From deep-sea salmon farms and seabed mussel hatcheries to commercial seaweed and kelp fields, offshore wind power is set to radically change the narrative for the next era in industrial mariculture in the northern seas. Darius Snieckus looks at a number of pioneering projects that are shaping thinking in the transition to a blue economy

Offshore wind’s pivotal role in the global energy transition starts in the electrification of the world’s onshore grids, with expectation that some 2TW of arrays will be exporting power to land by mid-century, but is also evolving toward supplying clean energy to sea-based industries, from offshore oil field decarbonization schemes and coastal desalination plants to deep-sea fish farms.

Though not yet making headlines like Hywind Tampen – the world’s biggest floating wind array, which is being used to offset one-third of emissions at Equinor’s Snorre Gullfaks oil & gas complex off Norway – development of a wide range of wind-linked mariculture projects has quietly been picking up speed in the past year.

Pilots co-locating offshore wind developments with salmon farms, mussel hatcheries and seaweed farms are all moving forward, part of a growing trend toward sustainable construction and operations in the sector – which will also increasingly key in ‘non-price criteria’ offshore wind auctions being launched by European nations.

“We have been looking into the offshore wind-aquaculture coexistence opportunity for several years,” says Aker Solutions’ head of aquaculture business development Lars Wasa Andersen.

“In the context of the energy transition, we believe that the focus from governments will be stronger in the future on making better use of ocean space. And we believe there are synergies between aquaculture and offshore wind, as well. Not just for a power source, but also for making better use of a location where you can share infrastructure and supply and service vessels and so on.”

Aker, which has lived many lives as a maritime contractor in the shipping, offshore oil & gas, renewables, and carbon capture industries, has been developing a green deep-sea salmon farm concept that envisions connecting floating wind turbines to salmon 'ocean cages' (pictured above), harsh-environment semisubmersible structures skirted by a double-net barrier and featuring a remote-controlled, onboard feeding system.

“The areas now being proposed for offshore aquaculture are very close to offshore oil & gas projects we have worked on. [Aker’s ocean cages] are designed to survive in this hostile environment,” says Aker Solutions' head of aquaculture technology Kristoffer Kjellså Jakobsen.

“And building far-offshore salmon farms has ‘biosecurity’ – by getting away from the big challenges of traditional salmon farming in fjords, where the close proximity can lead to sea-lice being passed easily between two or more [facilities].”

“It is a good fit with the space you need to have between [offshore wind] turbines to avoid wake effects”, where turbulence created by one machine’s turning rotor impacts on others’ power production efficiency, he says.

The Norwegian government has identified a number of zones in territorial waters – over 25km from its coastline – that could be well-suited to offshore wind-powered salmon farms, with three totaling some 7,500km² of North Sea acreage in water depths of 200-400m highlighted.

‘Thinking beyond green generation’

Irish blue economy developer Simply Blue, which having started as a wave power outfit has evolved to become a leading new-model floating wind player in the past decade, has been exploring North Sea waters not only for salmon but also for seaweed.

Through a recent tie-up with Arctic Seaweed, which has farms already set up off Bergen and Ålesund, Norway, as well as off Greenland, it hopes to integrate future offshore wind and seaweed farms to generate a marine crop that could be a meat substitute and low carbon feed-stock as well as for “replacing resource intensive products like plastic, fossil fuels or conventional fertilizers”.

“We have been looking at the multi-use of offshore space. Wind is by far the biggest part of our company, but we are also looking at what else we can do with the oceans to address climate change – insofar as the oceans are seen as being able to deliver 20% of the next savings on CO₂ required to hit 1.5C [the Paris climate action target],” says Christoph Harwood, head of aquaculture at Simply Blue.

“The thinking goes beyond generation energy from a [wind] farm, to what use that energy is put to – and how that works with the reality that we are not ‘making seabed’ anymore, it’s a limited resource, so how to make fullest use of it.”

By Simply Blue’s calculus, the roughly 2km² of open water that lies between four 15MW floating wind units – which equates to around 300km² in a gigawatt-scale array – is ready-made for aquaculture farms. “You wouldn’t use all of that space, you might get a third of it. And you could use it for wave and floating solar or you could use it to grow things – salmon, yes, but also seaweed and mussels and so forth,” says Harwood.

Simply Blue places salmon and seaweed together as playing “key roles in the delivery of a low carbon economy globally, with the former a high protein source with only 7kg of CO₂ per kilogram of flesh versus almost 40kg for the same weight of beef, and the latter a Swiss army knife of fossil fuel product replacement.

“If you want power to a fish farm 24/7, are you going to hike a cable out [from shore] specifically for this purpose? What if these farms had their own power from wind turbines and wave devices and you could also charge-up crew transfer vessels and the like? This is ultimately about best use of sea-space,” says Harwood.

“Salmon is tops in terms of value for now, but in seaweed you’ve got a really new industry with farms today that are 0.1km² and so needs to scale up massively [to meet demand] from buyers of, say, 10,000 tonnes or 100,000, when most operations are producing 2,000 tonnes a year.

“This will require sites of at least 1km²,” he adds, noting that Simply Blue is in discussions to build an inshore pilot in Ireland that “will then be taken offshore at scale”.

“We could then find an offshore wind farm owner-operator that would like to host an industrial-scale seaweed farm, for a number of reasons including that it would give them credibility for future [non-price] leasing rounds.”

