[Coral-List] OTEC around coral reefs

Tue Jun 23 21:54:40 UTC 2020

Well "close to freezing" means different things to different people.  I was
thinking 4-6 C was "close to freezing."  Freezing for ocean salt water is
about -2.3 C.  For purposes of getting cold water for growing shrimp or
abalone, or air conditioning, or scuba diving 4-6 C is very cold indeed.
It is most of the way from surface temperatures like 27 or 28C down to -2.3
C.   For cooling corals to combat bleaching, it is very cold indeed, in
fact one would need to be mindful that it would kill corals if they were
reduced to that temperature.  As for depth, yes, I was wrong, though I did
say "600 feet or more".  But the point is, you can get water that is plenty
cold enough to do whatever people have proposed to do with it, if you have
deep water nearby.  You wouldn't need 4-6 C for many applications, I'd
think, unless maybe you want to grow Antarctic krill.  Will cost more for
piping to get to those depths, so if not needed, why put the pipe that far
down?  Some places the deep water is not close enough to land.  Cost of
piping is probably the main barrier, cost of pumping is trivial compared to
the heat energy that the water can absorb (the pumping cost is vastly
cheaper than the electricity needed to run air conditioning, but think of
the cost of running a full set of pipes to every building in a city like
Honolulu or Miami.  You'd have to tear the city up.  Prohibitive, not cost
effective.  There are two hotels in French Polynesia that use it for air
conditioning, and love it.   I note that there is a facility on the Big
Island in Hawaii that has long been trying to use the temperature
differential to produce energy.  My understanding is that they haven't been
able to do it in a commercially viable fashion yet.  They've been doing it
for quite a while (decades I think), it's not like they haven't been
trying.  That's  too bad, it is a huge source of energy.  Not everything is
commercially viable.     Cheers,  Doug

On Tue, Jun 23, 2020 at 7:31 AM Dennis Hubbard <dennis.hubbard at oberlin.edu>
wrote:

