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Materials and resources

Home Forums Archive TSI Research Materials and resources

This topic contains 23 replies, has 8 voices, and was last updated by Avatar of Ken4g64 Ken4g64 3 years, 8 months ago.

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  • #1200
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    This was a response to a new member introduction, but I thought it would be better placed here.

    Here is the link to Oliver’s introduction: seasteading.org/interact/forums/community/introductions/some-ideas-a-new-member

    Welcome to Seasteading! First, I would love to be completely self-sufficient, but if you really make a list of all the things you would need to produce/make, I think you would quickly realize just how impossible it is in order to sustain any modern standard of living. That said, I do think there are certain areas that should be targeted for self-sufficiency. Food would be my highest priority, right next to water treatment, which is a prerequisite in my book. Next for me would be textiles, ceramics, steel, aluminum and all other types of raw materials required for basic production. I would target production of materials and commodities needed for daily living, export products and finally for making more Seasteads – in that order.

    When I lived in the Philippines I investigated the use of shipping containers. The large 40′ variety can be purchased used and in excellent condition for about $1000 each. If you are will to take ones with a few holes, you could probably get them for as little as $800 – which is not always a problem as you can likely place doors and windows where the damage is anyway. They are very sturdy and made to survive in a high salt ocean environment. I did actually see them used there for housing. There was a fire that burned down a local barangay and the government provided about 20 or so shipping containers for habitat use. I also saw a small police station that was build in a smaller 20′ shipping container. The only thing I saw wrong was that the containers have very low ceilings, especially for us westerners. But for temporary housing, offices, workshops and storage, they can’t be beat. But I don’t think you would want to live in these for permanent housing. Instead I would use these while more permanent structures are being constructed and for low use buildings. They are also available in 60′ length, but I didn’t find out the costs for these.

    I actually don’t think it would be a bad idea to make a surface ‘dredge’ to collect the plastics floating around in your garbage patches. If nothing else, the plastics have a very high joule heat value when burned, and there are available technologies to do this cleanly. But I think the better use is to pelletise the plastics for recycling and making new plastic products for both domestic use and export. The plastic pellets themselves can also be sold. The technology to do this is not particularly expensive (the pelletizing, not the plastic mold injection), but separating the different types of plastic is labor intensive.

    As for non-food crops I would place on the top of my list, hemp. We are not talking about the kind you smoke, but the kind that produces food (I know, I called it a non-food crop…), fiber, oil and cellulose. The fiber and cellulose can be used to make critcal fiber board for construction. The cellulose can be turned into fuel, oils, plastics, and all manner of necessary chemicals. The hemp seeds are rich in essential fatty oils and a rich source of protein – in fact it is the most balance plant protein for human consumption in all of nature. The seeds taste great and can be make into breads, cereals, etc.The fiber can be made into rope, sails, clothing, fiber board (replacing sheetrock, lumber and other wood products), artificial leather and more. The plant grows like a weed (pun intended) because it is one of the few plant that can utilize uv-b sunlight. I could go on, but I think you get the idea. And again, true hemp has no significant THC, so it will do you no good to smoke it. I’m also interested in bamboo and your Empress Tree. However, I do worry about how practical it is to grow trees on a Seastead with such limited growing space.

    I also think pulling up minerals from the sea bed has merit and needs more investigation. I’m particularly interested in the mineral nodules found on the sea floor. See en.wikipedia.org/wiki/Manganese_nodule. These are rich in Manganese (27-30 %), Nickel (1.25-1.5 %), Copper (1-1.4 %) and Cobalt (0.2-0.25 %). Other constituents include Iron (6 %), Silicon (5%) and Aluminium (3 %), with lesser amounts of Calcium, Sodium, Magnesium, Potassium, Titanium and Barium, along with Hydrogen and Oxygen. This can be the basis of a metals production industry on the high seas. Typical extraction of the nodules used dredging of the sea floor from surface ships, which has proven to be too costly. I think a better approach is to use semi-autonomous robotic units that have conveyors on the underside with electro-magnets to collect the nodules. They conveyor belt would be in a mobius band configuration and would drop the nodules into a bin that sit between the top and bottom of the belt. When the bin is full, compressed air would fill a balloon attached to the recovery cart and bring it to the surface for collection and processing. Empty bin would need to be dropped back down and the robotic units would need to be able to “reload” the new cage. I’m not saying any of this would be easy, but I do think this might bring the cost down to make it economical to recover these minerals without damaging the sea floor. Besides, I love the idea of underwater robotics .

