Commercial Opportunities for Back-Up Generation (including diesel generators) and Load Reduction via National Grid, the National Electricity Transmission System Operator (NETSO) for England, Scotland, Wales and Offshore.

This article written by:

Mark Duffield

Senior Account Manager

Contracts and Settlements

UK Transmission – Network Operations

National Grid

National Grid House

Warwick Technology Park

Gallows Hill

Warwick CV34 6DA

National Grid is the National Electricity Transmission System Operator (NETSO) for England, Scotland, Wales and Offshore.  Electricity cannot yet be stored on a large scale, and so one of our key roles as the NETSO is to balance the demand for electricity with supply on a second by second basis.

We do this partly through purchasing “Balancing Services”. Back-Up generation and/or load reduction has the ability to provide these services, potentially offering a further revenue stream for an existing asset.

More details on the suite of Balancing Services that back-up generation or load reduction might offer can be found on our website and specifically in a recent presentation given to a number of potential demand side providers.   However the following summary offers an overview of the three main services.

Service Name

Min Service Size

Max Notice Period before service delivered

Time limits around service delivery

Typical Payment

Short Term Operating Reserve (STOR)


(smaller sites can be aggregated into a 3MW load)


Must be able to sustain delivery for minimum of 120min if required

£40,000 (per MW per year)

Fast Reserve



Must be able to sustain delivery for minimum of 15min if required

£50,000 (per MW per year)

Frequency Response



Able to sustain up to 30min if required

£56,000 (per MW per year)

All of these services are procured through tender processes that National Grid runs several times each year.

The STOR service is the one in which we have seen by far the greatest involvement from the demand side (i.e. the customer / energy consumer side).  As of December 2009, of 2369MW contracted to provide STOR, the demand side provides 839MW (35%) from 89 sites.  Of this 839MW approximately 750MW is back-up generation, of which around 500MW is diesel generators – typically standby sets, with the secondary STOR function – with the remaining being load reduction services.

The above provides a flavour of the types of service back-up generators or load reduction can offer National Grid.  Much more information regarding the services and tender information can be found on our website or by contacting Mark Duffield, Senior Account Manager at National Grid by email at


See Also -(Ed):


(Note also, it is variously estimated that there are about 20 – 100 GW of diesel generators that could be brought into this service in the UK at very low cost, since they are already bought and paid for. Clearly these will have a major contribution to meeting load balancing needs in the event of large scale introduction of intermittent renewable energy sources. – Ed.)


  1. Reply

    This is an excellent post. There are a number of other articles on a similar theme – enter a search term such as diesel in the top left to locate. Admin

  2. Reply

    I would like to ask a few questions about the use of distributed standby generators (remote-from-the-utility) to back up the National Grid. Is this generation fed directly into the grid? Is it more often used on site to lower the Customer’s demand? Is this generation manually started at a notice from the National Grid? I read about a system called SRD that initiates STOR. Is this a manual or automatic system? Does anyone in Europe (to your knowledge) use a dispatchable system, remotely dispatching standby generators to run and provide additional energy to the grid?
    I work for Portland General Electric; our program uses standby generation 1) as spinning reserves and 2) to provide additional MWs as needed, directly to the grid. Ours is an remotely dispatched system.
    My task is to research the use of distributed, dispatchable, standby generators to provide energy to the grid elsewhere in the US and Europe.
    I appreciate you taking the time to respond.
    Thank you,

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