Renewable Energy & Cables
Offshore renewable energy interests - wind, wave and tide - represent an increasingly important response to tackling the dual challenges of climate change and national energy security.
The marine aggregate industry represents an important part of the supply chain needed to support these developments – by providing the contract fill and construction aggregates for the new port facilities required to manufacture maintain and support these new developments. Also, as a source of the large volumes of construction aggregates that would be required in manufacturing concrete gravity base foundations (GBFs), which are likely to become increasingly used as offshore renewable developments move into deeper water, further offshore.
The marine aggregate industry operates in most English and Welsh offshore regions where marine renewable energy interests are being investigated and developed. As a consequence, there are some broad issues that may arise as both interests seek to develop and operate in close proximity to one another.
Beyond the immediate potential for interaction with current and future marine aggregate interests through the placing of structures and cables, there is also the potential for less obvious operational impacts.
A dredging licence producing 1 million tonnes a year would see 200 cargoes of 5,000 tonnes being dredged - each representing 4-8 hours on site. Vessels therefore require safe access to the licence areas and the flexibility to navigate safely within a licence while dredging operations are underway.
The potential for interaction with marine aggregate operations also needs to be considered even if a potential offshore renewable site may appear to be a considerable distance from such interests. Some 28 marine aggregate dredgers operate in British coastal waters, producing over 20 million tonnes of marine aggregate every year. This represents some 7000 cargoes being dredged – equivalent to 4-5 cargoes per vessel every week. Dredgers are therefore constantly transiting British coastal waters, as they navigate between production licence areas and the ports being supplied.
To assist with the consideration of potential indirect impacts on marine aggregate interests, BMAPA has generated a series of charts to show the extent of dredger transit routes between member companies production licence areas and the ports that are supplied relative to Round 1, 2 and 3 offshore wind interests.
The dredger transit routes themselves are also available to be downloaded for third party use in Mapinfo and ArcView GIS.
Proximity Guidelines – Marine aggregate extraction and subsea cables
The location of existing seabed cable infrastructure in close proximity to a proposed marine aggregate application could have a significant impact upon the layout or location of that application. Conversely, the location of an existing marine aggregate production licence could have a significant impact on the precise routing of a new cable installation.
BMAPA and Subsea Cables UK (SCUK) have therefore worked together to produce a new document (February 2016) that provides guidance on the considerations that should be given by all stakeholders in the development of projects requiring proximity agreements between marine aggregate interests (planned applications or existing production licences) and submarine cable projects (planned or existing) in UK waters.
The Guidelines address installation and maintenance constraints to submarine cables and constraints to marine aggregate extraction operations where both interests will occupy proximate areas of seabed, and discusses some of the key factors determining proximity limits to be taken into account in reaching a proximity agreement. The importance of early stakeholder consultation should be appreciated at the outset of a project and it is recommended this is undertaken as early as possible for all new marine aggregate applications or cables.
It is the consideration of the Guidelines that no proximity agreement is required where the minimum approach of the proposed/existing marine aggregate licence and planned/existing subsea infrastructure exceeds one nautical mile (1NM) (1.852 km).
However, at a separation of approximately 1NM, it is considered good practice that high-level consultation is undertaken thereby ensuring that all Stakeholders are aware of each other’s activities and requirements. In all instances, it should be the responsibility of the incoming party to constructively engage and consult with the existing interest(s).
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