I think definitely that we can prevent on-shore methane explosions,
and saturated methane laden water pockets that are approaching
nucleating point.
There are 3 types of methane leaking:
1) generic leaking of methane from melting permafrost over large
areas that provide widespread methane haze
2) spot type ongoing methane leaking from permaforst or onshore gas
fields that are losing their subterranean gas compression due to
ruptures.
3) explosive methane eruptions (methane clatrates, Lake Cheko's
conical basin gas field failure in Tunguska 1908 as river fell into
gas field and drove methane out).
No. 1 you cannot control. No. 2 depends on how big and focused the
leaking is, there are vast bubbling spots, in Azerbaijan there are
flaming mountains where gas comes out of rocks. These you can
control. No. 3 can be controlled by method of Professor Michel
Halbwachs. Often methane can be spotted as a very focused leak on sea
floor which might be possible to cap. So, I think the idea is valid
in certain cases, in other cases it may not be workable.
------------------------------------------------------------------------
Date: Mon, 25 Jul 2011 11:28:12 +0100
From: [email protected]
Subject: Re: Arctic methane workshop, London, 15-16th October CONFIRMED
To: [email protected]
John, I think you are on a hiding to nothing trying to trap or
destroy the methane.
The reason is simple - the emissions are spread over such a vast area
of many millions of sq.km. Even to trap and destroy the methane
emissions from 1sq.km would be a fantastically difficult and
expensive task.
So you can simplify things by just ruling this one out at the start!
Oliver.
--
Oliver Tickell
On 22/07/2011 18:29, John Nissen wrote:
Dear all,
In case you were not aware, the workshop, which was to have been
3-4th September, is now going to be on 15-16th October. Here is
the background and purpose of the workshop...
A group of scientists and engineers (including myself) is deeply
concerned about the potential of methane from thawing permafrost
in the Arctic to cause irreversible, catastrophic and
unsurvivable global warming. Major factors are the unexpectedly
rapid retreat of sea ice [1] and the unexpectedly large
quantities of carbon which might be emitted as methane [2]. In
June 2010 we wrote an open letter to Obama's scientific adviser,
Dr John Holdren, suggesting action was urgently needed to address
the methane issue [3]. Some sea ice experts, including
Professor Peter Wadhams in our group, now reckon the Arctic Ocean
will very likely become seasonably ice free this decade if there
is no action to cool the Arctic.
Recently Peter Wadhams has drawn my attention to work of Natalia
Shakhova with Igor Semiletov on East Siberian Arctic Shelf (ESAS)
- particularly concerning the present large emissions of methane
and the possibility of release of much larger quantities "at any
time". So we have been wondering whether anything can be done
quickly to reduce this methane threat. We have been discussing
possible action, and plan further brainstorming at a workshop in
October in London.
We are hoping this workshop will lead on to a pilot project to
trial the most promising techniques. Here is an extract from the
proposal, concerning management of the methane environment at the
local level (e.g. in ESAS):
[begin quote]
Approaches can be categorised according to where the intervention
action takes place.Where the methane is from lake or sea bed, the
action could be:
* below the permafrost, where there may already be methane or
methane hydrate;
* in the permafrost, or to plug gaps in the permafrost where
methane is rising;
* in the bed of the sea or lake, above the permafrost layer;
* in the water at the bottom of the sea or lake;
* at the surface of the sea or lake, and below any ice;
* at the point of emergence of methane into the atmosphere.
In the case of methane from wetlands, some of the above actions
would be relevant to ponds, commonly forming above permafrost and
emitting most of the wetlands methane.There is also the
possibility of pond drainage as a means to reduce methane emissions.
Returning to the case of lakes and deeper water, the problem with
trying to deal with methane below the permafrost is that any
disturbance is liable to trigger an eruption of methane through
gaps in permafrost known as taliks.Commercial methods of
extraction of natural gas can be used when there is in
impermeable layer above the gas, but cannot be applied in our
situation because of the danger either from puncture of the
permafrost or from enlarging existing taliks.
In the bed of the sea or lake there may be aerobic microbes,
capable of ‘digesting’ the methane and converting it into less
harmful products.Supply of oxygen and nutrients to such microbes
could be helpful.Microbes may also congregate in a ‘biotic layer’
at the bottom of the sea or lake.These could be boosted or
encouraged to proliferate.
Methane can dissolve in the water.At atmospheric pressure and
freezing point, 0.04 grams of methane will dissolve in a litre of
water.Therefore one approach could be to extract the water when
it is nearly saturated with methane.A more commercial approach
would be to use a specific methane solvent in a relatively heavy
layer, resting on the seabed (or lake bed).From time to time the
solvent would be extracted, scrubbed to remove the methane, and
replaced.A major issue could be containing the solvent and making
sure there was no long-term harm to the marine habitat.
A general problem with emissions of soluble gas from the beds of
lakes and shallow seas is that the water column can become
unstable – with the dissolved gases coming out of solution,
leading to a sometime violent upwelling.Because of the low
density of the rising column of bubble-filled water, ships on the
surface can sink!Furthermore any turnover of the water allows
warmer surface water to be transported towards the bottom, which
can lead to permafrost melt and enhanced methane production.Thus
any underwater approach to methane must take into account the
stability of the water column.
However if the methane is already bubbling to the surface, then
one could consider capturing it before it escapes into the
atmosphere.One way would be to use ice, which will anyway be
present in winter.The methane collects under the ice, and boring
through the ice, one could collect the methane that emerges.The
problem would be keeping an intact layer of ice throughout the
year.Therefore one might consider strengthening the ice to
produce ‘pykrete’ [3].However a more promising approach would be
to have mats, preferably of methane-absorbing substance
(biological or chemical) which could be harvested to collect the
methane.But care would be needed not to deplete oxygen from water
underneath the mats, since oxygen is required from the important
methane-digesting microbes in any biotic layer that has formed
above the sea or lake bed.
If and when some methane bursts into the atmosphere, it could be
burnt or ‘flared’.In remote areas, and in open water, this could
be problematic.Furthermore, methane only burns in air at between
5% and 15% concentration by volume.As it disperses quickly, one
would need to torch the methane within a few seconds of
eruption.It is almost impossible to imagine how this could be
done in a remote location, unless the methane is laser-zapped
from a monitoring satellite!
[end quote]
The pilot project will promote a three-prong attack, though
trials will focus on local action (particular item 2):
1. cooling the Arctic, regionally or locally, using SRM
geoengineering;
2. management of the methane environment at the local level (see
quoted text above);
3. capture or destruction of methane, already in the atmosphere.
The capture or destruction of methane in the atmosphere is a last
resort, if other approaches fail. It would also be vital if
there were a sudden large emission of methane with serious
warming potential.Such "air capture" or destruction could be
local or not. The advantage of local air capture is that
efficiency may be improved through having the methane at higher
concentration (as the efficiency is for CO2 air capture).
The workshop is intended as a brainstorming session to establish
the most promising techniques which might be trialled in the
pilot project. If you have already expressed an interest in
attending the workshop, please confirm that the new date is OK.
If you have not yet expressed an interest, and would like to
attend, let me know.
John Nissen
Chiswick, London W4
[1] Copenhagen Diagnosis, 2009
http://www.ccrc.unsw.edu.au/Copenhagen/Copenhagen_Diagnosis_LOW.pdf
see figure 13 page 30.
[2] Ibid, see page 21 - referring to Shuur et al 2008.
[3]
http://geo-engineering.blogspot.com/2010/06/sea-ice-loss-stuns-scientists.html
