Changes in the type of LNG trading has resulted in an increased demand for vessels with greater operational flexibility and efficient propulsion plants. This has led to the demand for the capability to re-liquefy boil-off-gas (BOG) and return it the cargo-tanks and sell it as cargo or burn BOG or fuel oils depending on the relative costs at the time. This allows energy companies to divert LNG to markets with high seasonal peak demand and take advantage of highest prices, yet still meet long-term SPA's.

The research in this paper was conducted by means of qualitative data collection and subsequent analysis using market management tools to ascertain the technical viability. From this point, the data was fed into economic analysis to produce quantitative data that allowed for a determination for a final investment decision for a number of market scenarios.

LNG carriers with re-liquefaction capability are positively differentiated from those without it. They are capable of greater operational flexibility, and as a result, their competitive position is improved. They can demand higher charter rates as the increase in cargo quantity offloaded results in increased revenue. They present a lower environmental footprint as there is no requirement to thermally oxidise excess BOG in a GCU. The analysis shows it is technically viable to retrofit a re-liquefaction plant onboard 150,000 m3 Dual Fuel Diesel Electric (DFDE) LNG carriers. The economic viability is more complicated, situation-dependent, and influenced by market forces, environmental legislation, and political interference.

液化天然气贸易类型的变化导致对具有更大操作灵活性和高效推进装置的船舶的需求增加。这导致了对重新液化蒸发气体 (BOG) 并将其返回货舱并作为货物出售或燃烧 BOG 或燃料油的能力的需求，具体取决于当时的相对成本。这使得能源公司能够将液化天然气转移到季节性高峰需求高的市场并利用最高价格，但仍能满足长期 SPA。

本文的研究是通过定性数据收集和随后使用市场管理工具进行分析以确定技术可行性的方式进行的。从这一点开始，数据被输入到经济分析中以生成定量数据，从而可以确定针对多种市场情景的最终投资决策。

具有再液化能力的液化天然气运输船与不具有再液化能力的运输船有着明显的区别。他们能够获得更大的运营灵活性，从而提高了他们的竞争地位。随着卸载货物数量的增加导致收入增加，他们可以要求更高的租船费率。它们呈现出较低的环境足迹，因为不需要在 GCU 中热氧化多余的 BOG。分析表明，在 150,000 立方米双燃料柴油电动 (DFDE) 液化天然气运输船上改造再液化装置在技术上是可行的。经济可行性更加复杂，取决于具体情况，并受到市场力量、环境立法和政治干预的影响。