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Battery storage systems with high energy density, safety, cost-effectiveness and wide operating temperatures are needed for smart grid integration. High-energy lithium-ion systems, quasi-solid-state configurations and sodium-ion batteries were among the main strategies pursued in 2025 to achieve that goal.
Rapid expansion of renewables has thus far mostly covered fast-growing energy demand rather than displacing fossil fuels. New demand drivers such as data centres and cooling could reverse declining demand trends from 2024–2025 without further effort.
In 2025, water electrolysis for green hydrogen production continued to progress towards gigawatt-scale deployment worldwide, whereas CO₂ electrolysis for carbon-based fuels and chemicals synthesis saw advances at the cell and catalyst levels and moved towards pilot-scale demonstrations. Although at different stages of technical readiness, the two fields share common future challenges.
Despite uncertainly around climate-focused policy, the policy outlook for clean-energy technologies remained resilient in 2025, owing to the cost-competitiveness of key technologies combined with emerging priorities relating to energy security, data centres, defence and economic opportunities.
Perovskite photovoltaics entered a transformative phase in 2025, characterized by the widespread transition from n–i–p to p–i–n architectures, rapid progress in tandem device integration and improvements in long-term operational stability. These advances collectively highlight the maturation of perovskite solar cells towards commercial viability and industrial scalability.
In 2025, enhanced geothermal systems advanced from demonstration to commercial-scale deployment, supported by continued improvements in drilling and well performance. New pilots exceeding 330 °C enabled breakthroughs towards accessing superheated or supercritical resources, an important frontier for geothermal power generation.
The importance of renewable integration into grids came to the forefront in 2025. New challenges in stability, storage, artificial intelligence demand and policy changes defined a year that tested whether power systems can become reliable, flexible and equitable in a net-zero world.
