Friday's power cut 'underscores need for flexibility'

In the wake of a large power cut which affected large parts of south England on Friday (9 August), policymakers and power generators must prioritise investments in flexible energy systems.

The outage was caused by a proportion of Hornsea offshore wind farm (pictured) coming offline within minutes of the Little Barford gas plant 

The outage was caused by a proportion of Hornsea offshore wind farm (pictured) coming offline within minutes of the Little Barford gas plant 

That is according to RenewableUK, which responded yesterday (12 August) to concerns around whether the outage was made more likely by the varying output of renewable energy arrays.

The outage happened after RWE’s gas-fired power station experienced an unplanned shutdown at 4.58pm, with two-thirds of Orsted’s Hornsea Two offshore windfarm unexpectedly coming offline just a few minutes later.

In this short space of time, almost 1.5GW of generation was lost from the transmission network, until normal service was resumed at 5.40pm. Due to system frequency falling below 49Hz, National Grid ESO was forced to cut power supplies for around one million customers in order to prevent a cascading failure. Business and domestic customers for all "Big Six" energy suppliers were affected. 

National Grid has claimed that in the event of energy generators coming offline, a network of fast-responding energy assets called the frequency reserve service usually rapidly provide power to the system to make up for the shortfall. It is now investigating why this was not the case on Friday – but has confirmed that the outage was not due to the varying output of Hornsea Two.

Responding to the outage, RenewableUK’s head of external affairs Luke Clark said that the event, which National Grid ESO has described as “rare and unusual”, “underscores the need to invest in a flexible, modern system that can respond rapidly to changes in supply and demand”.

“We need to prioritise regulation, markets and infrastructure that helps the grid respond rapidly and builds in flexibility to the system - from storage to smart technology, and from balancing markets to charging reform,” Clark said. “That is the lesson of last week - and it will need a collective effort from Government and industry to deliver it”.

Government action

In the wake of the outage, which affected numerous transport and healthcare businesses across the South of England, Energy Secretary Andrea Leadsom has commissioned the Energy Emergencies Committee to conduct a full investigation.

She has additionally urged National Grid to “urgently” review the incident and report back to regulator Ofgem, which has itself requested an “urgent, detailed report” from National Grid. Ofgem has additionally approved a modification to the Distribution Code that aims to prevent distributed generators from nuisance tripping in response to disturbances on the power grid. 

National Grid ESO’s statement of response reads: “The National Grid ESO is… very pleased that the Government has commissioned the Energy Emergencies Executive Committee to consider the incident and how it played out, and we will work closely with that investigation to ensure that learnings can be reflected in industry processes and procedures going forward.

“In the meantime, the ESO has already initiated its own internal review of the response, and is collaborating closely with Ofgem, local distribution networks and affected power stations /generators to understand the cause of (Friday’s) power cut.”

Business concerns

For some, however, the action being taken by National Grid, the Government and Ofgem is too little, too late. Energy industry sources have this week told The Guardian that the frequency of the power grid, which should be held at a steady 50Hz, has dropped below 49Hz a further three times in recent months.

This has prompted concerns from businesses as to how best they can ensure a secure, resilient energy supply while playing their part in the transition to net-zero by 2050.

When asked for the body’s advice on the matter, an Energy Networks Association (ENA) spokesperson told edie that businesses should consider investing in a backup generator in the short-term if they rely on energy for commercial reasons. If this is not the case, the firm should still consider whether backup generators will be required in the longer term.

The ENA spokesman additionally encouraged businesses to participate in region-specific energy resilience forums, to support the development of a collaborative approach to power outages.

Battery company Anesco, meanwhile, is encouraging policymakers to better support businesses to invest in energy storage, after its 6MW battery facility in Clayhill, Bedfordshire, helped balance the grid during the power cut.

“There has never been a clearer example of the vital role of storage for the grid,” Anesco’s executive chairman Steve Shine said.

“Battery storage technology would have resolved this issue and is absolutely essential as we move towards a renewable network. Despite everyone knowing how important they are to the system, and promises being made about tariffs that would make batteries investable, it’s 18 months later and we are still waiting. It’s incredibly frustrating and if something isn’t done, it will be the end of batteries - as no one will build them and no investor will touch them.

edie has contacted National Grid for information on how many businesses were affected by the incident.

Sarah George



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