    As for sea sand, it is usually impractical for use as a building material, particularly in cement. This is sad, but true. The first problem is it’s high salt content, which is very corrosive to any iron rebar. To clean the sand requires large amounts of fresh water, which will be at a premium on a Seastead. The next problem is the grain size which varies greatly in sea sand. The second problem can usually be solved by “sorting” the sand by size, but the first problem is intractable. But if a solution could be found, it would be a very valuable resource indeed. I’m unsure of any other uses for seas sand, but maybe others know.

    I would also be curious as to the availability of clay on the sea floor and to it’s potential uses. I have never seen this talked about before. Ceramics would be of extreme value at sea. I know from a quick google search that clays do exist on the deep sea floor, but I find no references as to composition or known uses (other than it readily sticks to radioactive elements. Hmmm….).

    And although TSI has ruled out Seacrete as a viable option (for admittedly good reasons), I still think the idea has some merit (please don’t shoot me for mentioning the word Seacrete on this forum). The largest problem with aggragating seacrete is the increase in resistance as the seacrete forms on the electrodes. However, I wonder if the electrical cost would be as high if the Magnesium hydroxide and Calcium carbonate were concentrated before attempting aggregation on the electrode? I also suspect you could dramatically lower the energy costs by using a much higher surface area for the electrode. What I’m thinking is the use of a “skeleton” material with high conduction and a high surface area so that the resistance can’t build so quickly. Think of a sponge type material with all of the pores covered in graphite. With the higher concentration of salts and the lower resistance, I wonder if this idea could be resurrected. I think the idea at least deserves more research.

    There are also other valuable minerals that might be extracted from sea water. The main obstacle has always been to concentrate the minerals to a level where they can be economically extracted. I have read about research in using algae, microbes and plants to concentrate minerals prior to mineral extraction. I think if this was economical, it would already be done. But it would again be something for Seasteaders to research further. And if you could find an economical way to extact gold from the sea…

    – You may get what you want, but will you want what you get?

    #9652
    Avatar of daggath
    daggath
    Participant

    Wow, I’m impressed at the size and speed to which my post got a reply!

    Thanks for the warm welcome :-)

    Concerning the shipping containers, what about the possibility of welding them together to create larger rooms?

    Also do they float? If they do then they could be used as a foundation on which the rest of the seastead is built.

    Your comment about pelletising the plastic is a wonderful idea. As for seperating the types of plastic, could we use a centrifuge(wave powered) to make it less labor intensive?

    I also agree with you on hemp, it is a wonderful plant that I forgot to add on my other post.. Bamboo requires a large root system to grow tall, so it may be limited in seastead use as well. To address the limited space issue we could begin culturing a population toward our goals, I mean if a MIT student can turn carrots purple for his thesis project, I’m sure we could something as well.

    I like your idea of underwater robotics dredging the sea floor, and as for sea sand, perhaps we could use bamboo instead of iron rebar? Also we could melt it down to make glass.

    What can we grow/make that we can use to filter sea water? ( such as the plankton and silt )

    Once filtered, we can then use solar collectors to create fresh water and sellable salts.

    > And although TSI has ruled out Seacrete as a viable option (for admittedly good reasons), I still think the idea has some merit

    I agree, with your thoughts about seacrete, much research still needs to be done in this area. Who knows, perhaps we will discover a way to gather gold from the ocean :-).

