Global pollution from electricity generation was set to fall last year, thanks to the growth of renewable energy. Then came the droughts.
Hydropower, the biggest source of renewable energy in the world, was crippled by lack of rain in several countries last year, driving up emissions as countries turned to fossil fuels to fill the gap. To cope with the electricity shortfall, China and India turned to coal plants, and Colombia to natural gas.
A recent report by the International Energy Agency showed that hydropower’s decline last year pushed countries to use dirtier sources of energy that produced an extra 170 million metric tons of carbon dioxide. That’s like turning on an extra 42 coal-fired power plants for a year. In China, the worst-hit country, hydroelectricity generation saw the steepest fall in the past two decades, according to the I.E.A.
This year, the dip in hydropower has continued in some countries, including Ecuador and Turkey, as temperatures continue to shatter records. Because its giant hydroelectric dams didn’t have enough water, Canada imported more electricity from the United States than it had done in over a decade, as my colleague Ivan Penn wrote this week.
But even in rainier years, hydropower comes with a catch.
Today, I want to explain why this century-old technology is struggling, why it may not be as clean as many people think and also why, despite all this, experts believe it still has an important role to play.
As Joe Bernardi, who tracks the industry for Global Energy Monitor, told me: “Hydropower remains a key piece of the global transition away from fossil fuels.”
Why hydropower has declined
Climate change’s role in the struggles of hydropower plants isn’t always clear. But studies have shown that pumping more carbon into the atmosphere changes precipitation patterns, increases the evaporation of water and melts glaciers that feed into some of the world’s biggest rivers.
All of this can dry up reservoirs that fuel hydropower plants, making it harder for countries to abandon dirty sources of energy that contribute to global warming.
Last year, El Niño, the weather pattern that makes many parts of the world dryer and warmer, added to the hydroelectric sector’s challenges. El Niño is associated with lower rainfall in several parts of the world that have large hydropower dams, such as the northwest of the United States and the southwest of China.
In the United States, hydropower generation fell 6 percent last year. The decline was mostly attributed to high temperatures having melted snow too quickly in the Northwest, leading to huge water loss that curbed energy production in hydropower plants.
In China, hydropower generation fell around 4.9 percent last year, according to the I.E.A., because of a severe drought in the southwest provinces of Sichuan and Yunnan, which can generate almost half of the country’s hydroelectricity. Still, renewables have grown so much in China that there is reason to believe that the country’s emissions may have peaked last year, as Carbon Brief reported.
Connectivity helps
Climate change doesn’t lead to drier conditions everywhere. In some parts of the world, it increases rain. In Brazil, lack of rain has dried up large dams that fuel power plants in the north, while frightening floods have come to the south, where there are even larger dams.
While climate change is still expected to present enormous challenges for hydropower in Brazil, rain in one part of the country can help offset drought in another. But that can happen only because Brazil’s grid is fully interconnected, meaning that the energy that each plant produces can be directed to almost any part of the country that needs it.
Experts say a better connected electric system in the United States and Canada would help the region cope with hydropower declines. Instead of one fully interconnected grid, the United States has three grids that connect only in a few points and share little power between them, as my colleagues Nadja Popovich and Brad Plumer explained.
“Most models suggest that a more interconnected grid is a better grid,” Shelley Welton, a professor at the University of Pennsylvania who helped write a recent report on the United States’ grid, told Penn. “I do think there is power in being interconnected across North America. We need scenario planning. We need long-term planning.”
A new way to think about hydropower
Unstable water cycles aren’t the only problem plaguing hydro. Methane emissions from organic matter that accumulates in reservoirs are an increasing source of concern, though they’re not yet fully understood. And a growing number of experts have pointed to hydropower’s overall carbon footprint, Inside Climate News reported last year. The construction of hydropower plants has led to significant biodiversity loss, as large ecosystems get flooded after dams are built.
Still, some policymakers are counting on hydroelectricity to help decarbonize their economies. Hydropower power plants that can be built to work as enormous batteries, called pumped hydro, are spreading around the world, as my colleagues Mira Rojanasakul and Max Bearak described last year. Importantly, these plants can often be built without large, traditional dams.
Still, many governments that rely on hydropower plants are projected to struggle to deliver as much electricity as they have historically. Experts suggest that these governments should gradually shift to using hydropower as a backup to intermittent renewable sources of electricity, like solar and wind, instead.
Bernardi told me that, while global warming can present a short-term challenge to hydropower, governments can avoid longer term problems by building more renewable power sources that can fill the gap when hydro can’t.
“Many hydropower plants are dispatchable,” he said, meaning that “they can be turned on and off as needed, making them a crucial part of the electric grid around the world.”
Why U.S. wind is struggling
When President Biden signed the 2022 Inflation Reduction Act, it was expected to set off a boom in renewable energy, with hefty tax breaks that would make solar and wind power cheaper than fossil fuels.
So far, however, that dream has come only partly true. Solar panel installations are indeed soaring to record highs in the United States, as are batteries that can store energy for later. But wind power has struggled, both on land and in the ocean.
The country is now adding less wind capacity each year than before the law was passed.
Some factors behind the wind industry’s recent slowdown are more easily fixed, such as snarled supply chains. But wind power is also more vulnerable than solar power to many of the biggest logistical hurdles that hinder energy projects today: a lack of transmission lines, a lengthy permitting process and a growing backlash against new projects in many communities.
It’s still possible that wind power could rebound. In fact, some experts argue that the recent slowdown is only a temporary artifact of tax policy. But if wind power continues to stagnate, that could make the fight against global warming much harder, experts say.
“Right now, solar is pretty much in line” with what experts projected, said Trevor Houser, a partner at the Rhodium Group, a research firm that has tried to model the effects of the climate law. “But wind really needs to grow by quite a bit. Going forward, we’re definitely much more concerned about wind.” — Brad Plumer and Nadja Popovich
P.S. Remember those mantled howler monkeys that were dropping from trees amid a brutal heat wave in Mexico? Some of the monkeys are recovering. In the past few days, Cobius, a nonprofit conservation group, released nine of them. Watch Dr. Gilberto Pozo and one of his colleagues release one fully recovered monkey here.