We are a separate company

On 1 April the Electricity System Operator became a legally separate company within the National Grid Group. Find out more about what this change means.

Reserve services

At certain times of the day, we need access to sources of extra power in the form of either increased generation or demand reduction. This enables us to manage a greater than forecast electricity demand on Britain's transmission system. These additional power sources available to us are called 'reserve services'.

Different sources need different timescales in order to be ready to deliver the required service. In this section, we list reserve services according to their timescales (shortest timescales first):

Fast reserve

Fast reserve provides rapid and reliable delivery of active power through increasing output from generation or reducing consumption from demand sources.

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Short term operating reserve (STOR)

Short term operating reserve (STOR) is a service that provides additional active power from generation or demand reduction.

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Demand Turn Up

Developed to allow demand side providers to increase demand as an economic solution to managing excess renewable generation when demand is low.

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Super SEL

The ability for synchronous generation to reduce their minimum generation level (SEL) in times of low demand on the system.

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BM start up

On-the-day access to additional generation Balancing Mechanism units (BMUs) that would not otherwise have run.

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Replacement Reserve (RR)

Provision of an increase and decrease of active power between participating TSOs.

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