The Power Environment: Using offshore wind to farm seaweed

Matthew Farmer 1 February 2021 (Last Updated February 5th, 2021 15:09)

Making power green does not make it harmless. While electricity generation has started shifting towards sustainable solutions, practical problems present new issues for local ecosystems. The Power Environment looks at innovative interactions between nature and the energy industry.

The Power Environment: Using offshore wind to farm seaweed
Seaweed aquaculture is set to grow by 9% per year, and farming the crop among wind farms could provide an interesting synergy. Credit: Ben Wicks/Unsplash.

Offshore wind power relies on a whole industry of maritime operations that conventional power development has no need of. The maritime industry has grown around a relatively new industry in shallow, often near-shore waters, which has helped create a window of opportunity for synergy with other seafaring industries.

In Belgium, shareholders in the Norther wind farm have plans to use offshore wind turbines for maritime agriculture, known as aquaculture. They plan to automate the growth and harvest of seaweed, developing a system for use at other wind farms.

As a result, a Belgian-Dutch consortium has put together the ‘Wier and Wind’ project. This aims for large-scale cultivation of ‘Wier’, Dutch for seaweed, over three years. Previous test projects have grown smaller amounts of seaweed closer to the shore, but this larger project would be the first to cover up to 20,000m² (4.9 acres) in less sheltered waters.

The logistics of using offshore wind for aquaculture

The Norther Wind Farm lies 23km off the Belgian coast near Zeebruges, close to the country’s border with the Netherlands. The project began in 2009, and now 44 wind turbines generate 370MW for the Belgian grid.

Three European renewable power producers control the wind farm: Belgian Elicio owns half, with Dutch Eneco and Diamond Generating Europe owning one quarter each.

Among the two hectares of turbines, Wier and Wind has created seaweed farms between turbines, with a buffer zone between. The six project partners will use the project as a test bed for scaling up multi-use aquaculture alongside wind. A statement by the project leads estimates that seaweed cultivation will grow by 9% per year. Collaboration with offshore wind farms gives the opportunity to realise this.

Aquaculture business community North Sea Farmers is one of the partners behind Wier and Wind. A spokesperson told us: “We believe this would be viable at other offshore wind farms.

“Within the Wier and Wind project, we are working on scalable solutions for seaweed cultivation in offshore wind farms. At our test site, we are able to facilitate pilot initiatives so that they can demonstrate viability of seaweed cultivation as well as other forms of multi-use for application within wind farms.”

The project started in July 2019 and will run until June 2022. The project sowed its first crop in October 2020, which will mature this spring.

In December 2020, North Sea Farmers announced the start of tests on a similar initiative for offshore floating solar farms. Offshore solar supplier Oceans of Energy aims to develop its technology for small tropical island nations. However, its “world first” trial project has survived the cold North Sea for a year, lying 12km off the coast of the Hague in the Netherlands. It will use an unspecified amount of its output to power a cultivator farming 15,000kg of seaweed per year.

What use is seaweed production?

Seaweed is hardly a mainstream crop in the West, with more use in Asia. But as all diets shift toward more plant-based dishes, its use is increasing at an estimated 9% per year. North Sea Farmers have attempted to raise the plant’s profile, acknowledging its low appeal to western diets.

Outside of food, seaweed contains several important nutrients making it useful in agriculture. Studies have found that, with some processing, seaweed can also form part of a feedstock for animals.

Closer to the cutting edge, seaweed can be used in production of bio-plastics and biofuels. The plant acts as a carbon sink when grown, but few options to permanently capture the sunk carbon currently exist. The solar seaweed cultivation device would currently capture 1.8 tons of carbon every year.

Seaweed production involves long underwater cords, with seaweed growing at regular intervals along the cord. North Sea Farmers aims to grow its seaweed production to 400km of seaweed production by 2030.

A spokesperson said: “Together with wind farm operators like Norther, we have developed technical solutions, safety precautions and ways of working to ensure synergy between producing energy from wind and producing food such as seaweed in the same offshore area. This will include combining site visits, planning of periodic maintenance, operating onshore facilities and combining purchase efforts.

“Furthermore, the seaweed multi-use activity is better protected against inadvertent sail-through and the wind farm could benefit by creating multi-use zones and potentially wave dampening. Last but not least, we will cultivate seaweed in a nature-inclusive way, creating new habitats and creating biodiversity on the seabed.”

Is offshore wind and aquaculture going to take off?

North Sea Farmers is only one group among a wide range of interested partners. The EU UNITED project specifically develops pilots of multi-use offshore areas and has given funds for North Sea projects. The EU Interreg project has backed the project, aiming to promote co-operation in North Sea projects. The European Regional Development Fund provided half of Wier and Wind’s funds, aiming to tackle some of the problems solved by aquaculture.

Seaweed production companies obviously aim to develop the industry, with offshore wind generation presenting the largest possible opportunity for collaboration. In return, wind farm operators could receive the benefits of multi-use areas, such as easier licensing and a better public image.

Wier and Wind project coordinator Bert Groenendaal has said he believes that seaweed cultivation will require only “one or two” journeys offshore per year, in order to retrieve the produce.

The seasteading community also has a significant interest in multi-use projects growing. Seasteading is an idea aiming to establish permanent settlements offshore, relying on renewable power sources and farming projects similar to Wier and Wind.

The idea has captured the imaginations of many in Silicon Valley, who long for greater freedom from systems of government. However, the movement remains speculative, due to prohibitive costs and the legality of permanently living offshore.

North Sea Farmers say they have already been approached by companies in the UK interested in the plans. Seaweed is only one part of the group’s push for North Sea aquaculture. In 2018, a project planted oyster beds in the Borssele V project, and the group has trialled mussel farming as well.

Ultimately, co-developments will come down to cost. Seaweed farming is already profitable but relies mostly on Asian exports. The project has not factored costs into its trial, but given the trend of changes to diets, land regulation, energy generation and climate, seaweed looks set to grow in future.

Read more about efficiently using land for renewable generation in Future Power Technology.