An operating gas system for an underwater vehicle, particularly for a submarine or an unmanned underwater vehicle, includes a fuel cell system and an operating gas vessel connected in terms of flow to the fuel cell system. In order to achieve simple and efficient storage of boil-off gasses, a gas-receiving device is also provided and is connected to the operating gas vessel. The gas-receiving device contains a sorbent for receiving boil-off gas from the operating gas vessel. The boil-off gas, which is produced in the operating vessel with an operating gas for the fuel cell system and which cannot be consumed directly in the fuel cell reaction, is therefore collected and stored with the aid of the sorbent in the gas-receiving device. A method for operating an operating gas system and an underwater vehicle are also provided.

A ship for bunkering liquefied fuel gas to a liquefied-fuel-gas propulsion ship includes: a liquefied-fuel-gas storage tank installed in the ship; a fuel supply pipe connected to the liquefied-fuel-gas storage tank and supplying fuel to the liquefied-fuel-gas propulsion ship; and a BOG collection pipe collecting BOG produced in a liquefied fuel gas tank of the liquefied-fuel-gas propulsion ship.

A vessel hybrid combined cycle power and propulsion system includes a steam turbine, a gas turbine, an auxiliary generator, an electric propulsion drive system, and an energy storage system, each connected to an AC bus. The system further includes a source of steam for the steam turbine, a control system for controlling operation of the steam turbine, gas turbine, auxiliary generators, electric drive propulsion system and energy storage system. The primary source of steam for the steam turbine is exhaust gas from the gas turbine. The primary source of gas for the gas turbine is boil off gas from the cargo hold. The AC bus includes a plurality of sections of AC bus coupled together by bus ties closed in normal operation forming a closed ring AC bus. The electric propulsion drive system includes a variable speed drive, driving an electric motor coupled through a drive shaft to a propeller.

Natural gas is produced when LNG that is contained in an insulated LNG cargo tank(s) of a non-self-propelled LNG carrier (i.e., a barge) evaporates as a result of heat leakage through the walls of the insulated cargo tank(s). The natural gas is transferred from the barge to a tugboat or a towboat that is equipped with natural gas burning engines through a flexible gas transfer assembly so that the tugboat is powered by the natural gas fuel. The pressure in the cargo tank(s) on the barge is, therefore, effectively managed to prevent or substantially reduce the buildup of pressure within the LNG cargo tank(s). The LNG can then be contained within the LNG cargo tank(s) for an appropriate period of time and can be delivered at an appropriate and acceptable equilibrium pressure and temperature.