes the structure of methane ice: a cage of water molecules around methane gas molecules, allowing high methane concentrations. One unit volume of methane hydrates contain over 160 volumes of methane gas and less than one unit of water at surface pressures and temperatures. (1) Methane ice burns when it meets fire.

METHANE

 

Methane ice was originally thought to occur only in the outer regions of the solar system. Today it is well known to occur abundantly in earth’s marine and Arctic permafrost sediments. For example, the United States has as much as 200,000 trillion cubic feet of methane in hydrate systems in (Alaskan) permafrost regions and surrounding waters, which is over a hundred times greater than the estimated conventional US methane gas resource. (2)

Methane ices are known to pose risks for 1) marine safety and 2) seafloor stability, as follows:

1. Marine Safety and Methane

Arctic and marine hydrates can cause problems during drilling and production of conventional hydrocarbons. “Difficulties include gas release during drilling, blowouts, casing collapse and well-site subsidence. These problems are generally the result of dissociation of gas hydrates caused by the heat of circulating drilling fluids or flow of warm production fluids. Pipelines carrying warm fluids may suffer loss of support due to underlying hydrates,” according to the Department of Energy’s “Strategy for Methane Hydrates Research and Development.” (3) Little is known about the long term impacts on seafloor stability and safety due to methane gas production from methane ice (see more below).

2. Seafloor Stability, Methane Outgassing, and the Storegga Submarine Landslides

Methane ices can break down at certain temperatures and pressures, permitting the gas in the clathrate cages to be released. This process is what experts believe triggered the ancient catastrophic “Storegga” submarine landslides off the coast of Norway. The Storegga landslide complex is a world-class geographic feature and one of the largest areas of known slope failure anywhere in the world.

The complex consists of three very large underwater landslides known to have taken place during the last 100,000 years. The landslides departed from the destabilized slope and “flowed” into the deep ocean crevasses below. The Second Storegga Slide was large enough to have caused a megatsunami around 7,100 years ago that triggered widespread coastal flooding in Scotland, Norway and other coastlines bordering the eastern North Atlantic and North Sea. (4) For example, at a number of localities near the eastern coast of Scotland is a sand deposit as deep as 25 feet above sea level that has been dated to about 7,000 years ago. One researcher in 1989 proposed that this sand is a megatsunami deposit resulting from the sediment displacement associated with the Second Storegga Slide. (5)

Bathymetry and acoustic seafloor imagery of the Storegga Slide have identified seafloor depressions or “pockmarks” up to 1500 feet in diameter and less than 15 feet in depth, which are associated with the presence of gas. (6) The pockmarks are consistent with the remnants of old methane gas explosion sites that triggered the landslides at Storegga.

Extensive seafloor mapping following the December 2004 Indonesia earthquake/tsunami was conducted to identify submarine landslides and pockmarks similar to those at the Storegga Slide complex. (See “Dramatic Direct Visuals of the December 2004 Bay of Bengal Epicenter Earthquake Rupture Zone” at: http://www.semp.us/biots/biot_187.html; accessed November 26, 2005.)

Commercial Production from Deep Sea Methane Fields

The Storegga Slide was discovered while companies were searching for oil and gas in the North Sea Northern. “Norsk Hydro”, one of the world's largest offshore oil companies, discovered the “Ormen Lange” natural gas (methane) field in the Storegga Slide depression in 1997. The company has committed to the commercial production of natural (methane) gas from the Storegga Slide depression even though at a depth of approximately 2,700 feet, the site is so deep that the 24 wellheads and 120 km pipelines to shore must be built using underwater robot technology and advanced installation techniques. (7) No conventional offshore platforms will be used. A direct pipeline will be built from the Norway refinery to England.

Other challenges confronting Norsk Hydro in the commercial production of methane from the methane fields in the Storegga Slide area are:

1. Subsea temperatures below zero, which cause the methane gas and water in the pipelines to form brash methane ice, blocking the pipes if production were to stop. Ensuring good flow in the pipelines is critical, so Hydro’s solution is to add continuous anti-freeze at the wellheads to prevent the well stream freezing. The anti-freeze will be separated out and reused when it arrives onshore.
2. Mountainous seabed topography, requiring difficulty routing of pipelines through peaks that rise between 90 feet and 180 feet. The pipelines must be routed through this rocky underwater landscape in such a way that unsupported pipe spans don’t become too long, allowing unacceptable vibrations, or ensnare fishing trawler’s nets.
3. Some of the strongest underwater currents anywhere in the world, and some of the stormiest weather conditions.
4. Requirement for well stream pipelines to ascend an 1800 feet high underwater cliff created by the massive Storegga Landslide 7,000 years ago.
Danger of Commercial Drilling of Methane Fields, Seafloor Destabilization, and Tsunamis
Before Norsk Hydro began its commercial production of methane gas, it obtained expert risk analysis of the probability that drilling and removing methane gas would destabilize the seafloor, cause more landslides, and huge tsunamis. The experts concluded that this would not happen. (4)

Sources:

1. US Department of Energy and Office of Fossil Energy: “A Strategy for Methane Hydrates Research and Development,” p. 10, at: http://www.netl.doe.gov/scngo/NaturalGas/hydrates/...; accessed November 26, 2005.

2. Ibid, p. 1.

3. University of Wisconsin: “Chemical of the Week: Methane” at: http://scifun.chem.wisc.edu/chemweek/methane/metha...; accessed November 26, 2005.

