The recent mass blackout in Spain and Portugal has raised concerns over whether something similar could hit the UK, and what the fallout would be for British businesses.
Spain And Portugal Plunge Into Darkness
On 28 April, large parts of Spain and Portugal lost power in a sudden, widespread outage. Train lines stopped mid-journey, airports froze, and internet and mobile networks failed. Even hospitals had to fall back on emergency generators as grid operators raced to identify the cause.
While investigations continue, Portuguese energy officials have pointed to a “rare atmospheric phenomenon” that disrupted interconnectors and triggered a chain reaction across the Iberian grid. Some experts suspect a link to geomagnetic disturbances caused by heightened solar activity, a known but unpredictable risk to high-voltage systems.
By nightfall, much of the region remained in darkness. For two countries that pride themselves on modern infrastructure, the blackout was a reminder that even advanced grids have vulnerabilities.
Could It Happen In The UK?
One comforting fact is that the UK (to date) has never experienced a total grid failure. This is because our energy infrastructure is among the most advanced in Europe, with built-in protections and a growing focus on resilience. However, that doesn’t necessarily mean that a full national blackout (however unlikely) isn’t possible.
According to government risk assessments quoted in The Blackout Report, by Chris Owens, marketing manager at Riello UPS (a company specialising in standby power systems), there’s roughly a 1-in-200 chance (0.5 per cent) that the UK could suffer a grid shutdown within a five-year period. That’s statistically more likely than being struck by lightning. For another perspective, for anyone who buys a lottery ticket each week, that degree of chance means you are over 225,000 times more likely to experience a national UK blackout than to win the lottery jackpot.
As Chris Owens says in his (2019) report: “Britain’s grid is strong, but not invulnerable,” and that, “The reality is, as we integrate more renewable sources and become more interconnected, we also increase the number of possible failure points.”
But What About 1974?
Many may still remember the rolling power cuts of the early 1970s, particularly during the 1974 miners’ strike and the infamous Three-Day Week. At that time, power outages were largely the result of industrial action, energy supply restrictions, and political decisions rather than failures in the grid itself.
Today’s electricity system is vastly different, far more technologically advanced, diversified, and automated. Today’s challenges are less about fuel rationing and more about cyber resilience, system complexity and environmental extremes. In short, the causes behind 1970s-style blackouts are not the same as today’s threats.
What Could Take The Lights Out?
When considering how things could go horribly wrong today as regards the grid, there’s no single culprit. The risks are most likely to come from a range of natural and man-made factors, often acting in combination. These could, for example, include:
– Extreme weather. From gales to floods, storms can down power lines, damage substations and leave thousands cut off, as seen during the 1987 Great Storm.
– Solar flares. High-energy eruptions from the sun can trigger geomagnetic storms that interfere with transmission systems, potentially taking out transformers and affecting grid stability.
– Cyber attacks. As digital control systems become standard, so too does the risk of targeted cyber operations. Ukraine’s 2015 blackout, caused by malware disabling multiple substations, remains a sobering precedent.
– Technical failures. Grid infrastructure is tightly coupled. A problem at one site, e.g. the lightning strike near London in 2019, can cascade if backup systems fail to respond in time.
– Fuel supply shocks. A disruption to imported gas or outages at generation sites can create sudden imbalances, especially during cold weather when demand spikes.
As Dr Iain Staffell, senior lecturer in sustainable energy at Imperial College London highlights: “Today’s grid is a delicate balancing act,” and that “You have to match supply and demand in real-time, across thousands of miles. When something unexpected happens, the knock-on effects can be rapid and wide-reaching.”
Restoring Power Wouldn’t Be Quick
If the entire UK grid did go down, restarting it wouldn’t be as simple as flipping a switch. Most power stations require electricity to function, and during a total blackout, none is available.
Instead, a process known as a “black start” would be triggered. This involves using a small number of specially designated generators to slowly rebuild the system. In the UK, only a few stations are equipped for this role, mostly older hydro or gas plants.
According to National Grid ESO, 60 per cent of power could potentially be restored within 24 hours, but full restoration could take between five and seven days, depending on conditions and location.
The Business Impact Could Be Severe
Not surprisingly, for businesses, the stakes are high. A nationwide blackout would disrupt not just lights and laptops but entire supply chains, communication networks, and service delivery. For example, just a few hours without power could result in:
– Retail and hospitality losses. Fridges fail, card readers stop, bookings collapse.
– Office paralysis. Without internet or mobile networks, emails, cloud access and remote work all go dark.
– Manufacturing delays. Automated systems stop mid-cycle, risking damage to equipment and materials.
– Healthcare disruption. Hospitals switch to emergency power, but care homes, GPs and pharmacies may not be as well equipped.
– Logistics breakdowns. Traffic lights, rail systems and fuel pumps go offline, stranding deliveries and staff.
The Financial Cost
A 2023 government resilience study warned that a multi-day blackout could cost the UK economy up to £7 billion, and that’s before factoring in the social cost, i.e. vulnerable populations without access to heating, information, or clean water.
