Here you’ll find answers to some of the most frequently asked questions about Sea Link.
We hope they answer your questions and we will continue to update them as our work progresses. If your question is not listed below, get in touch with the team using the details provided on the Contact us page.
About Sea Link
Sea Link is a proposed electricity transmission network reinforcement between Suffolk and Kent, via a new, primarily offshore 2 gigawatt (GW) high voltage direct current (HVDC) link.
To bring the power from the subsea cables into and out of the electricity network in both Suffolk and Kent, we would need to build new onshore infrastructure including converter stations, substations and new underground and overhead electricity lines, as well as upgrading existing overhead electricity lines.
Power will be able to flow along the Sea Link cables in either direction, depending on where renewable energy is being generated at that time and where in the country power is needed.
With more of our power coming from renewable energy, including out at sea, and demand rising fast, we need to scale up our network and undertake the largest overhaul of the electricity network in generations.
Suffolk and Kent are both areas where the electricity network needs upgrading, as more power is set to come into the network than it can transport.
Sea Link is part of the solution to add capacity to the network. By using a subsea connection, we are overcoming some of the main pinch points in the network allowing power to flow in either direction to homes and businesses across the country.
Sea Link only works if it is connected in certain locations in Suffolk and Kent.
In Suffolk, Sea Link must connect in the Sizewell area to transport power from generators like Sizewell and new offshore wind farms, providing extra capacity in the network for this new generation.
In Kent, the existing network which runs between Kemsley in Sittingbourne (via Canterbury and Richborough) and Lovedean in Hampshire is one area that needs upgrading. This means that Sea Link needs to connect between these two locations
Building Sea Link in a different location would not create more capacity on the network where it is needed.
In Suffolk, our proposals include:
- a connection from the existing transmission network via the proposed Friston Substation, including the substation itself. Friston Substation already has development consent as part of other third-party projects. If Friston Substation has already been constructed under another consent, only a connection into the substation would be constructed by Sea Link
- a high voltage alternating current (HVAC) underground cable of approximately 1.9 kilometres (km) in length between the proposed Friston Substation and a proposed converter station (below)
- a 2 GW high voltage direct current (HVDC) converter station up to 26 metres (including permanent access from the B1121 and a new bridge over the River Fromus) high plus external equipment (such as lightning protection & railings for walkways) near Saxmundham
- a HVDC underground cable connection of approximately 10 km in length between the proposed converter station near Saxmundham, and a transition joint bay (TJB) approximately 900 metres inshore from a landfall point (below) where the cable transitions from onshore to offshore technology
- a landfall on the Suffolk coast (between Aldeburgh and Thorpeness).
You can read more information about our proposals in our Project update document.
Our marine proposals for Sea Link include:
- Approximately 122 kilometres (km) of subsea high voltage direct current (HVDC) cable between the Suffolk landfall location and the Kent landfall location.
You can read more information about our proposals in our Project update document.
In Kent, our proposals for Sea Link include:
- a landfall point on the Kent coast at Pegwell Bay
- a TJB approximately 800 m inland to transition from offshore HVDC cable to onshore HVDC cable, before continuing underground for approximately 1.7 km to a new converter station (below)
- a 2 GW HVDC converter station (including a new permanent access off the A256), up to 28 m high plus external equipment (such as lightning protection & railings for walkways), near Minster. A new substation would be located immediately adjacent
- removal of approximately 2.2 km of existing HVAC overhead line, and installation of two sections of new HVAC overhead line (totalling approximately 3.5 km) from the substation near Minster to the existing Richborough to Canterbury overhead line.
You can read more information about our proposals in our Project update document.
Some major infrastructure projects (such as new overhead power lines, power stations and airports) are classified as nationally significant infrastructure projects, or NSIPs. The size and status of these projects means that the decision on whether or not to build them is made by the Government, not your local council.
The Planning Inspectorate (or PINS) will now check the application meets its requirements before accepting it for examination. It has 28-days to carry out these checks. If the application is accepted, you can register as an Interested Party with PINS and take part in the examination.
Visit the PINS website here to view our full application.
Click here to watch a short video on the planning process for NSIPs.
Our application will be published in full on the Planning Inspectorate’s website here.
