Fast response from battery schemes

UK transmission system operator, NGET (National Grid Electricity Transmission), has procured 200 MW of battery storage to provide what it calls Enhanced Frequency Response, through a tendering exercise held in July 2016.

The winning tenders and tender prices (£/ MW of EFR/h) were:

• EDF Energy Renewables: 49 MW scheme at West Burton, Nottinghamshire, £7;
• Vattenfall: 22 MW scheme at Pen Y Cymoedd near Neath, £7.45;
• Low Carbon: two schemes totalling 50 MW at Cleator and Glassenbury, £7.94 and £9.38;
• E.ON UK: 10 MW scheme at Blackburn Meadows biomass CHP and district heating site near Sheffiel £11.09;
• Element Power: 25 MW TESS scheme, £11.49;
• RES: 35 MW scheme through Battery Energy Storage Services 4 Limited, £11.93;
• Belectric: 10MW Scheme at Nevendon, £11.97.

The facilities have expected start-up dates between April 2017 and March 2018.

Enhanced Frequency Response is defined by National Grid as being a service that achieves 100% active power output within 1 second (or less) of registering a frequency deviation.

This compares with existing frequency response services procured by NGET to balance the transmission system: primary and high, which have timescales of 10 seconds, and secondary, which has timescales of 30 seconds.

ERF is a new service that is being developed to improve management of the system frequency pre-fault, ie, to maintain the system frequency closer to 50 Hz under normal operation, NGET says.

The changing generation mix is reducing the contribution that synchronous generation makes to the energy market, NGET observes, which in turn is reducing the level of system inertia, particularly on low demand days when there is a high penetration of renewable plant. Lower system inertia affects the ability of the system operator to manage the system frequency within normal operating limits. This in turn drives the procurement of larger volumes of the existing frequency response services. EFR has been designed as an alternative to procuring increasing volumes of frequency response, and is expected to achieve considerable savings. By responding faster than existing frequency response services, EFR “will help reduce the increasing response required in times of low system inertia”, says NGET.

For the first tender round NGET set an initial requirement of 200 MW of EFR with a maximum 50 MW cap per provider.