Advanced H2 ICE development aiming for full compatibility with classical engines while ensuring zero-impact tailpipe emissions 2024-37-0006

The societies around the world remain far from meeting the agreed primary goal outlined under the 2015 Paris Agreement on climate change: reducing greenhouse gas (GHG) emissions to keep global average temperature rise to well below 20°C by 2100 and making every effort to stay underneath of a 1.5°C elevation. Current emissions are rebounding from a brief decline during the economic downturn related to the Covid-19 pandemic. To get back on track to support the realization of the goal of the Paris Agreement, research suggests that GHG emissions should be roughly halved by 2030 on a trajectory to reach net zero by around mid-century.2 Although these are averaged global targets, every sector and country or market can and must contribute, especially higher-income and more developed countries bear the greater capacity to act. In 2020 direct tailpipe emissions from transport represented around 8 GtC02e, or nearly 15% of total emissions. This number increases to just under 10 GtC02e when indirect emissions from electricity and fuel supply are added, for a total share of roughly 18%. Following the current trend, direct and indirect emissions in transport could reach above 11 GtCOeq by 2050. Roughly 76% of transport emissions are related to land-based passenger and freight road transport. Emissions from aviation and shipping account for the remaining 24% of 2020 emissions. Efficiency and fuel switching, including electrification, allow scaled emissions mitigation in the Central scenario, and sustained action will be needed to ensure that by 2030 emissions are reduced by roughly 27% from 2020 levels. Reductions must reach nearly 78% by 2050. When indirect emissions are included, transportation provides the opportunity to eliminate around 9.4 GtCOeq of emissions by 2050 (7 GtC02eq direct and 2.4 GtC02eq indirect), or around 13% of total mitigation. Carbon neutrality impose substantial changes in our energy mix. Hydrogen (H2) is in this scenario considered to play a key role as a carbon-free and versatile energy carrier Combustion of hydrogen in an ICE offers the potential to accelerate the introduction of carbon-neutral mobility in the short to medium term at competitive cost due to the utilization of well-proven and mature technology elements. Given the high technological maturity of internal combustion engines (ICEs), there is an increasing interest in ICEs powered by hydrogen as a CO2-free solution for on- and off-road vehicles as well as construction equipment. Efforts are therefore being made to replace Diesel and natural gas engines with hydrogen ICEs, with at least the same power density and efficiency. The content of this publication displays the necessary engineering steps to successfully convert a diesel-based engine to H2 DI operation. All along the development, the objectives were set to develop the right technological combination which offer power, torque, and transient response comparable to current diesel engine. Upfront simulations work dictated the newly designed combustion system layout that fulfills the requirements for high level of charge motion with the maximum degree of communality with the Diesel base engine and its flat cylinder head design. The results shown demonstrate the great potentials of the hydrogen engine technology. The engine KPI are matching the ones from the diesel base engine while offering near-zero emission concept thanks to the alignment of engine control and aftertreatment system calibration. Remarkable experimental results regarding emissions at zero impact level, high specific power, dynamic response and efficiency are presented as well as further potentials and needs for the following research and development work. The paper closes with a direct comparison of the key functional data of the origin Diesel engine and the newly engineered H2-powered variant.