The ambitious EU objectives for the marine renewables industry are resulting in an increase in the number of Offshore Renewable Energy (ORE) Installations. The most dominant and developed type of ORE is Offshore Wind Farms (OWF), but research and testing are progressing on other technologies (see “sector’s characteristic” below).
At the same time, the EU aquaculture sector is slowly but steadily growing with an increasing demand for aquaculture products. The strategic guidelines for a more sustainable and competitive EU aquaculture provide a vision for the further development of aquaculture, in a way that contributes to the European Green Deal. The Communication ‘Towards a strong and sustainable EU algae sector' complements the guidelines with specific actions to support the development of algae production.
The ORE and aquaculture sector show great potential of coexistence and even multi-use, as the synergetic development of ORE and aquaculture facilities at sea is also a way to reduce costs through shared infrastructure. This fiche sets out the key possibilities for both sectors to co-exist and engage in synergetic multi-use activities.
Offshore Renewable Energy
Offshore Renewable Energy (or Marine Renewable Energy - MRE) is a major source of green energy that significantly contributes to the EU’s 2050 Energy Strategy and the European Green Deal. The EU therefore set ambitious objectives for the marine renewables industry, that will need to scale up five times by 2030 and 25 times by 2050 to support the Green Deal’s objectives [1].
MRE technologies can be broadly divided into 7 categories [2]:
- Offshore wind power: Electricity is produced by turbines, which harness energy from the wind blowing over stretches of sea;
- Wave power: capturing the movement of sea waves and turning it into electrical energy;
- Tidal power: harnessing energy from tides and converting it into electrical energy;
- Stream Energy: harnessing kinetic energy from currents and turning it into electrical energy;
- Osmotic power: Collecting the energy released by the difference in salt concentrations when a river flows into the sea;
- Ocean energy thermal conversion: using the temperature difference between deep water and the surface to generate electricity;
- Marine biomass: algae could be used to produce fuels.
These technologies have very different degrees of development and maturity: some are already very advanced and widely operated worldwide while others are still at research level. As Offshore Wind Farms (OWF) are the most developed technology when it comes to MRE, they will constitute the main example of OREI in the following pages.
Aquaculture
Aquaculture is defined as “the rearing or cultivation of aquatic organisms using techniques designed to increase the production of the organisms in question beyond the natural capacity of the environment” [3]. The EU aquaculture sector is slowly but steadily growing and is ranked the eleventh largest worldwide with a 0.9 % share of the volume of global output in 2021 [4]. At EU level, the activity is framed by the guidelines for sustainable and competitive EU aquaculture. It is a hugely diverse industry [5]: fish farming refers to the growth of fish in controlled aquatic enclosures, farming of shellfish is the cultivation and harvest of molluscs and crustaceans, and algaculture focuses on the farming of algae species. The EU Algae Initiative aims at making a wider use of that resource, that is not sufficiently developed [6].
Physical factors (water temperature and quality, currents, nutrient availability, etc.) have a direct effect on the growth of aquaculture species. Companies are therefore looking for the most suitable locations for their farms, also considering the associated costs of operations such as depth or distance from port that modify transport possibilities as well as construction, and maintenance costs [7]. This makes distant offshore farming more expensive and more exposed to extreme weather hazards. One of the main challenges is therefore the limited availability of inshore sheltered areas.
For more European statistics and data you can also visit the Eurostat website
Related challenges
As explained in the introduction, the two sectors show great possibilities of synergetic interactions, and bringing them together could allow to generate economic and environmental benefits. Therefore, the relationship between these two sectors is more characterized by the possibilities of synergies than by the existence of “challenges” per se, as they rarely compete for the same spaces. On one hand, suitable areas for the development of marine aquaculture are usually close to shore, ensuring that servicing costs are kept to a minimum. On the other hand, ORE installations and mainly Offshore Wind Farm (OWF) must comply with regulatory measures which require them to respect a minimum distance from the shore, which is typically beyond the nearshore locations favoured by aquaculture developments. Some ORE technologies can be placed closer to the coastline and could therefore overlap with aquaculture developments, but for OWF, being the most widespread ORE technology, the incidence of such potential interactions is very limited.
However, some difficulties can be identified when studying the possibility of collocating ORE and aquaculture.
The first challenge is linked to the cost of operations for the aquaculture sector when developing aquaculture operations within ORE installations. As explained in the introduction, marine aquaculture facilities are usually located close to shore to ensure construction and servicing costs are kept to a minimum, as the costs of transport and maintenance make distant offshore farming more expensive. This could be an issue in the sense that collocating aquaculture with ORE located offshore such as OWF would result in greater costs for aquaculture operators compared to locating their facilities within more traditional coastal areas. It must be specified that the trend towards more automation in aquaculture operations [8] could partly resolve this issue.
