China's $167 billion mega dam faces setback as weak rains hit hydropower

By David Fickling

 

The world’s biggest polluter is keeping emissions under control. It’s getting no help from the weather. 

Electricity generation from thermal power stations in China fell 1.3 per cent through July this year. Combined with a 4.5 per cent drop in cement production and 3.1 per cent fall in steel, that’s a sign that coal consumption is still falling, even as factory activity continues to grow. Given the country is responsible for about a third of all carbon emissions, that’s unalloyed good news.

 

It was a far closer thing than it should have been, however, thanks to the continued underperformance of hydroelectricity. That should give China’s leadership pause as they embark on the $167 billion Yarlung Tsangpo dam, a project being built on the eastern edge of Tibet that will be the biggest power plant ever built once completed.

 

 

China has increased the capacity of its hydro generators by more than a third since 2020, but so far this year their electricity production is up only 11 per cent. Hydro generation through July fell by 27.8 terawatt-hours compared to 2024, almost as dramatic as the 37.4 TWh drop in thermal power. For reasons that aren’t entirely clear, the country is getting fewer and fewer electrons back for all the concrete that it’s using to dam up its rivers. 

 

One clear factor is a run of disappointing rainfall. If you want to understand the direction of emissions in any given year, look to the amount of water flowing through the basin of the Yangtze river. Its network of dams provides about a fifth of the world’s hydroelectricity. When those channels ebb, it’s coal that makes up the shortfall.

 

This year is no exception. Despite floods and typhoons that have lashed Beijing and coastal provinces over the past month, rainfall in the basin was 25 per cent below long-term averages in July. This year is shaping up to be the fourth dry year out of the past six. Without the H20 to turn their turbines, all those hydro generators end up sitting idle. 

  With luck, the dry spell that began in 2021 is simply an unfortunate cluster of lean years, and will normalize over time as rainfall returns to its historic trend. But one thing we know about our warming planet is that the historic trend is a bad guide to the future. Much of the earth is rapidly drying out as the climate changes, adding an area of arid land the size of California every six months. 

 

A surprising factor that may be contributing to this phenomenon in China is its success in tackling pollution. It’s easy to forget, but a decade ago, few news stories were complete without hellish images of cities smothered by clouds of particulates belched by its power stations. A crackdown beginning around 2013 changed this utterly. Airborne concentrations of PM2.5, a variety of pollutants associated with elevated risks to human health, fell about a third by 2019. That’s already estimated to be saving hundreds of thousands of lives a year.

 

The reduction has other effects, however. All that haze was reflecting sunlight back into space. Its disappearance means more rays are making it to the surface of the earth, where they can warm the atmosphere. More than 80 per cent of the acceleration of global warming since 2010 can be attributed to reductions in sulfur dioxide as a result of East Asia’s particulates crackdown, according to a study published in the journal Communications Earth & Environment last month.  

 

Particulates can also affect rain, by forming airborne “seeds” around which humid air can coalesce into droplets and, eventually, storm clouds. These relationships aren’t well understood, but might provide an explanation for the spell of dry years in the Yangtze. Rainfall in the area increases with industrial pollution and decreases as the skies are cleaned up, researchers at Nanjing Normal University found earlier this year. PM2.5 concentrations at the heart of the basin fell by half between 2013 and 2020, though they’re still higher than levels considered safe.

 

This suggests a troubling possibility. Beijing started planning its vast hydroelectric system as its only serious bulwark against rising carbon emissions, before the rise of wind, solar, batteries and electric cars changed the rules of the game.

 

The dams were mapped out based on the climate forecasts of the pre-2013 era, when the weather of southwest China was being driven by the choking particulate smog produced by the first stage of its economic boom. The case for the Yarlung Tsangpo, the last and greatest of these projects, is predicated on similar observations of rainfall that may already be past their use-by date.

 

Should the current run of drought years and underperforming dams continue, China is going to have to work harder when its citizens crank up the air conditioning in the summer monsoon heat of a warming planet. Its coal generators, currently in retreat thanks to the growth of wind and solar, will be able to eke out a few more years of damage, too. If the Yangtze’s dry spell doesn’t break soon, all of us will suffer.  

(Disclaimer: This is a Bloomberg Opinion piece, and these are the personal opinions of the writer. They do not reflect the views of www.business-standard.com or the Business Standard newspaper)