Minimum summer demand forecast to drop to 15.6GW

National Grid ESO has forecast electricity demand on the transmission network to bottom out at 15.6GW over the summer, continuing a long-running trend of declining summer minimums.

In its latest Summer Outlook, the electricity system operator said there could be periods in which wind output alone exceeds demand on the power grid.

Forecast and historic summer minimums (weather corrected)

In most of these periods, the ESO said the system could be balanced by reducing wind output and interconnector imports and increasing consumption by pumped hydro storage plants.

However, during some periods, mostly likely on windy weekends in September, the ESO said inflexible generation could still exceed demand. It assumed only 8GW of wind capacity could be operated flexibility due to the number of actions that would be required by the control room.

Day-by-day generation and minimum demand

In such cases, the ESO said it can issue local or national Negative Reserve Action Power Margin (NRAPM) notices to request more flexibility from generators. To date a limited number of local NRAPM’s have been issued, but none at the national level.

Despite forecasting a lower minimum summer demand this year, the ESO said it does not plan to resurrect the Optional Downward Flexibility Management service which it introduced in response to the Coronavirus pandemic in 2020 and kept going in 2021.

The ESO said it expects the volume of actions it will need to take to balance the system to be higher this year than last year. Nevertheless, the body said it expects balancing costs to be 30% lower over the season due to reduced wholesale costs and enhancements to its balancing tools and capabilities.

Minimum summer demand on the transmission network has been trending downwards since the mid-2000s.