Post on 15-Jan-2016
Clathrate Hydrate
But First…
http://i.treehugger.com/images/2007/10/24/methane%20clathrate-jj-001.jpg
Papers
• Double spaced• 12 point font• 1” margins• Your own words (I
already read the reading assignment and I am familiar with the internet, so I don’t want you to make me read it again)
• I REALLY want to read what YOU think
http://bitsnbytesoflife.files.wordpress.com/2008/10/plagiarism1.jpg
Clathrate Hydrate
And Global Warming
http://i.treehugger.com/images/2007/10/24/methane%20clathrate-jj-001.jpg
What is a clathrate?
• A chemical substance consisting of a lattice of one type of molecule trapping and containing a second type of molecule
• clathrate is derived from the Latin clatratus meaning with bars or a lattice
http://focus.aps.org/files/focus/v4/st31/pic-v4-st31-1.gif
What is a clathrate?
• Consist of a host molecule (forming the basic frame) and
• A guest molecule (set in the host molecule by interaction)
http://en.wikipedia.org/wiki/Clathrate_hydrate
What is a clathrate hydrate?
• Crystalline water based solids physically resembling ice– "cages" of hydrogen
bonded water molecules
• Small non polar molecules (typically gases) trapped inside – low molecular weight
gases (including O2, H2, N2, CO2, CH4, H2S, Ar, Kr, and Xe), as well as some higher hydrocarbons and freons
http://chem.ps.uci.edu/~kcjanda/Group/images/4cages.jpg
Chemical or Physical?
• Without the support of the trapped molecules, the lattice structure of hydrate clathrates would collapse into conventional ice crystal structure or liquid water
http://i141.photobucket.com/albums/r71/sherbran/blog%20pictures/rust.jpghttp://www.freewebs.com/ayxl/magnet.jpeg
Methane
• Carbon’s molecular number is 6
• “Wants” 4 electrons in the valence shell
• Methane molecule is formed by one carbon atom and 4 hydrogen atoms – CH4
http://www.energy.gov.ab.ca/NaturalGas/graphics/NGC_Molecule.jpghttp://www.hk-phy.org/articles/laser/c-atom_e.gif
Greenhouse Gases (GHG)
• Greenhouse gases are in an atmosphere that absorb and emit radiation within the thermal infrared range
• Greenhouse gases are molecules of a compound
http://searchwarp.com/UserImages/102016/about-infrared-image.jpg
Global Warming Potential
• Measure of how much a given mass of greenhouse gas is estimated to contribute to global warming – Compares the gas in
question to that of the same mass of carbon dioxide (whose GWP is by definition 1)
– calculated over a specific time interval
http://www.nysforum.org/documents/html/2007/execcommittee/may/enterprisepowerconsumptionreduction_files/images/image6.png
Methane
• Properties of methane– 2CH4 + 3O2
2CO2 + 2H2O
– high global warming potential
• of 72 (averaged over 20 years) or
• 25 (averaged over 100 years)
– atmospheric half life of 7 years
spark
http://scienceguy288.files.wordpress.com/2008/01/cow.gifhttp://www.school-for-champions.com/chemistry/images/hydrocarbon-methane.gif
Methane
• Properties of methane (cont.)– Methane is the
major component of natural gas, about 87% by volume
– At room temperature and standard pressure, methane is a colorless, odorless gas
C CCH
H
http://en.wikipedia.org/wiki/Methane
Methane
• Properties of methane (cont.)– Methane has a boiling
point of −161 °C at a pressure of one atmosphere
– 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)
http://www.pnl.gov/science/images/highlights/cmsd/oil_welllg.jpghttp://www.citycollegiate.com/methane2.gif
Methane
• The abundance of methane in the Earth's atmosphere in 1998 was 1745 parts per billion, up from 700 ppb in 1750
• Still increasing
