Positions differ wildly when it comes to whether liquefied natural gas (LNG) improves or worsens the shipping industry's efforts to become more green.

Manufacturers see advantages to using the gas for shipping companies, arguing that LNG contributes to cleaner air because CO2 emissions are reduced. NGOs are on the opposite side, criticizing LNG for increasing methane emissions.

The debate has been revitalized after NGO International Council on Clean Transportation (ICCT) published a report last week concluding that LNG could in fact increase the shipping industry's climate footprint compared to sailing on conventional marine gas oil.

NGO criticizes LNG as fuel: Could do more harm than good 

But that is entirely wrong, according to Finland's Wärtsilä, one of the world's largest engine manufacturers.

"The report’s conclusion that LNG fails to deliver the required emission reductions is incorrect, since the assumptions and data do not reflect those of a modern gas engine," writes Juha Kytölä, Wärtsilä's director of R&D and engineering, in a comment to ShippingWatch.

In another comment to ShippingWatch, ICCT maintains that its report is based on "modern" engines, without elaborating further on this definition, however.

The NGO instead refers to the report for a summary of the technologies and engines it was based on.

Wärtsilä is a proponent of LNG as ship fuel. Two factors in particular support it, the company says.

"The first is the excellent potential that exists for cutting methane-slip emissions from 4-stroke engines even further through the introduction of advanced combustion techniques," Kytölä writes, continuing:

"Secondly, the LNG technology that has been developed is perfectly suited for the burning of low-carbon bio- and synthetic fuels that will help the industry to lower its GHG emissions to the levels targeted by the IMO for achievement by 2050."

Fight over yardstick

According to the ICCT report, the most popular LNG ship engines emit 70 percent more greenhouse gases than marine gas oil over a 20-year period, as LNG engines have high methane emissions.

However, Wärtsilä is unhappy that the NGO is using a 20-year period as its basis for measuring.

"In reporting the impact of methane on climate change, the widely accepted 100-year time horizon should be focused on rather than a 20-year horizon," Wärtsilä's Kytöla writes to ShippingWatch.

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In the report, however, ICCT also concludes that LNG could reduce greenhouse gas emissions by 15 percent over 100 years.

But according to the NGO, this is only possible if ships sailing on LNG fuels use so-called high-pressure injection dual-fuel engines, where methane emissions are controlled.

These engines are in the minority, an evaluation by ICCT shows. It reveals that only 90 current or upcoming LNG vessels out of more than 750 use these engines.

Dual fuel should be rewarded

Elizabeth Lindstad is chief scientist at research company Sintef Ocean in Norway and has in-depth experience with LNG. Moreover, she contributed to ICCT's report.

According to the chief scientist, players in the shipping industry should stay critical of LNG with regards to methane.

"There is a need for regulation that obligates all LNG producers to bring down methane emissions," she says in an interview with ShippingWatch,

She holds that LNG, initially, has a positive effect – but in line with ICCT, she also points out that the incentives for choosing high-pressure engines need to be bigger.

"LNG on a ship makes shipowners appear more eco-friendly, but if LNG is to contribute to reducing greenhouse gas emissions, the IMO has to reward the use of dual-fuel high-pressure engines and technologies that can reduce methane emissions from dual fuel," Lindstad says.

Engine manufacturer MAN Energy Solutions concedes that methane emissions are a challenge that is being handled.

"Methane slip is a known challenge and it is being addressed by the industry," the company writes in a comment to ShippingWatch, where MAN also states that it is developing various solutions.

Transition fuel

Although Lindstad is critical of LNG's methane emissions, she believes that LNG can be a means to make the industry greener if it is used as a transition fuel.

"I see LNG as a transition fuel toward fuels with low or no carbon. That's my view, because if you invest in duel-fuel diesel technology like MAN does, for instance, you can switch to renewable ammonia when that hits the market," Lindstad says.

MAN takes the same position.

"On the way to a maritime energy transition MAN believes that LNG can only be the initial step. Climate neutral synthetic fuels have to follow," the engine maker writes, seeing the promotion of production of these types of fuel as a "pressing regulatory task".

English Edit: Jonas Sahl Jørgensen

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