Down to the electric wire

2nd April 2024


Tom Harris examines the supply chain constraints facing the growing number of interconnector projects

As 2024 began, Britain’s latest high-voltage direct current (HVDC) interconnector was switched on by National Grid. A record-breaking 760km long, Viking Link connects the Bicker Fen substation in Lincolnshire with the Revsing substation in Southern Jutland, Denmark. The project is the sixth of its type for National Grid, raising its operational portfolio to 7.8GW (gigawatts) of the UK’s now 9.8GW of interconnector capacity.

While Viking Link broke records with the length of its onshore and subsea transmission span, it is only the first of a further 16GW of interconnector connection capacity in the pipeline for completion by 2035. Since Britain became a net exporter of electricity for the first time in 44 years in 2022, National Grid has projected net power exports to increase to 64TWh (terawatt-hours) in 2030, and up to 104TWh by 2050.

Watts the demand?

Interconnectors are high-voltage cables linking the grids of countries, regions and/or offshore assets, enabling electricity to be transmitted between them. They use HVDC technology rather than the more commonly used high-voltage alternating current (HVAC), which is used across Britain’s overhead line pylon network. Although its components are more expensive, HVDC is highly efficient for conducting electricity over long distances, particularly underground or underwater. Electrical losses from DC transmission range between 2 and 3% in comparison with 5-10% by AC. Break-even distances to financially justify HVDC installation in terms of the cost benefit from reduced energy loss compared with an HVAC alternative are 50-95km for underground cables, and 24-50km for submarine cables, far smaller than the 600-800km required to break even when constructing HVDC overhead lines. However, HVDC transmission does require expensive converter stations at either end of a transmission span to switch electricity supply back to the conventional AC format.

As more countries seek to decarbonise their energy systems, there is a higher reliance on weather-dependent renewable energy generation to meet supply. Interconnectors allow for the importation of renewable energy from unaffected areas while managing the precise amount of power imported to aid grid stabilisation and management.

A tangled supply chain

Growth in HVDC interconnectors has put significant strain on the supply chains required to construct the cabling and the converter stations needed at each end of a transmission line. The European market for HVDC cabling and converter stations is dominated by a small pool of suppliers, because of the complexity of manufacturing parts and the high barriers to entry. Converter stations are typically provided by Siemens, GE Grid Solutions or ABB, while cabling is contracted to either ABB, Prysmian PowerLink, Nexans or NKT. On top of the backlog of component orders, the availability of specialist subsea cable installation vessels and support ships is also limited. The combination of these capacity constraints risks an increase to cable delivery lead times and programme costs for interconnectors in the pipeline and those requiring maintenance. This is all while the EU has set a minimum interconnection target of 15% by 2030.

National Grid has previously suggested the need to broaden the supply chain beyond traditional European manufacturers – its 720km North Sea Link interconnector was built by Japanese supplier Hitachi Energy. The developer, which is also behind the proposed 3,800km Xlinks interconnector linking Morocco to the UK, aims to construct purpose-built cable factories to meet the volume of cable required.

If the benefits of interconnectors to energy security and decarbonisation through the facilitation of renewable generation are to be realised, the HVDC supply chain must adapt or face ever-increasing costs and delay to programmes.

Tom Harris is a graduate EIA infrastructure consultant at Temple Group

Image credit: Shutterstock

Subscribe

Subscribe to IEMA's newsletters to receive timely articles, expert opinions, event announcements, and much more, directly in your inbox.


Transform articles

Swing voters show strong support for renewables

There is strong support for renewable energy as a source of economic growth among UK voters, particularly among those intending to switch their support for a political party.

16th May 2024

Read more

A project promoter’s perspective on the environmental challenges facing new subsea power cables

3rd April 2024

Read more

The UK’s major cities lag well behind their European counterparts in terms of public transport use. Linking development to transport routes might be the answer, argues Huw Morris

3rd April 2024

Read more

The UK government’s carbon capture, usage and storage (CCUS) strategy is based on optimistic techno-economic assumptions that are now outdated, Carbon Tracker has warned.

13th March 2024

Read more

The UK government’s latest Public Attitudes Tracker has found broad support for efforts to tackle climate change, although there are significant concerns that bills will rise.

13th March 2024

Read more

A consortium including IEMA and the Good Homes Alliance have drafted a letter to UK government ministers expressing disappointment with the proposed Future Homes Standard.

26th February 2024

Read more

Global corporations such as Amazon and Google purchased a record 46 gigawatts (GW) of solar and wind energy last year, according to BloombergNEF (BNEF).

13th February 2024

Read more

Three-quarters of UK adults are concerned about the impact that climate change will have on their bills, according to polling commissioned by Positive Money.

13th February 2024

Read more

Media enquires

Looking for an expert to speak at an event or comment on an item in the news?

Find an expert

IEMA Cookie Notice

Clicking the ‘Accept all’ button means you are accepting analytics and third-party cookies. Our website uses necessary cookies which are required in order to make our website work. In addition to these, we use analytics and third-party cookies to optimise site functionality and give you the best possible experience. To control which cookies are set, click ‘Settings’. To learn more about cookies, how we use them on our website and how to change your cookie settings please view our cookie policy.

Manage cookie settings

Our use of cookies

You can learn more detailed information in our cookie policy.

Some cookies are essential, but non-essential cookies help us to improve the experience on our site by providing insights into how the site is being used. To maintain privacy management, this relies on cookie identifiers. Resetting or deleting your browser cookies will reset these preferences.

Essential cookies

These are cookies that are required for the operation of our website. They include, for example, cookies that enable you to log into secure areas of our website.

Analytics cookies

These cookies allow us to recognise and count the number of visitors to our website and to see how visitors move around our website when they are using it. This helps us to improve the way our website works.

Advertising cookies

These cookies allow us to tailor advertising to you based on your interests. If you do not accept these cookies, you will still see adverts, but these will be more generic.

Save and close