Eight national parks and areas of outstanding natural beauty on shortlist, and £24m set aside for measures in other areas

The “biggest and ugliest” electricity pylons slicing through some of the UK’s most treasured beauty spots are set to be torn down.

National Grid will investigate ways to remove pylons from a shortlist of eight rural areas by putting the high-voltage transmission lines underground.

The firm has 571km (355 miles) of pylon lines running through national parks and areas of outstanding natural beauty (AONB) in England and Wales. The shortlisted areas are in the Snowdonia, Peak District, New Forest and Brecon Beacons national parks, and the Dorset, Tamar Valley, High Weald and North Wessex Downs AONBs, totalling 25km of lines.

“Having decided these are the biggest and ugliest ones, we now have to look at the feasibility,” said Chris Baines, an environmental consultant and chair of National Grid’s stakeholder advisory group. “Undergrounding is best when you can do it, but we also have to make sure the treatment isn’t worse than the disease. It can leave quite a scar that is hard to heal.”

Putting lines underground requires a 50-metre-wide trench to be dug to about two metres deep, to accommodate the six lines carried by pylons. Hard rocks or archaeological sites can also present obstacles. Alternatives include moving the pylons to less obtrusive locations. In the High Weald AONB in south-east England, the 50-metre-tall pylons may be moved down the hill, so they have wooded slopes behind them rather than sky.

The scheme will add £500m to electricity bills over eight years, or about £7m a pylon, which National Grid says is equivalent to 22p a year on an average customer bill.

Feasibility studies will be completed within a year, after which the final list of pylon-removal projects will be ready to go ahead. “There will be three or four of these shortlisted sections that are chosen for the full belt-and-braces disappearing act,” said Baines. Analysis conducted for the stakeholder group deemed 4km of Tamar Valley pylons to have by far the greatest visual impact and that project is being fast-tracked; 12km of pylons along the Woodhead Pass in the Peak District are also a priority.

High-voltage lines cross 30 national parks and AONBs and George Mayhew, director of corporate affairs at National Grid, accepts those not shortlisted are likely to be disappointed: “I suspect all 30 sites would say our infrastructure has an impact.” He said there would be a £24m fund available to pay for other measures in those areas, such as planting woods to obscure the view of pylons or filling in gaps in hedgerows.

The pylons to be removed were all erected in the 1950s and 60s when less consideration was given to their visual impact. The £500m bill for the scheme, approved by the regulator Ofgem, results from the cost of putting the lines underground: £20m-£22m a kilometre, compared with £2m for pylon lines. But Baines said: “These are particularly special places. No one would argue it would not be hugely beneficial to not have these pylons in these places.”

The shortlist was welcomed by Ingrid Samuel, historic environment director at the National Trust: “We know it can be a big challenge for modern infrastructure to work in harmony with the landscape but it can be done when people work together to find the best solution.”

Nick Clack, senior energy campaigner at the Campaign to Protect Rural England, said there had been thorough assessment and consultation: “This announcement is a really positive step. Given these welcome efforts to mitigate the impact of existing lines, National Grid needs to make sure it is doing all it can to mitigate the impact of new ones.”

National Grid plans to spend more than £10bn on new transmission lines by 2021 as windfarms and nuclear plants are built. But Mayhew said the mistakes of the 50s would not be repeated. He said, for example, the major lines needed to connect the planned nuclear power plant at Hinkley Point in Somerset would include 8.5km of underground cables through the Mendip Hills, and that underground cables were under consideration for a large and controversial windfarm in mid-Wales.