ANDREW Mitchell (letters, May 9) scoffs at the thought of National Grid’s drawbridge being raised at the rUK border in the event of an independent Scotland. Not so unthinkable really, only he has it the wrong way round. It would be south of the Border that would need to build an “electronic wall” to keep our excessive and unwanted volatile wind energy from blowing their transmission network. Much like Poland and the Czech Republic are having to do to protect themselves from Germany dumping its unwanted wind-generated electricity on to their grids.

The reckless deployment of too much onshore wind is encouraging abuse of the system at the expense of the consumer.

In times of low demand wind generators are paid to switch off by around 30 per cent more than if they were generating. As of April 19, 2017 £300 million had been paid out in constraints to UK wind farms; £260m of that was to Scottish developments.

Not all details of constraints are available to us. “Confidential bilateral trades” are not in the public domain.

In 2011, soon after wind constraints started to be paid and following a Parliamentary Question, it was revealed these “secret constraints” were running at 12.7m. The additional publicly-revealed figure was £12.8m. If today the public and “secret” costs are similar then there is another £300m sloshing around on our energy bills.

This is all paid by the UK consumer. In an independent Scotland it has been made clear all costs relating to Scottish turbines will be borne by us, eight per cent of the UK’s total consumers. In addition to constraints the consumer also pays the subsidy. Cautious estimates indicate this could be £600m a year for Scotland’s energy bill payers. That includes industry, which will pass those costs straight on to us through the goods and services we buy.

The question that needs answering is: why is the SNP still recklessly approving wind factories when newly connected ones swiftly rake in lucrative constraints to switch off? With SSE and ScottishPower pulling back on grid upgrades but apparently not wind deployment, people are asking if juicy constraints to shut down are being used to replace the now-closed onshore subsidies. If they are, Westminster needs to plug this loophole very fast indeed before something collapses – the grid or the ability to pay our energy bills.

Lyndsay Ward,

Darach Brae, Beauly, Inverness-shire.