Energy firms reveal underground cable routes

Reepham and surrounding villages will be significantly affected by cable-laying work if planned green energy projects go ahead, residents learned recently at two public meetings in the Town Hall.

Map showing the proposed routes of the two cables. The corridors are 200 metres wide; actual construction zone will be 50 metres or less. Map data: OpenStreetMap. Reepham Life has taken great care in preparing this map, but it is not a definitive document

Heavy traffic, road closures and disruption to farming are all likely during short periods from 2019 onwards as energy companies install underground cables to carry power from wind farms far out in the North Sea.
On 2 March, Dong Energy held a meeting to explain its Hornsea Project Three scheme, which has a planned capacity of 2.4 GW. The export cable for this project will make landfall near Weybourne and travel underground to an existing substation south of Norwich. Along the way it will skirt a mile to the east of Reepham town centre, passing close to Heydon, Salle Park, Moor Farm and Booton Hall (see map above).
Then on 30 March, Vattenfall showed off plans for its Norfolk Vanguard and Norfolk Boreas projects, each 1.8 GW in size. The cables for these projects will come onshore near Bacton or Happisburgh, from where they will take a common route to a substation at Necton, between Swaffham and Dereham. The cable corridor passes to the north of Cawston and Reepham before turning south to cross the A1067.
If all projects are approved, the underground cable routes are expected to cross in an arable field owned by Salle Estate to the north of Reepham, adjacent to the B1145, near the junction with the road to Salle. It is understood the two wind farm companies had a meeting in March to discuss how they could co-ordinate their respective cable-laying work. Construction could begin as early as 2019/2020.
Together, the three projects would generate more than 2 GW on average – nearly 6% of the UK’s power demand.
The meeting at Reepham had shown an “encouraging” level of local support for Norfolk Vanguard, said project manager Ruari Lean. “Participants highlighted the Reepham-Cawston Road as a major traffic route through Reepham and urged us to reinstate any affected roads and lanes promptly, once cable laying is completed,” he said.
Vattenfall said 830 people had come to the nine drop-in exhibitions it has held recently. The previous series of seven meetings in October last year attracted 780 people. Two-thirds of those attendees said they were “very concerned” about climate change, and there was a good level of support for renewable energy in the southern North Sea as a source of economic benefits.
The currently proposed cable corridors are around 200 metres wide. This will allow flexibility in avoiding archaeological sites or other sensitive areas, the two companies say. Depending on the electrical technology chosen, the actual working width could be up to 50 metres while each set of cables is being buried. Once the installation is complete, crops and hedges would be re-planted along the routes.
“Discussions with landowners are in full swing,” Mr Lean said. Although both Vattenfall and Dong say they will work hard to come to agreements with farmers, the wind farms’ status as Nationally Significant Infrastructure Projects gives the developers considerable powers to force their way if necessary.
Reepham’s location near the halfway point of each of the two cable corridors means it is likely that “booster stations” would need to be built not far from the town, if the cables are of the conventional high-voltage alternating current (HVAC) type.
As an alternative, both Dong and Vattenfall say they are considering high-voltage direct current (HVDC) technology, which would not need booster stations. However, HVDC is a relatively new technology that is more expensive than HVAC.
Both HVDC and HVAC would need onshore stations close to the landfall points of the various cables.
Charles Butcher
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