Science has named the seemingly unstoppable growth of renewable energy worldwide as the 2025 Breakthrough of the Year. Since the Industrial Revolution, humanity has relied on fossil fuels like coal, oil, and gas for energy. Carbon emissions from these finite resources have greatly contributed to accelerated climate warming. However, 2025 marked a significant shift in this paradigm as renewable energy generated from the Sun and wind began to surpass conventional fossil fuel-based energy production in several domains. This year, global renewable energy, led by solar and wind, grew fast enough to cover all the world’s new electricity demand in the first half of the year, and now supplies more electricity than coal worldwide. This transition is being led by China, whose efforts to scale up solar panels, wind turbines, and lithium battery storage have cemented the nation as a global leader in renewable energy production and technology. Elsewhere, small-scale rooftop solar systems – made affordable and widely accessible by China’s manufacturing dominance – are spreading rapidly, particularly across Europe, South Asia, and the Global South, and provide reliable, low-cost energy security for millions. Already, existing renewables have demonstrably slowed the growth of greenhouse emissions in China, hinting at a global turning point in addressing ongoing climate warming. What’s more, further technological innovations in this space, such as more efficient solar cells and battery chemistries, for example, promise to extend the reach and effectiveness of renewable energy. Many obstacles remain, however, including continued widespread coal use, infrastructure bottlenecks, and political resistance in some regions (including the United States). Yet, despite these challenges, this year’s breakthrough suggests that the transition from fossil fuels to clean, renewable energy is not just possible – it’s accelerating – and rapidly becoming the most practical and cost-effective choice.

 

Podcast: A segment of Science's weekly podcast with Greg Miller, related to this research, will be available on the Science.org podcast landing page [http://www.science.org/podcasts] after the embargo lifts. Reporters are free to make use of the segments for broadcast purposes and/or quote from them – with appropriate attribution (i.e., cite "Science podcast"). Please note that the file itself should not be posted to any other Web site.

Researchers present LightGen – the first all-optical chip capable of performing challenging advanced generative artificial intelligence (AI) tasks at speeds and energy efficiencies orders of magnitude beyond today’s traditional electronic hardware. Large-scale generative AI models can now create text, images, and video with remarkable fidelity. However, these sophisticated tasks require enormous computing power, time, and energy; existing hardware struggles to meet the demands of today’s large models. Photonic computing, which processes information using pulses of laser light instead of electricity, offers a promising path toward dramatically faster and more energy-efficient AI. Although early photonic systems already outperform conventional chipsets in speed and efficiency, fundamental limitations in their design and function have hindered their use in advanced AI applications. According to Yitong Chen and colleagues, solving these issues is crucial to enabling photonic hardware that can drive ultrafast, energy-efficient generative AI. Here, Chen et al. present LightGen, an entirely optical generative AI chip that could overcome the challenges of traditional photonic systems. The authors developed a so-called optical latent space and Bayes-based training algorithms, that allow varying the optical network dimensionality using pure light-based processes. What’s more, the chip hosts more than two million photonic “neurons,” enabling it to perform complex generative tasks, including high-resolution image synthesis, video manipulation, style transfer, and denoising. Chen et al. show that LightGen could achieve these tasks with exceptional speed and energy efficiency, exceeding current state-of-the-art electronic chips by orders of magnitude.