National Grid warns of lower winter power capacity
And this handy infographic:National Grid has warned that its capacity to supply electricity this winter will be at a seven-year low due to generator closures and breakdowns.
Spare electricity capacity, which ran at about 5% over the winter months last year, would be nearer 4% this year, National Grid said.
Three years ago the margin was 17%.
But National Grid said it has contingency plans in place to manage supply, including paying big firms to switch off on cold winter evenings.
In basic terms, the National Grid needs to have some spare electrical generation capacity above and beyond the predicted peak demand. This allows them to better manage the system, makes power available for unexpected events (like another bitterly-cold winter), and means that failure of one or two power stations (eg. the recent Didcot fire) won't result in the whole house of cards tumbling down.
It seems like this winter's spare capacity will be around 4% of forecast demand, the lowest since 2006-7 (but still far above 2005-6 when there was barely 1% of spare capacity). This in turn means there's a greater risk of brownouts or blackouts - although the National Grid spokesman confidently claims that they would selectively cut-off major industrial users rather than letting John and Jane Smith shiver.
The lesson for us seems to be to make sure our preps are in order!