The worldwide markets around the globe endure far from meeting the originally arranged primary objective outlined under the Paris Agreement on climate change in 2015: mitigating greenhouse gas (GHG) emissions to retain global average temperature rise to well below 2°C by 2100 and making every effort to stay below a 1.5°C elevation of the average temperature. Today’s emissions are rebounding from an intermediate decline during the economic downturn related to the implications coming from Covid-19 pandemic. To get back on track with the realization of the targets of the Paris Agreement, research suggests that GHG emissions should be reduced by approx. 50% by 2030 on a guiding trajectory to reach net zero by around mid-century. Although these objectives are all averaged global targets, every sector and country/market need to participate, especially prosperous and more developed countries bear in general the higher responsibility to act.
In 2020 direct tailpipe emissions from transport represented around 8 GtC02e, or approx. 15% of overall GHG emissions. This number elevates to nearly 10 GtC02e, if indirect emissions from electricity and fuel supply are added, accumulating to a total amount of roughly 18%. Following the latest tendency, direct and indirect emissions in transport could reach above 11 GtCOeq by 2050. Roughly 3/4 of transport emissions are related to land-based passenger and freight road transport. Emissions from aviation and marine transport account for the remaining 24% of the 2020 emissions. Efficiency enhancement and fuel change, 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 are foreseen to 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.
In this context, carbon neutrality imposes substantial changes in our energy mix. Hydrogen (H2) is in this mainstream scenario considered to take 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 all kinds of vehicles and applications, incl. racing. Depending on the application functional parameters differ in the ranking between power output, efficiency, and reliability, besides the efforts for the conversion for changing the fuel type.
The major intention and aim of this paper is given by the identification and description of the major modification and adaptation needs for the conversion of a classical Diesel engine towards hydrogen operation in order to pave the fast way forward to carbon-neutral propulsion systems in the mobility sector. The detailed content of this publication displays the necessary engineering steps and provides an orientation for the utilization of an advanced toolchain to successfully convert existing mature engines straightforward and effectively into high-efficiency H2 operation with ultra-low tailpipe emission behavior according to the targeted specifications, incl. high performance attributes. It is especially foreseen to pinpoint the major hurdles and obstacles during the engine conversion process from conventional fuel usage to hydrogen operation.
The paper closes with a compiling overview and examples of realized achievements, before summarizing the intention and motivation for the publication.