Hydropower is still ‘the forgotten giant of electricity’ – and that needs to change

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. Hydro is the third largest source of power generation worldwide after coal and natural gas. Last year, it generated around 4 500 terawatt-hours of electricity, or 14% of the global total. That’s similar to all the power produced worldwide by solar and wind combined, and 50% more than the amount generated from nuclear plants.

In some countries, hydro’s share of the power mix is significantly higher, even covering close to 100% of electricity demand. Nonetheless, hydro is frequently an afterthought in global energy policy discussions. As I said, a forgotten giant.

Now, as decision-makers around the world contend with how to meet renewed strong growth in electricity consumption, I believe it’s high time to give hydropower the attention it deserves.

As the IEA has long pointed out, electricity demand is set to rise much faster than overall energy demand in the years ahead, signalling the emergence of 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.

A dispatchable low-emissions source of electricity, hydropower has 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.

Flexibility is also an asset for countries looking to integrate rising levels of solar and wind into their electricity systems. In periods when the sun doesn’t shine or the wind doesn’t blow, hydro can quickly and cheaply fill the gaps.

And hydro resources are not only used for electricity generation – they are also a significant source of electricity storage. Pumped-storage hydro plants are like giant batteries that use water instead of chemicals. In fact, they are currently the largest form of electricity storage worldwide, with the capacity to hold 30 times more power than batteries.

As a result of its dispatchable nature and storage potential, hydropower can play a big role in ensuring electricity security and boosting power system flexibility. In advanced economies, especially those where variable generation is rising, it remains a cornerstone of resilient power systems.

New opportunities include adding turbines to dams that don’t have electricity generation units, enhancing storage at operating plants, and developing pumped-storage potential. But we must also remember that 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.

Meanwhile, 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.

For communities, it brings low-cost electricity to households that lack it, as well as water services such as irrigation. For industry, cheap and reliable hydropower reduces costs, enhances competitiveness and attracts more business activity. Hydropower can also generate revenues through cross-border electricity trade and is source of job creation, supporting broader economic development.

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

Governments need to make financing more accessible and affordable to modernise older plants and enable emerging and developing economies to build new ones. They must also ensure smooth permitting processes to avoid construction delays. Countries need to invest in making hydropower infrastructure resilient, especially as fluctuating rain conditions become more common due to climate change. And in all cases, robust sustainability standards and measures are needed to ensure hydro projects gain public acceptance.

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