Nitrogen fixation, a $200 billion market in the US alone, converts atmospheric nitrogen into ammonia at a scale of more than 150 million tonnes per year, which is needed to produce fertilizer supporting 50% of the world’s food production.86 Green nitrogen fixation now aims to reduce the significant carbon footprint of conventional nitrogen production, which currently accounts for 2% of global energy consumption.87 In nitrogen fixation, microorganisms convert nitrogen in the atmosphere into forms that plants and other organisms can use for nutrients, primarily ammonia. The key challenge in nitrogen fixation is breaking the extremely stable triple bond that holds together the two nitrogen atoms that make up atmospheric nitrogen (N2). In the state-of- the-art Haber-Bosch process, this step requires temperatures of 400-500°C, pressures 130 to 150 times greater than that found in the Earth’s atmosphere, and hydrogen primarily sourced from natural gas88 in a CO2-generating reaction. While the principle of alternative nitrogen fixation was discovered in the 1930s, only recently has there been considerable progress towards large- scale commercialization. For example, bio-based approaches use engineered bacteria and enzymes to fix nitrogen89 and sunlight, or green electricity can provide energy and reduction equivalents. Bio-inspired systems also show promising results, replicating enzyme function by inorganic polyoxometalates or anionic metal-oxide clusters.90 Further, electrochemical technologies relying on lithium as mediators are at the brink of commercial application.91 Green nitrogen fixation technologies are currently being explored by both established and start- up companies. Australian Jupiter Ionics is spearheading lithium-based nitrogen fixation technology, whereas California-based Ammobia is focusing on new, more efficient catalysts. Such alternative technologies would also allow decentralized production plants, enabling ammonia to be generated using locally abundant renewable energy, such as wind and solar. The ammonia produced locally could then be efficiently stored and/or processed into fertilizer on-site,92 saving transport energy and costs. Progress in creating localized green ammonia production would not only reduce ammonia production’s carbon footprint but also would reduce related CO2 sources, such as in required transport.93 Means of transport will also benefit, as commercial vessels are already employing ammonia as diesel fuel and estimates project that more than 30% of global marine fuel could be carbon-free ammonia by 2050.94 Next-gen technologies employing lithium chemistry or biology-based approaches to nitrogen fixation are being explored, but their commercial viability has yet to be established.95 In contrast, ammonia production plants using green hydrogen instead of natural gas have proven viable and are currently being scaled globally.96 The ammonia industry is in a transition,97 where increasing R&D efforts in green ammonia fixation technology paired with an increasing demand (as, for example, from the transport sector) will spark additional innovation and investment towards net- zero carbon ammonia production.Javier Garcia-Martinez Professor, Director of the Molecular Nanotechnology Lab, University of Alicante Krishna Kumar Chief Executive Officer, Cropin Sage Sang-Yup Lee Senior Vice-President, Research; Distinguished Professor, Korea Advanced Institute of Science and Technology (KAIST) Wilfried Weber Scientific Director and Professor for New Materials, Leibniz Institute for New Materials Boxed Icons Build industry-agriculture partnerships – Create focused collaborations between green nitrogen technology developers and major agricultural stakeholders to establish pilot programmes demonstrating cost and environmental benefits.Ecosystem readiness map Boxed Icons Accelerate alternative process technologies – Invest in targeted research to improve lithium-mediated and biological nitrogen fixation methods to provide viable alternatives to traditional processes.KEY ACTIONS TO ACHIEVE SCALE TechnologicalSocial Economic EnvironmentalPolicy Image: Green nitrogen fixation uses renewable energy and biology to produce ammonia sustainably, reducing emissions and enabling local production. Credit: Midjourney and Studio Miko. Prompt (abbreviated): “Highly detailed green bio fibres interweaving and connecting.” Read more: For more expert analysis, visit the green nitrogen fixation transformation map. Authored by: Hailong Li and Zequn Yang. Top 10 Emerging Technologies of 2025 28