Toward Sustainable Energy Production with Plasma-Assisted Combustion*

Sustainable energy production requires that the CO₂ emissions caused by fossil-fuel combustion, which represents today over 80% of the primary energy production, be stringently reduced or eliminated. To supplement clean electrified solutions, novel CO₂-neutral combustion technologies with sustainable fuels are widely considered, but like traditional combustion they face increasingly stringent regulations on pollutant emissions, in particular nitric oxides, carbon monoxide and particulates. The problem of NOx emissions is also a key issue for CO₂-free combustion with hydrogen or ammonia. An effective way to reduce these pollutants is to burn at low temperatures using lean fuel-air mixtures.  However, these flames may cause safety issues because they are prone to instabilities and extinction. Plasma-assisted combustion (PAC) is a promising method to stabilize lean flames thanks to the extraordinary ability of plasma discharges to efficiently produce combustion-enhancing radicals.

In this presentation, we will start by reviewing the challenges that can be addressed with plasma-assisted combustion in industrial configurations. We will then review the tremendous advances of the past decade toward elucidating the fundamental thermal, chemical, and hydrodynamic processes in flames sustained by nonequilibrium discharges and their impact on pollutant emissions. We will show in particular the importance of nonequilibrium chemical effects. We will also describe the status of advanced modeling of PAC effects and provide illustrative examples of complex 3D numerical simulations of PAC in turbulent flames with traditional and sustainable fuels for various combustor configurations and a wide range of operating conditions. Finally, we will present the remaining challenges and the ongoing efforts to extend the application of PAC to high power combustors representative of industrial configurations.