Using standby diesel generators for short term reserve to support main power grids – potentially good news from National Grid

Using standby generators for short term reserve. (emails published with permission of authors from Quigg Associates and National Grid)


I was delighted to see you last week. The topic I mentioned, using standby generators for short term reserve is one in which I am not currently involved but it does strike me as a useful technique for reducing CO2 emissions. There are a few ‘fleets’ of standby generators arranged to quote the National Grid for this service but the short term nature of the contracts offered are I think a deterrent to the potential which could be exploited. I was involved with the Wessex Water operation which was heading towards 20MW when I left. This, together with some sewage gas generation has now been changed into a separate company. Another successful operation is run by Alastair 

Alastair is a contributor to Claverton Energy Group.  He became interested in the short term reserve potential and was one of those who wrote a paper for government which shows that there is a potential saving of 90% in the emissions to provide this service.

His paper is the first on the list at – As you might guess he trades under the Flexitricity name. However the conclusions in the paper seem sound enough.

When I was with Wessex Water the obstacles to a larger expansion of the technique were:-

i) the risk of not getting National grid contracts regularly – annual tenders don’t give any financiers great confidence. The competition is  elderly thermal plant of any type which is written down and the owners objective is to extract revenue before scrapping a plant. There are of course the other means of filling generation gaps angd NGC will optimise the mix

ii) the cost of modifying existing generators includes such items as synchronizing kit which can require a new LV board as well due to fault level increase. Also there are issues with network compatibility which can often require neutral displacement protection. The DNOs have a very expensive eway of providing it.

iii) the centralised control features necessary to bring together at least 3 MW in order to bid. Managing the quality of broadband connections needs specialist skills

iv) larger fuel tanks. when finishing a run for NGC there must still be fuel for the primary standby function.

v) organisation to manage this function. People with the specialist skills are not available min many organisations. I think that if the contracts offered ran for 5 or 7 years the capacity available would expand rapidly. No new technology is available and I think it could be a good one to accelerate.

I believe that in France there are a few GW of standby generators used for system support.

Kind Regards

Bernard Quigg

Quigg Associates


Hi Dave

I read Bernard’s note, attached email with interest as it’s always good to see that there is interest out there in providing Short Term Operating Reserve (STOR, previously known as “Standing Reserve”) from new sources, whether someone is interested in approaching us directly or through an aggregator.  I did note that in your last line you said that if contracts could be made available for a longer period of time then this might elicit more interest from parties.  On that front there is potentially good news, the changes that we introduced to the STOR contract form a year or two back, allow users to tender for a contract of up to 10 years duration, and as part of the STOR review ( and also where I mention the STOR Review put in the one for the review document ( that my colleague Craig Maloney is undertaking at the moment we may potentially be looking to extend that capability to even longer term contracts.

If you want to put this up on your site it would be good if you could incorporate a link to the National Grid website for STOR (

Also happy if you want to put my email address in there if anyone wants further details.



Mark Duffield

mark.duffield the at sympbol

Senior Account Manager

Contracts and Settlements

UK Transmission – Network Operations

National Grid

National Grid House

Warwick Technology Park

Gallows Hill

Warwick CV34 6DA

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