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Seaweed Aquaculture: An Answer to Sustainable Food and Fuel?

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"Seaweed Aquaculture: An Answer to Sustainable Food and Fuel?"


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by Cole Mellino

When copying the model of land-based industrialized farming, current aquaculture practices can have many of the same negative environmental impacts inherent in industrial-scale agriculture.

U.S. aquaculture operations, primarily producing shellfish, are subject to stringent environmental regulations. But due to the poorly regulated use of high amounts of chemicals and antibiotics to maintain massive, centralized monocultures of fish and shrimp particularly in South America and southeast Asia, aquaculture farms have gained a reputation for polluting water and producing poor-quality food.

But it doesn’t have to be this way. The Atlantic had a fantastic piece this week on the growing movement to clean up aquaculture operations — producing better food, sustainable biproducts, and making them a solution to environmental problems:

Unsurprisingly, once information got out among the general public, “aquaculture” quickly became a dirty word. Industry responded with a strategy of mislabeling seafood and upping their marketing budgets, rather than investing in more sustainable and environmentally benign farming techniques.

But a small group of ocean farmers and scientists decided to chart a different course. Rather than relying on mono-aquaculture operations, these new ocean farms are pioneering muti-tropic and sea-vegetable aquaculture, whereby ocean farmers grow abundant, high-quality seafood while improving, rather than damaging, the environment.

One of the keys? Seaweed. This type of algae, which can be used for everything from food to fertilizer, could be a major piece of creating a network of sustainable farming operations:

Seaweed farms alone have the capacity to grow massive amounts of nutrient-rich food. Professor Ronald Osinga at Wageningen University in the Netherlands has calculated that a global network of “sea-vegetable” farms totaling 180,000 square kilometers — roughly the size of Washington state — could provide enough protein for the entire world population.

The goal, according to chef Dan Barber — named one of the world’s most influential people by Time and a hero of the organic food movement — is to create a world where “farms restore instead of deplete” and allow “every community to feed itself.”

But here is the real kicker: Because they require no fresh water, no deforestation, and no fertilizer — all significant downsides to land-based farming — these ocean farms promise to be more sustainable than even the most environmentally-sensitive traditional farms.

Along with being a fantastic source of food, seaweed could be a substantial feedstock for biofuels production. A lot of research has been done on seaweed as a biofuel source, and some pioneers are beginning to farm it for energy production. And while there are no seaweed-based biofuels being produced at commercial scale, there are a lot of good reasons to continue pursuing it.

Firstly, seaweed is not a major source of food globally. And it’s also one of the fastest growing plants in the world. It can grow 9-12 feet in three months. Additionally, fifty percent of seaweed’s weight is oil, so we would theoretically only need to set aside three percent of the world’s oceans for seaweed farming to meet world energy needs.

If you compare efficiency of algae as a fuel source to other proven sources, there’s no comparison. Soy produces 40 to 50 gallons of biofuel per acre, rapeseed between 110 and 115, mustard 140, and palm oil 650. Algae, on the other hand, has the potential to produce 10,000 gallons of biofuel per acre. And most importantly, seaweed can absorb five times more carbon dioxide than land-based plants.

The Atlantic explores the potential for seaweed-based biofuels further:

Finding a clean replacement for existing biofuels is becoming increasingly urgent. A report commissioned by the European Union found biofuels from soy beans can create up to four times more climate-warming emissions than equivalent fossil fuels. Biofuels have also forced global food prices up by 75 percent — far more than previously estimated — according to a confidential World Bank study. And a recent report from the International Food Policy and Research Institute, warned that U.S. government support for corn ethanol was a major factor behind this year’s food price spikes.

Seaweed and other algae is increasingly looking like a viable substitute. About 50 percent of seaweed’s weight is oil, which can be used to make biodiesel for cars, trucks, and airplanes. Scientists at the University of Indiana recently figured out how to turn seaweed into biodiesel four times faster than other biofuels, and researchers at the Georgia Institute of Technology have discovered a way to use alginate extracted from kelp to ramp up the storage power of lithium-ion batteries by a factor of ten.

The Pentagon has taken a special interest in seaweed and other algae-based biofuels as well. In the words of Alan Shaffer, the Pentagon’s principal deputy director of defense research and engineering: “The beauty with algae is that you can grow it anywhere and to grow it needs to absorb carbon dioxide, so it’s not only a very effective fuel, in theory it’s also a carbon sink. That’s a pretty good deal.”

A pretty good deal indeed.

- Cole Mellino is an intern on the energy team with the Center for American Progress. Climate Progress blogger Stephen Lacey contributed to this story.

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11 Responses to Seaweed Aquaculture: An Answer to Sustainable Food and Fuel?

  1. Mike Roddy says:

    Very promising, but plants need food, too. Seaweed only grows where there are nutrients and minerals, as on the continental shelves. Do these plans include fertilization or enclosures? Are there limitations? Seaweed is also great habitat for fisheries, of course.

  2. Leif says:

    If properly developed this could be a great resource for indigenous peoples around the world. Most are delegated to out of sight locations. Floating hardware could be manufactured else where and cheaply floated to where needed. i.e. Bio digesters for on site fuel production. Fuel is currently transported great distances at huge costs, (half way around the world?) and on site production would pay great dividends in local jobs and resources and money retained within the community.

