Nitrogen fixation converts inert atmospheric nitrogen (N₂) into forms usable by plants and industry, primarily ammonia (NH₃) for fertiliser. The Haber–Bosch process, which combines N₂ and hydrogen under high pressure and temperature using a catalyst, has fed the world for over a century but is energy-intensive and relies on fossil-derived hydrogen, accounting for a significant share of global energy use and emissions. Green nitrogen fixation aims to produce ammonia using renewable energy (electrolysis for green hydrogen, or direct electrochemical reduction of N₂) or biological and bio-inspired systems (nitrogenase enzymes, engineered microbes, or synthetic catalysts that mimic them). Early-stage approaches include electrochemical and photochemical reactors and engineered microbial or rhizobial systems.
The technology addresses the environmental footprint of fertiliser production and the need to decarbonise industrial chemistry. Fertiliser supports roughly half of global food production; demand will persist as population and dietary expectations grow. Green ammonia could also serve as an energy carrier or fuel. Research is advancing on catalyst design, reactor efficiency, and integration with renewable power. Electrosynthesis of urea (co-reducing CO₂ and nitrogen) is a related route that could produce fertiliser and utilise CO₂ in one step.
Scale and cost remain barriers. Haber–Bosch is mature and optimised; green alternatives must reach comparable scale and reliability. Policy and carbon pricing could accelerate adoption. If technical and economic hurdles are overcome, green nitrogen fixation could significantly reduce the climate and energy impact of fertiliser and contribute to sustainable food systems.