Yes. If the Planning Inspectorate (or PINS) accepts our application, it will carefully scrutinise the plans in the ‘examination’ stage of the process. There will be a number of opportunities for you share your feedback on the proposals as a whole, and to have your say on specific parts of the plans when PINS examines them.
To take part, you will need to register (as an Interested Party) during the pre-examination period. Registration would be open for at least 30 days. If the application is accepted, we will update our website and contact all those who are registered to receive updates from us. You can sign up to our mailing list to receive this update directly to your inbox.
Since 2022, we have held three rounds of consultation on the proposals: non-statutory consultation in 2022, statutory consultation in 2023, and targeted consultation in 2024. We refined our proposals between each consultation based on feedback received, and the outcome of ongoing survey and technical work across all areas of the project – such as environmental and technical assessments.
In November 2024 we ran a targeted engagement exercise to consult local stakeholders who are in close proximity to a small number of proposed changes to the plans. These changes were the result of further engineering work, environmental assessments and feedback to earlier consultations.
In March 2025 we submitted our application for development consent.
You can read about earlier consultations in detail on the document library of our website, and more information on submitting our application is available in the FAQs section. Our application will be published in full on the Planning Inspectorate’s website here.
We have made the following refinements to our proposals:
in Suffolk, the changes include an alteration to the cable route north of Aldeburgh, confirmation of the proposed access route to the converter station and changes to this access route and the associated bridge over the River Fromus. We are also proposing various changes to construction and maintenance access routes, compounds, and temporary overhead line diversion, and have identified additional land for environmental mitigation and enhancement. The strategy for coordination with other projects has also evolved
offshore, the changes include refinements to the cable route, additional marine areas for construction vessel maneuvering, and changes to the approach for backfilling marine trenches
in Kent, the changes include an increase of the overall maximum height of the converter station, confirmation of the type of pylon we intend to use for the connection to the existing overhead line and identifying a further construction and maintenance access route off Sandwich Road via the former hoverport. We are also proposing various other changes to construction and maintenance access routes, compounds, and temporary overhead line diversions, and have identified additional land for environmental mitigation and enhancement.
For detailed information on the full list of changes, please see our Project update document.
In 2023 and 2024, National Grid Electricity Transmission (Sea Link), North Falls (Offshore Wind Farm) and Five Estuaries (Offshore Wind Farm) carried out work to explore the potential for offshore coordination as part of the Offshore Transmission Network Review (OTNR) “Early Opportunities” workstream. The projects, acting together in a consortium led by North Falls, were awarded funding by the Department of Energy Security and Net Zero (DESNZ) through the Offshore Coordination Support Scheme (OCSS) in December 2023.
On 28 March 2024, the consortium submitted a high-level feasibility study that formed the first step of the grant funding agreement. The study assessed the feasibility of a coordinated offshore connection specifically: the capital costs; building blocks; construction and commissioning methodologies and overall programme associated with a coordinated solution.
The Secretary of State for Energy Security and Net Zero subsequently reviewed this study amongst other information and, in September 2024, decided not to grant further funding to the consortium. The feasibility study identified that coordination is technically feasible however, it also identified:
- an increase in capital costs of up to £890m
- constraint costs associated with an outage on Sea Link of over £500m*
- a programme delay for North Falls and Five Estuaries of up to five years
Given the significant extra costs and the negative impact on the delivery timeline of connecting more renewables to the UK energy system, especially considering the government's commitment to quadruple offshore wind and fully decarbonise the UK's electricity system by 2030, the consortium supports the Secretary of State’s decision and will not be further pursuing a coordinated offshore connection. We would like to thank DESNZ for its continued engagement throughout the grant term.
*This figure is attributed to the constraint costs associated with an outage on Sea Link in 2032/33 only.
We are currently in the process of updating stakeholders on the changes we are making to our plans for Sea Link. We intend to make an application for development consent in early 2025, though this date is subject to change.
The start of construction depends on the approval of our application for development consent. We submitted our application for development consent in March 2025, and a decision will be made by Autumn 2026. If approved, construction would start in early 2026 or 2027.
We anticipate the construction process will be complete around 2030. This is to ensure the link is in place and connected by the end of 2030. Some of the reinstatement works would continue into 2031.
