Santiago Molina

The increase in the overall global temperature and its subsequent impact on extreme weather events are the most critical consequences of human activity. In this scenario, transportation plays a significant role in greenhouse gas (GHG) emissions, which are the main drivers of climate change. The decline of non-renewable energy sources, coupled with the aim of reducing GHG emissions from fossil fuels, has forced a shift towards a net-zero emissions economy. As an example of this transition, the European Union has set 2050 as the target for achieving carbon neutrality. Hydrogen (H₂) is gaining increasing relevance as one of the most promising carbon-free energy vectors. If produced from renewable sources, it facilitates the integration of various alternative energy sources for achieving a carbon-neutral economy. Recently, interest in its application to the transportation sector has grown, including different power plant concepts, such as fuel cells or internal combustion engines. Despite exhibiting significant drawbacks, such as low density, combustion instabilities, and incompatibilities with certain materials, hydrogen is destined to become one of the future fuels. In this publication, experimental activities are reported that were conducted on a spark-ignition engine fueled with hydrogen at different operating points. The primary objective of this research is to gain a better understanding of the thermodynamic processes that control combustion and their effects on engine performance and pollutant emissions. The results show the emission levels, performance, and combustion characteristics under different conditions of dilution, load, and injection strategy and timing.