Opposition politicians and trade unions claimed the issuing of a supply margin alert by National Grid last week highlighted failures in the UK Government’s energy policy.

The network operator made the Notification of Inadequate System Margin (NISM) after a number of breakdowns at power stations.

More electricity was generated by the remaining power stations in response to the alert and National Grid stressed that there had been no risk of electricity supplies being disrupted.

A spokesman for the company said: “The market duly responded to this signal.”
National Grid described the NISM as “one of the routine tools that we use to indicate to the market that we would like more generation to come forward for the evening peak demand period”.

Extra 500MW

The operator asked for an extra 500MW of power to be generated between 4.30pm and 6.30pm on Wednesday 4 November.

About 40MW of demand-side balancing reserve was brought into play.

Alastair Martin, Chief Strategy Officer at Flexitricity, one of the demand response providers, said: “For this event, we’ve engaged 46 sites, most of which have delivered by turning down building ventilation.

“We have several hundred megawatts across the portfolio,” he added.
‘Energy security crisis’

But opposition politicians and trade unions rounded on the UK Government following the NISM.

Lisa Nandy, Labour’s Shadow Energy Secretary, said: “National Grid has now begun using emergency measures to prevent blackouts.

“The chopping and changing of energy policy under this government is creating an energy security crisis.

“It is preventing investment we now urgently need to keep the lights on and it could cause household bills to rise.

“David Cameron should step in and end the policy vacuum to get new power stations built as quickly as possible.”

Brian Strutton, National Secretary for Energy at the General, Municipal & Boilermakers (GMB) trade union, added: “Government must instruct National Grid to ensure that there is enough base load capacity to cope when interconnectors and renewables cannot be relied on.

“As for demand-side response this is the bonkers policy where National Grid use consumer’s money to pay firms to stop work in order to avoid blackouts.”

Read the GMB's comments in full