“You can just see the buoys of the seafarm,” Dr Sophie Steinhagen yells over the high whine of the boat as it approaches the small islands of Sweden’s Koster archipelago. The engine drops to a sputter, and Steinhagen heaves up a rope to reveal the harvest hanging beneath: strand after strand of sea lettuce, translucent and emerald green.

She says that this is one individual that we would collect now and keep as a parent because it is growing very fast. Steinhagen and the seafarming group at the Marine Laboratory have their peak season in the spring.

It means less animal and plant life on the seaweed. You don't want a crab or snail eggs for seaweed. Sea lettuce is the most important vegetable in the spring.

seaweed could be a key crop in the shift away from meat. The harvest here last spring was close to the level that would make it compete against the world's other big sources of meat and soya.

Seaweed farming in Sweden could be a vital component of the shift away from eating meat for protein.

Seaweed farming in Sweden could be a vital component of the shift away from eating meat for protein.

Steinhagen believes that this plant can be a more sustainable alternative to soya. Sea lettuce doesn't draw on scarce resources of land and water. We need to go into the ocean because we can't extend farmland. seaweed could provide a lot of the compounds we need as we shift to a bio-based economy.

Ulrica Edlund is a professor at the KTH Royal Institute of Technology in Sweden and she uses seaweed to make plastic films. You don't have to wait 50 years for the forest to grow until you can harvest those materials.

New startup packaging companies are using these advances to develop seaweed-based plastics, such as the UK's Notpla or the US company Sway, though there are challenges, too: unless you take steps to alter their chemical structure, seaweed plastics absorb rather than repel water.

Seaweed ecologist Dr Sophie Steinhagen at work in the Koster archipelago.

Seaweed ecologist Dr Sophie Steinhagen at work in the Koster archipelago.

Outside Asia, seaweed farming is in its infancy. The techniques Steinhagen's team helped develop are starting to be applied more widely. Nordic Sea Farms, a company spun-off from the laboratory, has been growing sugar kelp for many years and has seen demand from local restaurants and biomaterials companies. In October, it launched an EU-funded programme to develop commercial sea lettuce at Otter Island. The first 20 km of seeds will be set out this autumn and the first harvest in the spring of next year.

Europe's Atlantic and North Sea coasts are starting to see seaweed plantations. There are seaweed farming companies in Norway. Ocean Rainforest is Europe's leading seaweed producer. In the Netherlands, the UK, Ireland, Spain and Portugal, others have sprouted. Dutch-owned The Seaweed Company operates farms in Ireland, India and Morocco. Europe produces a tiny fraction of the world's seaweed, which is mostly produced in Asia.

Steinhagen inspects the tanks in her “seaweed kindergarten”.

Steinhagen inspects the tanks in her “seaweed kindergarten”.

A report by the advisory firm Systemiq argues that the EU could potentially produce 8 million tonnes of seaweed by the end of the decade, against 35 million currently. Asian countries have been doing this for a long time, but some of them are low-income, so their methodologies are not suitable for us.

The Seaweed Company is growing seaweed in the North Sea in an attempt to find more sea access. Some companies are trying to make the job less labor intensive by developing their own seaweed harvesting machinery. There is no seaweed equivalent of a combine harvester or tractor on the shelf. Steinhagen is trying to improve seaweed strains to make them more productive, just as they have improved crops over the centuries.

Steinhagen seeks the holy grail of high-growth, high-protein strains of seaweed.

Steinhagen seeks the holy grail of high-growth, high-protein strains of seaweed.

In the laboratories, she shows the rows of bubbling cylindrical tanks where she breeds new varieties, clones new plants, and seeds plants on rolls of twine which are then wrapped on the ropes and laid out to sea.

She shows me a container of sexually mature sea lettuce, which is brownish in the outer margins. A team at the University of Technology in the city of Gothenburg is looking at how to most efficiently and economically extract the protein. seaweed is getting more seaweed is getting more, but Prof. Ingrid Undeland wants it.

She concedes that the new product will have more of a marine flavour profile than the soy and whey products.

Jo Trigo is a PhD student working in the lab. He says he can only get about 10% of theProtein in sea lettuce. It would take three grams of dried sea lettuce to fill 100g of dry sea lettuce. In his office, he holds up a test tube containing a small amount of green crystalline flakes which took a whole sack of sea lettuce to produce.

The solution might be a biorefinery approach, with the first step being the removal of the protein, followed by other useful substances such as thickening agents and polysaccharides. It would be a shame to throw this away, because there are so many sophisticated molecules in there.

Steinhagen believes that her pilot farm is the start of a new industry. It takes time.