Hydrogen Carriers as Alternative Fuels on Ships

The shipping industry is responsible for a approximately 2 to 3% of the global greenhouse gas emissions. The International Maritime Organization (IMO) has set a goal in 2023 to reduce these emissions. This goal entails that the sector becomes net-zero by 2050, which should be partly realized by adding alternative fuels to the energy mix. In general, methanol, ammonia and hydrogen are considered as promising alternative fuels. However, all three have challenges, such as toxicity (methanol and ammonia) or explosivity (hydrogen). Additionally, none of them have volumetric and gravimetric energy densities that are close to the current standards of heavy fuel oil (HFO) and marine diesel oil (MDO).

Hydrogen carriers can solve these challenges. Hydrogen carriers are chemicals that store and release hydrogen on demand. There is only very little pure hydrogen gas on board, which reduces safety risks. Additionally, hydrogen carriers can store a relatively large amount of hydrogen, up to over 20 wt%, enhancing the volumetric and gravimetric energy density. Finally, the inherent properties of each hydrogen carrier determine their applicability. Since some carriers behave similarly to oil, they offer a significant advantage for existing bunkering and fuel-transport infrastructure....