Automated height adjustment of seaweed lines (First Post)
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Hello!
I'm currently studying towards a master's in design engineering in the UK. I live on the coast and have become increasingly interested in seaweed farming over the past few years, particularly in its contributions towards coastal communities and sustainable transitions.
As part of my current project, I'm hoping to develop a few prototypes experimenting with where some degree of automation/intelligence might help smaller seaweed farming operations. I don't want to build another sea-combine, this is very much a low-cost intervention with a realistic potential for impact.
I've really enjoyed learning through the courses provided here and was wondering if any of the community might be able to comment on an early concept.
Automated height adjustment of seaweed lines - I've read a lot about how the height at which seaweed grows might need to be adjusted for temp, salinity, light availability etc. I would be interested to hear if some tools to better automate or more easily adjust this could be of interest for those working in industry, potentially to increase yield, prevent biofouling or to extend the growing season of a specific strain.
I've struggled to find much information on this topic online and would appreciate any feedback you could give.
Thank you for your time and all the best,
Jasper
@jasper_mallinson -
Hi, Jasper. Yes, there is at least 1 private company (in the US) working on this idea. If you are interested, send me a direct message and I can email you the info (which I am only mentioning because I think the GreenWave staff can't have private companies promoted on this website since it might endanger their non-profit legal status -- IIRC it's part of their official rules for using the forum). Other than that 1 company, I am not aware of any other companies or researchers doing this, but there are other schemes for addressing the same problem (the question of availability of nutrients at different depths).
Cheers
@jasper_mallinson - Hi Jasper! Interesting question. I know that @clifford_goudey and @loretta_roberson are working on a farm design for tropical seaweeds that would have the ability to sink a farm from the surface to avoid hurricanes or other strong storm damage. And, as you mention, adjusting line height is a critical part of optimizing growth, so there certainly is interest in the field. Curious what others have heard on this topic. @david_bailey, @domenic_manganelli ?
@lindsay_olsen - Thank you for your reply! Brilliant, I've been exploring slinking the farm for strong currents/storms a little, I would love for the devices to have this function too. Maybe this could even open up new sites that might otherwise be too exposed?
It seems like the main issue, for now, is designing a cheap enough winch/buoyancy system. Designing it for the single horizontal line designs I see here is difficult without needing multiple devices (which is getting expensive...). I will keep exploring alternative farm designs and lifting systems for now though. If of interest to anyone, this paper had a bit more information on this topic (although for offshore) https://www.sciencedirect.com/... -
Thanks again and all the best,
Jasper
@lindsay_olsen - Thank you for your reply! Brilliant, I've been exploring slinking the farm for strong currents/storms a little, I would love for the devices to have this function too. Maybe this could even open up new sites that might otherwise be too exposed?
It seems like the main issue, for now, is designing a cheap enough winch/buoyancy system. Designing it for the single horizontal line designs I see here is difficult without needing multiple devices (which is getting expensive...). I will keep exploring alternative farm designs and lifting systems for now though. If of interest to anyone, this paper had a bit more information on this topic (although for offshore) https://www.sciencedirect.com/... -
Thanks again and all the best,
Jasper
@jasper_mallinson - Arctic Seaweed's system in Norway has that ability. The Climate Foundation's pilot platform in the Philippines as well. Phil Cruver in California (KZO farms) is trying to find a place to trial his cages in tropical waters that can also move up and down in the water column.
@steven_hermans - Those projects look great, thanks for pointing me in their direction!
@steven_hermans - Those projects look great, thanks for pointing me in their direction!
@jasper_mallinson said:
Certainly share more information here. I and others, I hope, may be willing to weigh in. Depth adjustments may be more critical in deeper water sites, or on offshore farms where lowering the system could protect against loss and damage during storm events, significant rain (many kelps blister when exposed to fresh water for extended periods of time), and/or to optimize access to nutrients in the water column, etc. Perhaps you've read about/been in touch with the ARPA-e MARINER program team working on the "kelp elevator" out in California?
The benefits may be less pronounced in near-shore/shallow water sites. In an ideal scenario, a farmer understands their water quality conditions and is able to optimize their farm design based on those conditions and other farm/business goals.
@david_bailey any thoughts on automated height adjustments?
@kendall_barbery - Thank you for your help! That makes sense regarding less benefit in near-shore operations when it comes to access to nutrients. I did come across a study looking at this in relatively shallow waters in Indonesia where they measured more nutrients deeper in the water column, although I suppose there is still little benefit if these levels are sufficient near the surface: https://www.researchgate.net/p...
I will keep exploring other potential sources of value in vertical cycling as well for now. A farmer here in the UK mentioned regulating temperature and biofouling to extend growing seasons of particular strains as a potential avenue, I would be interested if anyone had any thoughts on this?