Local communities and the environment
In March 2025, the Government published guidance on community benefits for areas that host new transmission infrastructure, such as our proposals for Sea Link.
We welcome the Government’s guidance on community benefits, which supports our view that communities should be rewarded for hosting new transmission infrastructure essential to boosting home grown, cleaner and more affordable power for the country. This guidance offers a clear framework and will enable us to work with communities and deliver meaningful, long-term, social and economic benefits through strategic investment.
In line with this guidance, community benefit funds must respond to community needs and be developed through engagement with communities and stakeholders. As this project develops, we will engage with local residents, community groups, local representatives and range of stakeholders to help shape our proposals for community benefits associated with SEA Link. Please keep an eye out for opportunities to share your feedback with us.
NGET's Community Benefit Plan aligns with National Grid’s Responsible Business Charter, emphasising impact in environment, communities, people, economy, and governance, shaping our strategic priorities with a focus on responsibility.
As part of the Environmental statement submitted in our application for development consent, we have prepared a further assessment that considers the cumulative impacts of Sea Link and other planned developments in further detail. This assessment includes detail of the measures we propose to take to mitigate and/or manage adverse impacts. Other developers will also be required to carry out their own cumulative impacts assessments as part of their project.
The Environmental statement built on Preliminary environmental information report (PEIR) published at our statutory consultation in 2023, which considered the potential cumulative impacts of Sea Link and the other projects planned for both Suffolk and Kent in the years ahead.
There are several key differences between these projects that restrict the ability of all applications to be brought forward as on single DCO.
Sea Link is part of The Great Grid Upgrade and is an essential network reinforcement and standalone project
The projects are being promoted by different companies, with different project teams covering several different geographical locations who are at different stages. Making coordination into a singular DCO or examination unworkable given the need to deliver Sea Link by 2030
The businesses are separate legal entities and have different statutory duties
We work closely with local communities to make sure we minimise construction impacts as much as we can and support community initiatives in areas where we are working to deliver social, economic or environmental benefits. During construction we will need to do a range of temporary activities such as creating equipment storage areas, site offices, and road and public rights of way diversions will need to be implemented. Before we do this, we will prepare a construction management plan that will set out controls and measures to reduce our impact on the local community. We might still need permanent access rights for maintenance.
Though Sea Link is not an energy generator, it will allow new, cleaner sources of energy to connect to homes, businesses and public services across the country by increasing capacity on our network. Without increasing capacity, we cannot connect cleaner energy sources. Sea Link alone will connect enough power for two million homes and is one part of our efforts to upgrade and decarbonise the grid.
EMFs are electric and magnetic fields. Electric fields are produced by voltage and magnetic fields by current flowing through a conductor. Overhead lines are a source of two fields: the electric field (produced by the voltage) and the magnetic field (produced by the current). Underground cables eliminate the electric field altogether as it is screened out by the sheath around the cable, but they still produce magnetic fields.
Background EMFs are present in most homes. They come from the house wiring, electrical appliances and the low-voltage distribution cables that carry electricity along streets.
Some people worry that Electromagnetic fields (EMFs) may have negative health effects. We take these concerns seriously and want to keep the public, our contractors and employees safe. We ensure all of our existing and proposed equipment, including those on this project, comply with independent safety guidelines set to protect us all against EMF exposure. After decades of research, the weight of evidence is against there being any health risks of EMFs below the guideline limits.
For further information on EMFs visit our website, www.emfs.info. If you would prefer to talk about your concerns, please do not hesitate to call the EMF helpline on 0845 702 3270 or email [email protected].
Background EMFs are present in most homes. They come from the house wiring, electrical appliances and the low-voltage distribution cables that carry electricity along streets.
Some people worry that Electromagnetic fields (EMFs) may have negative health effects. We take these concerns seriously and want to keep the public, our contractors and employees safe. We ensure all of our existing and proposed equipment, including those on this project, comply with independent safety guidelines set to protect us all against EMF exposure. After decades of research the weight of evidence is against there being any health risks of EMFs below the guideline limits.
For further information on EMFs visit our website, www.emfs.info. If you would prefer to talk about your concerns, please do not hesitate to call the EMF helpline on 0845 702 3270 or email [email protected].
