This paper presents fast time-domain propulsion system simulation models for the Duisberg Test Case (DTC) post-Panamax container vessel using both diesel and ammonia as a fuel. The paper also provides first results of a ship integration study, demonstrating how the innovative combined SOFC- ICE AmmoniaDrive power plant could be integrated into the ship design.
With the first propulsion system model presented, voyages of the DTC container vessel are simulated while operating on regular marine diesel fuel, i.e., VLSFO, in a regular marine two-stroke diesel engine. In other words, this model provides voyage simulations of the current situation for comparable vessels. The propulsion system model is then converted, using crude but effective assumptions, to simulate ammonia-diesel operation of the same vessel, mimicking a situation in which the ship, or its main engine, is retrofitted to operate on ammonia-diesel. In this model, the ship has the same direct-drive propulsion system as before, with the same main engine and power output.
After presenting the results for the current situation and a potential near-future situation of ammonia- diesel operation for the DTC container vessel, a new propulsion system model is presented, based on the so-called AmmoniaDrive power plant concept. In this concept, ammonia is used as a fuel for a solid oxide fuel cell, producing hydrogen-rich anode off gas and electric power for the ship’s systems and a part of the required propulsion power. The hydrogen in the AOG is used as a combustion promoter in a main propulsion engine that provides the majority of the required propulsion power using ammonia as primary fuel, hydrogen from the AOG as a secondary fuel and a very small amount of HVO diesel pilot fuel as ignition source using Diesel’s Compression Ignition concept. The results of this first, early version of a AmmoniaDrive Propulsion, Power and Energy (PPE) system model are presented, after which the integration of such a system in the ship design is investigated by implementing the ammonia storage system as well as the main AmmoniaDrive power plant system components in the ship envelope of the DTC post-Panamax container ship. The impact on the amount of containers that can be carried by the vessel is modest, with only ~3.5% less cargo carrying capacity than the current diesel-fueled container vessel. Due to the crude assumptions made and the differences in the two models, it is not yet possible to quantify the decrease in ammonia consumption of the ship with AmmoniaDrive power plant compared with the ammonia-diesel fueled ship. Harmful emissions are potentially reduced by more than 95%. This is not only the result of switching to ammonia as primary fuel, but also because of a homogenous charge compression ignition, with flame propagation as main combustion principle, in the future ammonia-hydrogen marine IC engine. ... Read more

Compared to other Arctic ice masses, Svalbard glaciers are low-elevated with flat interior accumulation areas, resulting in a marked peak in their current hypsometry (area-elevation distribution) at ~450 m above sea level. Since summer melt consistently exceeds winter snowfall, these low-lying glaciers can only survive by refreezing a considerable fraction of surface melt and rain in the porous firn layer covering their accumulation zones. We use a high-resolution climate model to show that modest atmospheric warming in the mid-1980s forced the firn zone to retreat upward by ~100 m to coincide with the hypsometry peak. This led to a rapid areal reduction of firn cover available for refreezing, and strongly increased runoff from dark, bare ice areas, amplifying mass loss from all elevations. As the firn line fluctuates around the hypsometry peak in the current climate, Svalbard glaciers will continue to lose mass and show high sensitivity to temperature perturbations. ... Read more

Melting of the Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (GICs) contributes about 43% to contemporary sea level rise. While patterns of GrIS mass loss are well studied, the spatial and temporal evolution of GICs mass loss and the acting processes have remained unclear. Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote sensing data, to identify 1997 (±5 years) as a tipping point for GICs mass balance. That year marks the onset of a rapid deterioration in the capacity of the GICs firn to refreeze meltwater. Consequently, GICs runoff increases 65% faster than meltwater production, tripling the post-1997 mass loss to 36±16 Gt -'1, or -1/414% of the Greenland total. In sharp contrast, the extensive inland firn of the GrIS retains most of its refreezing capacity for now, buffering 22% of the increased meltwater production. This underlines the very different response of the GICs and GrIS to atmospheric warming. ... Read more