Offshore Renewable Energy & Maritime transport

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. 

Maritime Transport 

Maritime transport includes shipment of goods and transport of passengers by sea. It remains the backbone of international trade, with the EU being one of the most important exporters and exporters worldwide.

In terms of infrastructure, maritime transport not only requires seagoing vessels, but also ports as central logistics hubs, rendering the sector intimately connected to land-based infrastructure and relying on a complex web of land-sea logistics chains. The governance of the sector is also split between leading global shipowners (MSC, MAERSK, CMA-CGM) and smaller competitors. 

Ship routing systems have been established by the International Maritime Organisation (IMO) in congested shipping areas of the world for safety reasons. To minimize potential environmental impacts of shipping, the International Convention for the Prevention of Pollution from ships aims at minimizing pollution of the oceans and seas. In addition, maritime transport is expected to meet increasing sustainable performance criteria linked to key Sustainable Development Goals (SDGs) and notably SDG 14.

Maritime transport is a well-established sector, with a post-covid increasing demand for goods but also in vessel size and number. This growth puts increasing pressure on the marine environment and can often put important ecosystems at risk, notably through greenhouse gas emissions, air pollution, underwater noise, oil pollution, and the introduction of non-indigenous species [3].

For more information about EU blue economy sectors please visit the EU Blue Economy Observatory website. 

For more European statistics and data you can also visit the Eurostat website

Co-design shipping routes in a collaborative process

The idea is to ensure that shipping routes are agreed upon by different maritime stakeholders and especially MRE stakeholders as the location of their facilities must comply with such layouts. Ideally, shipping lanes should be defined in a collaborative process, making sure the concerns of both sides and existing legislation (e.g. shipping safety) are fully considered. It is therefore useful, within the framework of maritime spatial planning, to form a consultation group to collect data and discuss the routing options.

A relevant example of such process can be found with the Belgium and Netherlands case, when project developer Wind aan de Stroom sought to develop offshore wind farms near the Scheldt estuary [4]. Conflict soon arose with the shipping sector as there was a concern that offshore wind developments would reduce the available space for navigation, and that this could affect the safety and efficiency of shipping in this area. It soon became apparent that a sectoral approach to planning for offshore wind developments was insufficient in this case, as there was a need for a more integrated approach to planning where the interests of the shipping sector would be taken into consideration to avoid possible conflicts and associated financial losses later. A Joint Belgium and Netherlands consultation group consisting of public authorities, ports, vessel operators, consultants, shipping companies and associations, as well as offshore wind farm developers was formed to define the best route and propose safety measures and rerouting to the International Maritime Organisation (IMO). A risk assessment of the proposed routing measures was also conducted by the Maritime Institute Netherlands (MARIN) to comply with IMO requirement. The proposal was then submitted and approved by the IMO. In this case, the cooperation between the two countries was crucial given the cross-border nature of this conflict. 

Another example is the interaction between shipping and planned offshore wind farms during consultations for the Dunkirk (France) OWF area. The initial demarcation of the proposed zone raised concerns from shippers: the Maritime and Commercial Union stated that the proposed area of 180 km2 subject to consultation presented a series of incompatibilities with the coastal access and shipping lanes to the two ports of Dunkirk [5]. The Maritime and Commercial Union worked on an alternative solution and proposed a usable zone of 70 km2 rather than the original 180 km2 delimited by the Maritime Prefecture. After these consultations two smaller areas (area A:68 km2 and area B: 55 km2) were selected for tender.

Similarly in the UK, the Nautical and Offshore Renewables Energy Liaison (NOREL) group is a forum for government and industry from the two sectors to discuss and consult on matters related to navigational safety and OWF [6].

Carry out a risk assessment on proposed re-routing options

The impact of any proposed measures (such as re-routing shipping lanes) on the safety of navigation must be confirmed by a Formal Safety Assessment, an IMO (International Maritime Organisation) requirement. The Formal Safety Assessment is a qualitative assessment of the impact of the proposed measures on safety based on local knowledge and expertise in shipping, also including workshops with all relevant stakeholders including captains/pilots, port operators, shipping representatives, etc. The Quantitative Risk Assessment is based on a validated risk model (number of collisions, economic consequences, etc.) that considers two scenarios: with and without proposed risk control options.
Such assessments can be based on data software such as the SAMSON (Safety Assessment Models for Shipping and Offshore in the North Sea) [7]. It relies on AIS (automatic tracking systems) data to calculate the risk of navigational accidents in the locality of offshore wind farms. It calculates and compares the probability and consequences of navigational accidents for various base-case (i.e. no OWF) and future case (i.e. OWFs in different layouts/locations) scenarios. The model can also consider various factors such as ship types, sizes and speeds, effect of OWFs on ships’ navigational equipment, as well as static and dynamic environmental factors, etc. This model can be also used to predict the damage to turbines and ships, environmental damage in terms of oil spills or human casualties, assess the economic and efficiency-cost of various risk control options (e.g. re-routeing) and supplement the cost-benefit analyses of different routing options.

Apply navigational risk assessment during the MSP process

A Navigational Risk Assessment (NRA) is usually conducted by OREI developers to obtain approval for their projects [8]. Through this process, developers can demonstrate to the relevant regulators that their projects do not pose unacceptably high risk to maritime activities and avoid conflicts in terms of impact to navigational safety and efficiency. Incorporating NRAs into the MSP process could substantially help to improve the coexistence of maritime activities and OREI. For example, Belgium and the Netherlands have already started using NRA tools during their MSP processes. In the Netherlands, an NRA is used by local authorities (i.e. MIW and Rijkswaterstaat) as part of the approval for the OWFs. The results of the NRA are presented to maritime stakeholders, along with specific design specifications for potential wind farms. The authorities are then responsible for ensuring that developers adhere to the guidelines during the approval and licensing process. All in all, this phase is especially relevant for stakeholder's dialogue and mutual dissemination of knowledge to prevent accidents. This allows to reduce conflicts and increase compatibility with maritime transport. The early dialogue between the two parties is the prerequisite for the operating phase to go smoothly.   