I am aware of the kelp elevator project which seemed like a very interesting context but I have not reached out directly yet.
All the best,
Jasper
@jasper_mallinson -As mentioned in the thread there are a couple of companies/projects that adjust the depth of their seaweed. This is typically done at farm locations where the surface nutrients are not sufficient for growth. During the day the seaweed is kept in the photic zone, enabling photosynthesis, then sunk below the photic zone at night, enabling nutrient absorption.
Seaweed farms in coastal waters typically have enough nutrients in the surface water, so depth adjustment is not needed. BUT depth maintenance is needed.... making sure the seaweed is at the optimum growing depth throughout the growing season. Depending of the type of seaweed that is being farmed the buoyancy will either need to be increased (negatively buoyant species) or decreased (positively buoyant species). This is typically done by adding floatation throughout the season. Automating this process would be very helpful.
@david_bailey - Interesting, I will definitely look into this further! Is it possible to say how regularly buoyancy might have to be increased/decreased throughout growth?
Thanks for the help and all the best,
Jasper
@david_bailey - I would say the major business case for depth adjustment is in the tropics, where waters are now often too hot, and where in places like the Philippines increasingly regular typhoons wipe out the crop unless you can sink it to protect it.
I heard The Climate Foundation's crop survived the recent typhoon in the Philippines, for instance, while everyone else's was destroyed.
Main problem here is that the investment necessary is difficult to carry by small farmers, and that going offshore tends to push women out of the industry because it is men who operate the machinery, steer the boats, swim, ...
@kendall_barbery - Thank you for your help! That makes sense regarding less benefit in near-shore operations when it comes to access to nutrients. I did come across a study looking at this in relatively shallow waters in Indonesia where they measured more nutrients deeper in the water column, although I suppose there is still little benefit if these levels are sufficient near the surface: https://www.researchgate.net/p...
I will keep exploring other potential sources of value in vertical cycling as well for now. A farmer here in the UK mentioned regulating temperature and biofouling to extend growing seasons of particular strains as a potential avenue, I would be interested if anyone had any thoughts on this?
I am aware of the kelp elevator project which seemed like a very interesting context but I have not reached out directly yet.
All the best,
Jasper
@david_bailey - Interesting, I will definitely look into this further! Is it possible to say how regularly buoyancy might have to be increased/decreased throughout growth?
Thanks for the help and all the best,
Jasper
@david_bailey - I would say the major business case for depth adjustment is in the tropics, where waters are now often too hot, and where in places like the Philippines increasingly regular typhoons wipe out the crop unless you can sink it to protect it.
I heard The Climate Foundation's crop survived the recent typhoon in the Philippines, for instance, while everyone else's was destroyed.
Main problem here is that the investment necessary is difficult to carry by small farmers, and that going offshore tends to push women out of the industry because it is men who operate the machinery, steer the boats, swim, ...
Jasper, there is a big difference between a system for controlling the depth of the farm and one to do so automatically. I'm not convinced that for normal farming methods automating such a feature would be worth the trouble. Responding to seasonal growing conditions or the varying needs of different stages of crop maturity seem like sufficiently rare events that I'd want to be on site and tend to those activities in person.
The variable-displacement spar buoys (VDSBs) that we've developed for our catenary modules have proven handy, but mostly for raising the system during deployment and growline installation, or for making adjustments to compensate for crop weight. It's a simple matter of adding or venting air from the lower chamber of the buoy. The system has worked well in Kodiak and next month a similar rig will be installed in Puerto Rico.
With that tropical system we will be utilizing the VDSBs ability to be sunk to the bottom upon the threat of a hurricane. In that case, remote triggering of the sinking is planned but clearly not something we'd "automate" by watching the barometer fall.
For more information see: https://www.tendocean.com/prod...
Cliff
@clifford_goudey - Thank you for your help!
Yes I am beginning to understand that aside from offshore sites there might be little advantage to daily cycling of grow-line depth. I'm moving towards looking at winch based systems focused on manually adjusting line height less regularly, maintaining line tension, and for protection from extreme weather.
Your system looks like a great solution though! I'd be interested to know if this has allowed you to farm in sites that might otherwise be too exposed to storms, or if it's more of an extra precaution for existing sites? Here in the UK I have been told that the limited availability of suitable sites could be a bottleneck in scaling up the number of farms.
All the best, Jasper
Jasper,
The main motivation for the tall, slender spar buoys is to eliminate the excitation that gets inserted into a farm from typical spherical or squat buoys that have most of their flotation concentrated at the sea surface. I think that sort of heave resistance is useful in protecting the crop at its earliest stages of growth and likely reduces snap loading on the system and its components during weather extremes.
