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Grid connection conundrum

Rufus Howard

As the UK's Round 3 projects gain momentum and move wind turbines further offshore, developers need to improve how they will connect their wind farms to the grid. So where will all the cable come from?

A recent report by the UK's Crown Estate estimated that the total cost for connecting the UK's Round 3 wind farm projects will be over £10 million.

There are countless issues which make grid connection a complicated and painstaking process to get right, and the industry is still learning lessons. Successfully engaging with the public and selecting the most appropriate technologies will become even more crucial when achieving consent for new developments.

From cabling to grave

From the work that Royal Haskoning has already been involved with on Round 1 sites in the UK, it has become apparent that cabling routes are getting longer, and are having to be laid further from the shore. In addition the huge Round 3 sites will dwarf anything the UK has seen before – so their distance from the shore will bring new issues and complications for developers to tackle.

Background to Round 3

  • Offshore wind in the UK is developed in a series of competitive leasing rounds. Two rounds have been completed and these projects are now being developed;
  • The Round 3 offshore wind energy programme was launched by The Crown Estate in 2008;
  • Round 3 was structured differently from two previous leasing rounds (Rounds 1 and 2), as tenders were put forward for 9 zones of development – each potentially containing multiple projects. The scale of some of these zones is much larger than anything seen before, with some zones potentially yielding 10 GW of projects. In total the size of Round 3 is anticipated to be at least 25 GW – compared to the combined total of 8 GW from Rounds 1 and 2;
  • Nine development zones have been allocated to companies and consortia – to start the development process. Wind lobbying organisation RenewableUK says that the scale of this project represents a “step change for the global industry”;
  • Another new feature of Round 3 is that within this process the Crown Estate will co-invest with developers, with the aim of “facilitating efficient delivery of the wind farms”.

To put into context the size and scale of Round 3 projects, the longest installed onshore cable – at the Sheringham Shoal development – stands at 22 km. The Dudgeon project, with the longest planned onshore cable route, more than doubles that, at 45 km.

Whilst these two onshore cable routes are substantial in length, both the Sheringham and Dudgeon onshore routes only required a single onshore gird connection. In contrast The Dogger Bank Round 3 site alone will potentially require a number of separate grid connections. This is uncharted territory for the onshore grid.

The picture is gloomier still for onshore developments that fall beneath the threshold for consideration by the Infrastructure Planning Commission. Gaining planning consent for grid cabling associated with offshore and onshore wind farm sites under the Town and County Planning Act is set to get even harder, with the effective removal of the largely pro-renewable regional planning tier, and the introduction of the new Localism Bill.

The difficulty and costs associated with obtaining planning permission is steadily increasing, and this will slow the system down even more, and could even reduce onshore wind's contribution towards binding UK and EU renewable energy targets. If developers don't give these issues sufficient consideration at the outset of a project, the impact on cost, timescales, and the level of public consultation necessary could be substantial.

Focusing on the new Round 3 developments, National Grid has already looked at the additional capacity the UK will require to accommodate offshore wind farms (see the organisation's Offshore Development Information Statement – ODIS). The aim of this statement is to “facilitate the development, in offshore waters, of an efficient, coordinated and economical system of electricity transmission”. With the capacity needs of Round 3 projects in mind, it gives a high-level strategic view of what existing capacity there is, and predicts where and when more capacity will be required.

With the smaller Round 1 and Round 2 projects, it was often possible to connect to existing substations or overhead lines. With Round 3, developers need to realise that they will require much larger onshore substations, or significant upgrades to existing ones. This will have a major impact on the cost of the project – not to mention the additional requirements for public consultation and the length of time this will take.

Beauly-Denny: the delay

In terms of public acceptance and visual impact it is not often viable to take the connection through overhead cables, despite being cheaper to install and maintain.

This has been demonstrated by the Beauly-Denny line in Scotland (600 pylons which will connect renewable energy projects to the grid), which only this year achieved planning permission after five years and a detailed public inquiry.

The wind industry does not have that amount of time to spare for every major offshore wind farm it seeks to build – these projects must progress if renewable energy targets are to be met.

Another hurdle surrounds availability of equipment and materials to physically install new cabling routes. Grid connection routes are getting longer and more complex, but despite this anticipated demand for more cable, manufacturing capacity to reach this level of demand does not currently exist. And the level of demand will be unprecedented. Many believe that even with the current capacity of all DC cable suppliers across the world, there won't be enough cable for the millions of miles that will be required for the Round 3 projects.

The need for significantly more cable, not to mention other materials, is a fantastic opportunity to create thousands of jobs – but it remains to be seen which country will seize this opportunity.

Cabling innovation is key

In order to minimise disruption caused by onshore cabling, Royal Haskoning has taken an innovative approach and proposed the use of ducts to install extra capacity for grid connections at the outset of a project, on the assumption that it will be required in the future.

This eliminates the need for ground disturbance on the second round of cabling, which is cheaper and environmentally desirable. In theory, this should appeal to planning officers, landowners and other interested parties, who will be conscious of the cumulative impact of numerous trenches being dug in the same areas. In reality though, there are many financial and legal obstacles to the installation of additional capacity, particularly in the development and consenting stage of the project cycle.

There is still a long way to go, and if the industry is to succeed in delivering the exciting promise of Round 3 wind farms and developing the UK's portfolio of onshore wind farms, serious thought needs to go into the practicalities of actually linking these projects to the national grid.

And the industry needs to get better at communicating the benefits of wind farm development, both onshore and offshore, to ensure that consenting for new projects is achievable.

Offshore grid will take time

Arguably, it would make sense to have an offshore grid that all wind farms can connect to. This would enable the UK to sell any surplus electricity to the continent and minimise the disruption of installing many individual connections. However, there are huge hurdles to this approach. Wind farms are owned by a number of different developers, unlike the National Grid, and it would require new legislation, and unprecedented levels of cooperation between rival developers, to make this a reality.

There have been positive signs from Europe recently, when Ministers from 10 European countries bordering the North Sea agreed in principle to the construction of a new offshore electricity grid. The grid will link countries across Northern Europe and make it much easier for Member States to trade energy. This also demonstrates the commitment by the European Union to reach emissions targets, and integrate its energy infrastructure.

An MoU was signed by Governments in the UK, Ireland, Belgium, Denmark, France, Germany, Luxembourg, the Netherlands, Norway and Sweden. However, the Crown Estate described the status of an offshore grid as “embryonic”, and until the concept is developed substantially, developers will need to press ahead with developments on a project by project basis.


Rufus Howard is a senior consultant at Royal Haskoning.

Renewable Energy Focus, Volume 12, Issue 1, January-February 2011, Pages 8-9

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