We know certain things about the power blackout that hit most the Iberian Peninsula on Monday around 12.30pm local time, forcing Spain and Portugal to declare a state of emergency.
We saw, through vivid reports, how some telephone networks went down quickly. We saw how ATMs failed. We saw how people were stranded in trains and trapped in elevators. We saw that major supermarkets became cash only or closed; only a handful of petrol stations kept working; that there was traffic light chaos. We saw people out in the streets socialising, drinking and having barbecues. We learned that it was good to always have a battery-powered radio, some cash and a torch.
We saw, in other words, the fragility of a society that is so dependent on an electricity grid.
But how much do we really know about the causes of the huge outage that left millions across Spain and Portugal without electricity, and what that says about the risks to our own grid system in the UK?
The answer is not so very much that is concrete just yet.
The operator of Spain’s national grid has said the power outage began when there was a “generation loss” in the southwest of the country, in which, in two separate incidents, power generation went down.
Before the blackouts, reportedly, systems were “stable”, but then, he said, the loss grew to the “point of instability”. Within a five second window, conditions exceeded the system’s capabilities. It took only few seconds before it went down and following that a split occurred in the interconnections with France and the Iberian Peninsula’s grid was cut off.
But that explanation doesn’t really tell us why – and into that space has flooded a storm of speculation and conspiracy theory. One story that circulated online, and in news articles, was an early report that Portugal’s grid operator, REN, had said the cause was a “rare atmospheric phenomenon” which had triggered ‘induced atmospheric vibration’.”
Later, however, REN refuted that it had made these claims.
Others speculated, unsurprisingly, over cyber attack. But both Spain and Portugal said they had ruled it out. Spain’s prime minister, Pedro Sánchez said the government has “not had any conclusive information to suggest” a terrorist attack. Nevertheless, we also learn that Spain’s High Court has said it will open an investigation to find out if a cyber attack was responsible.
The biggest question, though, for us in the UK, is what does it tell us about the risks to our own grid and what needs to be done, in an era of expanding renewables, to mitigate them.
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Not surprisingly the outages have also triggered speculation around the role that Spain’s high proportion of renewables may have played. On April 28, data shows solar photovoltaic (PV) energy was providing almost 59% of Spain’s electricity at the time of the blackout, while wind power was providing nearly 12%, nuclear almost 11% and combined cycle gas plants 5%.
Sánchez, however, has also said that there was not a problem with renewable energy access during the outage.
Nevertheless, some have speculated that the problem may have been the lack of what is called “inertia” in the Spanish system at the time.
What exactly is this inertia? Energy expert John Kemp in a blog on the Iberian blackout explained: “The massive rotating generators in thermal power plants (coal, gas and nuclear) as well as hydro generators can help the grid self-stabilise because they have enormous amounts of inertia and store huge amounts of kinetic energy. In the event load exceeds generation, rotating generators supply some of this stored energy back to the grid – losing momentum in the process with a corresponding decline in grid frequency.”
It’s the energy in such turbines that have helped balance the UK grid over decades.
Solar and wind generators, Kemp wrote, “do not ordinarily provide inertia and frequency control services, unless fitted with specialist equipment”.
Winds of Change on the Iberian blackout (Image: Derek Macarthur)
He also cited a multi-year study called Project Inertia by the European Network of Transmission System Operators for Electricity which examined the risks of system splits like the one which just occurred in the European grid, describing them as “serious, challenging, and realistic disturbances that push the interconnected system to the limits of its dynamic stability and incur the risk of large-scale blackouts”.
It should be noted that the UK’s power grid is not directly synchronised with the Continental Europe Synchronous Area grid (one of the largest synchronous grids in the world), but does trade electricity with European countries via subsea cables.
Kemp wrote: “The extent to which the high share of renewables on the Iberian grid contributed to the loss of pre-disturbance reliability and post-disturbance resilience is unknown but will come under intense scrutiny.”
But others, like Daniel Muir, senior European power analyst at S&P Global, have dismissed the idea that the high proportion of renewables was a factor.
“The nature and scale of the outage makes it unlikely,” Muir said to Politico magazine, “that the volume of renewables was the cause, with the Spanish network more often than not subject to very high volumes of such production. There was sufficient conventional generation available, with nuclear, hydro, cogeneration and thermal technologies all on the system prior to the event and … available to the operator.”
This isn’t the first time that the Iberian Peninsula was hit by a separation from the rest of the Continental Europe (CE) transmission system. In 2021, a wildfire near transmission lines carrying electricity from southern France to Spain triggered such an event, though the whole system did not collapse.
Of course the “inertia” problem is just one theory. And even if it was an element in the issue, it should provide a reminder of the need to factor other types of balance, like battery storage, into the system in a renewables-heavy grid. Some visions of a future grid revolve as much around smart solutions involving battery storage and solar PV at a domestic level as they do major infrastructure.
Professor Keith Bell ScottishPower Chair in Smart Grids at the University of Strathclyde said: “As of Tuesday morning, it’s very good to see that almost all demand for electricity in Spain and Portugal has now been restored.
“It’s not yet clear to me what happened to cause this very large outage.”
He also pointed out that such outages are at much linked to fossil fuel and nuclear supported grids as they are to a renewables grid. “Events of this scale have happened in many places around the world over the years, in power systems using fossil fuels, nuclear, hydro or variable renewables.”
“It doesn’t matter where you are getting the energy from, you’ve got to get the engineering right in order to ensure resilient supplies of electricity. Thanks to the design of power systems and well-established system operation protocols, major power outages like this are mercifully rare.”
“However,” he added, “it is impossible to guarantee that something of this scale will never happen. System operators and providers of critical services need to be prepared for what to do if and when they do.”
“System operators and equipment owners try to ensure that such major events don’t happen and to learn lessons when they do, sharing those lessons internationally once investigations have been completed.”
Lessons, no doubt will be learned, particularly in continental grid of Europe, so interconnected, and these events will be scrutinised. Whatever the cause of this paralysing blackout, it’s a reminder that vigilance is required, around the possibilities of cyberattack and the challenge of grid balancing.
If a renewables-heavy grid was a factor, the answer is not to retreat to fossil fuels, continuing the emissions that are driving the climate crisis, or turn to nuclear, but to find new solutions for a new era. There are already some in development – for instance, Statkraft’s Moray-based project, a giant flywheel, designed to mimic the spinning turbines of a traditional power station.