The review, which was published today (15 July), said that only 1.2% of spare capacity will remain on the system, down from 4.2% in 2014/15, due to the closure of a number of power stations, including Barking Power Station, Ferrybridge and Littlebrook.
The last time spare capacity was this low was in 2005/06, when the excess supply or ‘capacity margin’ was 0.9%.
However, National Grid said measures have been taken to ensure that electricity supply meets demand and avoid blackouts.
It has paid £36m to have several plants on standby to secure extra supplies.
It will also pay some large energy users with a National Grid contract to shift their energy demand to a less busy time of the day to help free up capacity during times of peak demand.
A total of 2.56GW of power has been secured by National Grid, which it said would increase spare capacity to 5.1%.
National Grid said it will now launch a consultation to consider whether it will need to secure more capacity for the future, beyond the 2015/16 winter.
National Grid director of market operation Cordi O’Hara 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. Together with the tools we already use to balance the network these additional services will significantly increase the energy reserve available this winter.
“The review of last year highlights that the winter was milder than average, and demand forecasts for gas and electricity were close to National Grid’s scenario planning. Gas came from a variety of sources, with a particular increase in liquefied natural gas (LNG).
“In electricity, the margin of generation above demand last winter was adequate, with peak demand hitting 53.2GW. There were high imports of electricity from mainland Europe at peak times, and wind generation delivered well at 44% of its capacity.”
Energy minister Andrea Leadsom said blackouts will not happen. She said: “Our priority is to ensure that British families and business have access to secure affordable energy supplies that they can rely on.
“Our plan to power the economy is working – and it means that the lights will stay on this winter as well as making sure our homes and businesses have the gas and electricity they need in the future.”
National Grid has also today published its Future Energy Scenarios (FES) report, which details what the energy landscape will look like over the next 35 years. The report is used as the basis for National Grid’s network and investment decisions.
