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Hank Roberts

Apr 12, 2015
12:46

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I'm not competent to do the math (or ecology, or economics) but glad to see the idea raised. Many questions were addressed in this 1999 article -- biofouling, total water volume, and so on: http://www.otecnews.org/portal/otec-articles/ocean-thermal-energy-conversion-otec-by-l-a-vega-ph-d/ which I hope has been updated somewhere; the host site for that article is worth a look. I know the earlier assumptions stated (e.g. that deep cold ocean water is bacteria-free) need another look. Can OTEC incorporate William Calvin's CoLab idea that he sketched in draft form for an earlier session? I know that has been elaborated since: https://www.climatecolab.org:18081/plans/-/plans/contestId/20/phaseId/203/planId/1304117

Jim Baird

Apr 13, 2015
09:07

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Hank, one of the problems I see with William Calvin's idea is the CO2 you pump down (who pays for this and where do you get the energy - I assume wave action) is likely released to the atmosphere and then some when you up-well the nutrients needed for the phytoplankton to consume CO2. At depth CO2 concentrations are considerably higher and it is natural upwelling that is causing much of the acidification problems with shellfish (see http://www.pacshell.org/water-quality.asp). Henry's Law states "At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid." so up-welled water will release considerable amounts of gas. The Caldeira study http://iopscience.iop.org/1748-9326/10/3/034016/article considers this atmosphere-ocean CO2 flux. With regards to the Vega article, I refer you to one by Paul Curto, former chief technologist with NASA, http://www.opednews.com/articles/American-Energy-Policy-V--by-Paul-from-Potomac-101214-315.html He states, "With a slightly different design, using an ammonia heat pipe instead of a cold water pipe, proposed by Jim Baird and Dominic Michaelis (British Patent No. GB 2395754), no water from the bottom is released into the upper strata of the ocean, trapping all the CO2 deep beneath the thermocline. Little pumping energy is used to circulate the ocean water, simply enough to pump warm surface water to flow over the evaporator end of the heat pipe. If the condensing end of the heat pipe is exposed to a thousand feet or more of near freezing temperatures below the thermocline, no cold water pumping is required. The parasitic losses are cut in half. The costs for the cold water pipe are eliminated, along with the cold water return pipe and condenser pumps, the cleaning system for the condenser, and the overall plant efficiency approaches 85% of Carnot vs. about 70% with a cold water pipe. The parasitic losses could be reduced as much as 50% and the complexity, mass (and cost) of the system reduced by at least 30%. The vast reduction in operating costs and environmental impacts would be worth investigation alone." Back to Calvin again, this proposal too can draw-down atmospheric CO2 per the following post http://theenergycollective.com/jim-baird/423076/carbon-sequestering-energy-production Many thanks for your interest.

Jim Baird

Apr 13, 2015
10:27

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Hank, one other thing, this article deals with the phytoplankton situation http://theenergycollective.com/jim-baird/184496/ocean-thermal-energy-conversion

James Lau

Apr 14, 2015
02:33

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There are a lot of details to talk about related to OTEC and the ocean.I have some proposal with OTEC plant construction materials and processes. I am sure OTEC can produce electricity at 2 cents a kilo-watt hour. I am also proposing ocean thermal desalination to solve the California drought problem. Fresh water at 4 cents per cubic meter is possible using the thermal resource off California coast. I can provide more information for all that is interested.

Carl Fischer

May 9, 2015
09:21

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Yes please, James, more information would be helpful. Thanks

Jim Baird

Jun 26, 2015
07:51

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A recent MIT News article, "A new look for nuclear power" is an excellent opportunity to compare offshore nuclear with OTEC. Everything the MIT researchers say about construction techniques and promising economics, abundant potential markets for offshore nuclear power plants are equally applicable to OTEC. The size of gigawatt platforms would also be comparable. One big difference is OTEC has no fuel costs, no waste considerations and an accident with a plant using CO2 or ammonia as a working fluid would have limited consequence compared to the destruction of a nuclear plant. The greatest difference however is in the way each produces and utilizes heat. The recent study by the Carnegie institutions Zhang and Caldiera shows that the energy released from the combustion of fossil fuels is now about 1.71% of the radiative forcing from CO2 that has accumulated in the atmosphere as a consequence of historical fossil fuel combustion. Nuclear plants are equally as inefficient as fossil fuel power generators and engines and thus release the same amount of waste heat most of which ends up in the ocean and since heat rises it remains on the surface where it contributes to most of the problems we are currently experiencing with global warming. We are currently using about 16TW of energy annually but Martin Hoffert and Richard Smalley have estimated we will need between 30 to 60TW respectively by 2050. At these rates the waste heat from nuclear plants starts to become a real problem. OTEC on the otherhand can convert as much as 14TW of surface heat to productive use and move about 280 more of the 330 TW of heat the oceans are said to be accumulating to the safety of the ocean abyss. This would remedy virtually every problem, including CO2 emissions, mankind is confronted by with respect to global warming. With nuclear all you get is carbon free power, which leaves our offspring to face another 1000 years with the problems we are currently experiencing.

James Lau

Nov 14, 2015
06:14

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I also participate in the Climatecolab with a proposal in the MIT alumni category. I am not an alumni but my proposal is already posted. I am also proposing OTEC. I include some calculation results based on Rankine cycle analysis, Moody diagram information for fluid flow analysis. My proposal is Cost effective OTEC electrical power plant. I hope to invite people to read my proposal there. You can also contact me with my email address jameslau2@gmail.com. I can send you files with more information than is posted.

OTEC is definitely geo-engineering. Compared to previous more localized geo-engineering such as city building, canal and dam construction where rigid structures are erected, OTEC is less rigid but create effect over much larger area. The promise is much greater. The risk should be minimal. OTEC is actually heat pipes with the additional advantage of solving the global energy problem. OTEC is the only option with enough energy capacity to solve the global energy problem.


Nils Aguilar

Jul 21, 2019
11:31

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Hi all, this sounds mind-blowing. As a journalist, I'm bound to ask: why on earth isn't the press picking this up? Could you please summarize the different reasons? Thank you

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