London, 10 October (Argus) — Peak UK power demand is forecast to rise this winter but the system is expected to remain well supplied, with the generation surplus no lower than 17pc, according to National Grid's winter outlook.

The minimum surplus margin is expected in the week commencing 26 November, while peak demand is expected in the week commencing 17 December, when there is a projected surplus of 19pc. The weather corrected demand peak forecast is 55.9GW, up from its winter consultation forecast of 55.3GW, reflecting an expected 0.6GW increase in underlying demand since last winter. The latest three-month weather outlook for October to December forecasts an increased risk of colder than average weather, the report said.

The report notes that forward prices for winter 2012/-13 continue to strongly favour coal burn over gas for power generation. “For gas and coal to be equitable the gas price for winter 2012-13 needs to fall by about 40pc, or around 30p/th. Alternatively there needs to be a further increase in the coal price by about $80/t,” it said. “While the price of coal and gas are influential in terms of power generation, other factors such as running hours for the [large combustion plant directive] LCPD, plant availability and generation portfolios will also influence fuel choice.”

The limited LCPD running hours will have an effect on coal-fired generation this winter with 500MW already lost from the Cockenzie plant and a further loss of 1GW at the end of December with the closure of two units at the Kingsnorth plant. An additional 3.5GW will have been lost by the end of March 2013 due to the closure of Didcot A and the remaining units at Cockenzie and Kingsnorth.

According to National Grid, 4.2GW of combined-cycle gas turbine (CCGT) capacity has been declared unavailable for the winter for a variety of reasons. This includes Keadby, Medway, Peterborough, Roosecote, Teeside, and Shoreham. “It is expected in the event of a change to market conditions such as lower gas prices, high levels of demand or large generation losses, some of this generation may become available to the market.”

National Grid anticipated 79.1GW of generation capacity to be available at the start of the winter, a reduction of 0.5GW from the winter consultation figure of 79.6GW as a result of the closure of the two oil-fired units at Grain and the extension of repairs at the Shoreham plant, while capacity has increased with the commissioning of the last two units at the Pembroke gas-fired plant and more wind farm capacity joining the system. There will be a further reduction of 1GW at the end of December from the gas-fired Derwent plant and the two Kingsnorth units.

There is some potential upside due to the commissioning of the West Burton B CCGT, re-commissioning of the Glendoe hydropower plant and an expectation of higher output at the Little Barford CCGT following refurbishment work. And there is another 500MW of import capacity available since the commissioning of the East-West Interconnector with Ireland on 1 October.

UK winter generation mix	Available capacity (GW)
Combined-cycle gas turbine	28
Open-cycle gas turbine	1.2
Pumped storage	2.7
Oil	2.1
Biomass	0.8
Coal	26.1
Wind	4.7
Hydro	1
Interconnectors	3
Nuclear	9.5

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