National Grid issues second warning of tight supply margin

National Grid Electricity System Operator (ESO) has warned of an expected 466MW shortfall in supply between 4.30pm and 6.30pm today (5 November).

This is the second consecutive day that the ESO has issued an electricity margin notice, alerting the energy market of its need for more generation – or less demand – and signalling to participants that higher-than-usual payments will be available. It also indicated that it may need to take out-of-market actions such as dispatching its reserves to keep the power grid in balance.

The ESO stressed that it had enough generation to meet demand, the margins were tight owing to factors including the weather, demand and the availability of generators.

The announcement came at 8pm last night, exactly 24 hours after the original notice, which warned of a 740MW shortfall. That notice was withdrawn at 1.30pm yesterday after additional generation became available.

The ESO last issued such a warning in 2016 when it was then known as a Notice of Inadequate System Margin.

According to the Energy and Climate Intelligence Unit, the forecast deficit for Wednesday was partly the result of the series of outages at three nuclear power stations (Hinkley B, Heysham 1, and Dungeness B), five combined-cycle gas turbines plants (Carrington, Fawley, Pembroke, Kings Lynn and Coryton) and the Drax biomass power station.

A partial outage at East Anglia One offshore windfarm was also expected to contribute to low overall wind generation, whilst imports via interconnectors were anticipated to be scarce due to reduced nuclear output in France.

Update: National Grid has withdrawn its latest electricity margin notice and said its forecasted margins for the next few days are “sufficient”.