How To Power a Seastead Island 2


(Glen Hendrix) #1

This is further information on a previous post “How To Power a Seaste Island” and another image I was unable to upload on the first post.

To reiterate, this is basically a wind turbine with its axis in the vertical, contained by a cylinder, with ambient wind diverted into the top of that cylinder and through a heat exchanger. The heat exchanger cools the air with cold ocean water pumped from the depths of the ocean. The cool air sinks, gaining momentum before passing through the turbine at the bottom of the cylinder.

There are several advantages:

Bird deaths eliminated.

The sound of the turbine is mitigated by its containment wall.

Flickering shadows on the surrounding landscape are eliminated.

Maintains a cool environment for heat-generating, rotating turbine/generator parts no matter the external temperature.

The vertical rotating axis of the turbine eliminates gravity and wind-load fluctuations seen by ordinary turbines, making blade construction cheaper.

Seawater in contact with the inner, hard-to-clean surfaces of the heat exchanger is too cold and salty to form algae, minimizing maintenance.

No chemicals to leak into the environment like in some OTEC.

Produces power when wind is still due to the reverse stack effect.

Brings to the surface nutrient-rich deep ocean water to use for aquatic farming.

No azimuth yaw mechanisms needed to keep wind turbine aligned.

Wind energy is forced through the turbine blade and not allowed to bypass around the blade tips.

There’s plenty of “fuel” since 90% of the ocean’s volume is between 32 and 46 degrees Fahrenheit and 40% of the world is tropical or subtropical.

Here is a link to a blog that more fully explains the device and how it works, including more images.
http://coldwatersystem.blogspot.com/2015/07/peak-water-new-technology-shows-promise.html

Here is that image I promised. This is the application that is salient to this site. My rendering is limited to cartoons in Autocad but I hope you get the gist.


(Kim Cowdroy) #2

Nice work.

My basic question would be : what percentage of the electricity generated would be used by the “Cold Ocean Water Pump” shown in the other diagrams, to pump water from the surface to the top of the silo? Or if water is collected below the surface, to pump the water out?


(stephen russell) #3

Add Thorium reactors to mix??? More Power, Fuel acessable, 24/7 Power.


(Glen Hendrix) #4

That is a good question but unanswerable in a definitive way at this point. It depends on the diameter and height of the supporting cylinder for the heat exchanger. It depends on what kind of flow is necessary for the heat exchanger to cool the air enough for a stack effect to turn the turbine, and to extract a maximum amount of water in doing so. A guesstimate would be up to 10% of the output of the turbine with much of that recovered from the seawater and the collected fresh water falling to grade. The larger the installation, the smaller that percentage will be. Not being a process engineer or having Comsol modeling access, I am resorting to actual testing. As for the stored water, the concept shows it stored below the ocean surface, but that may or may not be the case. It could be stored on barges. So that pumping height is quite variable right now.

Here is a link to a calculator to give you an idea of the power versus volumes involved.
http://www.engineeringtoolbox.com/pumps-power-d_505.html

I am currently running tests to see how much fresh water can be extracted at different air speeds and different cold water temperature here on the Gulf Coast. Humidity is running about 60-75 percent, temp is 80 to 90 degrees F. The cold water is 32-60 degrees. The pump flow is 12 gal/hr. The double helix test 1/4” copper coils are only about 4 and 6 in. in diameter and 16 in. long, but with a water temp of 40 and wind speed of just 4 mph, I’m making a cup and a half fresh water per hour. Yahoo!


(Glen Hendrix) #5

Who doesn’t love Thorium reactors. We should let the Chinese perfect them and then appropriate the design just for a little feng shui irony.

Seriously, I would worry most of all about the expense; second of all about losing a reactor at the bottom of the ocean due to unforeseen circumstances.

The scheme I’m touting does work 24/7 producing power, potable water, cool air, and nutrient laden seawater.


#6

Search this forum. You may not like radiation poisoning, or the shear mass involved in shielding from it, or trying to float the system. Certainly, the costs of the cabling will be prohibitive, but, heck, it’s your money…


(Larry G) #7

@admnelson1 @JL_Frusha

Please keep to the poster’s original topic. De-railed threads dilute the ability to find, follow, and contribute to a topic.


(Larry G) #8

I was the lead on a systems engineering team for engineering and installation of mini-data centers in Afghanistan a few years back. One HVAC problem I came across (not my primary responsibility but impacting my team) was that the airflow went through lots of bends in the ductwork. Lots and lots of turns. Turns, bends, or radius of any kind impact air flow drastically, for a ways upstream and downstream of the bend. Friction from the sides of a conduit also has a significant effect, and narrowing of an aperture causes back-pressure, also affecting flow.

Dynamic Pressure

Dynamic losses are the result of changes in direction and velocity of air flow. Dynamic losses occur whenever an air stream makes turns, diverges, converges, narrows, widens, enters, exits, or passes dampers, gates, orifices, coils, filters, or sound attenuators. Velocity profiles are reorganized at these places by the development of vortexes that cause the transformation of mechanical energy into heat. The disturbance of the velocity profile starts at some distance before the air reaches a fitting. The straightening of a flow stream ends some distance after the air passes the fitting. This distance is usually assumed to be no shorter then six duct diameters for a straight duct.

One concern I have about this design is the re-direction of the airflow from horizontal to vertical right at the beginning. That’s a massive lateral load if the drawing is anything like to scale. As much or more than any turbine blades I can think of. Second, you lose a lot of air velocity in that turn (Maybe you make it up again through the changing density, I don’t know- but it seems unlikely). Third, you need an outlet(s) as large or larger than the inlet or else you get back-pressure. It doesn’t take much back-pressure to really make a huge efficiency difference, and also wear and tear on a system that requires replacement/repair type of maintenance. You still need some kind of station keeping to point your wind funnel.

I really think that this type of system has a lot of potential for making fresh water, but I am not sure about concurrently producing a net energy surplus.

If the volume of air is massive, the speed can be fairly low, but it’s still a significant factor to have wind directed from high up constantly blowing across the surface of your living space.

http://efficientcomfort.net/Charts/Rules_and_Rules_of_Thumb_for_Duct_Systems.pdf

I do encourage you to create a proposal on the Wiki: https://wiki.seasteading.org/index.php?title=Proposals


(Glen Hendrix) #9

I was a principal designer for industrial furnace systems for I am embarrassed to say how long. Many of those involved ducting systems. There are some tricks to cutting down pressure losses on such systems. For one thing, the funnel to concentrate airflow into the transition elbow must have an apex angle of no more than 60 degrees and the less the better. Another is that the elbow has internal turning vanes that keep the flow more laminar. Also, the elbow has to be a long radius elbow. In other words, generally, the centerline radius of the elbow is 1.5 times the diameter (or more); or the equivalent thereof when it is rectangular.

Applying tricks like this can cut pressure losses on the order of from 80% down to 20-30%. Keep in mind these are gussied up patent drawings you are looking at. The real deal may look somewhat different.

There will be pressure losses from heat exchanger as well but it can also be designed to accommodate are flow.

The average wind velocity in the Gulf of Mexico is 18 mph. Let’s say we can get 1.35 times that speed with the funnel to 24.3 mph. We lose 25% going through the turn down to 18.23 - 3 (heat xchngr) = 15.23 but the density is changed to add 7 mph in the drop to the wind turbine. Total = 22.23 mph


(system) closed #10

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