To reduce global shipping’s impact on the environment and reduce the amount of GHG emissions being emitted, maritime players are forced to develop alternative propulsion systems for vessels. Depending on vessel type and range requirements, limited solutions are available as of now. For long distances, diesel or heavy fuel burning combustion engines are still the technology of choice. With penalties for port calls and emission control areas increasing, new technologies like battery and fuel cell hybrid systems are becoming increasingly viable. The integration of these technologies is possible with existing ship designs. Depending on the operational profile, hotel loads or short cruising modes can be covered already. Safety and regulatory guidelines are available and covered by the IMO. As both systems are new, updates in performance and reductions in prices are to be expected enhancing the total cost of ownership benefit over internal combustion engines even further.