UK-based Green Marine has received approval in principle (AiP) from RINA for Project Verdant, a plan to retrofit a crew transfer vessel (CTV) with hydrogen, fuel cells, and batteries to reduce emissions. The project, supported by Innovate UK, aims to cut CO2 emissions by up to 30% and NOx emissions by up to 40% by integrating hydrogen fuel cells with electric motors while working in conjunction with diesel engines. The ultimate goal is to enable zero-emission operations at slow speeds when servicing offshore windfarms. Key project partners include Waves Group, EMEC, Energys, and Engineered Marine Systems. The AiP milestone assures the vessel's ability to operate safely in UK waters and align with regulations for hydrogen-fueled ships. Green Marine plans to use the retrofitting experience to expand its fleet with newbuild zero-emission vessels. Experts from RINA and Waves Group highlight the importance of the project in advancing maritime decarbonization and ensuring safety in innovative concepts. The system design aims to enhance vessel redundancy and flexibility by utilizing readily available hydrogen sources, paving the way for decarbonization without significant impact on operational profiles. Additionally, EMEC's involvement provides economic insights on hydrogen refueling, logistics, and safety, leveraging their hydrogen R&D ecosystem in Orkney. Project Verdant demonstrates a step forward in utilizing hydrogen in the maritime sector and explores its applications in aviation and synthetic fuel production.