Developers are bidding into auctions now “under pressure to deliver greater economic and social benefits beyond clean power,” adds Harwood. “Plus there is the job creation, particularly for salmon farming – for seaweed you only need workers for deployment and harvest – which would be year-round. Co-location of wind and aquaculture will bring huge benefits to coastal communities.”

Baltic blue economy bonanza

Swedish developer OX2, which has some 14.5GW of offshore wind projects in its pipeline in Nordic waters, has also been exploring how offshore wind farms could be built and operated more sustainably, through connection to commercial mussel and fish hatcheries and algae and seaweed farms in a mariculture complex.

Since a first contract last year with Kobb and Nordic SeaFarm to investigate large-scale cultivation of kelp at OX2’s planned 400MW Galatea-Galene wind farm off Sweden, the developer has gone on to work with Baltic Sea aquaculturists including Under Ytan and Nemo Seafarms with the mission of seeing how “large scale offshore wind farms can improve the ecosystem and increase the biological diversity” through co-location and cultivation of reef formations around the turbine foundations and ‘fish hotels’ to boost cod populations.

“We, from the outset, saw a lot of environmental benefits [from marine ecosystem regeneration], better use of these industrial areas of the sea, and that we could create local jobs for communities that have relied on income from other maritime industries,” says OX2’s head of offshore wind development Emelie Zakrisson.

“Wind farms are getting bigger, very quickly, so they are going to be occupying so much more of the ocean. [OX2 has] the ‘greater good’ perspective: how do we make other maritime industries blossom within areas being developed [as offshore wind farms]. We need to change the mindset from offshore wind farms being a no-go zone for other ocean industries.”

The early learnings from the Gallatea-Galene pilot excited OX2 to look at its 5.5GW Aurora megaproject off Sweden, a development that would stretch across 1,000km² of “dead waters” in the Baltic, landing on introducing mussels to the site to improve the health of the area, ‘rewilding’ the seabed, and bringing the shellfish back to land as a food or feed for animals.

“Most trials in this area [of aquaculture] have been done only at a small scale, but having these vast offshore wind farms we are building now, we could really make use of them to scale things up,” says Zakrisson, looking ahead to a scoping study next year on the “many details still to be worked out”.

Zakrisson says seeing progress on such pilot projects as the mussel farm at the Netherlands’ Borssele 3 offshore wind farm – which has led to Dutch outfit OOS recently being greenlighted to install a semi-submersible mussel vessel at the offshore wind farm, an industry first – is “central” to advancing greater “constructive cohabitation” among sea-based sectors.

Sustainability and ‘non price’ auctions

Once-futuristic plans to dovetail offshore wind projects with aquaculture farms look likely to rapidly become as much about economics as environment, with governments in countries including Denmark, France, the Netherlands, Germany and Norway abandoning ‘pure’ price-based tender in favor of an auction model that has metrics linked to the quality of the project, when awarding new licenses, to relieve market-pressurizing forces.

Most countries employ the full 30% weighting on non-price criteria that EU state aid rules allow, and several have increased this to 50% for subsidy-free auctions, points out Ingrid Lomelde, head of sustainability at developer Mainstream Renewable Power. “These are positive signs.”

“Offshore wind can drive ahead a development where cutting emissions, protecting biodiversity, providing local benefits, and scaling up new technologies merge into one common agenda. But to achieve this, sustainability-linked non-price criteria will be the key, both to minimizing environmental impact and breaking the offshore wind gridlock.”  

“We will need to build 80GW of offshore wind every year going forward to reach this target [of 2TW, set by the International Energy Agency]. That is a massive endeavor made more challenging yet because of the need to – at the same time – usher forward a sustainable coexistence between ocean industries and their surrounding environment while developing the economic sustainability of all these [maritime] industries.”

Climate action imperative

No matter the terawatt-hours offshore wind will increasingly be flowing into national grids as the global energy transition gathers momentum, the potential for developing other industries in peaceful coexistence – and supplying clean power where needed – has a deeper resonance as climate emergency evolves.

As Jakobsen notes: “To do something about climate change, it's not enough to do something about the way we produce energy: we also need to do something about how we produce food to feed the planet – while reducing the something like 1/3 of climate emissions that come from food production, including transport and deforestation.

“And salmon among farmed animal protein sources is by far the best for the climate, [in terms of carbon footprint], ocean versus land use. And offshore, powered by floating wind, you can achieve more optimal use of an area. Co-location will be a big benefit.”

Offshore wind will necessarily be a main engine of the blue economy as it takes shape in oceans around the globe, says Harwood, with floating arrays not only harnessing the richest resources streaming over deep water but also being tapped to electrify other ocean-going industries.

“Floating wind is in our view part of the big ticket in delivering net zero. But as well as renewables from the ocean, we need e-fuels for [green] shipping, deep-sea aquaculture, carbon sequestration, and holistic biodiversity solutions,” he says.

“Lack of offshore real estate is once of the biggest barriers to a net zero economy. How can we not develop aquaculture with wind farms as the anchor technology – with power as and when needed?” Not least as such collocation will advantage developers with the most sustainable bids in the coming auctions.

“There is a lot of creative thinking already happening on this.”

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This article was first published in Aegir Insights' intelligence newsletter, Beaufort.

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