The Next Economy
Farming More Seaweed Could Be Sustainable Way Forward for Food, Feed, Fuel

New research published in Nature Sustainability shows that expanding global seaweed farming could offer a sustainable alternative to land-based agricultural expansion and go a long way toward addressing the planet’s food security, biodiversity loss, and climate-change challenges.

A group of Australian researchers — led by Scott Spillias from the University of Queensland’s School of Earth and Environmental Science, who collaborated with a research team from the University of Queensland, the International Institute for Applied Systems Analysis (IIASA), CSIRO and the University of Tasmania — investigated whether seaweed offered a sustainable alternative to land-based agricultural expansion to meet the world’s growing need for food and materials. Spillias started this work as part of his IIASA Young Scientists Summer Program project when he participated in the program in the summer of 2021.

“Seaweed has great commercial and environmental potential as a nutritious food and a building block for products including animal feed, plastics, fibers, diesel and ethanol,” he explains. “Our study found that expanding seaweed farming could help reduce demand for crops on land and reduce global agricultural greenhouse gas emissions (GHG) by up to 2.6 billion tonnes of CO2-equivalent per year.”

Not only would scaling seaweed farming eliminate emissions associated with land-based agriculture, kelp — a large, brown species and the largest subgroup of seaweed — absorbs up to 20x more CO2 per acre than land forests, making it a potential new powerhouse in regenerative and climate-resilient farming. Add to that its use already as a nutrient-rich superfood and a biobased textile, and increasing supply feels like a win all around.

The researchers mapped the potential of farming more of the 34 commercially important seaweed species using the IIASA Global Biosphere Management Model (GLOBIOM). They estimated the environmental benefits of a range of scenarios based on land-use changes, GHG emissions, water and fertilizer use, and projected changes in species presence by 2050.

“In one scenario, where we substituted 10 percent of human diets globally with seaweed products, the development of 110 million hectares of land for farming could be prevented,” Spillias says. “We also identified millions of available hectares of ocean within global exclusive economic zones (EEZs) — in other words, an area of the sea in which a sovereign state has special rights regarding the exploration and use of marine resources, including energy production from water and wind — where farming could be developed.”

The largest share of suitable ocean was in the Indonesian EEZ, where up to 114 million hectares is estimated to be suitable for seaweed farming. The Australian EEZ also shows great potential and species diversity, with at least 22 commercially viable species and an estimated 75 million hectares of ocean being suitable.

Spillias added that many native species of seaweed in Australian waters had not yet been studied from a commercial production perspective.

“The way I like to look at this is to think about ancestral versions of everyday crops — like corn and wheat — which were uninspiring, weedy things,” he notes. “Through thousands of years of breeding, we have developed the staple crops that underpin modern societies; and seaweed could very well hold similar potential in the future.”

“This study uniquely highlights the need for integrated strategies bringing together terrestrial and marine ecosystems management to address some of the mounting problems of global sustainability facing us, as well as to avoid displacing problems from the land to the ocean, and vice versa,” concludes Petr Havlík, Interim Director of the IIASA Biodiversity and Natural Resources Program.

Case in point: In 2021, the ‘Kelp Bill’ lifted a longtime ban on kelp farming off the coast of New York — providing a valuable economic opportunity for further developing the state’s blue economy. Sean Barrett, founder of Montauk Seaweed Supply Company — which transforms Long Island seaweed into chemical-free fertilizers and biostimulant products — told Sustainable Brands® that local farmers can now be incentivized to engage in the industry and begin generating the nitrogen-sequestering and carbon-capturing aspects of kelp farming that the local ecology — and the rest of the world — desperately needs.

“We are on the verge of harnessing kelp and seaweed from the ocean in a way that will provide nearly infinite resources to populations across the globe and unleash a regenerative supply of valuable materials that the global community desperately needs,” Barrett said. “Expect to see exponential growth in the kelp industry in the coming years to keep up with growing global demand.”