Hi All
A problem with pumping cold water up to the surface is that it will sink
quite fast.
Kaye and Laby give the density of 3.5% salinity water at 5 C as 1027.68
and at 25 C as 1023.34 kg/m3
We can work out the drag on various shapes of object and find the
velocity which gives a drag force equal to the buoyancy deficit.
For a 1 metre diameter sphere I make this 0.65 metres a second and a
more likely shape would be a torpedo nose down with less drag and an
even higher velocity.
It seems better to pump warm surface water down, let it mix with cold
water and then rise to a level set by the density of the mixture which
we can control. This allows the pipe to have a small positive pressure
so it can be made of thin plastic with no hoop rigidity.
If the method ends up warming because of reduced cloud cover why not use
an amount which will offset the increase of cloud cover due to the
expected increased evaporation?
We need lots of different tools in harmony.
Stephen
Emeritus Professor of Engineering Design. School of Engineering,
University of Edinburgh, Mayfield Road, Edinburgh EH9 3DW, Scotland
[email protected], Tel +44 (0)131 650 5704, Cell 07795 203 195,
WWW.homepages.ed.ac.uk/shs, YouTube Jamie Taylor Power for Change
On 15/09/2017 16:03, Ken Caldeira wrote:
Folks,
To point out the obvious, the results of Kwaitkowski et al may or may
not scale to smaller deployments, and the effects of smaller
deployments are likely to be regionally dependent.
I have been wanting to look at combined climate / energy implications
of widespread deployment of OTEC facilities.
If anyone knows of an exceptional candidate for a postdoctoral
position in my group interested in pursuing these questions, please
send them my way. (If someone is merely capable of conducting this
investigation, I am not interested in hiring them.)
Best,
Ken
/Ken Caldeira/
*Carnegie Institution for Science*
Dept of Global Ecology
260 Panama St
Stanford CA 94305 USA
+1 650 704 7212
http://CarnegieEnergyInnovation.org
http://dge.stanford.edu/labs/caldeiralab
Assistant, with access to incoming emails: Jess Barker
[email protected] <mailto:[email protected]>
On Wed, Sep 13, 2017 at 3:34 AM, Chris Vivian
<[email protected] <mailto:[email protected]>>
wrote:
There are also the papers by Oschlies et al 2010 and Yool et al
2009 that are quoted in the Kwiatowski et al 2015 paper. Copies of
these papers attached.
Chris.
On Tuesday, September 12, 2017 at 12:30:42 AM UTC+1, Andrew
Lockley wrote:
https://www.sciencedaily.com/releases/2015/03/150319143337.htm
<https://www.sciencedaily.com/releases/2015/03/150319143337.htm>
Geoengineering proposal may backfire: Ocean pipes 'not
cool,' would end up warming climate
Date:
March 19, 2015
Source:
Carnegie Institution
Summary:
There are a variety of proposals that involve using
vertical ocean pipes to move seawater to the surface from
the depths in order to reap different potential climate
benefits. One idea involves using ocean pipes to
facilitate direct physical cooling of the surface ocean by
replacing warm surface ocean waters with colder, deeper
waters. New research shows that these pipes could actually
increase global warming quite drastically
On 12 Sep 2017 00:21, "Robert Tulip" <[email protected]>
wrote:
Dear Andrew
Thank you very much for bringing this potential problem
with Deep Ocean Water as an algae nutrient source to
attention. I would like to find out more about the
possible mechanism that you allude to. I looked again at
the 2005 IPCC paper on Ocean Storage
<https://www.ipcc.ch/report/srccs/> led by Professor
Caldeira but did not find anything to support your
reference. If more recent work shows that raising DOW
could cause warming I would like to see it. I am
following up other responses to my comments directly with
their authors.
Robert Tulip
------------------------------------------------------------------------
*From:* Andrew Lockley <[email protected]>
*To:* Robert Tulip <[email protected]>; geoengineering
<[email protected]>
*Sent:* Friday, 8 September 2017, 10:47
*Subject:* Re: [geo] Carbon budget/removal in NYTimes
interactive
Caldeira et al showed that moving water in this way causes
warming.
A
On 8 Sep 2017 00:15, "'Robert Tulip' via geoengineering"
<[email protected]> wrote:
Thanks Cristoph.
Deep Ocean Water, with volume about a billion cubic
kilometres below the thermocline, has about three ppm
nitrate and phosphate, about 3000 cubic kilometres of
each, as I understand the numbers. Tidal pumping
arrays along the world's continental shelves could
raise enough DOW to the surface, mimicking natural
algae blooms, to fuel controlled algae production at
the scale required for seven million square kilometres
of factories. Piping CO2 from power plants etc out to
ocean algae farms could clean up all the polluted air
of the world.
