A turbo-electric COGAS power-plant

Combined gas and steam (COGAS) is the name given to marine compound powerplants of gas and steam turbines, the latter are fed with steam generated with the heat from the hot exhaust of the gas turbines. This way some of the otherwise lost energy can be reclaimed and the specific fuel consumption of the plant can be decreased. Large (land based) electric powerplants built using this combined cycle can reach conversion efficiencies of over 58%. Image File history File links COGAS-diagram. ... Image File history File links COGAS-diagram. ... A turbo-electric transmission uses electric generators to convert the mechanical energy of a turbine (steam or gas) into electric energy and electric motors to convert it back into mechanical energy to power the driveshafts. ... This machine has a single-stage radial compressor and turbine, a recuperator, and foil bearings. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... Specific fuel consumption, often shortened to SFC, is an engineering term that is used to describe the fuel efficiency of an engine design. ...

For more details on this topic, see Combined cycle.

In case, the turbines don't drive propeller shafts directly and instead a turbo-electric transmission is chosen, the system is also known as COGES. In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator is combined with a steam turbine generator with the objective to increase the efficiency of electricity generation. ... A propeller shaft connects a propeller to an engine. ... A turbo-electric transmission uses electric generators to convert the mechanical energy of a turbine (steam or gas) into electric energy and electric motors to convert it back into mechanical energy to power the driveshafts. ...

COGAS differs from other combined marine propulsion systems in that's not intended to operate on one system alone. While this is possible, it won't operate efficiently this way, as it's with Combined diesel and gas systems when they run solely on diesel engines. Especially COGAS should not be confused with Combined steam and gas (COSAG) power plants, which employ a traditional, oil-fired boilers for steam turbine propulsion for normal cruise and added gas turbines for faster reaction times and higher dash speed. Combined diesel and gas, usually abbreviated CODAG is a type of propulsion system for ships, particularly warships. ... Principle of a COSAG propulsion system Combined steam and gas (COSAG) is a propulsion system for ships using a combination of steam turbines and gas turbines to power the shafts. ...

COGAS has been proposed as upgrade for ships that use gas turbine as their main (or only) engine, e.g. in COGOG or COGAG mode, like the Arleigh Burke class destroyers, but currently no naval ship uses this concept. Hower some modern cruise ships are equipped with COGES. E.g. Celebrity Cruises' Millennium and other ships of her class use turbo-electric plants with two General Electric LM2500+ gas turbines and one steam-turbine. Principle of a COGOG propulsion system Combined gas or gas (COGOG) is a propulsion system for ships using gas turbine engines. ... Principle of a COGAG propulsion system Combined gas turbine and gas turbine (COGAG) is a type of propulsion system for ships using two gas turbines connected to a single propeller shaft. ... USS Lassen (DDG-82), an Arleigh Burke class destroyer. ... USS Port Royal (CG-73), a Ticonderoga class cruiser. ... MV Pride of Aloha docked in Port of Nāwiliwili, Kaua‘i in the Hawaiian Islands A cruise ship, or less commonly cruise liner or luxury liner, is a passenger ship used for pleasure voyages, where the voyage itself and the amenities of the ship are considered an essential part... Celebrity Mercury shows the distinctive color scheme and X symbol on the funnel. ... Millenium is the lead ship of the Millenium class of cruise ships, operated by the Celebrity Cruises line. ... The General Electric LM2500 industrial and marine turboshaft gas turbine is a derivative of GE Aircraft Engines CF6-50 aircraft engine. ...