http://climateprogress.org/wp-content/uploads/2008/04/methane2.jpghttp://www.windows.ucar.edu/earth/Atmosphere/images/methane_atmosph_concentr_1984_2004_big.gif
Methane as a GHG
• Methane traps over 21 times more heat per molecule than carbon dioxide
• Expected to cause between 15 and 17% of the global warming over the next 50 years
http://www.eia.doe.gov/oiaf/1605/archive/gg97rpt/gifs/fig07.gif
Sources of Methane
• Of the total estimated methane present, little less than half is naturally occurring
• Rice agriculture attributes from 8 to 29% of the total emissions
Wetlands (incl. Rice agriculture) 37Termites 3Ocean 3Hydrates 2Natural Total 45
Energy 18Landfills 7Ruminents (livestock) 19Waste Treatment 4Biomass Burning 7Anthropogenic Total 55
Origin
Natural Emissions
Anthropogenic Emissions
% CH4 Emission
Sources of Methane
• Cows are the number one source of methane (guess how!)– Eat low energy diet
that is impossible to break down
– Rely on “gut flora” to break down grass
– Bacteria live without oxygen
http://www.moonbattery.com/archives/farting-cow.jpg
Methanogenic Bacteria
• Anaerobic (oxygen is poison to them so they live in atmospheres without it – like guts)
• Belong to Archaea• About 50 different
species described • Methane is waste
product when breaking down molecules to harvest energy
http://www.preciseenergy.com/lookandfeel/images/bacteria/fig5.jpghttp://www.soi.wide.ad.jp/class/20070046/slides/02/img/46.png
We Have Them Too!
• They are responsible for the methane content of flatulence
• So the next time you toot, you can say, “Oh, please excuse my gut flora!”
http://microimm.queensu.ca/people/faculty/Jarrell%20Lab/methanogens_files/image005.jpghttp://www.dailyhaha.com/_pics/girl_farting_water.jpg
Methane Hydrate
• Methane Clathrate (or methane hydrate) is cage of ice trapping methane gas inside
• Found in deep oceans around the world
• Found frozen in permafrost tundra in Northern Hemisphere
• May be found in deep lakes (e.g. Lake Baikal)
• Antarctica?• Flammable Ice
http://www.randform.org/blog/wp-content/2007/01/Burning_hydrate_inlay_US_Office_Naval_Research.jpg
Methane Hydrate
• Naturally occurring
• Represent ~2% of world’s total methane
• Estimated 7.055 trillion tons (14 quadrillion lbs) of methane clathrates
http://upload.wikimedia.org/wikipedia/commons/f/f8/Methane_Clathrate_Location_Map_USGS.gif
Clathrate Gun Hypothesis
• Rise in sea temperature can trigger the sudden release of methane from methane clathrate
• Because methane is a powerful greenhouse gas, it will cause further temperature rise and further methane clathrate destabilization
• Initiating a runaway process
• Irreversible once started as the firing of a gun
http://aphriza.files.wordpress.com/2006/07/methane_seep.jpg
Runaway Greenhouse Effect
• Venus– Atmosphere is over
96% CO2
– Clouds predominantly sulfur dioxide (SO2) another GHG
– Pressure at surface is 92 times that of Earth, or 6.5 times that of water!
– Add heat to gas and pressure goes up
– Hottest planet 860°F
http://zuserver2.star.ucl.ac.uk/~idh/apod/image/0405/venus2_gal_big.gif
Runaway Greenhouse Effect
• Evidence that Venus’ atmosphere more like Earth’s several billion years ago with oceans
• Runaway greenhouse effect evaporated water, pumping more GHG’s into atmosphere
• Positive feedback
http://zuserver2.star.ucl.ac.uk/~idh/apod/image/0405/venus2_gal_big.gif
One more piece to go…
• How has the Earth changed in the past
• Then, we can start putting all the pieces together to build a better understanding of the complexity and predict the future
• Questions?
http://scotese.com/future2.htmhttp://scotese.com/newpage5.htm