We are rigorously assessing potential environmental impacts and we will be adhering to the "mitigation hierarchy" by avoiding, minimising, restoring, and offsetting impacts. Our efforts include micro-siting cables, using non-intrusive construction methods, and ensuring a 10% Biodiversity Net Gain, which means we will leave the environment better than we found it. This will be achieved by a range of measures, such as habitat creation and enhancement for protected species.
We'll conduct a comprehensive environmental impact assessment, meeting legal requirements under the EIA Regulations. Stakeholders can comment on our Preliminary Environmental Information Report (PEIR), and when we submit our application for development consent, we will include the full Environmental Statement accounting for expert and public feedback received during consultation.
There are a number of different ways for National Grid to deliver biodiversity net gain.
The first is within the project’s development area, the second is offsite, outside of the project area on land owned or leased by landowners.
The third is offsite using financial contribution to offset impacts through discussions and agreements with the Local Planning Authority or Local Wildlife Trust through a Habitat Banking/Biodiversity Unit Provider through the use of Government Statutory Units (which is used as the last resort).
The ‘offsite’ locations could be either a wildlife site or nature reserve and would meet the ‘ecologically desirable’ criteria. National Grid will implement a range of strategies to protect and improve known wildlife sites and nature reserves as well as creating new habitats where appropriate.
Green Infrastructure (GI) features can contribute to a project's BNG calculations and there are a range of GI features that can be included, such as:
green roofs, green walls and Sustainable Drainage Systems (SuDS);
landscaping included within the Post-Development Plans.
It is possible to use sites delivering nutrient neutrality/ a suitable alternative natural greenspace (SANG)/Great Crested Newt habitat to also deliver net gain, on the basis that:
delivery of the non-BNG outcomes can contribute to a point equivalent to no net loss of BNG but NOT beyond
additional habitat features created or enhanced on the same land beyond those delivered for non-BNG outcomes (i.e.in addition) could take you into positive BNG territory.
Onsite: Within the project’s development area
Offsite:
land owned by the client
land leased by the client
Offsite: Use a financial contribution to offset impacts
through discussions / agreements with the Local Planning Authority /Local Wildlife Trust
through a Habitat Banking / Biodiversity Unit Provider
through the use of Government Statutory Units (last resort)
National Grid’s non-operational land can be used for offsite mitigation.
The ‘offsite’ locations could be either a wildlife site or nature reserve and would meet the ‘ecologically desirable’ criteria. National Grid will implement a range of strategies to protect and improve known wildlife sites and nature reserves as well as creating new habitats where appropriate.
Infrastructure and construction methods
A converter station houses the technology that converts electricity between alternating current (AC) and direct current (DC) and enables it to be transmitted over long distances. AC current is used in each country’s transmission system to power homes and businesses, while DC is used for sending electricity more efficiently over long distances.
Substations house electrical equipment which enables the system operator to control the flow of electricity. These substations come in many sizes and configurations depending on the need. Substations are also key in helping to isolate and fix faults and allow maintenance to be undertaken safely on the electricity network.
Cable joint bays are needed at intervals of approximately 500 metres to 1,000 metres when constructing underground cables, to allow for individual sections of cable to be joined together. In areas where a cable joint bay is needed, a wider cable corridor may be required.
Cable ducts are sections of tubing where electricity cables are placed.
A link box is an above ground kiosk which allows inspection and maintenance of the cables.
Transition joint bays are used to connect an onshore cable to an offshore cable. These are generally around 10 to 15 metres in length, 5 metres in width (dependent on design requirements) and are located near the coast.
We are proposing to use a range of construction methods for Sea Link. These include underground cable installation, which requires an area beyond the corridor, accommodating site compounds and material storage. Trenchless crossing minimises surface interaction, reducing impact on wildlife and communities. Subsea cable installation involves precise surveys and specialised cable-laying vessels.
The cables will come ashore deep underground and will be placed there using trenchless construction (directional drilling technology). This means there will be no disturbance to the land surface, and we will not be digging up the beach.
The same is true where the project interacts with the RSPB North Warren, again we will be routing the cable deep below ground.
