Hydropower is the world’s single largest source of green energy. On a global scale, hydropower plants produce more energy than all other renewable power sources combined.
However, the growth rate of new hydropower capacity has tapered off in recent years, and the sector is plagued by serious current and future problems, from increased incidents and intensity of droughts in a changing climate, and major negative environmental externalities associated with mega-dams.
Hydropower offers a critical benefit that other renewable energies don’t. It creates energy around the clock unlike solar and wind energy, which are dependent on weather patterns and therefore highly variable.
For this reason, hydropower is an extremely attractive option for river-endowed nations that want to boost their clean energy production levels without compromising grid stability or energy security. But in recent years, investment in expanded hydro has dropped off.
“In the last five years the average growth rate was less than one-third of what is required, signaling a need for significantly stronger efforts, especially to streamline permitting and ensure project sustainability”, the International Energy Agency (IEA) reported last year.
It continued that “Hydropower plants should be recognised as a reliable backbone of the clean power systems of the future and supported accordingly”.
But in recent years hydropower has not proved to be as reliant as its investors had hoped. Widespread droughts associated with climate change have caused rivers to run lower or even dry up entirely, causing seriously negative (literal) downstream effects for hydropower production plants.
In 2022, intense droughts in China’s Yangtze River basin slashed developed hydropower potential (DHP) by 26%, causing critical shortages and spurring an uptick in coal-fired power production.
In the last few years similar problems have cropped up in Brazil, Ecuador, the United States, and the Mediterranean region, too.
Critically, these are not isolated or one-off incidents; the risk of similar extreme droughts in the future rises by nearly 90% in a number of climate change scenarios, notably SSP585.
“Since September, daily energy cuts have lasted as long as 14 hours”, the New York Times recently reported from Quito, Ecuador.
“Highways have turned an inky black; entire neighborhoods have lost running water, even internet and cell service”, it added.
Not only does this have enormous implications for day-to-day life, these blackouts reverberate through the national economy. It is estimated that for every hour of blackout, Ecuador loses $12 million in productivity and sales.
Climate scenarios are just one of the factors deterring investors away from new hydropower mega-projects.
In the United States, investments in large hydropower plants all but drief up due to the simple fact that “there are no suitable river locations in the US for new ones”, according to recent reporting from CleanTechnica.
And the ones that do exist are associated with major ecological disruptions, changing flood patterns and blocking salmon runs for tens of millions of fish, among other environmental issues.
“There are certainly rivers in other countries which could be tapped using conventional hydropower technology, but not in the US”, Frederick Hasler wrote for CleanTechnica.
“Going forward, current US hydro needs to be maintained, but cannot be significantly increased”, he said.
And there are indeed major projects being planned in the rivers of other countries, but these are not without their own problems.
In the Congo, plans for the world’s largest hydropower project have been stalled for years after much enthusiasm at the outset. Some blame the Democratic Republic of the Congo’s poor governance for the Grand Inga dam’s failure to launch, while others point to a revolving door of international partners, a blisteringly high up-front cost of around $80 billion in one of the world’s poorest nations, and “deep concerns about the project’s environmental and social impact” according to reporting from the BBC.
But the need for the Grand Inga is enormous and impossible to ignore. Around 600 million people in Sub-Saharan Africa lack access to power completely, making electrification a critical step for economic and social development in the region.
But Africa does not have the luxury of emitting greenhouse gases indiscriminately as the developed world has done over the past 150 years.
Instead, the continent is under enormous international pressure to “leapfrog” over fossil fuels and straight to the development of clean energy systems.
It’s hard to imagine how this will be possible without large-scale hydropower.

By: Haley Zaremba