Navigating the challenges of global NOx emissions throughout the energy transition: state of play and outlook

Abstract

Global nitrogen oxide (NOx) emissions have surged over the past fifty years, contributing to pollution problems such as surface-level smog. Primarily produced during the combustion of fuels, NOx emissions are challenging to fully mitigate across various industries due to regulatory gaps and inefficient, costly abatement technologies. This perspective provides an overview of NOx emissions, and details the significant increase in emissions that could occur with the shift to renewable fuels such as hydrogen and ammonia. A summary of key incumbent and emerging post-combustion NOx abatement technologies is provided, with costs of treatment in the range of $2-8 per kg NOx. Finally, the existing NOx regulatory landscape is reviewed, underscoring the critical need for stringent and global emission limits, particularly when certifying and regulating renewable and low-carbon fuels. To attain net-zero emission targets, regulations must evolve alongside innovative NOx abatement technologies that address the shortcomings of current solutions.