An Overview of Hydrogen Applications in Internal Combustion Engines Toward Transport Decarbonization

Hydrogen as a fuel exhibits significant potential for integration into energy systems, potentially enabling the decarbonization of the transportation sector and achieving sustainability goals in alignment with global and European Sustainable Development Goals strategies (SDGs). The decarbonization of the energy sector is outlined in the Paris Agreement, which sets specific objectives that United Nations member states are obligated to meet by 2030 and 2050. This paper explores the latest trends in the development and application of hydrogen in internal combustion engines (H₂ - ICE) as a fuel. It covers the fundamental principles of H₂ - ICE operation, including necessary modifications to conventional internal combustion engines (modification of fuel supply systems, combustion chamber design, thermal load management, and H₂ storage systems in vehicles). Additionally, the paper examines the compliance of H₂ - ICE technology with European strategies, including the European Green Deal and Euro 7 emission standards. The European Union's regulatory framework (Hydrogen Strategy and REPowerEU plan) defines guidelines for accelerating the transition to renewable energy sources and achieving energy independence, supported by financial mechanisms that encourage the adoption of hydrogen in the automotive industry. Furthermore, the study provides an analytical overview of industry trends among leading vehicle and engine manufacturers, highlighting the development processes of hydrogen engines and their applications in passenger and commercial vehicles. Through an analysis of the advantages and limitations of H₂ - ICE, the paper positions H₂ - ICE as a complementary technology to fuel cells (hybrid electric vehicles) and offers specific conclusions and recommendations for future research, including improvements in engine efficiency, emission reductions, and the development of hydrogen infrastructure. These efforts aim to ensure a sustainable and economically viable transition toward clean transportation.