National Grid’s power failure on Friday 9th August led to over 900,000 customers being disconnected for around 15 minutes. The failure caused widespread disruption from London, to Ipswich and up to the North East, with severe train delays and power cuts to critical infrastructure, such as Newcastle Airport and Ipswich Hospital. An investigation has been hastily launched by OFGEM into the causes of the failure, the likes of which last occurred in 2006 (source Limejump), but without the same level of disruption.

National Grid has blamed the failure on a very rare occurrence, where two large scale generators connected to its network came offline within two minutes of each other. Interestingly these weren’t two renewable generators, often blamed for their intermittency, but a mixture of conventional and renewable. The generators involved were the 740 MWe combined cycle gas turbine at Little Barford in Bedfordshire, operated by RWE, and Orsted’s 1.2 GW Hornsea 1 wind farm. According to Lord Adonis, together they accounted for approximately 5% of generation on National Grid at the time of failure.

The circumstances raises interesting questions for the UK’s policy on flexible power and the role of energy storage, as well as National Grid’s part in incentivising these assets. The rapid failure of the two assets resulted in a frequency drop on the network, with automatic failsafe systems shutting down some areas to preserve others. The situation was exacerbated by the large proportion of wind generation in the mix creating a lack of inertia (source Limejump).

The first question is whether the presence of an increased number of flexible generation and battery storage assets, within National Grid’s network could have prevented the issue. Had either of the specific generators been able to rely on a dedicated battery storage unit, which could have reacted within seconds, the level of generation could have possibly been maintained for an interim period, allowing National Grid to call on other flexible generation assets. The second is whether the use of standalone battery storage assets in the right locations could have reacted to control the frequency changes within the network and prevent the issue.

The outcome of the review by OFGEM will be telling. Whilst the private sector has reacted positively over the last four years to deliver both battery storage and flexible peak power generation projects, policy from both National Grid and central government has created a rather ‘stop-start’ market. Examples include the uncertainty of pricing in the frequency response auctions (FFR and EFR) and work to blend the two contracts by National Grid, through to changes in the rules relating to de-rating of batteries in the Capacity Market auctions, and then the temporary and indefinite withdrawal of payments by the government. Admittedly the latter has been out of their control given the EU’s ruling in relation to State Aid rules. Policy has also lacked a geographical focus to pinpoint new assets to point within the network that need them most. Recently DNO’s have sought to change this, but on a relatively small scale.

These issues have stalled a significant number of projects which have found it difficult to attract the debt funding required to move forward and allow them to contribute to the new flexible and resilient network the country needs.

It is also of note that a significant amount of new generation projects constructed in the last 15 years have been connected to the distribution network. This is in contravention to how the national transmission network was originally designed and has resulted in National Grid having to balance and account for reverse power flows. The ongoing closure of large coal fired power stations has also created further in-balance. This trend is illustrated by BEIS statistics below:

This power outage appears to be symptomatic of the changes that have occurred to the UK’s energy mix over recent years. The energy industry requires coherent and stable policy measures to ensure investment in the type of new clean generation, flexibility and storage assets the country needs. Perhaps this incident will kick start these changes creating a stable environment for new infrastructure investment.