> Doug:
>
> When we made Alvin dives off the north coast of St. Croix, the temperature
> registered on the sub's thermistor read WELL above freezing until we were
> WELL beyond 2000 meters. I can't easi;y get to my notes due to Covid, but
> the temperatures weren't particularly low (or the nutrients particularly
> high - Susan Williams participated in the project) until we got a lot
> deeper (remember - no Gulf Stream).
>
> Denny
>
> On Tue, Jun 23, 2020 at 8:18 AM Douglas Fenner via Coral-List <
> coral-list at coral.aoml.noaa.gov> wrote:
>
>> I bet if you go deep enough (likely 600 feet or more) it will be close to
>> freezing.  That's true of most all of the world's oceans, so far as I know
>> (with exceptions such as shallow continental seas such as the
>> Arabian/Persian Gulf which has a maximum depth of around 295 feet).
>>
>> On Mon, Jun 22, 2020 at 3:10 AM Melbourne Briscoe via Coral-List <
>> coral-list at coral.aoml.noaa.gov> wrote:
>>
>> > "Cold" water near Bonaire isn't very cold. Efficiency is going to be
>> very
>> > low.
>> >
>> > On Thu, Jun 18, 2020 at 2:22 PM Alina Szmant via Coral-List <
>> > coral-list at coral.aoml.noaa.gov> wrote:
>> >
>> > > Eric: with deep cold water comes nutrients.  Be concern about local
>> algal
>> > > blooms.
>> > >
>> > >
>> > >
>> > > Sent from my Samsung Galaxy smartphone.
>> > >
>> > >
>> > >
>> > > -------- Original message --------
>> > > From: "Meesters, Erik via Coral-List" <coral-list at coral.aoml.noaa.gov
>> >
>> > > Date: 6/17/20 8:36 AM (GMT-05:00)
>> > > To: coral-list at coral.aoml.noaa.gov
>> > > Subject: [Coral-List] OTEC around coral reefs
>> > >
>> > > Hi all,
>> > > There are now plans for an OTEC facility on Bonaire.
>> > >
>> > > It basically means pumping up cold water from the deep to cool things
>> and
>> > > discharging warmer water (often shallower).
>> > >
>> > >   *   Here are some examples: https://nelha.hawaii.gov/
>> > >   *   http://otecokinawa.com/en/OTEC/WaterUses.html
>> > >
>> > > I can think of a lot of doomsday scenarios, but I'm looking for
>> reports,
>> > > assessments, thoughts, advice.
>> > > Does anyone have experiences with OTEC facilities in the
>> neighbourhood of
>> > > coral reefs?
>> > > it's often presented as the goose with the golden eggs, and
>> governments
>> > > seem to fall for it easily, but apart from glossy sales talks, I can't
>> > find
>> > > objective reports or EIAs.
>> > > Thanks for your responses.
>> > > Best wishes,
>> > > Erik Meesters
>> > > Wageningen Marine Research
>> > >
>> > > _______________________________________________
>> > > Coral-List mailing list
>> > > Coral-List at coral.aoml.noaa.gov
>> > > https://coral.aoml.noaa.gov/mailman/listinfo/coral-list
>> > > _______________________________________________
>> > > Coral-List mailing list
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>> > >
>> > _______________________________________________
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>> >
>>
>>
>> --
>> Douglas Fenner
>> Lynker Technologies, LLC, Contractor
>> NOAA Fisheries Service
>> Pacific Islands Regional Office
>> Honolulu
>> and:
>> Consultant
>> PO Box 7390
>> Pago Pago, American Samoa 96799  USA
>>
>> "mitigating climate change is the critical wedge to set coral reefs on a
>> recovery trajectory"  Duarte et al 2020 Rebuilding marine life Nature
>>
>> "Already, more people die  <http://www.nws.noaa.gov/om/hazstats.shtml
>> >from
>> heat-related causes in the U.S. than from all other extreme weather
>> events."
>>
>>
>>
>> https://www.npr.org/2018/07/09/624643780/phoenix-tries-to-reverse-its-silent-storm-of-heat-deaths
>>
>>
>> Even 50-year old climate models correctly predicted global warmng
>>
>> https://www.sciencemag.org/news/2019/12/even-50-year-old-climate-models-correctly-predicted-global-warming?utm_campaign=news_weekly_2019-12-06&et_rid=17045989&et_cid=3113276
>>
>> "Global warming is manifestly the foremost current threat to coral reefs,
>> and must be addressed by the global community if reefs as we know them
>> will
>> have any chance to persist."  Williams et al, 2019, Frontiers in Marine
>> Science
>> _______________________________________________
>> Coral-List mailing list
>> Coral-List at coral.aoml.noaa.gov
>> https://coral.aoml.noaa.gov/mailman/listinfo/coral-list
>>
>
>
> --
> Dennis Hubbard
> Chair, Dept of Geology-Oberlin College Oberlin OH 44074
> (440) 775-8346
>
> * "When you get on the wrong train.... every stop is the wrong stop"*
>  Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"
>

-- 
Douglas Fenner
Lynker Technologies, LLC, Contractor
NOAA Fisheries Service
Pacific Islands Regional Office
Honolulu
and:
Consultant
PO Box 7390
Pago Pago, American Samoa 96799  USA

"mitigating climate change is the critical wedge to set coral reefs on a
recovery trajectory"  Duarte et al 2020 Rebuilding marine life Nature

"Already, more people die  <http://www.nws.noaa.gov/om/hazstats.shtml>from
heat-related causes in the U.S. than from all other extreme weather events."

https://www.npr.org/2018/07/09/624643780/phoenix-tries-to-reverse-its-silent-storm-of-heat-deaths

Even 50-year old climate models correctly predicted global warmng
https://www.sciencemag.org/news/2019/12/even-50-year-old-climate-models-correctly-predicted-global-warming?utm_campaign=news_weekly_2019-12-06&et_rid=17045989&et_cid=3113276

"Global warming is manifestly the foremost current threat to coral reefs,
and must be addressed by the global community if reefs as we know them will
have any chance to persist."  Williams et al, 2019, Frontiers in Marine
Science