Environment & Energy

2025
BREAKTHROUGH OF THE YEAR
18 DEC 2025 2:00 PM ET

GOOD MORNING, SUNSHINE
The seemingly unstoppable growth of renewable energy is Science’s 2025 Breakthrough of the Year
BY TIM APPENZELLER

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.

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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.

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