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A new line of undergrounded power cables is planned for the Glaslyn estuary in Gwynedd . The proposed work near Porthmadog is part of the National Grid’s biggest upgrade since the 1960s. Trenches will need to be dug under three railway lines through an area that regularly floods. Efforts to hide the cables, and so avoid unsightly pylons, has echoes of earlier battles to prevent ugly “wirescapes" destroying the area’s spectacular landscapes. The National Grid is upgrading the high-voltage power network in northwest Wales to cope with the ongoing switch to renewables. The need to heat homes, drive electric vehicles and power factories with clean energy is predicted to double the demand for electricity by 2050. This requires the existing electricity network between Pentir and Trawsfynydd to be “reinforced”. Some elements are underway already, the largest being a new 3.3km tunnel beneath the Dwyryd estuary . This is adjacent to the Glaslyn, where cables were undergounded 3.6 miles in the 1970s. The decision to bury the 400kV cables followed a 1960s campaign led environmentalist Cecily Williams-Ellis, sister-in-law of Portmeirion founder Clough Williams-Ellis. Agreed after a public inquiry, it was a costly outcome for the state-owned Central Electricity Generating Board (CEGB), which was in the throes of building a 1,150-mile “supergrid” across Britain to replace ageing infrastructure. Join the North Wales Live Whatsapp community now To preserve views of Yr Wyddfa (Snowdon) from the estuary, the CEGB agreed to allocate an extra £2.5m (£45m at today’s prices). When Minister of Power Frederick Lee demanded more undergrounding, the final bill was pushed up to £4m, equivalent to £75m today. However these figures pale in comparison with the current upgrades: the Dwyryd estuary tunnel will alone cost £207m. This will replace 10 pylons marching across the landscape that 1960s campaigned failed to prevent. The buried cable route ran from Wern to Y Garth between Tremadog and Minffordd. As with the existing connection, the new cables will need to run beneath the Traeth Glaslyn Nature Reserve. However a slightly different route is needed as the existing cables will need to stay connected while the new ones are installed. These will cross a field west of the A487 roundabout joining Porthmadog High Street, then along the top of Ysgol Eifionydd’s playing field. It involves navigating under Porthmadog’s two heritage railway lines, as well as the main Cambrian line. National Grid said: “We know this is a challenging and environmentally sensitive area that floods regularly, and we are accommodating these sensitivities in our project designs. “We have already been discussing these technically complex proposals with the relevant organisations, so we can carry out the work safely and sensitively. We will also work closely with local communities and businesses to minimise any disruption.” Trickier obstructions will see the use of Horizontal Directional Drilling. This involves drilling a bore hole under an obstacle, installing a duct and pulling the new cable through. Following a recent pre-application consultation, which ended last week, National Grid intends to seek formal planning consent from Cyngor Gwynedd and Eryri National Park Authority in the coming weeks. Consent will also be needed from the Department for Energy Security and Net Zero (DESNZ). It will be one of four applications submitted. The other three are: The aim is to begin construction next spring or summer - and to complete the upgrades by 2030 to meet the Welsh Government’s 70% renewables deadline. Ahead of the work, the National Grid has been doing its homework. The company said: “We have carried out extensive ground investigations and surveys, including working with environmental experts to ensure that we understand the project area and its characteristics. “We are working with farmers, landowners and other organisations whose land we need to cross, acquire or access to explain our project and confirm the areas where we think we will need to work." Get all the latest Gwynedd news by signing up to our newsletter - sent every Tuesday Find out what's happening near you
