This thesis investigates the total environmental impact of various alternative marine energy carriers while taking the powering increase into account due to their disadvantageous spatial requirements compared to conventional fuel. A parametric design tool for bulk carriers, tankers, container ships, and trailing suction hopper dredgers has been developed for the future marine energy carriers to determine the total installed engine power increase. A more environmentally friendly energy carrier can be overturned because the total installed engine power increase is proportionate to the energy consumption increase. A comparative life cycle assessment (LCA) has been performed on fuel oil, methanol, LNG, liquid hydrogen, ammonia, and batteries for the conventional and a bio/renewable version of their well-to-wake pathway. The powering impact results indicate that all ship type and energy carrier combinations require a higher total installed main engine power and consequently a higher energy carrier consumption. The total environmental impact results indicate that only renewable liquid hydrogen and renewable ammonia have less adverse effects on global warming, and cause less damage to human health, ecosystems, and natural resource availability.

In this thesis the differences between the monohull and semi-submersible are investigated. For a general heavy lift crane operation and its operational profile, the difference is performance and total cost are calculated. These are used to determine the turning point, the point where the semi-submersible is more favourable for a heavy lift crane operation. The monohull has relatively low capital and operational costs, but also a lower workability. There is thus a balance that has to be investigated and compared between the two vessel types. This is done for the North Sea and West Africa, which have significantly different sea conditions.