OREANDA-NEWS. UK power supply margins are now forecast to remain positive throughout winter 2016-17. Predicted margins were revised sharply higher following UK utility SSE's decision to keep its Fiddlers Ferry coal-fired plant open.

The tightest period of next winter is expected to come in the week beginning 16 January, when the minimum supply margin is forecast at around 180MW. But this is revised up from around minus 775MW last week, while the average minimum supply margin for the whole of winter 2016-17 is now forecast at around 2.8GW, up from just 1GW a week earlier.

And the forecasts do not account for additional capacity and supply provided through the UK's interconnections with the Netherlands and France, nor the capacity held in reserve under transmission system operator National Grid's supplemental balancing scheme.

The minimum supply margin had been forecast at negative values for several weeks of winter 2016-17 because of the planned closure of capacity at five UK coal-fired plants this year. And although Ferrybridge, Eggborough and Longannet exited the wholesale market last month, SSE has delayed plans to close three of the four units at Fiddlers Ferry, keeping 1.5GW of capacity available to the grid this winter.

UK supply margins pre-winter are expected to be at their widest in the week beginning 30 May, when the minimum power surplus is forecast at around 10.4GW. This comes at a time when there is typically minimal heating or cooling demand, and before the start of planned summer maintenance.

The narrowest supply margin of the summer months is expected to come in the week beginning 11 July, when a minimum power surplus of around 5GW is forecast. French energy firm Engie plans to permanently close its 1GW Rugeley coal-fired plant at the end of June.