The transmission system operator said it has taken the “sensible precaution” to increase margins to just over 6 per cent through extra measures to keep power plants in reserve and reduce demand over peak hours by 319MW.
National Grid has contracted three older thermal plants totaling 940MW of de-rated capacity to remain on standby in case they are needed to ramp up generation to prevent a shortfall; including RWE’s 1.25GW oil- and coal-fired Littlebrook plant, SSE’s 1.1GW Peterhead and Scottish Power’s 715MW Rye House gas-fired power plants.
By de-rating the total amount of reserve available National Grid is able to take into account breakdowns and shortfalls which typically impact generation output.
In addition, National Grid has secured 319MW of demand side reduction contracts, de-rated to 160MW, which were offered to large energy users to cut their dependence on the grid during peak demand hours.
The UK’s security of supply has come under increased scrutiny in recent months following a string of unplanned outages, including two recent fires, which cut winter supply margins from 5-10 per cent estimated by Ofgem in June, to just over 4 per cent based on National Grid’s latest projections.
With National Grid’s steps in place the UK’s de-rated capacity margin is expected to increase from 4.1 per cent to 6.1 per cent, the operator said in its winter outlook report.
“The electricity margin has decreased compared to recent years, but the outlook remains manageable and well within the reliability standard set by Government,” said National Grid’s director of market operation Cordi O’Hara.
“As system operator, we have taken the sensible precaution to secure additional tools to bolster our response to tighter margins,” she added.
Concern over blackouts mounted in recent weeks as doubt hung over the availability of 3GW of generation capacity including the fire-damaged Ferrybridge coal-fired power plant and four of EDF Energy’s nuclear reactors which were taken offline due to safety concerns.
Following this, a major fire at RWE’s 1.3GW Didcot gas-fired power plant less than a fortnight ago cut over half its generation capacity, raising blackout concerns further.
Since then, SSE has confirmed the return of one of the two Ferrybridge units to service by the November and EDF have confirmed that one unit at Heysham and one unit at Hartlepool will also return at the beginning of next month, with Hartlepool 1 returning at the end of November.
The remaining Heysham unit will return at the end of the year, but all will return at approximately 20% reduction in capacity, National Grid confirmed.
“We will continue to keep a close watching brief across both electricity and gas throughout the winter so that we’re strongly placed to respond to any unanticipated events,” O’Hara said.