Robert Tulip
------------------------------------------------------------------------
*From:* Christoph Voelker <[email protected]>
*To:* geoengi...@googlegroups. com
*Sent:* Friday, 8 September 2017, 8:43
*Subject:* Re: [geo] Carbon budget/removal in NYTimes
interactive
I must admit that I am getting skeptical when I hear
numbers in that order of magnitude:
The total net primary production in the oceans
presently is about 50 Gt carbon, and 80% of that is
converted back into inorganic carbon (and nutrients)
by heterotrophs before it gets a chance to sink out
from the sunlit upper layer of the ocean. The roughly
10 Gt carbon (some newer works even estimate just 6 Gt
carbon) that sink out have to be balanced by the
upward mixing of nutrients (and a little bit by
atmospheric deposition of bioavailable nitrogen and
phosphorus) in the Redfield ratio of about 106:16:1 of
C:N:P.
So, if you want to remove 20 Gt carbon per year from
the atmosphere, you'd have to increase the nutrient
supply to the total surface ocean by a factor of
three, maybe four. Maybe I am a bit too pessimistic
here, because there are species like Sargassum which
have a higher C:N:P ratio than the average
phytoplankton, so you get somewhat more carbon per
nitrogen/phosphorus. But even if it is just doubling,
I can't imagine that you can sustain such a nutrient
consumption by fertilizing from outside the ocean
(especially since phosphorus is scarce already now),
you'd have to tap into the inorganic nutrients stored
in the deep ocean. How long can you do that?
If we assume that we harvest all the 20 Gt carbon in
algae from these factories and do something durable
with them (to minimize lossed through heterotrophy and
problems with creating oxygen minimum zones), we
effectively remove nitrogen/phosphorus from the ocean.
How much is that per year?
Let us for simplicity assume Redfield ratios, I grant
errors by a factor of two or so. 20 Gt carbon then
corresponds to (20 g/12(g/mol)/6.625(molC/molN))*
1.0e15 or about 2.5e14 mol nitrogen. The ocean has a
volume of 1.33e18 m^3, and the average concentration
of available nitrogen (mostly nitrate) is 30
micromol/L or mmol/m^3 (calculated from the world
ocean atlas), most of that is in the deep ocean. This
gives a total inventory of 4.0e16 mol nitrogen. 2.5e14
mol/year is thus more than half of a percent of the
total available nitrogen in the world oceans, which
means you could try that for about 150 years, then
everything is gone At that pace, nitrogen fixers are
unlikely to resupply the loss (nowaday, the residence
time of nitrogen is roughly 5000 years), and they can
do that only for nitrogen, not for phosphorus anyway.
Letting technological problems aside (like: How do you
move 2.5% of the total nitrogen in the world oceans
evry year up to an area 2% of the ocean surface) I
would call the whole idea - at least that the scale
suggested - a prime example of an unsustainable process.
Best regards,
Christoph Voelker
On 07.09.17 23:37, 'Robert Tulip' via geoengineering
wrote:
The assumption behind the NYT interactive model
<https://www.nytimes.com/interactive/2017/08/29/opinion/climate-change-carbon-budget.html?action=click&pgtype=Homepage&clickSource=story-heading&module=opinion-c-col-right-region®ion=opinion-c-col-right-region&WT.nav=opinion-c-col-right-region>
that the upper bound for carbon removal is 12 GT CO2
by 2080 is too slow and small. We should think five
times as much and five times as fast.
Immediate aggressive investment to build industrial
algae factories at sea could remove twenty gigatons of
carbon (50 GT CO2) from the air per year by 2030,
using 2% of the ocean surface, funded by use of the
produced algae.
That would stabilise the climate and enable no change
in emission trajectories, a policy result that would
satisfy both the needs of the climate and the
traditional economy.
Robert Tulip
------------------------------------------------------------------------
*From:* Eric Durbrow <[email protected]>
*To:* geoengineering <geoeng...@googlegroups. com>
*Sent:* Thursday, 7 September 2017, 3:13
*Subject:* [geo] Carbon budget/removal in NYTimes
interactive
FYI There is a slick interactive graphic at the
NYTimes that lets people see if they can meet the
world’s carbon budget restriction but a combination of
reduced emissions AND achieving Carbon Removal.
At
https://www.nytimes.com/ interactive/2017/08/29/
opinion/climate-change-carbon-
budget.html?action=click& pgtype=Homepage&clickSource=
story-heading&module=opinion-
c-col-right-region®ion=
opinion-c-col-right-region&WT.
nav=opinion-c-col-right-region
<https://www.nytimes.com/interactive/2017/08/29/opinion/climate-change-carbon-budget.html?action=click&pgtype=Homepage&clickSource=story-heading&module=opinion-c-col-right-region®ion=opinion-c-col-right-region&WT.nav=opinion-c-col-right-region>
I failed after clicking on Reduce in all geographic
areas and Achieve in Carbon Removal.
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Alfred Wegener Institute for Polar and Marine Research
Am Handelshafen 12
27570 Bremerhaven, Germany
e:[email protected]: +49 471 4831 1848
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