What Australia must learn from Spain’s 50-million-person blackout

Australia had a stark reminder of grid fragility in June, when a fault at Callide Power Station in Queensland triggered a widespread outage and forced load-shedding. While that incident was contained, it echoes deeper concerns raised by a far more severe event in Europe: the April 2025 blackout across Spain and Portugal. Together, they reinforce a single truth — technical resilience must keep pace with the speed of the energy transition.

On 28 April, a massive blackout cascaded across the Iberian Peninsula, cutting power to over 50 million people in one of the most extensive outages in European history.

Official findings confirmed that the failure began with a voltage surge, poorly managed by the grid operator, which triggered cascading generator trips due to insufficient reactive power control. Synchronisation with France was lost, and the entire Iberian grid collapsed within seconds.

With Australia heading toward 82% renewables by 2030 — bolstered by record rooftop solar and large-scale wind — experts say the event is a wake-up call. It highlights the urgent need to strengthen system security, expand grid-forming capability, and tighten oversight across voltage, frequency, inertia, and interconnection.

The Australian Energy Market Operator (AEMO) did not comment on the specific causes of the blackout but said it is reviewing the investigation closely and will consider any relevant learnings from those events and assess their applicability to the Australian energy system.

While AEMO has not detailed specific risks, voltage control and protection settings — central to the Iberian collapse — are increasingly relevant for Australia, particularly during periods of high renewable generation.

What went wrong in Spain?

A midday disturbance triggered voltage oscillations on Spain’s high-voltage grid. A 2.2 GW generation trip occurred — first near Granada, then spreading across Badajoz and Seville. Protection relays were activated as voltages spiked, disconnecting additional generation.

Within six seconds, frequency fell below 48 Hz, severing the France–Spain interconnect and plunging the peninsula into darkness. 

Spain’s Energy Minister, Sara Aagesen, confirmed that the grid lacked sufficient voltage control, and some generators failed to absorb reactive power despite being contracted to do so. Authorities ruled out cyberattack or weather-related causes.

IMAGE: Power frequency in Southern Spain just before the blackout in orange (5 cycle average) and ROCOF in blue. Dashed lines in green indicate the thresholds for under-frequency load shedding (UFLS).

Source: Luis Badesa, Associate Professor at UPM, Madrid

New problems require new solutions

According to Sahaj Sood, Senior Associate at BloombergNEF, the event illustrates the complexity of operating modern grids with high levels of renewables.

A high penetration of wind and solar makes managing a grid more complicated due to the variable nature of their generation, their asynchronous output, and the frequent failure of regulation to keep pace with new technologies. 

While renewables are essential to cutting emissions, their variability means dispatchable generators — like coal and gas — still play a stabilising role by ramping up when renewable output dips. “Traditional, dispatchable technologies also provide system-stabilising inertia to the grid through the rotating mass of their turbines,” Sood said.

As these traditional assets retire, new technologies are stepping in. “The uptake of batteries can ease the integration of variable renewable energy. Batteries can respond incredibly fast, charging when wind and solar generation jumps and discharging when it drops,” he said. “Many new batteries under construction will also be able to provide ‘synthetic inertia’ to the grid to help replace the system-stabilising role of traditional coal and gas assets.”

BloombergNEF forecasts that utility-scale battery capacity in Australia could quadruple to nearly 10 GW between 2024 and 2027, making it a global leader in storage investment.

“Grid stability can also be augmented through new technologies, like synchronous condensers, or through expanding interconnections between regions, allowing neighbouring grids to strengthen each other when things go wrong,” Sood added.

Building a more resilient grid

Transmission operator Transgrid is investing $16.5 billion in New South Wales over the next decade as part of its System Security Roadmap. The plan includes major projects such as EnergyConnect, HumeLink, and VNI West — designed to connect renewable energy zones, increase interstate resilience, and enable secure operation during periods of 100% instantaneous renewables.

“Transgrid is currently implementing its comprehensive System Security Roadmap to overcome complex challenges as coal generation retires,” a spokesperson said.

The roadmap includes deploying up to 14 synchronous condensers and 5 GW of grid-forming batteries, as well as upgrades to control room technologies. “This critical upgrade will arm control room operators with smarter tools, better training and faster decision-making.

“These vital assets will connect new large-scale renewable energy generators and storage to the grid, integrate five renewable energy zones in NSW, and augment transmission interconnection with our neighbouring states. This means more flexibility for network operators and a more stable energy supply — even during disruptions.”

A decentralised energy future

Professor Andrew Blakers of the Australian National University says the Iberian failure demonstrates why a decentralised, well-planned renewables system can outperform fossil-based grids.

“A properly designed renewable energy system is more reliable and resilient than a fossil or nuclear system,” he said. “Instead of a few large power plants, there are thousands and millions of small plants, which makes it virtually impossible to suddenly and unexpectedly lose a significant fraction of generation capacity.” 

A renewables-based grid includes added resilience at every level — from rooftop solar to household batteries to national-scale pumped hydro. Weather systems can be forecast days in advance, and spreading solar and wind generation across large areas smooths local variability.

It’s “the most stable domestic energy system in history.”

Blakers also pointed out the strategic value of energy independence: no more imports of oil, gas and coal at national, provincial, city or domestic levels — which confers vast resilience in the event of war, trade war or pandemic.

Regulation must evolve

Regulation has historically lagged behind technological developments in the grid — and that this could have dangerous consequences for grid stability.

“Market operators have previously failed to anticipate how renewables would respond to rapid changes in grid conditions, or set adequate rules to govern their response,” he said. “This can have catastrophic consequences — as occurred in August 2016 when the Australian Energy Market Operator failed to anticipate that a grid fault would lead 500 megawatts of wind capacity to disconnect and eventually contribute to a state-wide blackout in South Australia.”

IMAGE: Energy mix prior to the Iberian blackout. Source: Red Eléctrica de España

The Iberian blackout reinforces the need for stronger inverter standards, mandatory reactive power contributions, and smarter protection settings — including updated ride-through rules and frequency thresholds.

Lessons for Australia’s clean energy push

Spain’s failure points to key areas for action:

• Voltage and reactive power: All generators — including renewables — must be capable of absorbing or injecting reactive power as required. Australia’s Generator Performance Standards are a step in the right direction.
• Fast-response capacity: Spain lacked fast-acting resources. Grid-forming batteries, synchronous condensers, and fast frequency response (FFR) services must be scaled.
• Interconnection: Iberia functioned as an “electric island” with only 3% interconnection to Europe. Australia similarly needs robust inter-state links and the capacity to swiftly restore islands after disturbances.
• Protection systems: Spain’s over/under-voltage logic contributed to cascading failures. Australia’s protection standards have been strengthened but must be continually reviewed.

A grid ready for the future

Spain has since launched reforms, including removing legacy privileges for coal and gas plants and imposing new voltage-control responsibilities on all generators. A panel under ENTSO-E is reviewing future inverter standards and operational requirements.

In Australia, AEMO has proposed mandating grid-forming capabilities for large new renewable projects, while Transgrid’s roadmap sets out a national model for secure integration.

“Australia is on the cusp of an energy transformation,” said Sood. “The path to 82% renewables by 2030… must be underpinned by investment in system strength, fast frequency response, flexible capacity, and forward-looking regulation.” 

The Iberian blackout was a glimpse of one possible future. If Australia wants a grid that withstands the strains of transition, it must act now.