Thanks Peter. However, you don't address whether pumping water into sealed tubes or greenhouses would be viable.
Deep water isn't that deep - water for my toilet is pumped much further. As long as the water lifted was kept away from the atmosphere and surface ocean, it should be effective at fertilization of algae without releasing CO2 A On 15 Sep 2017 18:15, "Peter Flynn" <pcfl...@ualberta.ca> wrote: > This prompts several comments, and apologies for the delay and to those > for whom this is too basic: > > > > 1. The ocean can be thought of as two relatively independent bodies of > water, the shallow and deep ocean. There is a fairly sharp boundary between > the two, called the thermocline. Transfer between the two is limited, as > discussed below. Once something in solution is in the deep ocean, on > average its residence time before getting to the shallow ocean is 600 to > 1000 years. This is an average; there are regions of the ocean where > circulation between the deep and shallow ocean is very limited, and the > site specific residence time is longer. > > > > The deep ocean is cold and dense. Mixing with the shallow ocean is > energetically difficult because of the energy required to move a dense > element up against gravity across the thermocline into a less dense zone. > > > > 2. The interaction between shallow and deep is limited to downwelling and > upwelling currents. There are two major zones of downwelling current, a > zone in the north Atlantic called the GIN (named for its proximity to > Greenland, Iceland, and Norway) and a zone in the Antarctic by the Weddell > Sea. The GIN downwelling current is called the North Atlantic Deep Water > (NADW), and is the countervailing flow to the Gulf Stream. Downwelling is > driven by a combination of temperature and high salinity (the high salinity > is in part driven by evaporation in the Mediterranean Sea, a current from > which joins the Gulf Stream). NADW and the companion Gulf Stream were > interrupted for about 1200 years when Lake Agassiz, a glacial fresh water > lake in North America, flowed into the Atlantic after an ice dam melted. > The result was a 1200 year European cold period known as the Younger Dryas. > > > > Europe has centers of high population at latitudes higher than any other > region on the globe; the Gulf Stream is credited for enabling this. One > concern cited about global warming is that melting of Greenland ice could > interrupt the NADW / Gulf Stream again: the irony is that an early product > of global warming could be a European “ice age”. > > > > 3. Songjian Zhou and I looked at whether one could move CO2 from the > atmosphere into the deep ocean by increasing the concentration of CO2 in > NADW. Our answer was no: the surface water descending into the NADW was > saturated in CO2. But the deep ocean is not saturated in CO2, because of > its higher pressure. > > > > 4. Hence discussion of moving deep ocean water into the shallow ocean > baffles me. Yes: it contains nutrients. But it also contains CO2, which > would flash as the pressure dropped and temperature increased. It strikes > me that we should think of the deep ocean as the sink for CO2, not a source > of a “fix”. Any plan to use the nutrients in the deep ocean to grow marine > biomass to be sunk into the deep ocean (or utilized as biofuel) would have > to be carefully tested against the CO2 release. > > > > 5. Glen Tichkowsky and I looked at a scheme in which ocean side pools of > sea water would be used to grow algae. Evaporation would increase the > salinity of the pond to a point where the water could be moved as a batch > into the deep ocean without pumping. The rate limiting step, by an order of > magnitude, was the rate of transfer of CO2 from atmosphere to ocean; it was > sufficiently slow to make the cost of carbon sequestration by this scheme > prohibitive. I understood after this work why commercial algae growing > operations often include agitation (to enhance mass transfer) or CO2 > injection. Transferring CO2 into solution is well served by a higher > concentration, e.g. flue gas. > > > > I hope this is helpful. > > > > Peter > > > > Peter Flynn, P. Eng., Ph. D. > > Emeritus Professor and Poole Chair in Management for Engineers > > Department of Mechanical Engineering > > University of Alberta > > peter.fl...@ualberta.ca > > cell: 928 451 4455 <(928)%20451-4455> > > > > > > > > > > > > > > > > *From:* kcalde...@gmail.com [mailto:kcalde...@gmail.com] *On Behalf Of *Ken > Caldeira > *Sent:* Monday, September 11, 2017 7:03 AM > *To:* Geoengineering <Geoengineering@googlegroups.com> > *Subject:* [geo] SOS 2017 Session spotlight 4 - Ocean NETs - CO2 > Sequestration Via Ocean-Based Negative Emissions Technologies > > > > fyi > > > > [image: > http://sable.madmimi.com/view?id=37127.2887543.1.7549b994549320031d05f495dbf42a2e] > > Sustainable Ocean Summit 2017 SESSION SPOTLIGHT Ocean NETs: CO2 > Sequestration Via Ocean-Based Negative Emissions Technologies (NETs) The > Internatio > > > > [image: SOS2017 bannerRegistrationOpen 600x150px] > <http://sable.madmimi.com/c/37127?id=2887543.2303.1.c94303a2dc2c5c07d90790b5f2ba98d4> > > > Sustainable Ocean Summit 2017 SESSION SPOTLIGHT > <http://sable.madmimi.com/c/37127?id=2887543.2304.1.a0bb2736e6402dc798ad4baa8e92c3d4> > > > > [image: ***] > > > Ocean NETs: CO2 Sequestration Via Ocean-Based Negative Emissions > Technologies (NETs) > > > > [image: Screen Shot 2017-09-08 at 21.10.24] > <http://sable.madmimi.com/c/37127?id=2887543.2305.1.93a67d8d56ade51b064a6de73b758487> > > > > The International Climate Agreement (Paris 2015) requires negative > emission technologies (NETs) to remove carbon dioxide from the atmosphere > in order to meet planetary safe limits. NETs need to transfer carbon from > the atmosphere to a safe and environmentally sound storage. Developing and > implementing NETs are critical to all industries with a carbon footprint > who already or will in the near future have a price on their carbon output. > > Although there is much attention to potential land based NETs, there is > growing evidence that the ocean is the dominant player in global carbon > cycling and storage and in the planet’s temperature regulation. This means > that ocean-based NETs must be given serious consideration for their > potential to make a significant contribution to climate mitigation. > > Chemical and biological Ocean NETs are being explored, including: ocean > alkalinity shifts (introducing bicarbonates), direct CO2 injection (seabed > and water column), growing seaweed for deep ocean deposition, expansion of > coastal ecosystems that store carbon, adjusting ocean primary productivity > (e.g. artificial upwelling, addition of macronutrients nitrogen and/or > phosphorus, addition of trace elements such as iron and silicon, enhanced > light penetration, promoting the growth of nitrogen fixing cyanobacteria). > > Researchers, private enterprises and public bodies exploring Ocean NETs > coordination could benefit from a structure and process to enhance > coordination and exchange. 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