The Netherlands armed forces have adopted the Operational Energy Strategy in order to reduce the dependency of operations on their logistic supply lines of fuel and reduce the impact of their operations on the environment. In this lecture, the Defence Materiel Organisation will discuss the developments in the future Royal Netherlands Navy fleet in support of this energy transition, through two case studies: the propulsion and power generation plant of the future frigate and the power generation plant of the future hydrographic survey vessel. For the future frigate various hybrid propulsion configurations have been compared on basis of energy efficiency and various performance parameters. The control strategy turns out to provide opportunities to find a good trade-off. For the future hydrographic survey vessel, various future technologies, such as batteries, fuel cells and combustion engines running on alternative fuels have been investigated. The results of both studies will be discussed.