Aquaculture operations require a high level of maintenance and the need for operators to safely access the production site to undertake such operations. However, ORE installations, such as OWF, often pose restrictions to navigation for safety reasons. This could be a problem for aquaculture operators trying to access their site. More widely, as identified by the EU funded project MERMAID, the operational nature of the two industries is very different. For example, aquaculture cages must be regularly retrieved for maintenance, and the logistical requirements of both activities must comply with one another.
As mentioned in the sector’s presentation, the aquaculture sector is hugely diverse, and the species cultivated, and techniques used vary greatly. ORE installations such as OWF are usually placed offshore and are therefore more exposed to weather events than more protected coastal locations. This could impact the development of cultivated species that might not thrive, nor survive, in these more exposed environments. Additionally, species cultivated on offshore facilities could be more exposed to potential industrial risks such as pollution from oil or fuel spills, from passing ships or even from the OWF itself, notably through antifouling.
Obstacles may be faced as collocating ORE and aquaculture installations is a relatively new activity, with few legal frameworks, and a lack of corresponding standards [9]. This issue has been notably highlighted in a work on “Planning and licensing for marine aquaculture” [10] and stems from the fact that “co-location and integration of multiple activities create major issues for planning and licensing as these activities have individual and cumulative needs and impacts”.
Concerns exist on insurance matters, as shared space could increase risks arising from multiple uses and users. Costs of insurance may increase as the variety of potential accidents could diversify [11]. There could also be difficulties in obtaining insurance for aquaculture productions placed offshore in extreme conditions.
Related enablers
This section will describe global enablers that can be fostered through the Maritime Spatial Planning (MSP) process, and that can apply to all potential ORE-aquaculture projects to facilitate their integration.
- Develop effective procedures for stakeholder involvement within MSP
ne of the main difficulties when trying to collocate ORE and aquaculture is to enable discussion between two very different sectors with varying objectives. MSP could provide a platform to foster such exchanges, as exemplified by the European Blue Forum, that allows “users of the sea to coordinate a dialogue between offshore operators, stakeholders and scientists engaged in fisheries, aquaculture, shipping, tourism, renewable energy and other activities” More precisely, the EU funded project MERMAID identified different key steps to follow in this process, such as the identification of the relevant stakeholders, the importance of taking stock of their potentially differing views, and finally relying on a restricted expert pool to jointly define design options of the offshore multi-use platform. Another enabler identified is to collaborate and take stock of the experience of stakeholders already involved in similar initiatives.
- Develop a common regulatory framework within MSP
- As mentioned above, common frameworks guiding the co-location of ORE and aquaculture are lacking at all stages: political, legal, regulatory, normative, administrative, etc. Licensing procedures can be an opportunity to harmonise and create a common framework for the development of activities, facilitating access to space and administrative procedures. For example, in Poland, Regulations for the licensing process for offshore wind farms include a specific selection criterion for enabling other activities to take place in the same space. This criterion is not mandatory but will provide positive scoring to the applicant, aiming to encourage investors to include multi-use in their offshore wind farm (OWF) from the outset. If investors declare that their OWF will allow other activities, this will be written into the permit to ensure that the commitment will be fulfilled. These co-located activities can include marine aquaculture, as marine aquaculture is a permitted activity in the MSP (depending on the investors’ willingness) [12]. More broadly, as stated by a 2020 study entitled “Offshore multi-purpose platforms for a Blue Growth: A technological, environmental and socio-economic review” [13], the development of MPPs (Multi-Purpose Platforms) could “result in the development of a common regulatory framework, resulting in more co-ordinated marine spatial planning and simplified licensing procedures.”
- Develop synergies to ensure Operation and maintenance (O&M) cost reduction
Pairing ORE installation both to share intervention capabilities and the corresponding costs. A recent study on “Operation and Maintenance Costs of Offshore Wind Farms and Potential Multi-use Platforms in the Dutch North Sea” [14] suggests that sharing O&M between the OWF and the aquaculture operators could allow for a cost reduction of 10%. Different logistical opportunities account for this potential cost-saving. As exemplified by the article, “when a multi-purpose ship sails out for a week to transport a maintenance crew to and from the wind turbines, it can inspect the longline-installations and/or harvest the mussels, while the crew is busy carrying out the maintenance work. When tasks are finished, the ship takes the crew on board again and brings the harvest ashore”.
