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John Brown

Jan 21, 2016
10:36

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Very interesting!!! 

Here's a 5 minute video which includes a simple schematic of Makai's operational research facility in Hawaii:

https://www.youtube.com/watch?v=LJV4d4XtHuo


James Lau

Jan 23, 2016
11:27

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Thanks  to the comment. Two months after entering the proposal, there is finally a comment. I hope to see more. I haven't seen any evaluation for any of the proposal. I hope the judges do read the proposals.

I hope you do read the proposal and understand the importance of OTEC. Contacting me with email at my email address in the proposal can provide more information about my proposal. I am aware of Makai and their effort. My analysis clearly concluded that OTEC plants should be submerged in ocean location with 1000 meter depth using vertical main cold water pipe. The land based Makai test facility have to use much longer (then 1000 meter) main cold water pipe and need to use much more energy to move the cold cooling water for the circulating working fluid. Makai also use compact heat exchangers. The small temperature range covered by the working fluid in the Rankine cycle clearly make OTEC to have high ocean water flow rate (and working fluid flow rate). The most cost effective heat exchanger design is therefore larger volume with minimum pressure loss (energy usage). Compact size can allow using less materials, but the pumping power  (for both ocean water and working fluid) would use up much higher fraction of the converted electricity. Makai apparently use the main cold water pipe built around 1980 and constrained by the costly (both for initial construction and now for higher ocean water pumping power). Apparently Makai found out in 2015 that marine grade 5086 aluminum is satisfactory as heat exchanger material. Using the easily fabricated, low cost 5086 material can shift the heat exchanger optimum design to larger volume configuration. I hope Makai take advantage of their own data.

My information seems to indicate that the Hawaii renewable lab marine energy focus may be shifting away from OTEC into marine kinetic energy (wave, tide and current). Such as shift is a serious mistake because the store energy resource in ocean thermal is hundreds times more than all the kinetic energy forms combined. The basic thermal mechanical energy conversion factor clearly indicate that 1 degree Celsius temperature increase has as much energy at water moving at 90 meters per second (200 mph). Pay attention to the basics. 


Nofrills Flyer

Jul 27, 2019
03:32

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Such as shift is a serious mistake because the store energy resource in ocean thermal is hundreds times more than all the kinetic energy forms combined. The basic thermal mechanical energy conversion factor clearly indicate that 1 degree Celsius temperature increase has as much energy at water moving at 90 meters per second (200 mph). Pay attention to the basics. 

no frills flyer