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

Abstract

Global nitrogen oxide (NO_x) emissions have surged over the past fifty years, contributing to pollution problems such as surface-level smog. Primarily produced during the combustion of fuels, NO_x emissions are challenging to fully mitigate across various industries due to regulatory gaps and inefficient, costly abatement technologies. This perspective provides an overview of NO_x 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 NO_x abatement technologies is provided, with costs of treatment in the range of $2–8 per kg NO_x. Finally, the existing NO_x 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 NO_x abatement technologies that address the shortcomings of current solutions.