Reducing greenhouse gas emissions and other environmental impacts is the key challenge facing the shipping industry today. Green fuels and propulsion solutions bring challenges regarding ship design for new build vessels and adaptation for retrofit solutions, safety on board, fuel supply, and crew training. Alternative fuel uptake is slowly increasing and lessons can be learned from those fuels gaining traction. Development of methanol as a fuel from the first trials on commercial vessels in Sweden to recent projects with inland waterway vessels is presented as an example, showing how parallel work on regulation development, onboard trials, bunkering, and fuel supply can come together for successful introduction. Key challenges and opportunities for other green propulsion solutions including battery electric, hydrogen and ammonia will also be highlighted.