Ammonia is a carbon-free liquid energy carrier that could enable renewable energy from fixed locations such as solar farms to power commercial aviation and other transportation applications. Due to its low flame speed, ammonia is usually co-fired with hydrocarbon fuels such as natural gas. In a new publication in the Proceedings of the Combustion Institute (https://doi.org/10.1016/j.proci.2020.06.094), we show that in these cases the ammonia dramatically suppresses soot particle formation from the hydrocarbon fuel. Comparison of ammonia/methane flames with nitrogen/methane flames shows that this is a direct chemical effect, not a consequence of fuel dilution or temperature changes. We measured significant increases in nitrogenated hydrocarbons such as acetonitrile in the ammonia flames, which suggests that the mechanism involves sequestration of carbon into nitrogen-containing species that do not contribute to soot formation. This paper has been accepted for presentation at the 38th International Combustion Symposium, so — pandemic allowing — Matthew will present this work in Adelaide Australia in January 2021.