The Executive Director of the International Energy Agency (IEA), Fatih Birol, has renewed his call for the global energy community to give hydropower the attention it deserves, warning that the sector remains “the forgotten giant of electricity.”

In a LinkedIn post published on October 17, Birol said that four years after the IEA released its major report on hydropower, the technology continues to be left out of key energy policy discussions despite its central role in global electricity systems.

“Four years ago, the International Energy Agency (IEA) released a major report on hydropower. It noted that hydro is often left out of conversations on energy, despite its huge role in electricity systems around the world. At the time, I described hydropower as ‘the forgotten giant of electricity’. Unfortunately, this is still the case today,” Birol wrote.

Hydropower remains the third largest source of power generation worldwide, after coal and natural gas, generating around 4,500 terawatt-hours of electricity last year — 14% of global supply. “That’s similar to all the power produced worldwide by solar and wind combined, and 50% more than the amount generated from nuclear plants,” Birol noted.

Hydropower, Birol said, is uniquely placed to help countries meet rising electricity demand as the world enters what the IEA has described as a “new Age of Electricity.”

“Hydropower can help meet this increasing power consumption as populations and economies grow, electrification advances and investment pours into digital infrastructure like data centres,” he said.

Birol also highlighted hydropower’s role as a dispatchable low-emissions source of electricity with “unmatched capabilities when it comes to flexibility.”

“Hydro plants can quickly adjust their generation up and down – and can be stopped and restarted relatively smoothly. This enables them to quickly adapt to shifts in demand, helping to keep the lights on in times of strain – and usually at a lower cost than most nuclear or coal plants,” he wrote.

He added that hydropower is a crucial partner to renewables: “In periods when the sun doesn’t shine or the wind doesn’t blow, hydro can quickly and cheaply fill the gaps.”

Birol also underlined hydropower’s critical role in electricity storage, noting that pumped storage hydro plants “are currently the largest form of electricity storage worldwide, with the capacity to hold 30 times more power than batteries.”

Birol pointed out that in many advanced economies, hydro plants are decades old and in need of refurbishment.

“Many hydropower plants in advanced economies are over 40 years old. Refurbishing them is vital to sustain output, and owners should consider simultaneous upgrades that improve flexibility and storage,” he said.

In contrast, developing and emerging economies hold vast untapped potential.

“In emerging and developing economies – where about 60% of hydro potential remains untapped – hydropower can both expand energy access and power industrialisation, spurring economic growth,” Birol wrote.

He emphasized the multiple benefits hydropower can bring to communities and industries alike — from low-cost electricity and irrigation services to jobs and cross-border trade.

Calling for urgent action, Birol urged governments to make financing more accessible and affordable, speed up permitting processes, and strengthen the resilience of hydropower infrastructure in the face of changing rainfall patterns due to climate change.

“Hydropower development requires long-term planning, so challenges need to be addressed now,” he said. “This is why I believe it’s essential to move hydropower up today’s energy policy agenda.”

“These actions can be taken now. And I hope that in another four years’ time, hydropower will no longer be a forgotten giant.”