Minimising environmental impact of offshore wind farm, thanks to latest technology.
Norfolk Vanguard is a proposed 1.8GW Offshore Wind Farm in the southern North Sea, 47km from the coast. The project will meet the electricity requirements for around 1.3 million UK households.
Norfolk Vanguard is classed as a Nationally Significant Infrastructure Project (NSIP) and consequently, Vattenfall needed to apply for a Development Consent Order (DCO). Vattenfall commissioned Royal HaskoningDHV’s (RHDHV’s) offshore wind team to lead the Environmental Impact Assessment (EIA) to enable the delivery of the Environmental Statement (ES) and support the DCO application. The DCO application included all offshore and onshore infrastructure associated with the offshore wind farm and its connection to the National Grid, including the wind turbines, associated platforms, array and interconnector cables, offshore export cables, landfall works, onshore export cables, a new project substation and an associated extension to an existing National Grid substation near Necton, Norfolk.
The challenge is to deliver a source of safe, reliable, cost effective, renewable energy, generated in the UK, that provides power to the UK market. The Government will reach a decision at the end of 2019 as to whether consent will be awarded or not.
To deliver this project, RHDHV’s in-house multi-disciplinary team worked collaboratively with Vattenfall’s project team from the very beginning, providing insight and expertise to enable site selection, engineering decisions and design development to reduce impact and incorporate best practice. It was important to identify opportunities to reduce environmental and technical risks while delivering environmental enhancement wherever possible. As well as the ecological sensitivity of the area, this was also vital for the socio-economics of the region. The RHDHV team’s key specialisms in this project particularly relate to onshore traffic, noise, air quality, water resources and flood risk, onshore ecology, seabed ecology, marine mammal ecology, and onshore and offshore archaeology.
The onshore cable route, which is approximately 60km long, makes landfall at Happisburgh, a historically important settlement where the earliest human footprints in Europe have been previously discovered. This meant sensitive siting of the landfall location and identification of mitigation needed to be undertaken in close consultation with specialist archaeological organisations, including Historic England.
The cable route from Happisburgh to the nearest suitable substation at Necton, passes through rural Norfolk. This required detailed consideration of issues relating to ecology, water crossings, traffic, noise, visual impacts, tourism and recreation, and land use. The cable route also crosses the cable route of another offshore wind farm, which is going through planning on a similar timescale. This provided challenges in terms of data sharing to inform the cumulative impact assessment of the EIA.
Offshore, there are numerous other wind farms in the operation, construction or planning stages, providing challenges for the consideration and mitigation of cumulative impacts. For example, the Norfolk Vanguard wind farm itself is located within a Special Area of Conservation (SAC), designated for harbour porpoise. The team were able to resolve issues relating to the mitigation of cumulative effects on harbour porpoise using an innovative Site Integrity Plan, instigated and developed by RHDHV.
The offshore cable corridor also passes through an SAC designated for Sabellaria spinulosa Reef and Sandbanks. The team have worked closely with Vattenfall and relevant stakeholders to establish a mitigation solution to ensure impacts can be minimised to an acceptable level.
RHDHV led a range of consultation with local, regional and national stakeholders, forming a voluntary Evidence Plan Process to structure the discussions and inform the development of the EIA. RHDHV also supported the client in an extensive programme of community consultation. These enabled the community and stakeholders to feed into the site selection and project design and lead to a number of targeted mitigation commitments to minimise impacts on the local community and other receptors.
RHDHV were able to establish a close working relationship with the project engineers, land agents, project managers and communications team. This has been key to ensuring all members of the project team had a clear understanding of all the constraints and opportunities posed by Norfolk Vanguard. As a result the project team were able to develop the design of the project in order to minimise environmental impacts. RHDHV undertook a thorough constraint analysis and site selection exercise for the onshore infrastructure, which enabled a number of impacts to be avoided by design.
In a key mitigation, Vattenfall committed to a High Voltage Direct Current (HVDC) export solution which avoids the need for an onshore cable relay station, reduces the number of cables required and therefore the extent of cable installation works onshore and offshore.
Through the EIA, the team carried out a variety of environmental assessments. Following the completion of RHDHV’s assessments, significant technical design revisions were made to the proposals that will greatly reduce potential environmental impact.