    One example is the desalination of seawater by evaporation energy. At the edge of shallow coastal waters of tropical seas we find the luscious green of mangrove swamps. Mangroves can live on the saline water of the ocean, which destroys other green terrestrial plants. In some species of mangroves the sap is almost salt-free, though the roots are washed by sea water. They extract the salt by using the transpiration energy in the narrow capillaries of their roots to suck up the sea water and then filtering it through thin membranes in which the salt is detained.” (Tributsch 1984:184)(http://www.asknature.org/strategy/f580efcadd6c8c19dadf3811bdd6222d)

    Seeing this, perhaps we could grow these for the filtration potiential as well as for wood. Oh also all plants perspire, and if we capture that perspiration we can get fresh water, something I learned from some survival book i read once.

    Also when burning wood, the hotter the better as then you can get higher thermal effeciency and less smoke. (http://www.off-grid.net/2009/01/15/100-efficient-wood-stove-or-gas-furnace/)

    Oh another idea is a kelp forest, you could have a platform underneath the seastead to act as a place for the kelp to grow from.

    Sorry for all the randomness… I am not very good at organizing my thoughts.

    salt water food crops in developement http://www.seeddaily.com/reports/Scientists_Closer_To_Developing_Salt_Tolerant_Crops_999.html

    A long term option that would be really cool is if we figured out how to genetically engineer a plant to be the seastead. Of course I know that it would be nigh near impossible today, but in 20 years who knows :-)

    #9653
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    daggath wrote:

    Wow, I’m impressed at the size and speed to which my post got a reply!

    Thanks for the warm welcome :-)

    You’re very welcome. I find it hard to get people to engage in deeper discussions in these forums – quick quips, but no thought out responses. New people tend to bring new ideas and fresh perspective, and for that I thank you.

    daggath wrote:

    Concerning the shipping containers, what about the possibility of welding them together to create larger rooms?

    Also do they float? If they do then they could be used as a foundation on which the rest of the seastead is built.

    Yes, they can easily be linked together to make larger rooms. Holes can be cut for doors and windows to be installed. Electricity and plumbing can also be installed.

    daggath wrote:

    Your comment about pelletising the plastic is a wonderful idea. As for seperating the types of plastic, could we use a centrifuge(wave powered) to make it less labor intensive?

    I don’t think there is any significant density differences between the different types of plastics. They are usually sorted by hand using the markings on the underside of the cartons/containers. I don’t think getting low cost labor would be any issue, but I never see this discussed here. All I see is talk of rich people going out to sea in floating casinos/whore houses. I don’t see how you can make a sustainable society from this. Anyway, I digress. See http://www.lotfi.net/recycle/plastic.html.

    daggath wrote:

    I also agree with you on hemp, it is a wonderful plant that I forgot to add on my other post.. Bamboo requires a large root system to grow tall, so it may be limited in seastead use as well. To address the limited space issue we could begin culturing a population toward our goals, I mean if a MIT student can turn carrots purple for his thesis project, I’m sure we could something as well.

    I like your idea of underwater robotics dredging the sea floor, and as for sea sand, perhaps we could use bamboo instead of iron rebar? Also we could melt it down to make glass.

    Here is an existing discussion on bamboo reinforced concrete seasteading.org/interact/forums/engineering/structure-designs/bamboo-reinforced-concrete and a study romanconcrete.com/docs/bamboo1966/BambooReinforcedConcreteFeb1966.htm.

    Some arguement is made against it’s use because of it’s lower tensile strength and greater “flexing”; however, in some applications this is considered a superior trait. For example, it would be an excellent subsitute for Non-bearing concrete walls. Sheetrock performs very poorly in marine environments. However, I suspect that bamboo will be difficult to grow at sea, for the reasons you give. Hemp cellulose makes great fill in concrete and a laminate hemp fiber layer can give it great strength. This makes an excellent light weight cement fiber board that can be used just like sheetrock. And unlike sheetrock, it will not mold or mildew if it gets wet. Oh ya, it is probably alright to use sea sand with this since the salts will not corrode hemp.

    http://www.freepatentsonline.com/4363666.html

    http://www.hempmuseum.org/ROOMS/ARM%20BUILDING%20MAT.htm

    http://www.naturalhomemagazine.com/natural-home-living/hemp-concrete-promising-new-green-building-material.aspx

    daggath wrote:

    What can we grow/make that we can use to filter sea water? ( such as the plankton and silt )

    Once filtered, we can then use solar collectors to create fresh water and sellable salts.

