Albert
If there is a pipe connection to the underside of the plastic the
pressure below the film will be close to atmospheric and it will be
clamped firmly down by several bar of water pressure. I can also get
some sand over the film.
I am more concerned about anoxic conditions of which I am totally
ignorant. Gases can come up from below. Maybe we could get a film with
some oxygen permeability. But if there is oxygen there now why is there
any methane?
I was going to design for 0.15 metre per second sea bed current.
Would you recommend any other value? I am working on a way to recover
the film later.
Stephen
Emeritus Professor of Engineering Design
Institute for Energy Systems
School of Engineering
Mayfield Road
University of Edinburgh EH9 3JL
Scotland
Tel +44 131 650 5704
Mobile 07795 203 195
www.see.ed.ac.uk/~shs
On 05/10/2011 18:58, Veli Albert Kallio wrote:
We need to consider carefully the plastic film, this could cause
anoxic conditions under the plastic sheet.
The shallow portion of Arctic Ocean is likely to develop large storm
surges and resulting currents as ocean becomes ice free. Every storm
surge on surface is maintained by reverse flow on bottom that could
pile up any plastics and cause hazards. Funnelling can only be
considered for spot like emissions, not if methane bubbles over large
areas.
The difficulty will be how to cope with monitoring and controlling if
there will be thousands of sites where methane is collected that are
sparsely distributed. Maintenance is a challenge.
> Date: Wed, 5 Oct 2011 10:31:28 +0100
> From: [email protected]
> To: [email protected]
> CC: [email protected]; [email protected]; [email protected];
[email protected]; [email protected];
[email protected]; [email protected];
[email protected]; [email protected]
> Subject: Arctic methane workshop: 15-16 October - Methane vents
>
>
> Dear Professor Westbrook,
>
> Thank you for your response about the width of the shelf margin.
> Stephen Salter is working on a method using large plastic sheets to
> funnel the methane bubbling up from across an area of the sea bed
into a
> concentrated stream, and then capturing it. But of course this
> funnelling can occur naturally, as one can see from the hundreds of
> underwater plumes that you have detected arising from the seabed of the
> West Spitzbergen continental margin [1]. Am I right that, at present,
> few of these plumes are reaching the surface? Is this because the water
> is sufficiently oxygenated for oxidation to occur within the water
> column? Is there a danger of this oxygen getting used up? But, if
> oxidation does continue, isn't there a danger of excessive ocean
> acidification, given the quantities of methane?
>
> Do you have any suggestions for how one might deal with the methane
> rising in a plume, to minimise the various associated hazards:
> greenhouse gas warming if it reaches the surface, deoxidation of water
> making it sterile, acidification of the water disrupting the marine
food
> chain that relies on shelled creatures, etc.?
>
> Best wishes,
>
> John
>
> Tel: +44 20 8742 3170
> Skype: john.nissen4
>
> P.S. I want as much brainstorming done before the meeting as possible,
> especially to involve people who might not be able to attend in person.
>
> [1] http://eprints.soton.ac.uk/64607/1/2009gl039191%2Baux.pdf
>
> ---
>
> On 03/10/2011 18:03, John Nissen wrote:
> >
> > Dear Professor Westbrook,
> >
> > A workshop has been arranged on the weekend 15-16 October in
Chiswick,
> > London W4, to see how to tackle the Arctic methane problem - in
> > particular how to prevent large quantities of methane reaching the
> > atmosphere and aggrevating global warming. For some years it has been
> > apparent that there is vast quantity of carbon locked up in
> > permafrost, which is liable to be released as methane as the Arctic
> > warms [1]. Global warming potential of methane is high but lifetime
> > is short, so the speed of discharge is very important to know.
> > Unfortunately recent evidence suggests that the Arctic warming is
> > accelerating, the Arctic Ocean could be seasonably ice free within a
> > few years, and there is already much methane venting taking place.
> > Therefore the situation appears extremely dangerous, and it is vital
> > that some plan of action is developed as quickly as possible. That is
> > the basic reason for the workshop.
> >
> > We had originally planned for the workshop to concentrate on the
> > methane from the East Siberian Arctic Shelf, ESAS, since Shakhova et
> > al claim that up to ~50 Gt of methane could be released "at any
> > moment" [2], e.g. if there were an earthquake (and the ESAS contains
> > an earthquake zone). However just in the last few days, I have seen
> > reports of high levels of methane in the upper atmosphere which could
> > have originated from shelf margins, and I came across a paper you
> > co-authored [3].
> >
> > I would be extremely grateful if you could come to the workshop, even
> > if only for part of one day (preferably Saturday 15th), to discuss
> > your work on the methane from shelf margins, which I see is one of
> > your main research topics [4].
> >
> > One of the main contributors to the workshop is a brilliant engineer
> > and inventor, Professor Stephen Salter, who has some ideas for
> > capturing methane underwater. He needs to know the conditions of the
> > shelf margins and distribution of venting over the field. For
> > example, what is the typical width of the shelf margin where the
vents
> > occur? In the paper [3], it is mentioned that 900 Kg of methane may
> > be emitted per metre of length of the shelf margin, but over what
width?
> >
> > Working in regions where there is sea ice is going to be a challenge,
> > so we have an expert on sea ice, Professor Peter Wadhams, coming to
> > the workshop. He is particularly concerned about the sea ice volume
> > decline, where the current trend suggests a zero volume for September
> > 2015 [5].
> >
> > BTW, some time ago I had asked Euan Nisbet to come to the workshop,
> > but unfortunately he is unable to attend. So I had been looking to
> > the PERGAMON project, and Jens Greinart, with his knowledge of
natural
> > gas venting. It now appears that he might not be able to attend
> > either. So your experience from the PERGAMON project could be very
> > valuable at the workshop.
> >
> > I apologise for the extremely short notice, but I look forward to
> > hearing from you.
> >
> > Kind regards,
> >
> > John (Nissen)
> >
> > College House,
> > Chiswick Mall,
> > London W4 2PR
> >
> > Tel: 020 8742 3170
> > Mob: 07890 657 498
> >
> > [1] http://www.aibs.org/bioscience-press-releases/resources/Schuur.pdf
> >
> > [2] Reported in http://en.wikipedia.org/wiki/Arctic_methane_release
> >
> > See also [2a] http://www.sciencemag.org/content/327/5970/1246.short
> > and [2b]
> >
http://earth.usc.edu/ftp/lund/BERING%20SEA%20EXP%20323/Uservol/Articles%20of%20interest/Eurasian%20Basin/Shakova%20and%20Semiletov%202007.pdf
> >
> > [3] http://eprints.soton.ac.uk/64607/1/2009gl039191%2Baux.pdf
> >
> > [4]
http://www.birmingham.ac.uk/staff/profiles/gees/westbrook-graham.aspx
> >
> > [5]
http://neven1.typepad.com/.a/6a0133f03a1e37970b015433129b3e970c-popup
> >
> > ---
> > [snip]
> >
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Scotland, with registration number SC005336.
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