Much has been said recently about the need to "farm the ocean", as well as the potential for growing seaweed for carbon capture and as the raw material for a range of products, from feed to bioplastics.
UK aquaculture business Seafields hopes to do both, while creating what it describes as the "world's largest" open-ocean seaweed farm, which, it claims, "will grow modularly until it reaches approximately 94,000 square kilometres" – just over the size of Portugal.
The company has been developing and testing new technologies to grow and capture Sargassum, or brown seaweed. The aquatic plant has a very high growth rate, capable of growing up to 10cm per day, and is considered a highly invasive species, spreading from its native Sargasso Sea environment to wash up on beaches across the Caribbean and beyond.
Seafields intends to both harvest wild-growing Sargassum as well as to cultivate it in floating modular aquafarms. The aim, the company says, is to remove over 1 giga tonne (one billion metric tonnes) of CO2 from the atmosphere each year by 2032.
The company has recently successfully tested the world's first floating aquafarm paddock – a floating, flexible aquafarm structure – which it says is "the first step on the road to farming in the open ocean".
Seafields has recently opened a private seven-figure investment round to support its next phase of development, intending to scale and commence the megafarm build.
"Seafields' approach of tracking, harvesting, baling and storing Sargassum that they have grown in aqua-farms in the South Atlantic Ocean gyres radically tackles the challenge of climate change," the company said in a statement.
"By baling and storing large quantities of seaweed in the depths of the Atlantic Ocean, Seafields is trapping its physical carbon away for thousands of years, and doing so in a way that won't damage the ecosystem."
Seafields plans to sell via offset credits in the voluntary carbon market to help reach a net zero society. The company also intends to extract valuable products from the seaweed before sinking it, in order to substitute products currently based on fossil fuels and thus avoid future emissions.
"Seafields' potential for tackling the climate emergency is immense; by sustainably growing Sargassum, we can use the vast space available in the ocean to meet the coming demand for carbon credits over the next two decades, while also removing billions of tonnes of CO2 from our atmosphere," said John Auckland, Co-Founder and Director of Seafields.
"This is the ocean equivalent of planting trees across the entire Sahara Desert. Not only that, but it will create multiple revenue streams, employ large numbers of people, and replenish our oceans."
Seafields intends to harvest the power of Sargassum seaweed to sequester carbon efficiently, by developing proprietary off-shore sustainable aqua-farms that control Sargassum's growth, supply a value chain of diverse products to avoid CO2 emissions, and bale and sink the carbon-rich left-over biomass to the deep sea floor to achieve long-term carbon sequestration.