New report argues LNG as a fuel could worsen shipping’s climate impact

A damning report published this week from the International Council on Clean Transportation (ICCT) argues that ships fuelled by liquefied natural gas (LNG) do not deliver the emissions reductions required by the International Maritime Organization’s initial greenhouse gas (GHG) strategy, and that using LNG could actually worsen shipping’s climate impacts.

The 40-page report, commissioned by international environmental organisation Stand.earth, states that high-pressure injection dual fuel (HPDF) engines using LNG emit 4% more lifecycle GHG emissions than if they used marine gas oil (MGO). The most popular LNG engine technology is low-pressure dual fuel, four-stroke, medium-speed, which is used on at least 300 ships. Results from the new study show this technology emitted 70% more lifecycle GHGs when it used LNG instead of MGO and 82% more than using MGO in a comparable medium-speed diesel engine.

“Continuing to invest in LNG infrastructure on ships and on shore might make it harder to transition to low-carbon and zero-carbon fuels in the future,” the report stated.

The ICCT report highlights the unintentional releases of methane from ship engines, known as methane slip. The authors found that using LNG could actually worsen the shipping industry’s climate impacts compared to MGO when considering the amount of heat these emissions will trap over a 20-year period.

Methane emissions are particularly problematic because methane traps 86 times more heat than the same amount of carbon over a 20-year period.

Of the hundreds of LNG-fuelled ships in operation or on order, the most popular engine type, by far, is also the worst offender with the highest rate of methane slip, according to data from the ICCT (see chart below).

“This groundbreaking new analysis is a damning climate indictment of LNG as marine fuel. For a sector that is already one of the largest contributors of global greenhouse gas emissions, this report reveals that switching ships to LNG is worse than doing nothing. This should serve as an alarming wake-up call for the International Maritime Organization, which must act now to ensure it includes all greenhouse gas emissions in its emissions reduction strategy,” said Kendra Ulrich, senior shipping campaigner at Stand.earth.

Dr Elizabeth Lindstad, chief scientist at SINTEF Ocean, argued it was vital regulators start to acknowledge the whole well-to-tank emissions of ship fuels.

“If we fail to include all GHGs and focus only on CO2, we might end up with a large number of ships fulfilling all efficiency requirements, but where the GHG savings are on paper only,” she said.

Lobby group SEA\LNG remains convinced that the chilled gas has a strong future as a “pathway” to get shipping towards zero-emissions.

Peter Keller, chairman of SEA\LNG, commented last month: “As convincing, qualified evidence supporting the environmental, operational and commercial benefits of LNG continues to emerge, acceptance of its credibility is becoming increasingly widespread and concrete. LNG is the only safe, mature, commercially viable marine fuel that offers superior local emissions performance, significant greenhouse gas reduction benefits today, and a pragmatic pathway to a zero-emissions shipping industry.”

The debate about LNG’s actual overall environmental footprint have been raging for a number of years.

In a widely read contribution on this site from 2018, Dr Tristan Smith from UCL Energy Institute wrote that methane is a potent greenhouse gas, and only a very small amount needs to escape to cancel out the combustion CO2 benefits from LNG as a ship fuel.

“LNG’s flaws are more fundamental – it is a fossil fuel that just like oil produces about three tonnes of CO2 for every tonne of fuel consumed. This makes it an ‘impasse’ in a world committed to decarbonise,” Smith argued.

Sam Chambers

Starting out with the Informa Group in 2000 in Hong Kong, Sam Chambers became editor of Maritime Asia magazine as well as East Asia Editor for the world’s oldest newspaper, Lloyd’s List. In 2005 he pursued a freelance career and wrote for a variety of titles including taking on the role of Asia Editor at Seatrade magazine and China correspondent for Supply Chain Asia. His work has also appeared in The Economist, The New York Times, The Sunday Times and The International Herald Tribune.


  1. “I am a finger pointing to the moon. Don’t look at me; look at the moon.”
    — Buddha
    All comparison must be made on the total life cycle.
    Considering some parts in isolation (in this case GHG instlead of total life cycle externalities as a while) will only lead to biased interpretation and substandard solutions.
    The fact that LNG is in principle worse than HFO in respect to GHG is spelled clearly in IMO third GHG study, for those who bothered reading it, due to the high CH4 emissions.
    So it is quite surprising that, six years later, a new report finds out what had already been concluded.
    HOWEVER, before convicting LNG on partial and shortsighted accusation it shall be recalled that LNG delivers a tremendous reduction in SOx and PM in comparison to HFO, MDO, MGO and LSFO.
    And SOx and PM are the big source of mortality and morbidity due to air pollution.
    In particular LNG is possible the best fuel to reduce mortality and morbidity, the best fuel to reduce total externalities, albeit at an increase in GHG.
    Again, this is nothing new. Data and reports have been there already long since.

    1. the issue of ultra-fine particulate emission which are far higher with LNG and potentially an even more deadly product than PM10 should not be overlooked

  2. I fully support above contribution of Mr Gennaro. One can only add that – again – a group of people has been spending money to find an outcome that already is written down. The money could have been used for environmental issues like collecting plastics from seawater etc… This seems much harder to realize than writing about our climate.
    And: What about LNG and northern route? This route is much shorter !

  3. “Look… there’s a squirrel!”

    We knew about the SOx and the particulates; so what?

    To base the case for more methane on SOx reductions in 2020 is a bit silly.

  4. Where do they find that upstream part of life cycle (gas extraction and treatment, liquefaction, transport and storage) is emitting more than oil based products ? I have always heard the opposite and it should be easy to retrieve the relevant studies on this. So I am very skeptical on this part.
    Moreover, piston engines (whether HP or LP, 2 strokes or 4 strokes) are not the only energy converters. There is no methane slip and no issue of methane number with gas turbines and boilers for instance.
    Finally, CH4 can be produced from methanisation and is not necessarly a fossil fuel.
    So there is still plenty of possibilities for liquid methane as a clean transition marine fuel towards lower GHG emissions.

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