Seaweed has superpower potential

Part 2 of our Exploring Seaweed Series

Minnow today

Today we cultivate about 30m wet tons of seaweed, worth about $6bn at the farm gate. Almost all cultivated seaweed is farmed in Asia, with China and Indonesia dominating labor intensive production. Farmed production has doubled over the past decade whilst wild harvests have remained stable at roughly 1m tons / year.

Roughly 85% of the crop ends up on our plates (seaweed is a mainstay in Asian diets), whilst most of the remaining 15% is transformed into hydrocolloids - a range of thickeners found in everything from ice cream to toothpaste. A tiny fraction is turned into other higher value compounds like mannitol and fucoidan, a sweetener and an antioxidant used in the pharmaceutical industry.

Global Seaweed Production

30m tons may seem like a lot of seaweed, but in agricultural terms it is but a small blip on the radar screen. Aquaculture produces just 1 percent of agriculture production even though oceans make up 70% of the world’s surface and oceans contain massive amounts of nutrients (e.g. 100 bn tons of phosphorus).

Whale tomorrow

But that may be about to change. Many maritime regions, especially those in cold waters with strong fishing industries such as Norway, Alaska and Chile, see the potential to grow a lot more seaweed. Between them they have thousands of miles of suitable coastlines and a significant amount of relevant infrastructure (boats and processing plants) already in place to support the fishing industry. They are experimenting with innovative, more efficient growing and harvesting systems and expanding nurseries to provide high quality seed stock.

There is also a big push to develop new technologies needed to make massive offshore farms feasible. In the US, ARPA-E has committed $22m to its Mariner program to fund everything from novel mooring systems to ultra long-line systems and genomic selection. To be sure, hectare scale offshore farms are still 5-10 years away, but it seems plausible that in the near future they will be as prevalent as offshore wind farms are today.

Global mariculture superpower

Why would we want to grow so much more seaweed? Well, one estimate suggests that by ‘afforesting’ 9% of the ocean with seaweed could produce enough biomethane for all our energy needs whilst removing 53bn tons of CO2 from the atmosphere. And as we covered in a previous post, seaweed is rich in useful chemical and bioactive compounds and it also doesn’t require any inputs to grow. Lastly, farmed seaweed provides valuable ecosystem services such as nutrient cycling whilst giving marine animals a valuable habitat to live in.

But if we are going to grow 100x more seaweed, what are we going to do with it? Clearly, the world cannot eat that much seaweed! As we will see in the following post, the key to realizing the potential of this zero input crop is the innovations in processing technologies that entrepreneurs and scientists are working on, so that seaweed can be economically transformed and used in a range of products.