The electricity grid operator reportedly stated that the blackouts were caused by an unexpected loss of frequency caused by the concurrent failure of British Energy’s Sizewell-B nuclear power station and Scottish Power’s Longannet-1 coal-fired power station.
The Sizewell-B and the Longannet-1 facilities account for 1,200MW and 2,600MW of electricity capacity, respectively. National Grid pointed out to the sudden outage at these major generating facilities as the reason for the blackouts. The grid operator claims to have restored power within 40 minutes.
Industry sources claim that Longannet’s four turbines were offline at the time of the blackouts. Scottish Power has stated that one turbine was functional, producing around 350MW of power, before it reportedly tripped due to a minor technical fault. British Energy has blamed the outage at Sizewell-B on faulty instrument reading. The shutdowns forced National Grid to suspend power deliveries to distributors.
Industry sources have also pointed out to insufficient contingency margins as the reason for the blackouts. National Grid is expected to maintain a 20% margin to cover for unexpected outages, but did not issue any notice of insufficient backup. Independent energy consultant McKinnon and Clarke has blamed the outages on crumbling infrastructure, while National Grid denies such systematic failure, according to The Times.