    Not sure on the sea water filters, and I’m not sure what application it would have. But I would like to talk about making fresh water. Most methods of making fresh water are very energy intensive. The only other option I have seen is some form of open-cycle OTEC. Unfortunatley, OTEC has been discarded as an energy production mechanism because of it’s high startup costs and it is an unproven technology. But one of the main features of OTEC is that of bringing up deep sea water from a km or more. This water can be as low as 40 F. But the cost of pumping this cold water to the surface for OTEC is high, but that is only because of the large quantity of cold water OTEC requires. I think this cold water resource as been too quickly thrown over-board with OTEC itself. Forget OTEC for a minute, and just consider the value of this cold, nutrient rich, sea water. The first obvious use for this cold sea water is to condense fresh water from the warmer surface water. Would the energy required to pump this deep seawater to the surface be more or less than other fresh water purification schemes? I suspect it will be far cheaper to pump it to the surface for this use. Next obvious application is for airconditioning. This is another energy hog – and here is all this cold water just waiting for you under your Seastead. Then there is the use for refridgeration, another consumer of electricty. It can also be used to improve the efficiency of any heat pump, such as large walk-in freezers. And finally, if you are using any heat engine based power generation, the cold water can be used to improve efficiency in the condenser stage.

    Now if the costs to pump this cold water to the surface proves too high, consider a closed loop to the ocean depth. You pump water to depth, heat exchange it to the colder deep water and cycle it back to the surface for use. Because it is closed loop, you do not incur the pumping energy cost from the differences in water density.

    daggath wrote:

    A long term option that would be really cool is if we figured out how to genetically engineer a plant to be the seastead. Of course I know that it would be nigh near impossible today, but in 20 years who knows :-)

    I thought about this idea when I was a kid – growing genetically engineered houses and structures – my parents just laughed at me. But someday…

    In the mean time, I really like the idea of growing structures from seacrete – all that is needed is a scaffolding for it to grow on and energy. That’s why I’m always looking for ways to produce copious quantities of energy at sea – it is needed for everything we want to do.

    Please check out my thread seasteading.org/interact/forums/engineering/infrastructure/coolearth-and-solar-balloons. I’m sad I have no replies .

    – You may get what you want, but will you want what you get?

    #9665
    Avatar of daggath
    daggath
    Participant

    CrosiarCM wrote:
    I don’t think there is any significant density differences between the different types of plastics. They are usually sorted by hand using the markings on the underside of the cartons/containers. I don’t think getting low cost labor would be any issue, but I never see this discussed here. .

    It seems that is can be done. http://www.plastic-separation.com/EN/centrifugesEN.htm#ReCENT

    The purpose of the sea water filters is to help try to make fresh water and higher quality salt (for export).

    And as for the growing houses and stuff, I figured out a way to ‘grow’ a 1 story house in 1 year when I was in highschool. It didn’t even require genetic engineering! The process used old fashioned cloning and splicing.

    bamboo is able to grow small, but for the thicker and taller bamboo stalks you need an extensive root system

    Here is an interesting and simple solar cooker that i found on the net http://solarcooking.org/plans/funnel.htm

    #9668
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    daggath wrote:

    CrosiarCM wrote:

    I don’t think there is any significant density differences between the different types of plastics. They are usually sorted by hand using the markings on the underside of the cartons/containers. I don’t think getting low cost labor would be any issue, but I never see this discussed here. .

    It seems that is can be done. http://www.plastic-separation.com/EN/centrifugesEN.htm#ReCENT

    [/quote]

    Wow, I have never heard of this; thanks for the great link. Ok, so this is even more possible than I had imagined. To some degree, I’m suprised there is no one out there now scooping up this concentrated waste for recycling. I think we only need to determine the economics of this.

    – You may get what you want, but will you want what you get?

