Fertilizer made in the field itself: sunlight and soil now brew urea in a Spanish pilot

A field in Viladecans, Spain, is making its own fertilizer. After three years of work, the CONFETI project — led by the Universitat Autònoma de Barcelona — has a pilot system running in a real farm setting that produces urea, the workhorse fertilizer crops depend on, from carbon dioxide and nitrates. The reactor runs on biobatteries, which draw electricity from microbes and organic matter in the soil, together with solar panels. A second, sunlight-driven reactor turns leftover nitrates in water into ammonia, another key fertilizer ingredient, so nutrients are recovered instead of washed away. The system kept working through the summer and through heavy rain. 'There is another way to produce fertilizers, using pollutants such as CO₂ and nitrates,' says project coordinator Gonzalo Guirado — made where the food grows, and made on demand.

SDG 2 · Zero hunger — Mechanism: tech innovation