LR looks to ‘cleaner’ production, bioLNG and synthetic LNG for improved LNG emissions performance

Reducing methane slip

Methane slip remains a key issue for ships that use LNG, but dual-fuel engine makers have been making advances in reducing the amount of unburned methane that escapes through the ship’s exhaust. Improvements in lowering methane slip and the greenhouse gas intensity of LNG come primarily through high-pressure diesel cycle technology and aftertreatment systems.

Lowering so-called fugitive methane emissions, including methane slip, is critical from both an environmental compliance and fuel efficiency perspective. Methane has a global warming potential 28 times that of CO2 over a 100-year timeframe and more than 80 times the CO2 intensity over the first 20 years of its presence in the atmosphere. 

For operators looking to improve energy efficiency and save money, unburned methane equates to higher fuel consumption, higher opex, and higher taxes under UK and EU emissions schemes. Reducing slip now will mean lower fuel costs when using more expensive bioLNG and synthetic LNG.

But the biggest sources of fugitive methane emissions for the LNG supply chain – production and distribution – fall outside of the scope of engine makers’ work.

LR points out that there are real benefits to improving current production and distribution through less carbon-intensive processes and lowering fugitive methane emissions, but that a transition to ’cleaner’ forms of LNG is needed to achieve deeper emissions reductions in the longer term.

“Already today, green liquefaction can reduce GHG emissions involved in LNG production by 10%. But in the longer term, cleaner LNG means developing the production and supply of methane from renewable sources, giving shipping access to far deeper GHG emissions reduction potential from LNG as a fuel,” said the class society.

“Crucially, regulators will need to acknowledge these supply chain improvements if they are to stimulate uptake of cleaner LNG,” added LR.

EU Renewable Energy Directive default values for fuels

The EU’s Renewable Energy Directive contains typical and default values for the GHG emissions savings from a range of biofuels by feedstock, against a fossil comparator of 94 g CO₂ eq/MJ, assuming no net carbon emissions from land-use change.

According to the report, there is a “wide range in the GHG intensity of biomethane, depending on the feedstock used, production process, and other factors.”

Using current default values, the report breaks down the GHG savings default values of biomethane production by feedstock and technological options.

Wet manure provides the best GHG emissions savings default values over the wide range of technological production options, ranging from a high of 202% to a low of 72%.

Further methane slip reductions needed

LR does make it clear that LNG fuel’s long-term emissions-reduction credentials rely on its GHG lifecycle analysis and reducing methane slip across the entire LNG value chain – from production to shipping to combustion.

The timing of the announcement of the release of the 47-page report, Fuel for Thought: LNG for Cruise, coincided with the cruise industry’s biggest players gathering this week in Miami for Seatrade Global Cruise 2026 to celebrate a year of exceptional growth and a record-breaking orderbook. Last year, 37M passengers travelled on cruise ships, and the value of the newbuilding orderbook is set to surpass US$100Bn.

LNG is the most widely adopted alternative fuel for cruise ships, with some 30 ships in service – just under 10% of the global fleet (20,000 gt and above). The current orderbook includes 29 LNG-fuelled ships, six methanol-fuelled ships, and two hydrogen-capable ships.

“For cruise operators, the report positions LNG not as an end point, but as a practical enabler of the industry’s decarbonisation pathway,” said LR global passenger ship segment vice president Francesco Ruiso.

The report examines the full lifecycle performance of LNG, including well-to-wake emissions, regulatory treatment under IMO and EU regimes, and the economic implications of emerging compliance mechanisms such as the IMO Net Zero Framework and FuelEU Maritime.

Cruise Lines International Association president and chief executive Bud Darr said his members are investing in environmental technology to decarbonise their ships and “have the backing of the banking community to do that.” 

During the keynote session at Seatrade Cruise Global, Mr Darr said that his members are still committed to achieving net zero by 2050, “even though the regulatory environment is very confused about it. We’re still moving forward, but we’ve got to have the fuels, and we really need to have a serious commitment to make that happen.”

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