Disclosed herein is a BOG reliquefaction method for LNG ships. The BOG reliquefaction method for LNG ships includes: 1) compressing BOG; 2) cooling the BOG compressed in Step 1) through heat exchange between the compressed BOG and a refrigerant using a heat exchanger; 3) expanding the BOG cooled in Step 2); and 4) stably maintaining reliquefaction performance regardless of change in flow rate of the BOG compressed in Step 1) and supplied to the heat exchanger to be used as a reliquefaction target.

Disclosed herein is a BOG reliquefaction method for LNG ships. The BOG reliquefaction method for LNG ships includes: 1) compressing BOG; 2) cooling the BOG compressed in Step 1) through heat exchange between the compressed BOG and a refrigerant using a heat exchanger; 3) expanding the BOG cooled in Step 2); and 4) stably maintaining reliquefaction performance regardless of change in flow rate of the BOG compressed in Step 1) and supplied to the heat exchanger to be used as a reliquefaction target.

An apparatus, system and method for heat and cold recovery onboard a floating storage regasification unit (FSRU). A heat recovery apparatus onboard a FSRU includes a LNG vaporizer, a heat transfer fluid configured to transfer heat of vaporization to LNG in the LNG vaporizer during active regasification mode and thereby obtain cold of LNG, a heat recovery fluid including a portion of the heat transfer fluid, wherein the heat recovery fluid is configured to employ the cold of LNG to completely cool FSRU machinery and an FSRU air conditioning unit during active regasification mode, and thereby the heat recovery fluid obtains machinery heat, and wherein the heat of vaporization includes the machinery heat and at least one additional heat source.

Disclosed is an energy storage system for a marine vessel, the energy storage system comprising a first fluid inlet to receive a first fluid from a first system of the marine vessel, and a second fluid outlet for supplying a second fluid to a second system of the marine vessel. The energy storage system further comprises a phase change material, having a melting temperature of greater than 0 C at atmospheric pressure, to receive and store heat energy from the first fluid received from the first system via the first fluid inlet and to supply the heat energy to the second fluid to be supplied to the second system via the second fluid outlet.

A refrigerant charging system includes: a reliquefaction system reliquefying boil-off gas generated in a liquefied gas storage tank by compressing the boil-off gas and subjecting the compressed boil-off gas to heat exchange with refrigerant supplied to a heat exchanger while circulating along a refrigerant circulation line; a buffer tank storing utility N.sub.2 to be supplied to the ship; a booster compressor receiving the utility N.sub.2 from the buffer tank, compressing the received N.sub.2, and supplying the compressed N.sub.2 to the refrigerant circulation line; and a first load-up line along which the N.sub.2 is supplied from the buffer tank to the refrigerant circulation line without passing through the booster compressor. Upon initial charging in a non-operation state of the reliquefaction system, the refrigerant circulation line is charged with refrigerant by supplying the N.sub.2 from by a pressure differential between the refrigerant circulation line and the buffer tank.

A vessel including a hull, an upper deck, an accommodation structure extending above the upper deck, a propulsion system powered by ammonia as a fuel, and a tank for storing ammonia for supplying the propulsion system, wherein the tank is located aft of the accommodation structure.

Disclosed is a marine fuel cell-based integrated heat, electricity, and cooling supply system comprising a power supply system and a waste heat recovery system; the power supply system comprises wind turbine generator sets, solar generator sets, and a fuel cell power module; the waste heat recovery system encompasses a turbine power generation module and a lithium bromide refrigeration module; the fuel cell power module is connected to both the turbine power generation module and the lithium bromide refrigeration module; the turbine power generation module is used to generate electricity using waste heat. This approach fully exploits the waste heat from the exhaust gas generated by the fuel cell power module, resulting in a high overall energy utilization rate. The self-consumption electricity and pure hydrogen fuel for the integrated energy supply system can be obtained from solar and wind energy, ensuring low carbon emissions for the entire system.