National Grid expects a de-rated electricity generation margin of 3.7GW to 4.9GW in winter 2017-18, equating to 7.2% to 9.9%.
The margin is the sum of de-rated supply during the time of peak demand minus expected demand.
On an underlying demand basis, the margin equates to a range of 6.2% to 8.2%, the UK TSO said in its Winter Review.
Winter 2017-18 is the first delivery year of the capacity market.
National Grid said transmission system demand was 50.9GW in winter 2016-17, 1.1GW lower at peak than forecast in last year’s Winter Outlook.
Over the winter, there was a higher output from wind generation than forecast during peak hours.
Across the winter as a whole, wind provided 10% of the UK’s total energy generation, similar to winter 2015-16.
Energy and Climate Intelligence Unit energy analyst Jonathan Marshall said: “This is the second successive annual increase in the grid’s capacity margin and with upper estimations of excess capacity nudging 10%, the security of supply debate is largely settled in the medium term.”
Image: T-pylon (National Grid)
