environment food

10 different uses for seaweed

One of the sustainability trends that I keep an eye on is ocean farming. It’s one of the most promising avenues for feeding the world, though progress is pretty slow so far. Seaweed has vast untapped potential, as demonstrated by these ten different uses for it:

1. Food – many cultures eat seaweed, mostly in Asia, where 99% of seaweed farming takes place. Other cultures used to eat more of it, including more locally in Wales and Cornwall, but it has become more specialist and niche with the passing years. The ocean has huge potential as a future food source, expanding production without increasing our impact on the land.

2. Feed – seaweed production doesn’t have to be for human consumption. Farmers in the Scotland and the north of England traditionally used seaweed as a supplement to winter fodder for their animals. Recent research has shown that seaweed can reduce methane emissions from cattle, which could turn out to be particularly important.

3. Plastics – the ocean could be a major source of future bio-plastics and plastic alternatives, replacing fossil fuels to create packaging that is plant based and entirely biodegradeable. See the UK start-up Sweed as one of many examples of those experimenting in this area.

4. Biofuel – biofuels have a potentially vital role in reducing fossil fuel use, but so far they have a mixed legacy. Many biofuels are little better than oil once their full environmental impact has been considered, especially where forests are cleared for plantations. The oceans could provide vast resources for biofuels that leave forests intact.

5. Fertiliser – another traditional product. Coastal communities in many parts of the world have used seaweed as a soil improver. If the world has less livestock in future – which it should do – then seaweed could take the place of manures and animal-based plant feed.

6. Carbon capture – as some of the fastest growing plants on the planet, seaweed can capture huge amounts of carbon in underwater forests, which is then locked in when the seaweed dies and sinks to the ocean floor. It’s one of the biggest opportunities for drawing carbon out of the atmosphere, and it may only be a matter of time before we start hearing about ocean based offsetting schemes.

7. Marine restoration – marine dead zones occur where nitrogen fertilisers wash off the land and into rivers, and then accumulate in the sea. This can lead to algal blooms that choke out other life and kill marine ecosystems. The only real way to restore these areas is to use plants to absorb those excess nutrients and remove them from the water. Certain seaweeds can also reduce ocean acidification.

8. Fishing – as well as restoring sea meadows and underwater forests in their own right, undersea plantings can help to restore fish stocks. They provide a safe habitat for hatchlings, and so seaweed aquaculture can support commercial fishing rather than competing with it for space.

9. Job creation – speaking of commercial fishing, ocean farming can help to regenerate coastal communities where jobs have been lost through the decline of fish stocks or economic marginalisation. It’s a potential growth area in regions that may struggle to attract investment in other ways, and keeps communities with a connection to the sea at work.

10. Industry – lastly, I’m using the word industry as a bit of a catch-all here to say that all kinds of useful ingredients can be derived from seaweed. They are used in medicine, in cosmetics or in food production. Many of them are more sustainable than the products they replace, such animal-free alternatives to gelatin.

Having highlighted these benefits, I should mention that all of them have to be done responsibly and sustainably. We don’t want a destructive goldrush into ocean farming. Neither should we hold back from using the oceans for fear of exporting our exploitative land-based farming into new territory. Human activity is already affecting the oceans, and when done well, many forms of ocean farming can be restorative.


  1. Ocean “farming” is just one more way of increasing human consumption and human impacts on natural habitats and ecosystems. This is not sustainable. That which cannot go on forever stops.

    1. Like farming on land, there are sustainable and unsustainable ways to farm the oceans. We need the sustainable kind – and as I point out, some forms of ocean farming are regenerative by design. Don’t throw the baby out with the seawater!

  2. To All Anchors of CNN

    Seaweed is ‘gold dust’ . Please make sure that we use this surfeit of seaweed for good purpose and not just land fill. Help save the planet!

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