Offshore wind farms could become the next frontier for sustainable food production

When people think about offshore wind farms, they usually think about renewable energy. But between the turbines, another valuable resource could be produced: food.

Over the past 15 years, researchers and industry partners have developed and refined methods for cultivating sugar kelp in Danish waters. The results show that seaweed can be grown at large scale, thrives under offshore conditions, and absorbs nutrients from the surrounding marine environment as it grows.

Now, researchers believe offshore wind farms could become the next frontier for seaweed production.

“We have the technology. We are ready to cultivate seaweed at scale. What we need now are partners who can use and market the products seaweed farmers are capable of producing,” says Annette Bruhn, Senior Researcher at the Department of Ecoscience, Aarhus University.

More than an energy landscape

Denmark is currently undertaking a historic expansion of offshore wind energy. By 2030, vast new areas of the sea will be dedicated to renewable power generation.

For researchers and stakeholders, this presents an opportunity to rethink how marine space is used.

Instead of allocating new areas for aquaculture, seaweed can be cultivated within existing offshore wind farms. The same stretch of ocean can therefore produce both renewable energy and food.

“We are not taking up new marine areas. We are using areas that have already been designated for another purpose. At the same time, we can share infrastructure, service vessels and operational resources,” says Annette Bruhn.

The concept is known as multi-use and involves combining several activities within the same marine area. The goal is not only to reduce competition for space, but also to lower costs and environmental impacts by sharing infrastructure and logistics.

According to the researchers, offshore environments may offer some of the most promising conditions for seaweed cultivation.

Water exchange is high, environmental conditions are relatively stable, and field trials indicate that both yields and product quality can be exceptionally good.

“We are seeing high yields, excellent quality and higher nutrient removal than we originally expected. The North Sea appears to be one of the most promising cultivation environments we have worked in,” says Annette Bruhn.

A crop that grows without farmland

Interest in seaweed is not driven solely by where it can be grown.

Unlike conventional crops, seaweed requires no agricultural land, irrigation or fertilisers. Instead, it grows using sunlight and nutrients that are already present in the marine environment.

Once harvested, the biomass can be used in a wide range of applications. Seaweed can be consumed directly as food, processed into ingredients such as gelling agents, stabilisers and antioxidants, or used in animal feed and bio-based materials.

Danish studies have demonstrated that sugar kelp cultivation can remove both nitrogen and phosphorus from coastal waters. At the same time, research suggests that environmental impacts remain limited when cultivation and harvesting are managed appropriately.

Seaweed farming is therefore not a substitute for reducing nutrient emissions at their source. However, it can complement existing efforts by producing valuable biomass while removing some of the nutrients that have already entered the marine environment.

The market is the missing link

Researchers have also investigated what could happen if seaweed cultivation was integrated into the large-scale expansion of offshore wind energy.

Their analyses suggest that even modest use of the space between turbines could support substantial production of seaweed and other marine resources. The potential is significant enough to support new value chains for food, feed and biorefining.

Yet production alone does not create a market.

For Annette Bruhn, the next step is therefore to engage a much broader group of stakeholders.

“We need food manufacturers and retailers to get involved. We need meal-kit companies, public kitchens and schools. These are the actors that help shape people’s eating habits.”

She compares the current situation to the transformation that has taken place around legumes in recent years.

“Five or ten years ago, legumes were far less visible in canteens and everyday meals. Today they have become a natural part of many diets. We would like to see the same development for seaweed.”

From research project to food system

Seaweed cultivation in offshore wind farms remains a relatively young field, and researchers and industry continue to optimise cultivation systems, document environmental impacts and develop new products.

But the conversation has changed.

Where researchers once focused on whether the technology would work, attention is now turning to how it can be implemented at scale.

“We know that seaweed can be cultivated. We know that we can produce large volumes of high-quality biomass,” says Annette Bruhn.

“The challenge now is to build stronger links between production, the food industry and consumers.”

For researchers, that marks an important transition. The scientific foundations have largely been established. The next phase will be about creating the partnerships, supply chains and markets needed to turn offshore seaweed cultivation into a viable industry.