NEW STUDY: Food waste, brown water and CO₂ to produce sustainable ammonia and urea

One hundred seventy-five million metric tons of urea, one of the most important nitrogenous fertilisers, is produced every year to support half of the global food supply.

However, its traditional production process to make its ammonia feedstock, known as Haber-Bosch, has been proven to produce about two tons of CO₂ for every ton of ammonia and to consume 30,5 megajoules of energy for every kilogram of ammonia formed.

A new approach developed by researchers at The University of Sheffield and EarthShift Global focuses on the synthesis of sustainable ammonia and urea by using food waste, brown water and CO₂ as feedstocks.

In the study, the energy intensity, greenhouse gas emissions, and the impact on the environment of processes utilising green technologies to synthesize ammonia and urea from waste were modelled to determine their respective efficiency compared to current production processes.

 

Major findings:

• A one-stage anaerobic digestion method would be the most efficient for reducing greenhouse gas emissions.

 

• A two-stage waste treatment system using a dark fermentation process along with anaerobic digestion and a water electrolysis-based hydrogen source would produce ammonia with the lowest energy intensity, making it nearly seventy percent more efficient than traditional water electrolysis coupled Haber-Bosch processes, and nearly thirty-seven percent more efficient than steam methane reformation coupled Haber-Bosch.

 

To learn more about innovative methods to use CO₂ as feedstock in ammonia and urea production, you can also follow our INITIATE project "Innovative Industrial Transformation of the Steel and Chemical Industries of Europe", which aims to demonstrate the conversion of residual gas from the steel industry into valuable products such as fertilizers (high purity urea).