Ironbridge Power Station will still close by end of the year, depite energy squeeze

It comes after the closure of three power stations was today said to have increased the risk of blackouts, according to new analysis by National Grid, forcing the country to rely on emergency measures to ensure the lights stay on.

Owners E.on announced earlier this year that the Ironbridge landmark would generate its last power at the end of 2015.

But it would also end its life if it passes the milestone of generating power for a total of 20,000 hours since January 1, 2008.

Figures from National Grid revealed that the "safety buffer" margin between peak winter electricity demand in and the output from Britain's ageing power stations is likely to fall to just 1.2 per cent – down from 4.1 per cent last year.

But an emergency system of backup power plants, first introduced last winter, will be in place again this year to help prevent blackouts, the company said.

Even with the back-up plants in place, the effective spare margin last winter was six per cent and this year will fall to 5.1 per cent – the lowest since 2007-08, Grid data shows.

The back-up power plant operators will be paid £37 million to guarantee they can fire up if needed in an emergency, and more if they are actually called upon.

The Ironbridge Power Station operates at a higher capacity if demand for electricity from the National Grid goes up.

Because of that, its closure could come sooner if demand rises for either air conditioning or heating.

E.on has placed a cloak of secrecy over the closure because it says it is commercially sensitive.

Closure of the power station is required by the EU's Large Combustion Plant Directive.

Cordi O'Hara, National Grid's director of market operation, said: "It's clear that electricity margins for that coldest, darkest half hour of winter are currently tighter than they have been, due to power stations closures.

"As system operator, we feel we've taken a sensible precaution again this winter to buy some extra services."

The back-up measures were not needed last winter because the weather was particularly mild, National Grid said.