Encourage the use of automatic tracking systems on ships and crew members to increase safety around and within wind farms.

The purpose of these devices is to identify the position, course, and speed of a vessel. They are used for various safety reasons and can help avoid collisions, notably between ships and offshore wind farms as they allow for tracking of vessels within and in close proximity to the wind farm. More specifically, such devices include AIS-SRT (Automatic Identification System - Search and Rescue Transmitter) or PLB (Personal Life Beacon). According to the study “Review on risk assessment on transit and co-use of offshore wind farms in Dutch coastal water” [9], the use of such devices allows for effective SAR (Search and Rescue) action within and in proximity of the wind farm.

Improving maritime surveillance and data sharing with the authorities in charge

This enabler is directly linked to the previous one as it concerns a technical solution aimed at improving navigational safety by using surveillance data. As the deployment of OREI increases, new means of surveillance are also being developed, such as satellite coverage and intruder detection [10]. This overall improvement of surveillance allows users to see with more clarity what is happening in a given area through data acquisition by radar systems or other similar tools. Such surveillance data can be shared with relevant authorities (such as CROSS in France [11]) to improve safety at sea. 

Foster research on crash barriers

Although very recent, an emerging innovation aimed at avoiding collision between vessels and OREI is being developed. Due to adverse weather conditions or navigational difficulties, ships can be drifting and unable to change their direction, potentially leading to collision with wind turbines [12]. To avoid such interactions that can be extremely dangerous, the Maritime Research Institute of Netherlands (MARIN) has been conducting several tests to ensure the reliability of a new device used to stop drifting ships and avoid potential collisions with OWF [13]. This innovation exists in 3 versions: one consists of a string of surface buoys secured by drag anchors, the second is a suspension net between fixed poles, and the third is an anchored underwater hook line designed to catch the anchor of the drifting vessel. Research in this domain is very promising as this device is considered capable of stopping drifting ships.

Collision can be avoided or reduced simply by enforcing a safety zone where navigation is prohibited around OREI such as OWF. International recommendations for the distances between OWF and maritime transport routes can be found within the International Regulations for Preventing Collisions at Sea (1972) by IMO, as well as in the UNCLOS regulations concerning the safety zones of maritime structures. Such sources  state that approximately 1–2 nautical miles (1.8–3.6 km) is considered a safe distance between wind turbines and vessel routes [14]. In reality, a 500 m safety distance around OREI is often the standard in almost all countries [15] as it corresponds to the distance between OREI and shipping routes under which the level of risk is considered unacceptable [16]. According to a study focussing on tolerance thresholds for minimum distances between turbine locations and shipping routes [17], the most common distance between a wind farm and shipping lane in Europe is approximately 1 nm. The enforcement of such minimum distances allows for more safety when navigating around OREI.

To avoid possible spatial conflicts, MRE related activities such as OWF construction works, or major maintenance activities can take place at selected times of year when shipping is less busy. For example, an analysis of seasonal variations in traffic [18] showed that summer months are clearly the busiest in all parts of the North Sea, including the coast of UK, i.e. the route from the English Channel to the entrance of Skagerrak and around the south coast of Norway. Subsequently, port areas and inland waters are also busier. This information was obtained by plotting the Vessel traffic from AIS (Automatic Identification System) data in density map format from European Maritime Safety Agency. European Maritime Safety Agency (EMSA) tasked all national governments in the North Sea to collect AIS information from their maritime areas and supplement it with data from other countries. This seasonality is to be considered by OREI developers and must be coherently fitted with the timing of construction and maintenance operations undertaken by developers. 

During the pre-planning and development stage of OREI, it can be useful to rely on existing international guidelines to mitigate risks and foster cross sectoral coherence. Such documents can be found at international level: for example, the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA), produced guidelines on navigational safety within marine spatial planning [19]. This document lists the specific navigational concerns that should be considered when developing offshore facilities for MRE. Such guidance documents also exist at the national level. The UK authorities have extensive experience with navigational risk assessments which is reflected in multiple published guidance documents for OWF developers including “Methodology for assessing the marine navigational safety and emergency response risks of offshore renewable energy installations” [20] and “Safety of Navigation: Offshore Renewable Energy Installations - UK Navigational Practice, Safety and Emergency Response” [21]. These documents also provide a comprehensive list of factors (e.g. vessel traffic, types of vessels, traffic characteristics, location of routes, routeing measures, bathymetry, waves, winds, currents, OWF layout, OWT marking and lightings, effect of turbines on navigational equipment, etc.) – as well as a non-exhaustive list of stakeholders (e.g. RNLI, lighthouse authorities, Chamber of Shipping, recreational shipping, local fishermen, ship-owners and operators, etc.) that need to be considered.

Shipping stakeholders have also developed recommendations for more suitable wind farm layouts [22]. Such recommendations include, for example, the publishing of detailed wind farm plans on nautical charts with the locations of exclusion zones, turbines, transformer stations and cable plans. This information should be made available by the wind farm owners. The wind farms should provide additional information on maintenance activities to the Coastguard, to be used in daily communication to sailors.