4. The Tsunami Initiative: “Tsunami Risk in the Northeast Atlantic: The Storegga Slides.” At: http://www.nerc-bas.ac.uk/tsunami-risks/html/HSE1S...; accessed November 26, 2005.

5. Dan Evans: The BGS deep-two boomer meets the Storegga Slide” in The Edinburgh Geologist, Issue no. 28, Autumn 1995, available at: http://www.edinburghgeolsoc.org/z_28_04.html; accessed November 26, 2005.

6. JP Foucher: “Fluid Escape Structures on the Storegga Slope.” Geophysical Research Abstracts. European Geophysical Society, 2002. Available at: http://www.cosis.net/abstracts/EAE03/11149/EAE03-J...; accessed November 26, 2005.

7. “Hydro” website: “Boiling tea with gas from chilly seas” at: http://www.hydro.com/en/press_room/features/ormen_...; accessed November 26, 2005.

Volatile Methane Ice Could Spark More Drilling Disasters

Energy companies used to avoid methane hydrates no matter what. Now the industry may be drilling right into danger.

By Eric Niiler
Wed May 12, 2010 07:00 AM ET
(7) Comments | Leave a Comment
THE GIST
  • BP, Transocean and Halliburton are placing the blame for the disaster on each other.
  • The rush to produce more oil has led companies to take more risks, including drilling in areas with methane hydrates.
  • Methane hydrates could make the seafloor unstable, or turn into methane gas and ignite the rig.
Deepwater Horizon
enlarge

Fire boat response crews battle the blazing remnants following an explosion on the offshore oil rig Deepwater Horizon. Click to enlarge this image.
AP Photo

The blame-game has reached hurricane force.

On Capitol Hill, executives from BP, Transocean and Halliburton are pointing fingers at each other, while in Louisiana, Coast Guard officials are grilling lower-level managers from the same companies. But the rush to figure out went went wrong from an engineering perspective misses the bigger picture, experts say.

WIDE ANGLE: Get all the latest news and information about the massive oil spill threatening wetlands and wildlife on the Gulf Coast.

The decision by BP and many other energy companies to drill through areas of unusual ice-like crystals -- called methane hydrates -- is a risky one fraught with huge consequences for failure.

"Methane hydrates are a geological hazard, and it's been well established for decades that they are dangerous," said Richard Charter, head of the Defenders of Wildlife marine program and member of the Department of Energy's methane hydrates advisory panel. "Until 10 or 15 years ago, the industry would avoid them no matter what."

Now, Charter said, the rush to produce more oil for domestic consumption has forced companies like BP to take bigger risks by drilling in deep waters that are a breeding ground of hydrates. And they worry that a new drilling push into the Arctic Ocean -- which President Barack Obama has authorized to begin next month -- could expose a fragile and remote environment to additional risks from catastrophic oil spills.

oil spills
WATCH VIDEO: In the hours before the Gulf oil spill hit the Louisiana Coast, James Williams discovered what Gulf Coast experts were most worried about.

Related Links:




Methane hydrates only exist in cold water -- just above or below freezing -- and at the undersea pressures found in deep water off the continental shelf. "It's a lot like ice," said William Dillon, a retired marine geologist with the U.S. Geological Survey in Woods Hole, Mass. "The conditions that form them exist at the seafloor and in the sediments below."

This slushy mixture of sea water and methane gas makes drilling more complicated. For one, the presence of methane hydrates in sediment makes the seafloor unstable. That's why BP was using a high-tech drilling rig that was positioned like a helicopter on the surface.

And if hydrates are warmed by oil moving through pipes, they can turn into methane gas (known as "kicks" to drillers) that can shoot back up the drilling pipe and ignite the rig. Investigators are already focused on that scenario as a possible cause of the blast aboard the Deepwater Horizon rig on April 20.

Several marine geologists told Discovery News that the location of methane hydrate fields are well-mapped by petroleum companies and the Minerals Management Service, which regulates the industry. Researchers aboard scientific drilling ships say they avoid methane hydrate fields because of the inherent risks.

In 2003, Unocal abandoned plans to drill in the deep water off Indonesia for the same reason. China has delayed plans for offshore oil development after finding large hydrate fields, but many industry officials say they can engineer proper safeguards.

Arthur Johnson heads up Hydrate Energy International, a firm dedicated to exploiting the potential energy source of hydrates based in Kenner, La. He doesn't believe that they caused the blast.

"Based on everything I've seen, there's no way naturally-occurring hydrates had anything to do with loss of the well," Johnson said.

Methane hydrates only exist 3,000 to 5,000 feet below the seafloor, Johnson said. The BP drill went down to 18,000 feet.

Robert Bea, a civil engineering professor at the University of California, Berkeley, and oil industry consultant, disagrees. He's been interviewing workers who were aboard the rig before it blew and said the BP platform shut down several weeks before the accident because of hydrate problems.

"Whether it was either methane hydrate or gas, it doesn't really make a difference," Bea said. "It has unanticipated, undesirable effects. Based on my interviews and investigation, (methane) hydrate seeped into the core."

Bea and others say the industry's drilling and spill cleanup technology hasn't caught up with the economic imperative to produce more oil.

In June, Shell Oil plans a series of exploratory wells in the Beaufort and Chukchi Seas north of Alaska. That region is remote and lacks the kind of spill gear that is being deployed in the Gulf of Mexico. While the White House has delayed plans for oil drilling off the coasts of California and Virginia, the Alaska project is still on for now.

Eric Niiler is a freelance writer based in Washington, D.C.