I also sense that in coastal waters there is sufficient mixing (at least in the winter) to provide nutrient mixing throughout the water column. I'd be interested in hearing if there are measurements to the contrary. Anyway, depth cycling chasing nutrients is not anything we are considering.
Cliff
@jasper_mallinson - I want to update this discussion of nearly 2 years ago when I stated, "depth cycling chasing nutrients is not anything we are considering." Things change, and lab results and research by others have revealed that there may be practical value in depth cycling under some conditions. The challenge, of course, is to find a method of doing it that is simple, robust, and sufficiently cost effective.
In collaboration with the MBL Tropical Seaweed Project supported by ARPA-E and led by @loretta_roberson, we have developed system for raising and lowering a 108' x 200' catenary farm off the SW corner of Puerto Rico. Because of its exposure to hurricanes, the ability to sink seemed a prudent idea. However last summer surface sea-water temperatures rose prompting us to sink the farm for most of August and September. At the same time experiments looking at the effect of nutrients and light on growth rates have suggested spending more time at the bottom (It's a 60'-deep site) would enhance growth rates and allow more frequent harvests.
We've recently shipped a new set of four variable-displacement spar buoys (VDSBs) to the farm and this month we will be installing them for testing. These VDSBs include a compartment for an 80 cf scuba tank, an radio link, electronics, and valves to allow their remote-controlled sinking and timed recovery. Air is vented from and subsequently added to the VDSBs ballast chamber to effect these movements. A well-trimmed farm (meaning one with a proper amount of buoyancy or weigh to balance the crop) can be cycled multiple times between scuba-tank changes. Will the enhanced growth rates be worth the hassle? Answering that question is the purpose of the experiment.
Cliff
@clifford_goudey - What a nice surprise to get an update on this two years on! Excited to hear the area is still evolving, sounds like an interesting set of problems to solve and a pretty major build. Out of a general interest, please do point to where we might be able to find your resluts when the project wraps up if this is something you are able to do.
Jasper
@clifford_goudey - Thank you for your help!
Yes I am beginning to understand that aside from offshore sites there might be little advantage to daily cycling of grow-line depth. I'm moving towards looking at winch based systems focused on manually adjusting line height less regularly, maintaining line tension, and for protection from extreme weather.
Your system looks like a great solution though! I'd be interested to know if this has allowed you to farm in sites that might otherwise be too exposed to storms, or if it's more of an extra precaution for existing sites? Here in the UK I have been told that the limited availability of suitable sites could be a bottleneck in scaling up the number of farms.
All the best, Jasper
Jasper,
The main motivation for the tall, slender spar buoys is to eliminate the excitation that gets inserted into a farm from typical spherical or squat buoys that have most of their flotation concentrated at the sea surface. I think that sort of heave resistance is useful in protecting the crop at its earliest stages of growth and likely reduces snap loading on the system and its components during weather extremes.
I also sense that in coastal waters there is sufficient mixing (at least in the winter) to provide nutrient mixing throughout the water column. I'd be interested in hearing if there are measurements to the contrary. Anyway, depth cycling chasing nutrients is not anything we are considering.
Cliff
@jasper_mallinson - I want to update this discussion of nearly 2 years ago when I stated, "depth cycling chasing nutrients is not anything we are considering." Things change, and lab results and research by others have revealed that there may be practical value in depth cycling under some conditions. The challenge, of course, is to find a method of doing it that is simple, robust, and sufficiently cost effective.
In collaboration with the MBL Tropical Seaweed Project supported by ARPA-E and led by @loretta_roberson, we have developed system for raising and lowering a 108' x 200' catenary farm off the SW corner of Puerto Rico. Because of its exposure to hurricanes, the ability to sink seemed a prudent idea. However last summer surface sea-water temperatures rose prompting us to sink the farm for most of August and September. At the same time experiments looking at the effect of nutrients and light on growth rates have suggested spending more time at the bottom (It's a 60'-deep site) would enhance growth rates and allow more frequent harvests.
We've recently shipped a new set of four variable-displacement spar buoys (VDSBs) to the farm and this month we will be installing them for testing. These VDSBs include a compartment for an 80 cf scuba tank, an radio link, electronics, and valves to allow their remote-controlled sinking and timed recovery. Air is vented from and subsequently added to the VDSBs ballast chamber to effect these movements. A well-trimmed farm (meaning one with a proper amount of buoyancy or weigh to balance the crop) can be cycled multiple times between scuba-tank changes. Will the enhanced growth rates be worth the hassle? Answering that question is the purpose of the experiment.
Cliff
@clifford_goudey - What a nice surprise to get an update on this two years on! Excited to hear the area is still evolving, sounds like an interesting set of problems to solve and a pretty major build. Out of a general interest, please do point to where we might be able to find your resluts when the project wraps up if this is something you are able to do.
Jasper