Internal combustion engines powered by syngas: A review

Syngas is an intermediate step towards the transition from carbon-based to hydrogen-based fuels, promoted by the emerging concerns about climate change and damages to the environment. The negative impact of power generation systems will surely increase due to the continuous rise in energy demand. As a result, alternative methods must be found to reduce stationary and transport engines energy consumption and pollutant emissions, and the use of syngas as a fuel could be a very promising solution. This review is an attempt to aim and promote a wider employment of syngas as a fuel for internal combustion engines. Hence, after an overview of the technologies for syngas production, a detailed analysis of different applications of this gaseous fuel is presented and discussed. Specifically, dual-fuel Compression Ignition engines, Homogeneous Charge Spark Ignition engines and Direct Injection Spark Ignition engines have been investigated under syngas operating conditions from both experimental and numerical points of views. The performance and the emissions of such engines are carefully analysed and discussed. Indeed, they are very sensitive to the physical and chemical properties of syngas, i.e. the amount of CO and H-2, the laminar flame speed, the wide range of flammability and the lower density of syngas compared to air density.