    #9671
    Avatar of admiral-doty
    admiral-doty
    Participant

    Seacrete is viable as a coating on a sandwich panel structure made of a conductive metal like aluminum or magnesium. Magnesium is readily available from seawater and also showed the best growth results with the least power consumption in Eric Lee’s experiments at Stanford. Unfortunately, Lee’s results are no longer online but a partial archived version is at http://web.archive.org/web/20070824145637/http://www.stanford.edu/~erlee/seament/seament.htm . Some magnesium is consumed in the process since it acts like a battery.

    One possible structure I have designed is a tetrahedral core with spot welded face sheets,

    tetrahedron sandwich panel

    This can be formed by stamping the core and bonding it to the face sheets by spot welding between a pair of rollers with spring loaded electrodes aligned with the vertices of the tetrahedrons. Fluid is free to flow throughout the panel for accretion on all surfaces.

    Another option is micro trusses:

    micro truss sandwich panelmicro truss manufacture punch

    micro truss manufacture fold

    Links for info on the mcro trusses:

    http://www.ipm.virginia.edu/newres/pcm.topo/

    http://www.ipm.virginia.edu/newres/pcm.manuf/

    http://www.cellularmaterials.com/corematerials.asp

    #9674
    Avatar of xns
    xns
    Participant

    Just thought I’d post that we(Hadean) might be building a shop sometime in october with 4, 20ft containers laid side by side with the middle walls cut out to create a large room. Mind you, this will be on shore. Though we might be placing one on the farm once our stress-testing is completed.

    Here’s a useful link: http://www.nordana.com/Equipment/ByName/40_High_Cube.aspx

    High cube containers offer an extra foot of headroom, which, IMO is perfect for most people. And yes, prices in Singapore are approximately US$800 to US$1200.

    King Shannon of the Constitutional Monarchy of Logos.

    #9675
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    admiral wrote:

    Seacrete is viable as a coating on a sandwich panel structure made of a conductive metal like aluminum or magnesium. Magnesium is readily available from seawater and also showed the best growth results with the least power consumption in Eric Lee’s experiments at Stanford. Unfortunately, Lee’s results are no longer online but a partial archived version is at http://web.archive.org/web/20070824145637/http://www.stanford.edu/~erlee/seament/seament.htm . Some magnesium is consumed in the process since it acts like a battery.

    Great stuff Admiral! I had reviewed the link you gave me years ago, but I’m very glad I re-read it. Yes, I really liked your ideas for both the panels and for using the Magnesium. In reviewing article and chemical reactions, a few things stood out. First, the accretion of Calcium Carbonate is but a byproduct of releasing of H2 and the resulting localized change in PH. From the paper:

    Seament wrote:

    The seament electrodeposition reaction is initiated by placing two electrodes in sea water and applying a voltage across the electrodes sufficient for hydrogen gas to be evolved at the cathode. For now we will ignore what is happening at the anode and concentrate on the reactions that are occurring at the cathode where the seament is being deposited.

    (1) As the voltage across the electrode rises there will be a point where the cathode will become electronegative enough to attract the hydrogen ions in solution in water, donate electrons to them and take them out of solution by converting them into hydrogen gas which then bubbles up to the surface of the ocean.

    2e- + 2H+ < => H2 (gas)

    (2) As the hydrogen ions become depleted near the electrode, there is a chemical reaction involving the carbonic acid in sea water that will try to reestablish the old equilibrium concentration. Carbonic acid can disassociate to form bicarbonate ions and hydrogen ions by the reactions:

    H2CO3 < => H+ + HCO3- < => 2H+ + CO3

    What is striking to me is that this equalibrium only triggers accretion because of the increased concentration of Carbonic acid in the vacinity of the electrode. This opens the possibility that there may be other chemical additives that could be used to increase this concentration. For example, could we add Sodium Carbonate to facilitate CaCO3 formation? I’m no chemist, so maybe I have this wrong. Further the article mentions agitating the water to release the CO3– from solution, just like shaking a soda bottle. Maybe use ultrasonic transducers? Whether my chemistry is right or not, the larger question is, can we modify the reaction to favor CaCO3 precipitation?