  3. RobLL says:

    And shouldn’t most sewage plants run the raw stocks through an algae production stage before finishing treatment, and consider the raw materical an asset rather than merely a pollutent?

  4. Leif says:

    Kelp and other seaweed grow fine in clean un-acidified ocean but research has revealed serious negative growth properties in acidified ocean water expected as soon as 2030 to 2050. Nice thought but looks like the ecocidal fossil industry is closing that door as well. A quick google search finds this:


    • perceptiventity says:

      There’s almost no time left, yes. But if it takes up CO2 to grow it can help with acidification if done on a large enough scale

  5. I have seen few articles with as little scientific and technical basis, and or even the most rudimentary understanding of the problems, or a realistic understanding of the potential of algae for food or fuel as the one above. The author should stick to topics with which he is at least somewhat familiar.

    The statement of sea weeds requirements and their composition (50% lipids? It would float like a cork – show me one commercially produced and harvested algae over 20% lipid.) is generally – totally erroneous. This year has seen more algae biofuel development companies (of the several hundred) withdraw or go under than any previous year. There’s a very good reason why – lack of economic feasibility and no foreseeable technical solutions to the lack of economic feasibility in sight. Couple the lack of economic feasibility of commercial contained culture algae’s requirement for peak phosphate (NPK) fertilizers and you have direct competition with global food production. Do you really think Exxon is interested in the environment? Not really, they are looking for new markets for their natural gas used to make nitrogen fertilizer (N). Unfortunately, the commercial production of peak phosphorus isn’t economically feasible as yet to create through any known processes (at the required scales) – though scientist have been researching the problem for the last 40 years.

    Open ocean (or open fresh water) cultivation of algae for food and animal feed is a different story, but is also a much more limited one in the developed world where the economics of recreational water use overrides those of food production. In developing countries it is limited by unpredictable water quality and food quality standards. Want a little Nori from Fukushima or down stream from China?

    For those wanting to be informed on the subject:








    The Rational Optimist – a book by Matt Ridley

  6. Joan Savage says:

    For those of us who have eaten seaweed pretty regularly, we are at least dimly aware of what is a well-developed multi-billion dollar market for cultivated seaweed. This article looks at expansion uses, but seaweed aquaculture is not a new idea.

    The points made by Mike Roddy and Leif about habitat limitations are important, and I’d add that as water temperature rises, the risk of toxic red tide and the like also increases.

  7. Graham Harris says:

    Some of the numbers quoted in this piece are without foundation. That doesn’t invalidate the concept, but expectations should be lower than this article suggests.

    Ocean acidification is a more pressing problem than global warming, in my opinion. If we can get seaweed farming running at large scale soon enough, it will be part of the solution. If we delay, the oceans may become too acid for it to work.

  8. Behold: another brilliant, counter-intuitive solution to a global problem shows itself in my RSS Feed. I’m not being sarcastic. I appear to encounter at least one or two of these a day–fixes that, if implemented universally, would help alleviate the suffering of millions and facilitate our transition into a civilization that’s actually likely to be around for a while.

    If all the great ideas that appear in my RSS feed every day received adequate funding for research, development and deployment, I think we’d all have a great shot at being all right. Hopefully all the moral appeals to world governments that have been made in recent months yield some positive results, eh?

  9. Kelpfarmer says:

    Here are a few comments on this story and individuals responses from a kelp farmer/master’s student finishing his thesis on kelp farming:

    I agree alot with what dduggerbiocepts has to say; this story is overly optomistic. In the hundreds of scientific journals I have read/skimmed/fallen asleep to, I have never seen any referring to 50% fat content. If that was the case there would be a whole lotta seaweed farming going on. I think that the value of oil, per barrel, for seaweed farming to become economically feasible is around $240.

    However, as a protein source, there are some seaweeds that can absorb so much nitrogen that they can have over 40% protein content (by weight). That could be a game changer. If the seaweed could be produced at an industrial scale it could replace other protein sources in livestock/fish feeds.
    In terms of the health benefits of eating kelp or other seaweeds, there are many who believe the longevity/general health/lack of obesity in the Japanese can be attributed, in part (I repeat, in part), to eating seaweeds.
    To Mike Rowdy, the limitations are money, money money. Seaweed isn’t worth much for industrial applications and the food market in USA/Canada, where seaweeds could be worth more, is not very large…yet. Also the infrastructure on which or in which to grow it (i.e. open-water or land-based), the infrastructure maintenance, and labour expenses are relatively high (hence seaweeds are grown in developing countries where labour costs are low). Also trying to secure the water leases in which to grow it is difficult mainly due to the general public (the “not-in-my-back-yard” sentiment).

    To Lief about ocean acidification (OC) problems: OA shouldn’t effect seaweed farming. The article which you reference refers to marine microalgae being effected and the microscopice stages of macroalgae (seaweeds). In marine macroalgal/seaweed farming the microscopic stages are controlled and manipulated in a lab and are not subject to open ocean problems such as OA. Seaweed farming should help with OA by extracting CO2 and bicarbonate and replacing it with 02 (the wonders of photosynthesis).