Pylons transfer power from wind farms to the National Grid
Snowdonia and Anglesey could be among five UK beauty spots spoilt if plans to build pylons over 170 miles of the countryside go ahead, say campaigners.
An alliance of countryside campaign groups want the UK Government to invest in smart electricity networks instead.
They are concerned about what the 50m (164ft) high pylons will look like and their environmental impact.
The Department for Energy said any development of the grid would take countryside protection into account.
There are currently around 22,000 high voltage pylons carrying 4,375 miles of overhead lines in England and Wales.
A recent report for the government said £4.7bn should be spent on the National Grid in order to transport the green energy needed to help meet the UK's target to produce 15% of the UK's energy from renewables by 2020.
However the campaign groups say this will mean transmitting energy through some of the country's most protected landscapes, as much of the wind energy will be generated in remote areas of Scotland or off the coast of Wales.
As well as Snowdonia, four designated areas of outstanding natural beauty, in Anglesey, Kent, Lincolnshire and Somerset would be affected by the new lines.
The existing traditional network will also need to be upgraded to accommodate electricity from new power stations, including nuclear, the report by the Electricity Networks Strategy Group for the government said.
The Campaign for the Protection of Rural Wales (CPRW) is among an alliance of groups aiming to influence a government's plan for a 'smart grid' and a new national planning policy on the future of the nation's electricity transmission network.
The smart grid would have less impact on the countryside, said the groups.
Peter Ogden director of CPRW said smart grids would see localised electricity produced and distributed at a more local level.
"It has been piloted in a number of countries both in Italy and even President Obama is looking at this approach in America," he said.
The alliance's manifesto calls for measures to reduce demand on the main electricity transmission grid, including smart meters, encouragement for community and small-scale local energy generation, and further research on methods of storage of electricity.
It also wants any new high voltage transmission lines to avoid areas of outstanding natural beauty, national parks, world heritage sites and green belt land.
In addition, it is calling for new offshore wind farms to be connected to the National Grid using underground cables to existing substations.
Mr Ogden said: "Nothing scars our landscapes more than huge electricity transmission lines marching across them.
"Developing the smart grid approach offers the long overdue opportunity to link modern methods of energy creation and transmission, with avoiding damage to distinctive upland panoramas and open spaces."
A spokesman for the Department for Energy and Climate Change said the new grid lines would be necessary to get new green energy to homes and businesses.
"However, it's far too early to say precisely which routes may be proposed for the development of new grid lines," he said.
"National Grid will bring forward detailed proposals in due course that will be subject to careful consideration by the relevant consenting authority, which would include considering all environmental aspects of a project.
"As part of this process individuals and local communities will have the opportunity to express their views on developments in their area."