Overhead electricity transmission lines typically involve building new steel lattice pylons to support the wires (conductors). The size, height, and spacing of pylons are determined by safety, topographical, operational, and environmental considerations. A typical 400 kV pylon is around 50 metres tall.
Draft order limits form the current anticipated boundary of the entire area within which Sea Link could take place.
Limits of Deviation lie within the Draft Order Limits, they give us flexibility when constructing the project in case of unforeseen circumstances (such as unexpected environmental constraints), they allow us to move infrastructure within the Draft Order Limits. We would not need all of the land within the draft order limits, but permanent infrastructure could be installed within the Limits of Deviation.
Yes. Potential effects on tourism have been assessed as part of our application. Measures to manage the impacts that could impact tourism (such as footpath or road closures, impacting journey times and travel patterns) have been considered throughout the construction phase.
What will you be doing to mitigate the impact of HGVs on the local road network during construction?
Within our outline code of construction practice, we are considering a range of measures that would help control the management of impacts on local traffic and transport. Our traffic management plan will set out how we plan to reduce route and journey mileage to and ensure considerate parking practices in local areas. We will work closely with the local authority and take guidance from them to further reduce our impact such keeping our movements to earlier in the day.
We are proposing temporary haul roads so that construction traffic avoids the local road network where possible. The average number of Heavy Goods Vehicle movements per day at the peak of construction would be 79.
National Grid needs to build a new 400 kV substation in Friston to connect ScottishPower Renewables (SPR)’s East Anglia ONE North and East Anglia TWO offshore windfarms to the existing transmission network. Construction work is yet to begin on the substation.
Cables in these areas would be installed using a trenchless construction method that would not disturb the ground above. We would not be digging up Aldeburgh Beach or the saltmarsh at Pegwell Bay.
The proposed bridge over the River Fromus is required for the construction and maintenance access route to the proposed Saxmundham converter station.
This access route has been shortlisted from three options; a proposed southern access was deemed unsuitable, while a proposed northern access route would cover a longer distance and still require a river crossing, therefore both of these options have been discounted.
The western access route we are proposing represents the most suitable, efficient route for construction and permanent access to the converter station.
We adjusted the design of this access following engagement with the Environment Agency and other stakeholders. You can view the latest design from November 2024 here.
Proposed working hours will be included within the environmental impact assessment.
In our targeted consultation, we proposed changes to the working hours to accommodate contractor requirements and to give us the flexibility to deliver the construction programme on time. Therefore, we included 7am to 5pm on Sundays and bank holidays within the core working hours.
Whilst this change would give us flexibility to carry out works when and where needed, we do not expect construction activity to take place on every Sunday or bank holiday. There will also be restrictions on the type of activity that can occur on these days.
We don’t anticipate closing any public footpaths permanently, but we will need to redirect public rights of way during the construction phase and possibly permanently. Our traffic management plan will set full details of where and when these will be implemented. We will keep the community informed at all times and provide as much notice as possible.
There is no such thing as a fully offshore grid. Power will always need to come ashore by cable to reach homes and businesses on land.
Underground and offshore high voltage direct current cables which can carry more power than 2 GW do not yet exist. If they did, it would mean more, not less, onshore infrastructure as more converter stations would be needed to cope with these cables. This is evidenced in the ‘offshore’ solutions being progressed in other countries.
In Belgium, the 3.5 GW from the proposed Princess Elisabeth Island will be connected to the onshore network by up to 10 cables coming ashore. To carry this energy to homes and businesses, over 100 km of new overhead lines and approximately 20 km of new underground cables also need to be built.
The German and Dutch transmission network operator TenneT is building at least 13 individual 2 GW connections from offshore wind farms directly to land. Each connection will use three cables, instead of the two used by Sea Link, and will have a converter station the same size as Sea Link. This approach does not mean that less infrastructure is required.
The evidence shows the offshore grid approach does not mean that less onshore infrastructure is required. An ‘offshore solution’ would not be faster or cheaper. It would involve a significant redesign of our project, delay the delivery of Sea Link and prevent new renewable energy connecting when it is ready. This will be costly to the economy, the environment and electricity bill payers.
Whilst we always look to new technologies and different ways to future-proof the network, it is vital that Sea Link is in place by 2030.
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