We analyzed pollution plumes originating from ships using liquefied natural gas (LNG) as a fuel. Measurements were performed at a station located on the Utö island in the Baltic Sea during 2015–2021 when vessels passed the station along an adjacent shipping lane and the wind direction allowed the measurements. The ratio of the measured concentration peaks ΔCH₄/ΔCO₂ ranged from 1% to 9% and from 0.1% to 0.5% for low and high pressure dual fuel engines, respectively. The ratio of the measured concentration peaks of ΔNO_x/ΔCO₂ varied between 0.5‰ and 8.7‰, which was not explained by engine type. The results were consistent with previously measured on-board or test-bed values for the corresponding ratios of emissions. While the methane emissions from high pressure dual fuel engines were found to fulfill the goal of reducing the climatic impacts of shipping, the emissions originating from low pressure dual fuel engines were found to be substantially high, with a potential for increased climatic impacts compared with using traditional marine fuels. Taking only the global warming potential into account, we can suggest a limit value for the methane emissions; the ratio of the emissions ΔCH₄/ΔCO₂ originating from LNG powered ships should not exceed 1.4%.

中文翻译：

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基于远程海洋站测量的 LNG 船舶甲烷排放评估

我们分析了来自使用液化天然气 (LNG) 作为燃料的船舶的污染羽流。2015 年至 2021 年期间，当船只沿着相邻的航道经过该站并且风向允许进行测量时，测量是在位于波罗的海 Utö 岛上的一个站进行的。对于低压和高压双燃料发动机，测得的浓度峰值ΔCH ₄ /ΔCO ₂的比率分别为1%至9%和0.1%至0.5%。测得的ΔNO _x /ΔCO ₂浓度峰值比在 0.5‰ 到 8.7‰ 之间变化，这不是由发动机类型解释的。结果与先前测量的相应排放比率的车载或试验台值一致。虽然发现高压双燃料发动机的甲烷排放实现了减少航运对气候影响的目标，但发现低压双燃料发动机的排放量非常高，与使用相比，有可能增加气候影响传统船用燃料。仅考虑全球变暖潜力，我们可以建议甲烷排放的限值；LNG动力船舶的排放量ΔCH ₄ /ΔCO ₂之比不应超过1.4%。