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Saturday, March 10, 2012

Floating villages

For some reason, I have always been fascinated by the thought of a floating village.  My interest was re-triggered by watching the amazing U-tube item on the chap, Richard Sowa, who built an island in a bay in Cancun, Mexico, which floats on plastic bottles held in bags of fishing net.  Have a look at this amazing video.

What a great idea.  I have often thought that the ideal place to put a floating village would be right in the middle of one of the Oceanic gyres.  Everything that floats finds its way into these areas and stays there.  It is not certain that a floating village that sticks up into the air would behave in the same way as something that is almost completely submerged; that it would say in the gyre but I think there is a pretty good chance it would.  Worth a try. 

An added advantage of this location is that these gyres are full of the necessary building material to build the floats on which the village would sit.  Tons and Tons of plastic waste are caught in these gyres.  There is a technique *  for melting unsorted plastic waste into  viscous liquid that can be injected molded into whatever form one wishes.  Better still, the link talks about the use of solar energy to accomplish this.  One little fly in the ointment is that all the pieces of plastic trapped in the ocean gyres of the world will have a film of organic material on them and often various fouling organisms.  One might have to find a way to clean the plastic before it could be used.

* Scroll down to the item on plastics in the above link.

I picture floats of, say, the size of a dining room table linked with flexible couplings to adjacent floats with a plastic factory chugging away, turning out new floats.  Rubber tires might make the ideal link as they are in great supply, themselves float if they are placed upright to trap air,  They are almost indestructible.  As the floats are finished, they are fastened to the island which just grows and grows.  The plastic melt can also be extruded rather than injected molded to make a wide variety of construction materials.  You can have solid rods, pipes, I beams, U beams or any other form you wish.  As the floating island becomes large enough you would add an extruder and manufacture light, strong members for the skeletons of your buildings.  You might be able to extrude the material with closed bubbles, making all the elements of the structure buoyant.

In case you are picturing a sterile sort of environment like the one in the movie 1984, look at the first link.  Richard planted Mangroves on his bottle supported island which grew very quickly with, of course, its roots in sea water and had various drums and pots growing tomatoes and other vegetables.  So what would the people do on this floating island.  Not everything could be produced on the island and it would be valuable to have an export product to trade for goods from the mainland.

My first thought is oysters and specifically the Pacific oyster.  The main reason that this came to mind is that I used to grow them as one of the crops of a mariculture farm.  Oysters need plankton to grow and the best plankton is diatoms.  So how do we grow plankton in the sunny but oligotrophic* water of the gyres of the world.

* Very poor in nutrients

The answer is to access the cold, nutrient rich water below the thermocline.  This is found at around 300m  in many tropical oceans and here we can use the wave action to do the pumping.  While there is not much weather in the center of the gyres, waves are sent across the oceans from all around.  By the time they reach the gyre centre, they are pretty gently rolling swells but that is just fine for our pump.  Black Polypropylene pipe is almost the same density as sea water.  If you put a weight on one end of, say a 400m piece of pipe, it will hang vertically in the water with only the mass of the weight you put on the bottom needing to be supported on the surface.  The pipe itself is virtually weightless in water.   So we connect this pipe to a float and attach a right angle at the top which feeds into a pipe that goes to our mariculture unit.  Now all we need is a one way valve somewhere in the pipe which allows water up but not down.  As a swell lifts the float and with it the pipe, the whole column of water is given an upward momentum (along with the pipe which is moving upwards at the same speed).  As the trough drops the float, the weight pulls the pipe down, the water continues up as the one way valve opens and water pours up the pipe.  If you need more water, you put down another inexpensive pipe.  So what do we do with this water.

Once we have this nutrient rich water in the euphotic zone, and remember, the centre of gyres are almost constantly sunny, Algae blooms just take off.  Almost certainly, there would be some phytoplankton in the water that would inoculate the process but if not, it is easy enough to inoculate the water. You might have to add a little water glass to the incoming water to encourage diatoms, perhaps not.  If so, water glass is cheap.  There might be a need for a little Iron salt too.  Apparently ocean water is quite poor in Iron.  So where does this water go.

