Aspects of Ammonia as Green Fuel for Propulsion Systems of Inland Water Vessels

Abstract

Ships are a crucial backbone of the transport system for goods and people. However, the currently utilized fossil fuels require a green replacement. Ammonia produced from green hydrogen is an interesting, carbon-free green fuel, which has been demonstrated to be promising for maritime applications. Its application under the specific boundary conditions of river ships and other inland water vessels still deserves a closer evaluation. In this work, ammonia as a green fuel for propulsion systems of inland water vessels is evaluated regarding several technological aspects. These include onboard decomposition for hydrogen release, combustion of ammonia–hydrogen mixtures in internal combustion engines and the thermal integration of the different components. To achieve favorable combustion properties of the fuel, a certain share of the ammonia has to be decomposed in an ammonia cracker to produce a mixture of hydrogen and ammonia. First single-cylinder engine tests show that the combined combustion of ammonia and hydrogen allow an efficient and reliable process for the investigated high-speed engine concept. Efficiency values of nearly 40% at part load already are achieved. With proper system integration, it is possible to reasonably operate small- and medium-sized ships with ammonia as a green fuel.