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As the UK progresses with the energy transition, domestic success in offshore wind and other low-carbon energy sources continues to gain attention. With such fundamental changes in the energy system, the way in which we transport our electricity from point of generation to point of use is evolving rapidly too.
The UK is highly successful in offshore wind, with more than 16GW of offshore operational capacity, according to RenewableUK. This figure is ever-growing; earlier this year, Neart na Gaoithe became the latest UK offshore wind project to become operational, generating up to 450MW of electricity.
There are numerous other projects in the pipeline too, including ‘Salamander’, which gained consent from the Scottish government in July 2025. Salamander is a joint venture partnership between Simply Blue Group and Subsea7, and will use cutting-edge floating offshore wind technology.
Considering Scotland specifically, ‘ScotWind’ (Crown Estate Scotland’s first leasing round for offshore wind) continues to progress at pace. Alongside 25GW of potential generation, this round includes specific provisions for floating offshore wind.
In Wales, the Celtic Sea region is an area of huge forecast floating growth too; most recently, Equinor and Gwynt Glas were announced as preferred bidders in the Celtic seabed leasing for 3GW of floating wind.
At a strategic level, the Clean Power 2030 Action Plan has been brought forward by the Department for Energy Security and Net Zero. Supported by the UK’s leading public finance institutions, investment bodies and industry, the plan cites the particularly important role of offshore wind as “the backbone of the clean power system”.
The UK’s transmission system is ageing, and the electricity grid was originally built to connect electricity generated from generally large and centralised power stations, run on fossil fuels, such as coal from the North and Midlands of England and South Wales.
Electricity generated through renewable and low-carbon technology is growing rapidly and this presents challenges. For instance, renewable and low-carbon energy – such as offshore wind – is more dispersed around the UK, and usually distant from the main sources of demand.
The overhaul of the UK transmission system will require a combination of upgrades and new infrastructure onshore and subsea. SSEN Transmission is the owner and operator of the high voltage (HV) electricity transmission system for the North and islands of Scotland, while Scottish Power Transmission is responsible for the transmission of electricity in central and southern Scotland.
National Grid Electricity Transmission (NGET) owns and maintains the HV electricity transmission network in England and Wales. These organisations are called ‘transmission owners’, or TOs.
The three TOs have each published business plans for the ‘RIIO-T3’ (a price control period from 2026-2031) and they all feature subsea upgrades.
When ISEP last covered the topic of subsea transmission (Transform, Dec/Jan 2022/23), two new subsea links between Scotland and England were highlighted – Eastern Green Link 1 and Eastern Green Link 2. At that time, energy market regulator Ofgem had approved the need for both projects, but they were still progressing through the consenting process and installation had not yet begun.
Since that point, all primary onshore and marine consents have been awarded and construction onshore is underway. Offshore, Eastern Green Link 1 and Eastern Green Link 2 are in the process of completing various final surveys to help support precise planning for how cables will be installed on the seabed, and to segue into installation.
Beyond these two projects, there are further plans for subsea transmission upgrades; of the 17 projects in NGET’s ‘Great Grid Upgrade’ (which it says is “the largest overhaul of the electricity grid in generations”), six feature significant subsea infrastructure. This includes Eastern Green Link 3 and Eastern Green Link 4, two new (and separate) primarily offshore HV links between Scotland and England. Alongside the subsea link, they will each feature onshore infrastructure, including onshore cables and converter stations at both ends used to turn HV direct current (typically used for long-distance transmission) into alternating current (to feed into the national grid).
Projects of this nature, scale and complexity involve a range of people in numerous disciplines, including environment and sustainability professionals. This involvement can vary hugely, based on project geography and approach, as the examples below show.
At this stage, a fundamental driver for a project may exist, but there may be limited definition on how to deliver it. This is an excellent opportunity for early influence into the development of the project, to ensure environmental and sustainability topics are considered. For example, a proponent of a subsea transmission upgrade may have found two broad regions that they want to link, but may not have identified specific landfalls where cables will come to shore. Environmental professionals can help inform this analysis and decision-making process, to ensure the selection of the best options on balance. Evaluation of important environmental factors is also crucial to the routeing process.
Time and energy invested at this stage can often result in improvements in environmental performance and a reduction in consenting risk.
At this early stage, surveys may also be planned and carried out to inform onward development. Environmental input into survey design, permitting and analysis of results is also vital. Environmental input into procurement is increasingly common, which means that environmental performance can be embedded into contractual requirements.
Subsea transmission links typically require a marine licence for some or all of their delivery. Marine licence applications are dealt with by the Marine Directorate Licensing Operations Team (in Scotland), the Marine Management Organisation (England) and Natural Resources Wales (Wales). Through the preparation of good-quality environmental assessments and supporting consent documentation, the regulators and interested stakeholders can accurately understand potential environmental impacts.
Inevitably, the consenting process will give rise to queries and areas of discussion – the involvement of environmental professionals is key to navigating this process promptly, to help secure consent in a timely manner.
It is a common misconception that environmental involvement concludes once consent is awarded. Ironically, it is often the case that new and greater challenges emerge during the complex and pressurised construction phase. It often takes many years between conceptualisation and installation, with various project personnel changes. Equally, incoming contractors may only have limited detailed knowledge of a project or specific geographies from tender. Being able to consolidate, record and then hand over comprehensive environmental information is therefore really important – the devil is in the detail.
Most marine licences will have a range of complex post-consent requirements to complete before, during and after installation of a subsea cable. They can vary dramatically, but could include the provision of in-depth design information or a marine construction environmental management plan before works start or provision of as-built/as-laid data once works have concluded (and anything and everything in between). More widely, there are a plethora of roles involved in ensuring compliance during the installation process.
Completing the upgrades required to the electricity transmission system is a huge undertaking, and many subsea cables are being delivered now or in the pipeline. Identifying landfalls and subsea cable routes is becoming more challenging because of busy UK waters and competition with other sectors, such as offshore wind and associated cables. A thorough appreciation of environmental, technical and commercial factors at this early stage can help project proponents manage the risk.
The UK’s marine regulators are busy and under constant pressure to do more with less, so it is particularly important to work proactively and in collaboration with them, to help them fulfil their regulatory responsibilities, while respecting their own space for decision-making.
In the pressure of the construction and installation process, promoting environmental performance, ensuring compliance and keeping to programme can be tough, particularly with multi-billion project costs. Staying focused, pausing the process if necessary and having the confidence to say ‘no’ is critical – the ISEP competency framework and Fellows Network have been key tools to help me with this in recent years.
The challenges can be hard to overcome, but it does mean there is never a dull moment. Actively contributing to an urgently needed component of our UK journey to net zero is also a good motivator for those particularly challenging days.
Ed Walker MEI FISEP CEnv is an environmental specialist working on a range of marine-power projects for global energy consultancy Xodus.
