MILD Combustion and Biofuels: A Minireview

Even in the presence of the formidable growth of renewable energy sources, advanced combustion processes have and will continue to have an irreplaceable role as a driving force for energy market. This is indeed motivated by the same huge amount of energy that can be conveniently stored in the form of energy carriers, made available from the renewable sources. The coupling of the appropriate combustion conversion technology with locally available biofuels certainly is among the most effective solutions, now on the table, to face the decarbonization challenge. In this framework, moderate or intense low oxygen dilution (MILD) combustion is among the best candidates to support the transition toward the net zero emission target. Indeed, due to its inherent features, it is highly fuel flexible and efficient, allowing for the utilization of whatever energy carrier can be considered in the decarbonization strategy. It is also characterized by an inherent low or absent pollutant emission. The novelty of this minireview is to highlight the relevance of the kinetics involved in MILD combustion processes with particular focus on biofuels, identifying invariant temperatures, relevant for process stabilization for any energy carrier. A critical evaluation of advantages and drawbacks of the use of raw bioliquids in MILD combustion conditions is reported. Then, challenges, open questions, and future perspectives on the use of biofuel in MILD combustion are discussed.