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Brian,
Where does the “value of this fertility to mariculture is sixty-fold the value of the OTEC power produced” come from?
The deep oceanic waters also contain high levels of dissolved organic carbon that need to be taken into account in calculating the overall benefit of CO2 being removed by phytoplankton production.
Also,
Best wishes
Chris.
(https://www.rechargenews.com/wind/futuristic-multirotor-design-could-make-floating-wind-competitive-as-soon-as-2022/2-1-1021312 - notice that for French people like me, the Eiffel tower is a convenient reference for measuring a 300 m height)
To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAAoq7hL2_FNXDeLyoos_Rr65aR5DTwbRaULvTyWBYyh5jO1%2BUg%40mail.gmail.com.
And more to the point, deep nutrient rich waters contain much higher levels of dissolved CO2 than surface waters, because both come from the decomposition of that constant rain of phytoplankton, so deep water upwelling INCREASES CO2 flux to the atmosphere more than the phytoplankton blooms can remove.
Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance
Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.
Technical Advisor, Blue Guardians Programme, SIDS DOCK
37 Pleasant Street, Cambridge, MA 02139
gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)
Books:
Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase
http://www.crcpress.com/product/isbn/9781466595392
Innovative Methods of Marine Ecosystem Restoration
http://www.crcpress.com/product/isbn/9781466557734
No one can change the past, everybody can change the future
Anyway, I hope that studying such synergies more thoroughly could be fruitful for all the approaches of such an idea: DAC; hurricane control through angular momentum; and the broader trend about wind energy being harvested over high seas and converted through power-to-liquid schemes.
Best regards,
Denis Bonnelle.
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From: Tom Goreau <gor...@globalcoral.org>
Date: Wednesday, October 6, 2021 at 9:57 AM
To: Brian Cady <brianc...@gmail.com>, Andrew Lockley <andrew....@gmail.com>
Cc: Renaud de RICHTER <renaud.d...@gmail.com>, Carbon Dioxide Removal <carbondiox...@googlegroups.com>, geoengineering <geoengi...@googlegroups.com>, Denis Bonnelle <dbon...@ipsl.fr>
Subject: Re: [CDR] Possible synergies among DAC, renewable energy production and hurricane control.
Hurricanes cool down the water along the path of the eye by up to 4 degrees C by induced upwelling. Here is a thermograph from the two worst hurricanes to hit Grand Turk Island, three days apart (L. Wells, F. Perez, M. Hibbert, L. Clervaux, J. Johnson, & T. Goreau, 2010, Effect of severe hurricanes on Biorock coral reef restoration projects in Grand Turk, Turks and Caicos Islands, Revista Biologia Tropical, 58: 141-149).
Since the 1980s when coral reefs passed the tipping point for mass high temperature bleaching, we have noticed that passage of hurricanes cooled the water and prevented bleaching along their track.
However there is a negative side to this, the upwelling causes large amounts of nitrate and phosphate to reach surface waters, causing harmful algae blooms that smother and kill coral reefs.
Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance
Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.
Technical Advisor, Blue Guardians Programme, SIDS DOCK
37 Pleasant Street, Cambridge, MA 02139
gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)
Books:
Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase
http://www.crcpress.com/product/isbn/9781466595392
Innovative Methods of Marine Ecosystem Restoration
http://www.crcpress.com/product/isbn/9781466557734
No one can change the past, everybody can change the future
From: <carbondiox...@googlegroups.com> on behalf of Brian Cady <brianc...@gmail.com>
Date: Wednesday, October 6, 2021 at 6:19 AM
To: Andrew Lockley <andrew....@gmail.com>
Error! Filename not specified.
(https://www.rechargenews.com/wind/futuristic-multirotor-design-could-make-floating-wind-competitive-as-soon-as-2022/2-1-1021312 - notice that for French people like me, the Eiffel tower is a convenient reference for measuring a 300 m height)
Of course, there are some differences with DAC: here, this structure bears relatively few wind turbines, not DAC devices ; and it is floating on the sea - by the way, I had never assumed that the 1,000 DAC structures would be built onshore.