Are We Prepared?
The good news is that it appears that Britain isn’t ignoring the risk. For example, in recent years, National Grid and government partners have invested in upgrades designed to strengthen resilience, including:
– Enhanced digital monitoring and fault detection.
– Increased decentralisation of power generation (e.g. solar and wind closer to where it’s used).
– More battery storage capacity to help stabilise peaks and troughs in supply.
– Regular emergency planning exercises, including simulated black start scenarios.
– A renewed cybersecurity strategy for critical national infrastructure, introduced in 2023.
There’s also an ongoing effort (although you may not have noticed it until the Spain and Portugal blackouts) to educate the public. For example, NESO recently reaffirmed the importance of basic preparedness, such as having wind-up radios, torches, offline maps, and a few days’ worth of water and food, echoing similar messages issued across Europe this year.
What About Geopolitical Tensions (The Increased Threat of War)?
That said, while NESO (the National Energy System Operator) hasn’t publicly tied its preparedness messaging directly to the greater current threat of war in Europe, the wider European push for civil resilience, including advice about wind-up radios, water supplies, offline maps and survival kits, does certainly appear to have been influenced by growing geopolitical tensions. In particular, this includes:
In early 2024, several European governments (notably Germany, Sweden, and Finland) restarted national resilience campaigns, urging citizens to prepare for emergencies, not just natural disasters but potential conflicts, cyber attacks, and energy disruptions.
The EU Civil Protection Mechanism has expanded its public messaging on the importance of 72-hour kits in the event of crisis, a move partly triggered by lessons from the war in Ukraine and disruptions to energy infrastructure across Europe.
The UK’s advice from NESO and the Cabinet Office’s “Prepare” guidance align with these efforts, albeit more softly worded, focusing on “general resilience” rather than citing war directly.
So, it’s worth quickly noting here that messages about ramping up civil contingency are also being influenced by a less predictable and more hostile global environment, as well as the events with Spain and Portugal’s grid.
How Businesses Can Protect Themselves
While the chances of a total grid blackout in the UK remain low, experts agree it makes sense for businesses to factor it into their resilience planning.
For example, Nicola Dean, a business continuity advisor with clients in the energy and transport sectors, makes the point that although “There’s no need for panic” and it seems “there is a case for being practical,” as “The pandemic showed us how quickly assumptions about stability can collapse.”
With this in mind, Dean advises companies to focus on five key areas, which are:
1. Backup power. Install uninterruptible power supplies (UPS) for servers and critical devices. Larger sites should assess the viability of generators or on-site solar plus battery storage.
2. Offline communication plans. Keep printed contact lists and emergency protocols. Use two-way radios or crank-powered devices as a backup.
3. Continuity planning. Have clear procedures in place for short- and long-term outages. Consider how you’d trade, serve customers, and protect data during downtime.
4. Insurance review. Ensure business interruption policies cover extended outages — and know the limits and exclusions.
5. Employee training. Make sure teams know what to do if systems go down, especially in customer-facing or operational roles.
A New Kind Of Preparedness
Although the recent blackout in Spain and Portugal may have been triggered by rare conditions, it highlighted vulnerabilities that many in the UK share, i.e. increasing reliance on digital infrastructure, complex energy systems, and minimal tolerance for disruption.
For UK businesses, the simple message may not be to expect the lights to go out tomorrow, yet not to wait until they do to start asking the right questions!
What Does This Mean For Your Business?
While no one is suggesting that a UK-wide blackout is imminent, the events in Spain and Portugal have offered a timely and unsettling reminder that no system is entirely immune to failure. For years, it may have seemed that major power outages were the kind of thing that only happened elsewhere. But as power grids become more complex and more interconnected, they also become more exposed to rare but high-impact threats.
For UK businesses, this is not a call to panic, but it is a clear prompt to think more seriously about resilience. Power is no longer just a utility in the background. It underpins every part of modern operations, from cloud access and communication to security, refrigeration and logistics. Without it, entire business models are quickly exposed. A few hours of downtime can be costly. A few days could be critical.
Thankfully, the reality is that Britain still benefits from one of the most robust and well-managed energy systems in Europe. Investments in digital monitoring, decentralised generation and cybersecurity are all important steps forward. However, preparedness now needs to extend beyond infrastructure alone. It should really include clear business continuity planning, staff training, emergency protocols and basic contingency tools that work without a plug.
For government agencies, critical service providers and civil planners, the lesson is equally stark. Public messaging must be consistent, proactive and realistic. Greater collaboration between sectors will also be needed if we are to build the kind of national resilience that can withstand not just rare events, but the unpredictable world we increasingly live in.
Whether you are running a retail outlet, a manufacturing site, a healthcare service or a home office, the question remains the same. If the lights went out tomorrow, would you be ready? The answer may not be urgent today, but it could be (very suddenly) tomorrow.