Upon delivery, the Millennium became the world's first cruise ship to use a turbo-electric COGAS power plant. The COGAS plant consists of gas and steam turbines, with the latter being driven by steam generated using the heat from the exhaust of the gas turbines. In this way, some of the otherwise lost energy is reclaimed and the specific fuel consumption of the plant is decreased. Propulsion is provided by two "Mermaid" azimuth pod-propulsion units from Kamewa and Cegelec (now Alstom).