Offshore wind energy develops strongly due to various reasons, among which social acceptance and the possibility to reach better winds (stronger and less time-dependent). Both reasons reinforce each other: there are two ways of getting better winds: being at a higher altitude, and being over the ocean. But taller onshore wind turbines face more opponents, so that going offshore makes twofold sense to make wind energy at scale possible, even if it is quite more expensive by the MW (but, due to these better winds, not that more expensive by the MWh; and with a larger economic value as it needs less power back-up, or as it enhances the capacity factor of conversion devices which would use this power, such as electrolysers).
Offshore wind energy can be either "near offshore", linked to the shore by electric cables, or "high sea offshore". The mainstream idea is that the latter would be useful only through on-board "power-to-liquid" transformation, i.e. water electrolysis and use of the hydrogen to synthesize ammonia, methanol (using CO2), or synthetic jet fuel (using CO2 through Fischer-Tropsch reaction). The latter two are included in the "U" of CCUS that you, as CDR and DAC specialists, know well, at least for CCS. Of course, such on-board chemical plants would be strongly characterized by economies of scale, which is another argument on behalf of very large scales such as the 300 m x 300 m cross-section of the above drawing.
But why wouldn't wind energy developers design wind turbines with, at least, a 150 m radius and a 200 m tall tower, just extrapolating the current trends, and benefitting from the fact that, offshore, you no longer face the same political oppositions which, onshore, prevent them from such bold extrapolation?
The answer to this question is, again, about scale economies. So far, larger and larger wind turbines have proved cheaper by the MWh, but this is only thanks to the reduction of the relative part of some costs such as development costs, maintenance, balance of power, etc. But the hard physics of the wind turbine per se shows the contrary of scale economies. To harvest the wind from a x4 cross-section, i.e. from a x2 radius, you might think that a blade with a x4 area would be enough, but this is not all. This blade must also be thicker just to keep an unchanged geometry, and it must be even more mechanically reinforced, as all of the forces it endures are converted to torques by being multiplied by a "r" coordinate which now varies up to a doubled maximum radius. All this multiplies the required materials quantity by, at least, a x8 factor, and probably even more.
Until now (i.e. the record ≈ 10 MW wind turbines, with their blades slightly longer than 100 m and their towers above 150 m), the cost of this material wasn't the main part of wind energy's costs, but if you'd aim at, say, 200 m or 250 m long blades and a ≈ 300 m tall tower, this could be no longer true, which is a first reason why such a structure with "small" wind turbines would make sense.
The other reason could be that small wind turbine factories would face a shortage of clients, while being fully depreciated from an accountancy point of view, so that they would be able to propose wind turbines at very attractive prices, overall if somebody offers to buy them by the hundred.
What is the relation with DAC?
First, it proves that such giant cantilevered structures can make sense, notably when it comes to facing strong winds. The same about floating on the sea.
(I had made some further comparisons with a classical wind turbine, whose tower undergoes a strong torque due to a force parallel to its shaft. Having two towers arranged in sort of a quite vertical triangle, would be cheaper, provided that this triangle could always be in a plane including the wind's direction. This is impossible onshore, as the wind's direction isn't constant. But a floating structure can be oriented so that it always quite faces the wind. Maybe the figure above is also derived from such a comparison.)
Forces parallel to the wind would also exist if some or all of the wind turbines were substituted by DAC devices. Then, you can choose between two possibilities: being strongly anchored to the undersea ground, of being pushed by the wind and slowed down by a hydrokinetic turbine under the hull, which could produce some power, maybe cheaper than wind energy, as the water is denser than the air so that smaller "blades" can be used.
When such structures are dedicated to power production for usual onshore needs, either case (anchored structure or hydrokinetic turbine) but even more the latter, imply on-board conversion of this power. I have already discussed power-to-liquid, through water electrolysis and synthesis reactions, but DAC could be an interesting use of such power, with liquid or solid CO2 as an output. Notably, it could be useful as a first "proof of concept" of the idea of producing offshore power from high sea winds, and using it onboard to generate dense chemicals, with no need of handling them too often to their final users.
