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​Enhanced frequency response (EFR)

​Enhanced frequency response (EFR) is a dynamic service where the active power changes proportionally in response to changes in system frequency. This service was aimed at improving the management of system frequency pre-fault to maintain system frequency closer to 50Hz.

​​​​​​We ran an invitation for expressions of interest in September 2015, which resulted in 64 parties pre-qualifying for a future tender event.  Over the following months, we engaged with these parties through a number of seminars and individual meetings to refine the service description and technical parameters to ensure that EFR delivered the optimum service to the control room in the most economical way.  This engagement culminated in the Invitation to Tender, which was published on 15th April 2016.  Pre-qualified parties had three months before the tender event, which closed on 15th July 2016. 

We targeted a procurement of 200MW of EFR through this event, with an individual cap per party of 50MW to stimulate competition and reduce first-mover advantage.  

From the pool of pre-qualified parties, we received 37 submissions covering 64 unique sites.  The submissions totalled 1.2GW of EFR capacity, with the majority comprising new investment.  The event was very successful, with around 600MW of tenders priced below the current frequency response market prices.  Tenders were split between transmission and distribution connected sites.  Most of the offers were battery storage technologies.    

We accepted 8 tenders totalling 201MW of capacity at a committed cost of £66M over 4 years, which were forecast to return an economic benefit of £244M in avoided costs.  The successful parties consist of large and medium existing industry parties (EdF, E.ON, Vattenfall), battery storage developers (Belectric, RES), and small renewable developers (Low Carbon, Element Power). 

All sites have commissioned and are now actively providing the service to the grid.  We have reviewed the learning from the project and continuous operation, and are using that for our development of future frequency response products.