Ships with hybrid propulsion or even purely electric ships are still a rarity and can mainly be found in the luxury segment. Environmental and climate protection are still not in the foreground when it comes to ship operation and new construction by the large cruise companies. Heavy fuel oil remains the fuel of choice for most existing fleets. Only a few truly future-oriented projects are in the planning and implementation stages. This is shown, among other things, by the cruise ranking of the German Nature Conservation Union (Nabu), even in the tenth year of its existence.