The variability of wind power “does not initially appear to be a cause” of the outage that blacked out a huge swathe of the UK – but the nation needs to be better equipped to manage system volatility as it moves to a zero-carbon future, said one of the country’s leading energy research groups.
The analysis by Aurora Energy Research came as debate continued to rage over the role of renewables in the incident, with John Pettigrew, the CEO of UK network operator National Grid, insisting on Wednesday that there was "nothing to indicate there is anything to do with the fact that we're moving to more wind or more solar".
UK energy secretary Andrea Leadsom said "National Grid has already confirmed that the incident was not linked to the variability of wind power", as she set out the scope of an investigation into the blackout.
Aurora said in a note that low system inertia – the network’s level of resistance to changes in frequency, which are exacerbated by high levels of 'non-synchronous' generation such as wind and solar –, insufficient flexible capacity and “oversensitive plant protection mechanisms” are all possible factors contributing to the outage, which on Friday caused chaos to transport and other infrastructure.
The near-simultaneous disconnection of 1.4GW across a gas-fired plant and the part-operating Hornsea 1 offshore wind farm, almost 5% of total demand by Aurora's reckoning, are at the heart of the blackout, which is the subject of an urgent inquiry by National Grid.
The culpability of Hornsea 1 – which when completed by Orsted will be the world’s largest offshore wind farm at 1.2GW – has been heavily discussed by the UK’s vocal anti-wind lobby, which claims the nation is becoming too dependent on “unreliable” turbines and solar panels.
Aurora concluded “wind variability in itself does not initially appear to be a contributing factor in this case” – but said National Grid will have to significantly up its investment in capacity and services capable of flexibility responding to such events as it moves towards a zero-carbon system.
Aurora said: “Low system inertia can be managed if there is enough flexible capacity (e.g. batteries, reciprocating engines, demand side response) able to provide ‘synthetic inertia’ and fast response in the case of an outage. Questions will arise over whether National Grid procures enough of this capacity through markets such as Firm Frequency Response and Fast Reserve.”
The Oxford based research group added: “Being prepared for every possible eventuality may be expensive, but we have seen that even short outages cause high levels of disruption and associated cost if key infrastructure such as airports, hospitals and railways are taken out. Currently around £170m ($205m) per year is spent on frequency response - doubling this would add £2 to an average annual household bill.”
National Grid is due to deliver its initial findings on the cause of the outage by the end of this week after being ordered to conduct an urgent inquiry by UK regulator Ofgem.