To grow diatoms we need to hold this cold deep water in the euphotic zone for one to two days.  So in our float system, we leave a space and put in a membrane shaped like the nets that salmon farms * use to grow salmon.  Essentially a pond. We attach it so that the rim is above the sea and organize the outlet so that the water in the pond is, say, 10cm above sea level.  The slight resulting 'head' (pressure) is what keeps the "pond" inflated.

*ps.  I have a lot of reservations about salmon farms but the video does show what sort of set up could be used in a floating oyster farm.

From the phytoplankton pond, the water flows through similar structures in the form of a trough with racks of oysters in the water stream.  The cycle for oysters is about 9 months in these types of conditions from spat to commercial size.  Oyster spat can be obtained from a variety of hatcheries around the world and could very easily be produced on our island.  The system is not complicated at all.  So what about the water that leaves the oyster troughs.

The oysters have utilized the plankton and mineralized* the nutrients they don't use.  The nutrients are in the ideal form to be taken up by macro algae (seaweed) of which many varieties have a good market.  Think of the seaweed that is wrapped around Sushi or the sea weeds from which Carageenan or Agar are refined.  Growing sea weed has the added advantage of removing nutrients from the water before it is returned to the ocean.

* Turned them back into simpler compounds.

You might wonder where the fresh water will come from for drinking, cooking and growing plants.  Fortunately we have the cold water from the depths to use. Water from 400m is about 7 degreesC.  Water from the surface, 25 degrees or more.  Using a bit of the electricity from the solar panels to power a vacuum pump, you can make the surface water in a closed vessel boil and it can be condensed using the deep cold water in a heat exchange.  It is possible that Multi-Stage flash distillation would be the most efficient option.  Experts in the field would be able to design the best system. With the humid air of the gyre, you might even be able to condense water out of the air using the cold deep water.  Ideally, you would use the cold of the deep water to make fresh water and discharge the warmed sea water into your mariculture system.  What else could the village do.

One of the most lucrative activities would be tourism.  Complete isolation, great sea food and warm tropical waters to swim in (inside a net to keep the sharks out) would be very attractive plus the completely unique nature of the vacation.

Since we are creating a mid ocean mini upwhelling, a unique assemblage of animals would likely develop around the village.   The village would act like a FAD (Floating Agrigation Device).  The village could also rent out space to one of the marine research institutions of the world such as Woods Hole or Scripts.   

One problem would be what to do with human waste, vegetable scraps, chicken manure and so forth.  Whatever portion of this the community felt comfortable with could be turned into compost via a worm farm to be used in growing vegetables but the rest could be turned into biogas which is about 70% methane and 30% Carbon dioxide.  Biogas can be used for cooking or for heating the plastic making equipment. It can also be used to run a diesel generator.  After the biogas has been generated, the remaining material still has all the necessary nutrients for gardening.

The key to this idea is developing a system that can turn contaminated plastic into durable floats which can be linked to make a large platform.  If the plastic units can be manufactured so that the material itself is lighter than water, so much the better.  























  

1 comment:

Anonymous said...

I had a similar idea but using seacrete [on wiki p] a grid built of 60deg triangles with each corner having another 60deg triangle in it to give the form, on plan, of a hexagon with three extended facets. In section the hexagon would be an inverted H with long legs and the corners would be n with legs long enough to contain sufficient air for bouyancy. They could be grown below sea level then air pumped in to raise the corners above sea level to provide working platforms. I originally thought these could be grown around low lying islands anchored to the seabed, but have since realised that a large number of possibilties exist, as to their viability thats another question.
This organisation http://www.algalita.org/index.php was founded to research ways to deal with the problem of the plastic residue. Ive been trying to think of ways to help but was unaware of the process you speak of which sounds ideal for part of the problem.
johnm33