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SeaFree: New technology turns waste from fish farming into seaweed

In an ambitious new partnership, researchers from the University of Copenhagen and Aarhus University are teaming up with several industry partners to create a sustainable co-production model for fish, shrimp, and seaweed. The innovative project, called “SeaFree,” aims to revolutionize the aquaculture industry over the next four years.

The heart of SeaFree is an advanced, land-based closed cycle that cleverly uses residual nutrients and carbon dioxide from fish and shrimp farming. These waste products will be repurposed to cultivate high-value seaweed, creating an eco-friendly system that benefits both the food and healthcare sectors.

The goals of the SeaFree project

Professor Marianne Thomsen from the Department of Food Science at the University of Copenhagen explained the project’s key goals: “The project aims to use seaweed production to absorb and convert emissions from land-based aquaculture into a high-value product.”

The seaweed, rich in umami flavor and health benefits, will be used in dietary supplements to prevent diabetes and fuel sustainable food innovations. 

“In addition to capturing emissions that would have otherwise been emitted into the atmosphere and aquatic environment, the seaweed produced is both healthy and rich in umami flavor,” said Thomsen.

SeaFree’s budget of DKK 14.4 million (€1.9m) is generously provided by Innovation Fund Denmark. The project is a collective effort, featuring partnerships with companies including Pure Algae, DryingMate, Food Diagnostics, Sigrid Therapeutics, XOventure GmbH/Rigi Care, KOST, SOF Odden Caviar, and HanseGarnelen.

SeaFree only requires a 40-foot container

The operational nucleus of the project is a 40-foot container fitted with eight one-thousand-liter tanks. This cutting-edge Plug’n’Play technology unit, brimming with export potential, combines salt water, CO2, nutrients, and LED lights to grow a full batch of seaweed in just one week – an astoundingly short harvest period.

Thomsen explains the technology’s potential impact on the aquaculture industry: “SeaFree represents the latest in recycling technology for land-based shrimp and fish farming. Besides capturing emissions, the system also recirculates surplus heat from the plants to the Plug’n’Play technology.” 

She further explained that the project incorporates an innovative technology that uses surplus heat to dry the seaweed for the healthcare industry, making SeaFree a model of sustainable and efficient production.

The result of this groundbreaking project is a set of climate-friendly products: fish, shrimp, and sea lettuce—a nutrient-dense seaweed species packed with fiber and protein. Sea lettuce, apart from being used in various dietary supplements, also serves as a healthy side dish to seafood meals.

Next steps – take this global

According to Thomsen, part of SeaFree’s mission is to raise public awareness of seaweed as a key ingredient in delicious home-cooked meals. She is also optimistic about the global potential of farming fish and seaweed as envisioned by SeaFree. Implementing this method across all the world’s land-based shrimp and fish farms could drastically reduce the carbon footprint of global food systems.

The fusion of aquaculture and seaweed cultivation in closed systems, as per the SeaFree model, holds promise as a significant new Danish export market.

Professor Thomsen underscores the global applicability of the SeaFree technology, marketed as “SeaFree Synergy Solutions.” 

She noted that they are already in discussions with South Korea, a country showing keen interest in the technology and the project’s development. “On a global level, it will be possible to implement the technology anywhere in the world. As for the technology’s environmental benefits, they are unequivocal.”

More about aquaculture

Aquaculture, also known as aquafarming, is the practice of farming aquatic organisms such as fish, crustaceans, mollusks, and aquatic plants. It involves cultivating freshwater and saltwater populations under controlled conditions, and is an alternative to harvesting wild marine life.

Aquaculture comes in many forms, and each type has different requirements and impacts on the environment.

Marine Aquaculture

Also known as mariculture, it involves the cultivation of species that live in the ocean. This can range from shellfish like oysters and mussels to seaweed and fish species like salmon. Marine aquaculture can take place in the open ocean, or in ponds or tanks on land.

Freshwater Aquaculture

This involves the rearing of aquatic organisms in freshwater environments. These can include ponds, lakes, man-made reservoirs, and tanks. The species cultivated can range from freshwater fish like tilapia and catfish to crustaceans and plants.


A form of aquaculture that involves the farming of algae. Algae are incredibly diverse and can be used for a variety of purposes, including food, biofuel, and as a means to mitigate carbon emissions.

Integrated Multi-Trophic Aquaculture (IMTA)

This is a practice in which the waste produced by one species serves as food for another. For example, fish waste can provide nutrients for plants or shellfish. This creates a system where waste is minimized, mirroring natural ecosystem interactions.

Aquaculture has both benefits and drawbacks. On the positive side, it can contribute to food security by providing a growing global population with a reliable source of high-quality protein. It also plays a part in economic growth, particularly in developing countries, by creating jobs and improving balance of trade.

However, if not managed properly, aquaculture can also have negative environmental impacts. These can include water pollution, habitat destruction, and the spread of diseases to wild fish populations. Intensive farming can also lead to problems with fish welfare and can contribute to the overfishing of certain species, used as feed for farmed fish.

In recent years, sustainable practices in aquaculture have been promoted to mitigate these issues. These include better management of fish health, reducing the reliance on wild-caught fish for feed, and developing systems like the one in the SeaFree project, where waste is recycled and used to grow other valuable products.


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