National Grid forecasts increased winter capacity margin

National Grid is confident there will be enough generation capacity on the power grid to meet peak demand over the coming winter, even if there is a repeat of the extremely cold temperatures experienced during the ‘Beast from the East’.

In its latest Winter Outlook report, the electricity system operator (ESO) has forecast a substantial de-rated capacity margin of 11.7 per cent – or 7.1GW.

The figure is up 1.4 percentage points on the forecast for last winter of 10.3 per cent – or 6.2GW. Accordingly, the loss of load expectation has fallen by a factor of ten from 0.01 hours per year to 0.001 hours per year.

It marks the third time in a row there has been a year-on-year increase in the forecast for the de-rated capacity margin.

Underlying demand during an average cold spell was predicted to top out at 60.5GW during the winter of 2018/19. The ESO said it expects there to be 65GW of de-rated generation capacity and 2.6GW of net interconnector imports available to meet the peak.

Nameplate capacity by generation technology

Source: National Grid, Winter Outlook 2018/19

The report also predicted a comeback for coal generation, stating: “For the last two winters, gas was the cheaper fuel type for electricity generation. However, as global gas prices have risen, it is likely that coal will replace gas in the generation merit order for some of the winter.”