The National Grid is working on a new formula which could cut by 50% the huge transmission charges facing developers of wind farms in Scotland, particularly in the Highlands and Islands.

The prospect of the massive boost is precisely because of one of wind power’s perceived weaknesses: the wind doesn’t blow all the time. It would represent a significant breach in the power industry’s locational pricing regime which First Minister Alex Salmond has denounced as a tax on geography.

It has long been an issue of bitter dispute between Holyrood and Whitehall that the areas which produce most renewable energy from wind, wave and tide are charged most to transmit the power.

A wind farm in the north of Scotland can pay charges of £22/kW while one in the south of England receives a subsidy of £8/kW, often multiplied by 50,000 or more.

This locational pricing regime is seen as holding back renewable energy development in Scotland, and undermining its drive to become the mainstay of European green generation.

Only five of the 27 EU member states apply network charges on such a locational basis and, of these, Britain has the widest intra-country range of charges and highest locational charge.

Meanwhile, the 11 member states that require generators have to pay a share of Transmission Network Use of System charges, the extent to which the wires themselves are used. Romania levels the highest charge (49.8%) with Britain next (27%), Denmark (2-5%) France (2%) and Poland (0.6%).

SNP MEP Alyn Smith is convinced this constitutes discrimination against Scottish renewable energy development and invited the ­European Commission to prosecute the UK Government.

Mr Smith, shortlisted in the Politician of the Year category at the Green Energy Awards in Edinburgh tonight, organised a hearing at the Brussels Parliament, gathering stakeholders from all sides of the energy compass to discuss the ongoing EC investigation into the UK’s charging.

After the meeting, Mr Smith said: “I was particularly pleased to hear the National Grid representatives mention that they are working on a new interpretation of the regime which would see costs for wind and, I take it, other renewable generators, halved, given that the renewables sector operates to a different and differing load factor.

“I have written to the National Grid for more details and when we might see it rolled out as this is a major step forward and indicates just how fast I suspect this agenda is going to move, when movement comes.”

However, it appears that wave and tidal power projects may still have to face the full charges.

A spokesman for the National Grid said wind­power isn’t a constant source of power. He said: “We recently ran a consultation on transmission charges. The outcome was that we agreed changes should be made to the existing methodology in some areas, specifically to take account of the lower investment required to connect up wind generation compared to other types of generation.

“By its nature, wind generation is variable so you don’t need the same level of infrastructure for connection. We are discussing with the industry how to take this forward. It is still very early days for this work, but the reduction in charges for wind generation could be indeed be substantial, perhaps up to half for some projects.”