Science’s 2025 Breakthrough of the Year: The unstoppable rise of renewable energy

Since the Industrial Revolution, human society has run on ancient solar energy—captured by plants hundreds of millions of years ago, stored in fossil fuels, and dug and drilled from the earth. But this year momentum shifted unmistakably toward the energy that streams from the Sun today. Renewable energy, most of it from sunlight itself or from wind, ultimately driven by the Sun, overtook conventional energy on multiple fronts.

This year, renewables surpassed coal as a source of electricity worldwide, and solar and wind energy grew fast enough to cover the entire increase in global electricity use from January to June, according to energy think tank Ember. In September, Chinese President Xi Jinping declared at the United Nations that his country will cut its carbon emissions by as much as 10% in a decade, not by using less energy, but by doubling down on wind and solar. And solar panel imports in Africa and South Asia have soared, as people in those regions realized rooftop solar can cheaply power lights, cellphones, and fans. To many, the continued growth of renewables now seems unstoppable—a prospect that has led Science to name the renewable energy surge its 2025 Breakthrough of the Year.

That promise comes against a backdrop of downbeat news, highlighted at the U.N. climate meeting in Belém, Brazil, in November. Global carbon emissions continue to creep up as countries fall short of cuts pledged in the 2015 Paris climate agreement. The goal of limiting global warming to 1.5°C—always a long shot—now seems completely out of reach. But Hannah Ritchie, a data scientist at the University of Oxford and a climate blogger, is among those who see hope. Thanks to renewables, the long-awaited decline of fossil fuels is in sight, she says. China is “just, just on the cusp … of actually starting to push out coal,” and fossil fuel use in the rest of the world is likely to follow.

China’s mighty industrial engine is the driver. After years of patiently nurturing the sector through subsidies, China now dominates global production of renewable energy technologies. It makes 80% of the world’s solar cells, 70% of its wind turbines, and 70% of its lithium batteries, at prices no competitor can match. “China really mastered this … with the help of the scale of its economy, its manufacturing capacity, and the fierce competition right at home,” says Li Shuo, director of the China Climate Hub at the Asia Society Policy Institute.

As production surged, prices fell and demand took off. Production scaled up to keep pace, further driving down prices and igniting more demand. The result was a virtuous circle in which renewable technologies grew into an industry that now accounts for more than 10% of China’s economy. Wind and solar became the cheapest energy in much of the world.

The tsunami of tech spilling from China’s factories has changed the country’s energy landscape—and its physical one, too. For decades China’s development was synonymous with coal, which produced choking air pollution and massive carbon emissions, still greater than those of all other developed nations combined. Now, solar panels carpet deserts and the high, sunstruck plateau of Tibet, and wind turbines up to 300 meters tall guard coastlines and hilltops (see photo essay, below). China’s solar power generation grew more than 20-fold over the past decade, and its solar and wind farms now have enough capacity to power the entire United States.

China’s burgeoning exports of green tech are transforming the rest of the world, too. Europe is a longtime customer, but countries in the Global South are also rushing to buy China’s solar panels, batteries, and wind turbines, spurred by market forces and a desire for energy independence. In Pakistan, for example, imports of Chinese solar panels grew fivefold from 2022 to ’24 as the Ukraine war pushed up natural gas prices and the cost of grid power. “For people who were asking, ‘How am I going to keep the lights on in my home,’ it was a very obvious choice,” says Lauri Myllyvirta, an analyst at the Centre for Research on Energy and Clean Air. In South Africa, old and unreliable coal plants drove a similar dynamic. Ethiopia has embraced solar and wind amid worries that hydropower, the country’s mainstay, will decline as droughts become more frequent.

So far, this is not a story of new technology. China is “more or less relying on the same core [solar] technology that the United States invented half a century ago,” Li says. In those days the U.S. made boutique panels for spacecraft; now, China makes them for the world—better, vastly cheaper, and in staggering quantities.

Technological progress could power future gains. Solar cells today are made of crystalline silicon, but another kind of crystal, perovskites, can be layered in tandem with silicon to make cells that gain efficiency by capturing more colors of light. Material advances are enabling wind turbine blades to get longer and harvest more energy, while designs for floating turbines could vastly expand the offshore areas in which they could be deployed. And the giant lithium-ion batteries now used to store energy when sunshine and wind falter could one day give way to other chemistries. Vanadium flow batteries and sodium batteries could be cheaper; zinc-air batteries could hold far more energy.

In the meantime, climate scientists are already seeing benefits from the existing technology. This year renewables helped bring the growth of greenhouse emissions to a virtual standstill in China and put a global carbon peak within reach. But to meaningfully cut emissions, the world needs to treat the thresholds crossed this year as just a starting point.

“It is worrying to me that China continues to build coal,” says Kelly Sims Gallagher, an energy and climate expert at Tufts University. Dozens of new plants were commissioned in the past year, though many sit idle, waiting to be fired up as “peakers” to meet spikes in demand. In the U.S., President Donald Trump’s administration has declared war on wind and solar development, and cheap Chinese solar panels face formidable trade barriers. U.S. coal consumption is rising this year after a long decline.

The infrastructure needed to take full advantage of wind and solar is another hurdle. China is building battery farms to store green power and long-distance transmission lines to get it to cities, but perhaps not fast enough. Air travel and heavy industries won’t be electrified anytime soon.

But if concerns lurk in the future, looking back brings home the astonishing progress renewables have made. In 2004, it took the world a full year to install 1 gigawatt of solar power capacity. Today, twice that amount goes online each day. Back then renewables had an aura of virtue: Buyers paid a premium over fossil energy because of climate concerns. Now, the real driver is self-interest: lower cost and greater energy security.

That change in motivation may be the most important breakthrough of all, ensuring that this year’s inflection points are just the beginning.

China’s turn to green energy dwarfs any other country’s, as a parade of astonishing numbers attests. In 2024 alone it installed new solar and wind generation equivalent to roughly 100 nuclear power plants, and the pace quickened early this year. Dozens of new, ultrahigh-voltage power lines are marching thousands of kilometers from western deserts where much of the solar energy is generated to the eastern cities where it is used. Hungrily awaiting the bounty of clean energy are millions of electric cars and a sprawling network of high-speed electric trains that can zip between cities 1000 kilometers apart in a morning.

China’s landscape reflects this metamorphosis. The vistas of smog, smokestacks, and coal heaps still exist, but glinting silicon panels now cover hills, deserts, and lakes. One solar farm on the Tibetan Plateau spans more than 400 square kilometers, an area more than twice the size of Washington, D.C. Wind turbines grow ever bigger; one meant for use offshore has blades 150 meters long. Arrays of house-size lithium batteries stockpile excess energy, and more is stored in mountaintop reservoirs, pumped full of water when energy is abundant and tapped as needed by allowing the water to cascade through turbines to a lower lake. The factories that produce the solar panels, turbines, batteries, and cars have added new industrial sprawl—but often without the smokestacks because they are electrified.

These days, the containers in China’s busy ports are packed with new wares: electric cars, solar cells, wind turbine blades. In building up its own green energy system, China has also created an export industry worth nearly $180 billion in 2024, putting low-cost renewable energy within reach for much of the rest of the world (see story, above). The revolution these images document is now going global.

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