When such mobile floating structures are pushed by the winds, a force appears, which means a momentum exchange. In the global momentum balance, this exchange is between the air and the water. This could be useful for hurricane control.
A basic idea for hurricane control is that tapping some wind energy from it reduces its kinetic energy, thus its devastating power, and this idea has been developed in, e.g., "Taming hurricanes with arrays of offshore wind turbines", a very interesting paper by Cristina Archer, Mark Jacobson and Willett Kempton, which compares the economic values of the power produced by these wind turbines throughout the year, and of the reduction of the hurricane's damage.
However, this paper only deals with near offshore wind turbines, built on shallow undersea ground off the US southern and eastern shores (so that no control of the hurricane farther from these coasts is possible), and it only deals with kinetic energy exchanges, not momentum ones.
Momentum exchanges are not interesting per se, but because they control a much more powerful lever about hurricanes: angular momentum exchanges.
Even if the physics of hurricanes is very complex, the idea of reducing their angular momentum exchanges to control them is emphasized by the fact that they can't appear too close to the Equator, which proves that angular momentum is vital for them, and this is logical: a very powerful hurricane needs a very low pressure in all its quite central air stormy cylinder, which must attract new air only at its bottom in order to harvest the ocean's latent heat; at all the other altitudes, there must be something to protect this low pressure cylinder from anarchic air inlets from the outside, and this something is the centrifugal force (and an increased Coriolis's force) which is generated by the rotation of the whole hurricane, proportional (and even squared) to its angular momentum. If it weakens, the whole thermal machine will be weaker even if the water temperature is still the same.
I'm quoting this temperature, as a hurricane relies on two positive feedbacks. The latent heat one is as follows:"more latent heat --> more air buoyancy --> a deeper low pressure near the hurricane's center --> stronger attraction of the winds by the hurricane --> more heat exchanges due to friction at the ocean's surface --> more latent heat in the whole machine".
It is quite difficult to act on it with a powerful lever, but it might be less difficult to act against the other positive feedback which hurricanes desperately need:
"rotation --> strong centrifugal forces --> the inner low pressures being protected at quite all the altitudes against anarchic air inlets --> this inner low pressure cylinder strongly attracting air from far outside at the ocean level --> this radial inwards air undergoing Coriolis's force along a quite long way and turning tangential --> this Coriolis effect reinforcing the strong rotation which was the first step of our positive feedback".
And if "acting" on it would mean having a large floating structure being drawn by the rotating winds so that (angular) momentum is transferred to the ocean, it would be interesting to look for synergies with the mere existence of such a floating structure being subjected to such winds and being designed to generate something else useful for the climate. You can't bypass the idea of something like "power-to-liquid" happening on-board, but this "liquid" (or dense) material being CO2 could be the technologically simplest idea to begin with.
Such a device could be used to control many hurricanes by rotating around them for a large part of the hurricanes seasons in both hemispheres; for the rest of the year, they would just capture CO2 on windy oceans, e.g. being anchored not far from the Patagonian coast.
Anyway, I hope that studying such synergies more thoroughly could be fruitful for all the approaches of such an idea: DAC; hurricane control through angular momentum; and the broader trend about wind energy being harvested over high seas and converted through power-to-liquid schemes.
Best regards,
Denis Bonnelle.
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The Pycnocline effectively prevents the vertical mixing of heat, CO2 and nutrients between deep water and the mixed layer.
OTEC is practiced in the tropical deserts where phytoplankton production is up to two order less in Northern latitudes per the following.
Allowing the productive areas to become less so by allowing them to become warmer insures these areas sequester less CO2.
Moving heat below the pycnocline with Thermodynamic Geoengineering is homogenous cooling of the surface at the expense of a .007 C warming of the 1000 deep column of the tropical ocean. It has no effect on the thermohaline, increases phytoplankton production in the productive areas and universally sequesters CO2 per the attached.
Jim Baird
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