Floating kelp raft writ large
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June 6, 2008 at 10:55 am #576
After remembering one of my favorite books, “The blue world” by Jack Vance (read it ! Really do, it’s a short tale that manages to squeeze everything that is mankind in one story), which takes place on an entirely-oceanic planet where the only “ground” is giant floating seaplants, and given a little web search on floating kelp and the free-floating rafts they often form after storm rip them off the coastal rocks, combined with Joep’s idea of a “mud curtain” as a breakwater and potenital expendable floating “land” and the potential businesses for seasteads in kelp harvesting, diving tourism and reef-growing, I started wondering…
- why not combine it all ?
Grow floating kelp (macrocystis), lots of it, on rigid supports. When there is enough of it (it grows very very fast) assemble the supports together so you have a large and thick ring of floating kelp that acts as a breakwater (flexible curtain) AND provides buoyancy AND acts as a suitable environment for other sealife, then build a structure right in the middle and sail off, harvesting the kelp for money. Or, if it’s not practical to use the kelp’s buoyancy for any structure, this kind of raft could still prove a good companion to other seastead designs.June 6, 2008 at 11:26 am #3045
A simple design for a kelp-sustained structure would be a solid hollow cylinder: kelp grown along the cylinder on one side would be cultivated in a “rolling” way: harvest at one side, let it grow at the other, rotating the cylinder along very slowly over time as new kelp grow and pull from one side and removal of kelp at the other end stops pulling. The main issue is emergency buoyancy, in case enough kelp is torn off by a storm and the whole thing starts sinking.June 6, 2008 at 5:24 pm #3061
Floating kelp platforms were built in the late seventies by Dr. Wheeler J. North and his assistants as a potential source of energy and food. Unfortunately, the submerged platforms were destroyed in storms. I attended a talk by Dr. North and was quite inspired by the idea. The oil glut in the 80’s led to an end in funding for the research. link: http://www.oceansatlas.org/servlet/CDSServlet?status=ND0zMTk5JjY9ZW4mMzM9KiYzNz1rb3M~
A current man-made kelp reef is at: http://www.sce.com/powerandenvironment/powergeneration/marinemitigation/kelpreefproject.htm . There are links to research publications here as well.June 6, 2008 at 5:45 pm #3062
Concluding paragraphs from http://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Biomass/B1.html ,
“Despite the misconceptions that plagued the Ocean Food and Energy Farm, Wilcox’s projection of 2% efficiency in conversion of sunlight to energy was not realistic. As mentioned above, NMI’s near-shore growth data demonstrated a 1% efficiency (conservative estimate), a number that confirms the viability of marine biomass as a source of energy. NMI also demonstrated that Macrocystis has an exceedingly high rate of biomass production (fifteen dry ash-free tons per acre per year), and that the plants can withstand quarterly harvests where up to half of the biomass is removed. Furthermore, survival of plants following repeated harvesting showed that substantial yields were possible without changing the standing crop.
Review of the marine biomass program provides valuable lessons for future development of marine farming. Of the many difficulties that plagued initial efforts to farm the sea, one in particular, stands out—the lack of communication between engineering and biological communities. The project began with the assumption that marine farming would not be technically difficult. Wilcox’s statement that “It’s not high technology… we’re just talking about plain old plants growing,” illustrates this lack of understanding. Ten years later, after the work of two contractors and several major experimental farming efforts, there was still no yield data for farmed Macrocystis. Plants were entangled with the farm structures, consumed by fish, infected, or dislodged and destroyed by storms. By 1980, it was apparent that building a “false bottom” for kelp plants in the open-ocean was not a “low-tech” task. Attempts to protect the structures with a fabric current shield (ripped away) also met with failure. While marine engineers learned from the QAM and grid experiments, biologists were unable to obtain any significant growth data from the experiments.
Many of the problems associated with marine farming were due to constraints on the overall Marine Biomass Program. In particular, Wilcox’s original concept required an enormous amount of marine biomass, near-shore work was not deemed to be worthwhile. This resulted in an approach that required both engineers and biologists to “walk before they could crawl,” an obstacle that contributed to the lack of data generated by the early open-ocean experiments. Without this crucial growth data, there was no way of testing Wilcox’s theory about the biomass potential of marine farming. NMI produced these data by planting and harvesting a near-shore marine farm. Current efforts to revive the program should take particular care not to overlook the experience of earlier investigators. Marine plant specialists must be involved from the very beginning and should play an active role in the design of farming structures. From an engineering perspective, the grid and QAM experiments were somewhat useful in that they highlighted the many problems encountered in placing artificial substrates in deep water. However, the lack of significant growth data demonstrated that the success of marine farming did not hinge solely upon the ability to anchor the structures in the ocean. In particular, engineers needed to account for the hydrodynamic requirements of the marine plants that they were attempting to grow. Future project managers must place the plants first in order to succeed in the production of marine biomass.”
Growing in the Sargasso would be easier in nice, warm, water, and doesn’t require a submerged structure. Kelp grows in cold water. General Electric’s research in biomass to methane conversion would be useful to review since it would apply to any type of seaweed harvested for energy.June 7, 2008 at 8:44 am #3082
Thanks for the link, this is the exact kind of research needed for evaluating this idea. Apparently the kelp would need its own breakwater, but otherwise it is feasible.June 7, 2008 at 5:26 pm #3098
A lot will depend on the location and corrsponding environmental conditions. Nutrient supply will be a critical factor in any location. Sargasso weed may grow much faster with supplemental nutrition from deep water, and maybe chelated iron .Seaweed is actually a form of algae, related to plankton, so may have a similar benefit from supplemental iron. Kelp is good as an accepted food, habitat and a fast growth rate if the anchorage problem can be solved
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