Some 15 years ago, when the concept of ‘ammonia as a carbon-free hydrogen carrier’ first started, NO and NO₂ emissions were a scary 1000 – 10,000 ppm, way higher than the typical 10-100 ppm range for natural gas fired lean premix burners. Additionally, N₂O species (273 times the global warming potential  of CO₂) and HCN started to show up when ammonia was co-fired with natural gas. Cofiring of ammonia was thought to be needed due to the poor combustion properties of ammonia.

Since then, intensive R&D and testing across labs worldwide appears to have resolved many of the issues. This includes developments by Siemens Energy in collaboration with IFRF member SINTEF using their high-pressure HIPROX test facility.  As part of the IFRF Preferred Research Partner network, access to this facility is available to IFRF members and supporters.

Using a Rich-Quench-Lean type combustor concept to cope with the high fuel-bound nitrogen content of ammonia, impressive reductions in NOx emissions has been achieved. 100% ammonia operation is also demonstrated so that natural gas pilot fuel is not needed. Further details are provided in our CIN article on the topic.