Researchers are scaling up solar-powered kelp farms | Hacker News Reader

Researchers are scaling up solar-powered kelp farms

spectrum.ieee.org

67 pointsgeox28 comments

Hmm..

"A quarter of the seaweed grown typically falls off the platform and sinks 1,000 meters to the seafloor, von Herzen says. At such depths, little oxygen is present, and biomass doesn’t readily decompose."

Let's hope that is thoroughly verified. Elsewhere, microbes break down biomass in oxygen-poor conditions into lots of methane. If that turns out to be the case, dropping masses of seaweed to the ocean floor could be a timebomb worse than the CO2 it sequestered.

Better aim for the other option:

"But he [Rod Fujita] believes the best strategy for mitigating climate change with seaweed is to turn it into fuels or plastics, construction materials, or additives that suppress methane emissions from cattle and rice paddies."

Yep. Win-win: sequester carbon, and produce something useful that replaces fossil-based goods.

This exact mechanism has been proved before in the historical record, several times in fact, leading to ice ages even with the massive sequestration of greenhouse gasses from such algae falling to the bottom of the ocean.

https://www.wired.com/2012/07/algae-ice-age-climate/

Yes, both mechanisms are well attested. We need to know which one is happening here.

Also I apologize for the double comment but I think its a point that stands on its own. Kelp is also very useful for dealing with eutrification from either sewer or runoff. There have been some successful pilot experiments in new york harbor on using kelp to clean the water (1). Where its farmed in bulk it also has significant cleaning properties for local waterways (2). So not only does it help with greenhouse emissions but water pollution as well.

https://www.thecity.nyc/2023/03/22/kelp-farming-climate-solu...

https://iopscience.iop.org/article/10.1088/1748-9326/ac3fd9

In terrestrial environments, similar things have been done with poplar trees:

https://s3.wp.wsu.edu/uploads/sites/2182/2017/09/Wastewater-...

Grow extremely fast and fix carbon in wood, absorbing excess nutrients along the way. IMHO every cash crop farm should stands of poplars or willows on their borders.

If we want to do anything to reduce carbon, we have to stop burning shit, not just burn some other shit.

Too bad the article doesn't cover the relationship with nutrient depletion. After all, nutrients taken up by their kelp won't make other algae grow. Given that ocean fertilization experiments have such big, unknown consequences (so that they are pretty much under memorandum), that would have been interesting to relate to.

Is that a problem?

What is the evidence?

Wikipedia about ocean fertilization '''... open-sea experiments [have] confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up to 30 times.'''

I.e adding nutrients leads to plankton growth. So I would assume removing nutrients will lead to less phytoplankton growth. Since phytoplankton is also a carbon sink, doing so via kelp might have zero benefit.

I’d speculate that if you did these offshore of river deltas where there is significant agrarian economy upstream you’d be able to capture fertilizer/waste run off, though not sure about the distance to deep water and dissipation at that distance

Pretty cool, but...

The article "Kelp is the planet’s fastest-growing plant"

... kelp is not a plant? Second sentence of its Wikipedia article.

Prescriptivism vs. descriptivism. Taxonomically, you're right — kelp is a macroalgae, not a plant. But most people don't really care (and don't need to care) about this taxonomical distinction in their day-to-day life. It has a stem and leaves, it eats via photosynthesis, it's rooted to a single spot, and it's green-ish — as far as I'm concerned, that's a plant!

I generally find that defining words descriptively (based on how most people use them most of the time) rather than prescriptively (based on how institutions or niche groups use them) is a good way to avoid conflict, both on the internet and IRL!

The same with trees and 'plants'. Many trees are more closely related to plants, than to other trees.

There are trees that aren't plants?

I think they missed a word: other plants.

Tree wood has evolved independently several times, much like the crab form.

I love the quote 'we’ve gone from designing systems on a chip in Silicon Valley to systems on a ship'

I had the opposite reaction. Reading that quote made me immediately take them a lot less seriously.

It smacks of the same old SV overconfidence. "I designed (hold your applause) chips. How hard could maritime engineering possibly be??"

Who cares, if it gets results, that’s all that matters.

We really need results right now.

  > Who cares, if it gets results

What I'm saying is, this (sad to say) lowers my estimate of the probability that this team will actually achieve such results.

Sorry if I was unclear.

Jokes on the downvoters who thought kelp couldn’t turn sunlight into biofuel.

https://news.ycombinator.com/item?id=37885853

That user was quite bullheaded it seems, claiming such things are impossible without even understanding how kelp are grown today. They are grown on lines trawled by ships, not the ocean floor where there are urchins perhaps and depth requirements. Its already a massive industry in East Asia. It's the US that is decades behind on this effort. 16 million tons of seaweed harvested in 2016 in these countries:

https://www.tandfonline.com/doi/full/10.1080/00318884.2019.1...

It is interesting how a cultural element, like food habits leading to development of aqueous agriculture, can guide later utilization of the resource in an unforeseen manner.

Agreed. I was surprised to read in a John Adams biography about their household use of seaweed as a foodstuff and fertilizer. It makes sense for a community largely based along the ocean coastline, but it’s not something I had heard about in the US… I wonder when the practice waned here

It was/is a dish in the Northern Europe called “Dulce” in Ireland that somehow fell out of favor, story below. I imagine the evolution was like the lobster, at one point something indentured servants wouldn’t eat, at another a delicacy of sorts.

https://news.ycombinator.com/item?id=37943843

Interesting project, the key take away is that if kelp can migrate to deeper water overnight, they have access to nutrients that typically end up depleted in the surface water. Oceanography-wise, this is not surprising - spring algal blooms in northern oceans are aided by winter storms mixing up the ocean surface and introducing nutrients from deeper waters. However, the climate blurb is a bit odd:

> "The extra kelp can be turned into food, fertilizer, and fuel, or it can be committed to the deep, locking away countless tonnes of carbon for centuries."

If you dump lots of organic carbon in the deep ocean, you end up with a lot of microbial respiration of that carbon (return to CO2) with an equivalent drawdown of free oxygen, leading to anoxic bottom waters (a process exacerbated by all the nitrogen fertilizer being dumped in the ocean from industrial agriculture).

Hence, schemes like providing carbon credits to seaweed farmers who dump their product in the deep ocean in exchange for the ability to sell those carbon credits to say natural gas producers who want to claim their emissions are being 'offset' should be viewed as the dishonest scams that they are.

Carbon credits are a scam, true

But I do not think it is a foregone conclusion that "...If you dump lots of organic carbon in the deep ocean, you end up with a lot of microbial respiration of that carbon (return to CO2) with an equivalent drawdown of free oxygen,"

Have you evidence?

https://www.climate-policy-watcher.org/nitrogen-deposition/m...

> "Any increase in the occurrence of anoxia in the ocean should therefore enhance the geologic organic carbon sink. The solubility of oxygen decreases with increasing water temperatures, so a warmer Earth should have a less oxygenated ocean (all other things being equal). Increased stratification will also reduce the downward transport of oxygenated surface waters to depth. An increase in carbon preservation and burial in marine sediments in response to global warming is therefore starting to look like a distinct possibility."

Basically, you end up re-creating the conditions that led to the formation of the majority of the world's large oil & gas deposits some hundred(s) of millions of years ago.

> Basically, you end up re-creating the conditions that led to the formation of the majority of the world's large oil & gas deposits some hundred(s) of millions of years ago.

Interesting

If I understand, that is carbon sequestration?

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