THE local tourist board calls it Big Tree Country.

But take a leisurely cycle around the hills and glens of Perthshire and you might be tempted to rename it Big Pylon Country. Work on the Beauly-Denny power line is well under way and the countryside is being invaded by giant metal skeletons. In the past few months their steady march has taken them up the Sma' Glen, around Crieff and on to the villages of Muthill and Braco. Soon they will be strung together with cables and later this year they'll start delivering power generated by wind farms in the north of Scotland to the Central Belt's centres of population.

The 400,000 volt line, strung between 600 towering pylons along a 137-mile route, is the most visible sign of the Scottish Government's dash for renewable energy. That policy finds itself at the centre of the referendum debate this week, with energy reports from the Scottish and UK Governments and a speech by First Minister Alex Salmond on how an independent Scotland could become the "intellectual powerhouse" of renewables. Unusually, the two sides in the debate agree on something: in this case that a UK-wide energy market makes sense. There, though, views diverge. The Scottish Government's study, published yesterday, argues that UK Government policy has created uncertainty for investors, hindered the growth of renewables in Scotland and focused too heavily on expensive new nuclear powers stations down south.

As a result, ministers say, the UK is facing its greatest risk of blackouts for a generation as potential demand nudges perilously close to generating capacity. Green power produced in Scotland could help keep the lights on and bills down across Britain. But an independent Scottish Government would require "a far greater degree of oversight" of a UK energy market that is failing badly at present. The analysis of those in the pro-UK camp is very different. They say talk of blackouts is irresponsible, a view shared by Scottish generator SSE, whose director of policy Keith MacLean told an industry conference last week such warnings were "scaremongering" and "misleading".

Moreover, they say Scottish renewable energy would not solve capacity problems in the south, as shortages are more likely to occur when the wind is not blowing and the considerable array of offshore turbines around the English and Welsh coasts grinds to a halt. On a dead calm day in the depths of winter, the UK would have to look across the Channel to French-generated nuclear power, much as it does at present.

The real danger, argues the pro-UK side, is that an independent, wind-dependent Scotland would end up purchasing English nuclear and gas-generated power at premium prices. As for UK taxpayers continuing to subsidise an independent Scotland's green power revolution (such as the £600 million Beauly Denny line), well, forget it.

Tomorrow the UK Government's energy report, prepared by the Department of Energy and Climate Change, is likely to put a frighteningly large number on what that would mean for average household bills in Scotland. Whether that puts the wind up voters remains to be seen.