The present invention relates to a power-saving liquefied gaseous fuel ship in which power consumption of a reliquefaction system can be reduced when using liquefied gas as fuel to treat boil-off gas generated by natural evaporation of the liquefied gas in the ship, and to a method for treating the boil-off gas of such a liquefied gaseous fuel ship. The power-saving liquefied gas fuel ship according to the present invention comprises: a liquefied gas storage tank for storing liquefied gas; an engine that uses, as fuel, the liquefied gas stored in the liquefied gas storage tank or boil-off gas generated by natural evaporation of the liquefied gas; a fuel supply means for supplying liquefied gas as fuel for the engine; the compressor is used for compressing the boil-off gas to the pressure required by the engine; a heat exchanger for cooling remaining boil-off gas not supplied to the engine among the boil-off gas compressed in the compressor; a refrigerant circulation line through which the refrigerant supplied to the heat exchanger circulates; a refrigerant compression unit provided in the refrigerant circulation line to compress the refrigerant discharged after heat exchange in the heat exchanger; and a cold and heat recovery device for recovering cold and heat of the liquefied gas supplied as fuel of the engine and cooling the refrigerant compressed by the refrigerant compression unit.

本发明涉及一种省电型液化气体燃料船，其中在使用液化气体作为燃料来处理通过船中的液化气体的自然蒸发而产生的蒸发气体时，再液化系统的功耗可降低，且涉及一种用于处理这类液化气体燃料船的蒸发气体的方法。根据本发明的省电型液化气体燃料船包括：液化气体储罐，用于存储液化气体；发动机，使用存储在液化气体储罐中的液化气体或通过液化气体的自然蒸发而产生的蒸发气体作为燃料；燃料供应构件，用于供应液化气体作为发动机的燃料；压缩机，用于将蒸发气体压缩到发动机所需的压力；热交换器，用于冷却在压缩机中压缩的蒸发气体中的未供应到发动机的剩余蒸发气体；制冷剂循环管线，供应到热交换器的制冷剂通过所述制冷剂循环管线循环；制冷剂压缩单元，设置在制冷剂循环管线中以压缩在热交换器中进行热交换之后排出的制冷剂；以及冷热回收装置，用于回收作为发动机的燃料供应的液化气体的冷热和冷却由制冷剂压缩单元压缩的制冷剂。