Seamonster: Some species of kelp can grow up to 30 metres long.

Just 2% of the world’s fertile ocean is used to grow seaweed. But environmental benefits and scientific innovation mean this overlooked industry could be about to experience a boom.

  • What is seaweed?

    It is a common name given to countless species of marine plants and algae that grow in oceans, lakes and rivers. They grow incredibly fast, taking energy from sunlight, and nutrients and carbon dioxide from the seawater.

    Seaweed is an extremely effective carbon sink. One dry tonne of kelp absorbs the same weight in CO2 during its lifetime. Plus, it takes up far less space than a terrestrial forest.

  • Why is it farmed?

    Seaweed has many advantages as a raw material. It is cheap, easy to harvest and available on every coastline. It doesn’t require fertiliser – or even freshwater – to grow. It grows up to three metres a day and whole forests can be harvested every 90 days. A single seaweed farm can make up to $120,000 a year.

    The seaweed revolution began in Asia and is still most common in China. But the trade is spreading around the world, from the US to the Faroe Islands.

    And the industry continues to grow. Between 2005 and 2015, volumes doubled, reaching over 30 million tonnes annually. According to Global Market insights, the global seaweed market could be worth more than $85bn by 2026.

  • So, what is it used for?

    Seaweed is an essential ingredient in dozens of everyday items from baby milk to medicine.

    One major product is food. Sea vegetables are one of the fastest growing foods industries worldwide. And in January, seaweed was named one of the biggest food trends for 2021.

    Often described as a superfood, seaweed has numerous health benefits. Iodine supports thyroid health and brain function. B vitamins, copper, zinc and potassium provide balanced vitamins. And fatty acids, calcium and amino acids are excellent supplements for anyone following a vegan diet.

  • And is it just for humans?

    No. It could soon be a supplement for cattle diets. Methane is 28 times more effective than CO2 at trapping heat – and a single cow burps out 120kg of the gas every year. It is a reaction built into the cows’ biology. When it eats grass, microbes in a cow’s stomach convert the carbon and hydrogen into methane.

    But researchers have found that seaweed contains a compound called bromoform that blocks the reaction. Tests have shown that cows with seaweed in their diet produce around 58% less methane.

  • What other eco benefits are there?

    Seaweed is an effective alternative raw material to oil – meaning it can be used to make plastic. Single-use plastics account for more than 300 million tonnes of waste generated each year. However, recent innovations mean more and more companies are turning to seaweed to make packaging, crockery – and even straws.

    The industry is quietly booming. In 2013, one company launched an edible plastic water bottle made from brown seaweed. In 2016, Japanese designers AMAM unveiled a biodegradable seaweed perfume bottle. Now, one London startup that makes edible water pods plans to release seaweed soy sauce sachets in the coming months.

  • Can it be used for anything else?

    Fuel. Despite a worldwide shift towards electric vehicles, biofuels are still an essential tool in the fight against climate change. And with 50% oil, seaweed is a perfect material for making them. It yields 30 times more energy per acre than other biofuel crops. Plus, unlike traditional biofuel crops like soy, it requires no deforestation to grow.

    Today’s wild kelp forests cover just 76,000 square kilometres – approximately the size of Australia. But this is just 2% of available fertile ocean. With 98% left to cultivate, the potential for new fuel, innovation – and possibly even climate change reversal – is vast.

You Decide

  1. Is seaweed the answer to fighting climate change?


  1. Choose one of the 22 innovations in the video from the expert links. Research it and write a review on whether you think it will succeed.

Word Watch

A simple, non-flowering and typically aquatic plant. It is a large group that includes seaweeds as well as many single-celled forms.
Carbon sink
A forest, ocean or other natural environment viewed in terms of its ability to absorb carbon dioxide from the atmosphere.
On dry land.
The world’s largest producer of edible seaweeds, China produces around five million tonnes
Faroe Islands
A self-governing archipelago, part of the Kingdom of Denmark. The islands are in the North Atlantic Ocean between Iceland and Norway.
A mineral that helps the body make thyroid hormones that control the body’s metabolism, bone and brain development.
A diet which contains no animal products.
A colourless, odourloess gas. It is a hydrocarbon with the chemical formula CH4.
Trapping heat
Both gases are greenhouse gases, meaning they act as absorbers of heat. The greenhouse effect is essential for life on Earth – but excessive greenhouse gases lead to global warming.
A fuel derived immediately from living matter as opposed to fossil fuels, created using dead biological matter. It is considered a source of renewable energy as products can be regrown, unlike coal.
Global production of soybeans has increased by 15 times since the 1950s. In Argentina and Brazil, where it is most commonly produced, deforestation risks lives of indigenous populations – as well as wildlife.

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