    Seament wrote:

    As the hydrogen ions near the cathode become depleted this reaction because of LeChatelier’s Principle will move to the right to try to create more H+ species in solution. This will also increase the concentration of carbonate ions ( CO3– ) in solution. In fact the concentration of CO3– ions can become large enough such that the reaction:

    Ca++ + CO3– < => CaCO3 (solid)

    can proceed to the right, precipitating out solid calcium carbonate onto the cathode when the solubility product of Ca++ and CO3– exceeds that of what can be kept dissolved as ions in solution. This solid calcium carbonate, also called argonite, is the good stuff in seament: hard, strong and nearly insoluble.

    The precipitation from solution of CaCO3 is the first accretion related reaction that occurs as the cathode voltage and current density is ramped up. As the cathode voltage and current density is increased further another reaction starts to dominate.

    Ok, here is my bigger idea. Instead of trying to make the entire structure from direct accretion, just focus on accretion of the CaCO3 onto metal sheets. The sheets of CaCO3 can then be mechanically broken up to produce aggregate of various sizes. The aggregate can then be mixed with lime and water and poured into forms as usual. In other words, can we use this process just for the creation of aggregate? Would this be more efficient since the electrical resistance would be easier to control in thinner sheet formation? Can we use chemical additives in combination with ultrasound to fascillitate Calcium Carbonate formation? Could we also use chemical additives to sequester the Magnesium and prevent Magnesium Hydroxide formation? Can we use solar heat and/or vacuum pressure to assist in releasing the CO3? It seems to me that the possibilities have not yet begun to be explored.

    Here is another patent I found of interest:

    http://www.faqs.org/patents/app/20090246511

    It carbonizes cellulose to create a thin graphite”shell”. This cellulose can be formed into sheets for use as a cathode in place of the metal sheeting. The cellulose would ultimately mineralize, adding more strength.

    All of this is speculative at this point. But my argument is that we should not be dumping the concept of Calcium Carbonate as a building material just yet.

    – You may get what you want, but will you want what you get?

    #9676
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    xnsdvd wrote:

    Just thought I’d post that we(Hadean) might be building a shop sometime in october with 4, 20ft containers laid side by side with the middle walls cut out to create a large room. Mind you, this will be on shore. Though we might be placing one on the farm once our stress-testing is completed.

    Here’s a useful link: http://www.nordana.com/Equipment/ByName/40_High_Cube.aspx

    High cube containers offer an extra foot of headroom, which, IMO is perfect for most people. And yes, prices in Singapore are approximately US$800 to US$1200.

    I had no idea high cube containers even existed. Yes, this changes everything. I could really see these being made into primary structures. Fantastic stuff!

    Who is Hadean?

    – You may get what you want, but will you want what you get?

    #9681
    Avatar of admiral-doty
    admiral-doty
    Participant

    I could see producing calcium carbonate flakes or powder using a rotating drum as an electrode and collecting it by scraping it off. Maybe the hydrogen gas from the reaction could be collected as well to reuse as fuel, which would lower the net energy going into the process. Interesting patenet on the cellulose fiber/crytalline graphite material. The 100% argon atmosphere is a pain but it would be an interesting material, cellosic fiber with a diamonoid coating.

    #9688
    Avatar of xns
    xns
    Participant

    Long Answer:
    Hadean is a wholly owned subsidiary of Hadean International Pte. Ltd. Biz Reg No. 201000235E Incorporated in Singapore on the 2nd of January 2010 of which I am the managing director. We deal in aquaculture and R&D of infrastructure for the purpose of aquaculture and seasteading. ;)

    Short Answer:
    My Seasteading Company =D

    King Shannon of the Constitutional Monarchy of Logos.

    #9689
    Avatar of admiral-doty
    admiral-doty
    Participant

    Another option to increase accretion rates is to use the concentrated brine left by boiling seawater for energy either with solar concentrators or a vacuum boiler OTEC system.

    #9694
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    Cool. Any chance you have access to a boat for testing at sea?

