Since the first ocean going LNG carriers were built on the 1960’s, the selection of the propulsion system best suited to the ship has been somewhat different than for other ship types.  In addition to providing efficient, safe, and reliable propulsion for the ship, there must also be a means of dealing with the boil off gas (BOG) from the cargo tanks.  Initially, the only propulsion system available that could also provide a solution to the BOG issue was steam turbine propulsion which burned the BOG in the boilers.  For about 40 years the steam turbine system was the only practical choice available.  Now several new propulsion systems have been developed that provide the ship designer with alternatives.  Two systems that have been applied in new ships delivered since 2004 are the dual fuel diesel electric (DFDE) and the slow speed diesel with reliquefaction (DRL).  A third system, combined gas turbine electric and steam turbine electric (COGES) has been extensively studied but not yet applied. Please click here to read more about LNG Propulsion Alternatives.