- Secure aquaculture activities
The localisation of aquaculture operations within OWF indirectly allows for better security for the activity. The regulation of activities within the OWF (restrictions to navigation, possible restrictions on fishing, etc.) also restricts the possibility of intrusion on co-located aquaculture operations. OWF are equipped with surveillance, through means such as satellite coverage and intruder detection [15]. This overall improvement of surveillance allows users to see with more clarity what is happening within the area through data acquisition by radar systems or other similar tools.
The enablers listed below are presented as a list of the different ORE technologies and their level of potential compatibility with aquaculture facilities, with relevant examples. This list is not exhaustive, as many ORE technologies are still being developed and it might be too early to assess their compatibility with aquaculture. The compatibilities listed below are therefore only examples of the growing possibilities to collocate ORE and aquaculture. As research and testing evolve, the list of validated compatibilities will expand.
- Pairing Offshore wind with aquaculture
As mentioned previously, fixed-bottom offshore wind is the most advanced and dominant technology when it comes to ORE. It would also seem that this technology is the most suitable for the implementation of aquaculture operations within its infrastructure. Research activities show the positive outcomes that might emerge from collocating aquaculture and OWF. A 2023 article published in Nature showed that allocating 10% of projected wind farm areas to blue mussel and sugar kelp aquaculture in the North Sea and Baltic Sea could yield significant results in terms of carbon captured, as well as seaweed and mussel shell production [16]. But this combination does not limit itself to research activities and is being implemented in several test pilot sites throughout the world. The UNITED project, and its follow-up ULTFARMS, aims to develop multi-use at sea and is based on several multi-use pilot sites. In the Belgian pilot, the objective is to combine OWF with flat oyster aquaculture production. The hard substrate around wind turbine poles constitutes an interesting substrate for oyster larvae to settle on and build natural oyster reefs, through the process of bio-colonization [17]. It should be noted that an increasing number of European projects are making significant progress on combining OWF with aquaculture production, both in the areas of research and concrete application [18].
- Pairing wave energy and aquaculture
Devices used to harvest wave energy could potentially be used for aquaculture operations, but research must be further continued to ensure the feasibility of this combination. Several combinations of offshore aquaculture and wave energy are currently being tested. In Scotland (Clift Sound), a submersible wave energy device was installed. It used the power of the waves to generate electricity and charge battery banks that are then used to power offshore aquaculture operations (computers, lights, sensors, etc.). The installation was tested over an 18-month period and yielded positive results [19]. Another interesting case study is taking place in Wales, in the frame of European project MARIBE. Two companies (Wave Dragon and Seaweed Energy Solutions) are partnering to install a device used to harness wave energy and create an area with reduced waves that is suitable for farming seaweed [20].
- Pairing tidal energy and aquaculture
For operating reasons, tidal energy devices are often placed close to shore and in restricted channels in order to benefit from concentrated tidal streams. They could therefore be strategically placed to power nearshore aquaculture operations. This combination is more with bivalve and seaweed cultivation, rather than finfish aquaculture, as fast-moving tides can be challenging for feeding fish [21]. A French society, Guinard Énergies Nouvelles has developed a project called Énergies Renouvelables au Service des Exploitations Ostréicoles (ERSEO). The project installed a tidal turbine in an estuary in order to meet the energy needs of surrounding oyster farms and validated the efficiency of this system[22].
- Pairing OTEC (ocean thermal energy conversion) with aquaculture
The idea is to use OTEC facilities to bring deep seawater to the surface. This water could be used for aquaculture production as it is rich in nutrients and contains fewer pathogens and pollutants [23]. Few OTEC and aquaculture combinations have been tested yet, but some pilots are being tested notably in Hawaii [24].
- Pairing floating solar PV with aquaculture
It is uncertain if floating solar PV can be considered as an ORE per se. However, the installation of floating solar panels at sea could be an interesting opportunity for aquaculture. Research in the domain is still progressing, but some interesting pilots are already being tested, notably in the Netherlands where a floating solar technology powering a seaweed farm has been installed [25].
- References
[2] https://www.quae-open.com/produit/136/9782759201846/marine-renewable-energies
[7] https://onlinelibrary.wiley.com/doi/10.1002/ece3.2637
[8] https://www.sciencedirect.com/science/article/pii/S1474667016381253
[9] https://thefishsite.com/articles/can-aquaculture-co-locate-with-offshore-energy-projects
[10] https://onlinelibrary.wiley.com/doi/full/10.1111/raq.12783
[11]https://thefishsite.com/articles/can-aquaculture-co-locate-with-offshore-energy-projects
Existing co-existence and multi-use initiatives
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