    #9692
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    admiral wrote:

    I could see producing calcium carbonate flakes or powder using a rotating drum as an electrode and collecting it by scraping it off. Maybe the hydrogen gas from the reaction could be collected as well to reuse as fuel, which would lower the net energy going into the process. Interesting patenet on the cellulose fiber/crytalline graphite material. The 100% argon atmosphere is a pain but it would be an interesting material, cellosic fiber with a diamonoid coating.




    Yes, this is another possible embodiment. My only concern is breaking off the Calcium carbonate – if you have ever tried removing scaling…. That’s why I’m looking for a more disposable cathode material – cathodes that can be broken up and mixed with the limestone aggregate. I’m thinking more now about using pure graphite as the cathode material. The carbon in the graphite should enhance the overall reaction:

    2Ca++ + 2C + 3O2 -> 2CaCO3

    The carbon coming from the graphite, the Oxygen from the disassociation of H2O at the cathode. In other words, the graphite will get oxidized and added to the total available Carbonate in the local solution, further precipitating the Ca++ out as CaCO3. I’m hoping that there is someone here that knows chemistry better than me to check this. Also, if this graphite sheet/drum could be heated, it would further increase the amount of CO3 available at the local surface near the cathode, removing the need to heat the entire solution; with the heat coming from solar collectors. Applying ultrasound at the cathode would also make the CO3 more available near the surface by means of agitation. Using an inverted sheet/cathode would also likely increase the available CO3, as it tends to disperse upwards, having a lower specific gravity. All of these embodiments should cause the reaction to more favor the formation of Limestone over Magnesium hydroxide. You could also place the cathode much closer to the anode and slowly pull it farther away as the precipitate forms on the cathode, thus reducing the total resistance and energy usage. Adding small amounts of Sodium carbonate to the solution may also increase the accretion rates and favor the CaCO3 reaction.

    Also, if there is a way to remove or sequester the Mg+ from the solution and/or increase the Ca++ concentration, that should also improve the reaction and quality of the product. We know for example that the Mg+ can be removed by high current electrolysis; and as you have pointed out, the magnesium itself does have potential applications.

    There is also a use here for thin membrane technology. In this embodiment, the solution used would be kept in a closed loop and flowed past a thin membrane with fresh ocean water on the other side. As Ca++ and CO3 are depleted from the solution, they would be replentished by new Ca++ and CO3 ions moving across the thin membrane from the ocean water. This has many advantages. For one, the solution could potentially be kept at a higher temperature than the ocean water. The available Mg+ ions in the solution may also be more easily controlled and/or removed. For example, by placing multiple membranes between an anode and a cathode, you should be able to concentrate the Mg+ in one solution layer, and the Ca++ in another layer, due to the Mg+ being more mobile at higher currents. Another advantage is that the Sodium carbonate would not be as easily lost to the environment, as it would be recycled until it is used up in reactions.

    The goal here is to increase the available Ca++ while reducing the Mg+ and increase the availability and concentration of CO3 at the cathode. All of this will cause rapid formation of the desired CaCO3 product. I think all of these embodiments can be tested on dry land in a suitable laboratory environment prior to final testing at sea.

    And yes, much of the energy used in the electrolysis will be generating H2, which can now be saved and used. So now we have a usable energy by-product – I’m sure we’ll find some use for . As I’m writing this, I’m thinking that the CaCO3 precipitate is better if it does not aggregate on the cathode – we can filter it out on drums and use the Limestone powder in large molds. It would also solve the electrical resistance problem. After all, this is a far better building material.

    – You may get what you want, but will you want what you get?

    #9693
    Avatar of CrosiarCM
    CrosiarCM
    Participant

    admiral wrote:

    Another option to increase accretion rates is to use the concentrated brine left by boiling seawater for energy either with solar concentrators or a vacuum boiler OTEC system.

    Yes, you did remind me, I forgot in my last message to mention that the solution in the closed loop should be at a slight vacuum to encourage CO3 beling released from solution at the cathode. I have thought about concentrating the ocean water, but I think it would be impractical because of the amount of energy needed to concentrate the brine; obviously OTEC would change that entire equation. Instead I’m focusing on concentrating just the needed ions in the solution by thin membrane and electrolysis.




    – You may get what you want, but will you want what you get?

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