This paper studies the emergence of natural gas powered ferries in Norway and their diffusion as a means to reaching the goals of reducing NOx emissions. Though experiences with naturalgas powered ferries have been good, there is little sign that there will be any further prioritizing of these over diesel ferries.I will analyze natural gas powered ferries in a sustainable development perspective, as an environmentally friendly alternative. Further, the values, policies and institutions affecting theferries are analyzed.Natural gas powered ferries could prove useful in the long term for reducing national emissions of NOx. Diffusion is going slow, and there is no official strategy to prioritize gas ferries when replacing the many old ones. Industry is interested in this new technology to build competencies but unwilling to make large investments alone. To reach international agreement for NOx reduction taxes on emissions will be introduced. Natural gas ferries as atechnological system might need support for infrastructure and a more overarching strategy to be significant.