Saudi researchers find biofuels could significantly reduce NOx and other GHGs

In Saudi Arabia, switching to renewable fuels could significantly lower exhaust emissions of toxic nitrogen oxides (NOx) as well as curbing global greenhouse gas emissions. Researchers at the King Abdullah University of Science & Technology (KAUST) have combined computer analysis with laser-based NOx concentration measurements to understand NOx production pathways in different fuel types. The results may inspire new ways to mitigate NOx emissions, the researchers say.

In the latest study, researchers examined NOx emissions from alcohol fuels, such as ethanol. These renewable fuels have gained attention because they are potentially carbon-neutral, but they also produce lower NOx emissions than conventional fossil fuels. Nitrogen oxides can be produced by various pathways, each of which dominates a different stage of combustion.

The researchers used planar-laser-induced fluorescence (PLIF) to measure NOx production throughout the flame, comparing alcohol fuels with an alkane fossil fuel surrogate. The technique helped the team differentiate nonthermal NOx production pathways, which dominate early in the flame, from thermal NOx production pathways, which mainly occur in the high-temperature post-flame region.