In April 2025, millions across Spain and Portugal were unexpectedly plunged into darkness due to a sweeping power outage that disrupted transportation, communication, and essential services. While power was eventually restored, the incident served as a stark reminder that even advanced economies remain vulnerable to massive blackouts.
But as disruptive as the Iberian blackout was, it pales in comparison to some of the largest outages the world has ever seen. Below, we explore the five biggest power outages in history, ranked by the number of people affected and the scale of their impact.
1. Java–Bali Blackout – August 18, 2005
People affected: About 100 million
Region: Java and Bali, Indonesia
Cause: High-voltage transmission failure
A failure in a major transmission line on the island of Java resulted in a 10-hour power outage that extended to Bali. This blackout impacted almost half of Indonesia’s population and caused major disruptions to businesses, airports, and communication systems. It remains one of Southeast Asia’s most significant energy crises.
2. Pakistan Blackout – January 26, 2015
People affected: Approximately 140 million
Region: Nationwide
Cause: Technical fault at a power plant
Triggered by a fault at a power plant in Balochistan, this blackout rippled across the national grid and affected nearly the entire population. Urban centers and rural areas alike were left in the dark. The power cut halted internet services, interfered with water distribution systems, and highlighted the fragility of Pakistan’s energy infrastructure.
3. Bangladesh Blackout – November 1, 2014
People affected: Around 150 million
Region: Entire nation
Cause: Transmission line failure from India
A malfunction in a power line importing electricity from India caused Bangladesh’s entire national grid to collapse. For nearly 12 hours, the country was without electricity. The blackout disrupted hospitals, mobile networks, and industrial production, making it one of the most comprehensive national blackouts on record.
4. India Blackout – January 2, 2001
People affected: About 230 million
Region: Northern India
Cause: Grid failure due to technical faults
A fault in the northern grid caused a domino effect across several populous states, knocking out power for nearly a quarter of a billion people. Critical services, including water pumps and public transport, were severely affected. The event underscored the vulnerabilities in India’s grid, especially during peak demand seasons.
5. India Blackouts – July 30–31, 2012
People affected: Over 620 million
Region: Northern, Eastern, and Northeastern India
Cause: Overloading of power grids
This is the largest power outage in human history, affecting nearly 9% of the global population at the time. On two consecutive days, massive failures in India’s power grid left more than 20 states without electricity. Railways stopped, traffic signals went dark, and hospitals had to rely on emergency backup systems. The blackout revealed deep infrastructure weaknesses and spurred government responses nationwide.
Conclusion: A Global Wake-Up Call
The 2025 blackout in Spain and Portugal is a reminder that even modern, interconnected energy systems are not immune to failure. While it affected millions, history shows us that the consequences can be far greater. In an increasingly electrified and digitally dependent world, the need for resilient and adaptable power infrastructure has never been more urgent.
From Indonesia to Pakistan, Bangladesh to India—and now Southern Europe—blackouts reveal not only weaknesses in infrastructure but also the vital role that electricity plays in every aspect of modern life.