Maritime - World Liquid Gas (WLGA)

Shipping, particularly maritime transportation, plays a significant role in the global economy, facilitating the movement of goods across long distances. However, it also has a notable impact on the environment, primarily due to emissions of greenhouse gases and other pollutants.

Ships primarily burn heavy fuel oil, which produces substantial amounts of CO₂. Ships also emit black carbon, a particulate matter that absorbs sunlight and contributes to the melting of ice and snow, accelerating climate change in sensitive regions. Shipping emissions include NOx and SOx, which contribute to air pollution and acid rain, leading to adverse health effects and ecosystem damage.

Decarbonising the capital-intensive marine industry is complex and expensive due to its large, long-life assets, thin margins and high dependence on energy-dense fuel.

While electric vessels present a potential solution for short-haul shipping, there is currently no affordable low-carbon energy source for deep-sea shipping, which accounts for 85% of greenhouse gas emissions from the maritime industry.

Maritime

Reducing emissions from maritime transport

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Historically, oil-based fuels have met over 99% of the total energy demand for international shipping.

Without major interventions, emissions are expected to double by 2050.

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In 2022, international shipping accounted for about 2% of global energy-related CO₂ emissions.

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Deep-sea shipping accounts for 85% of greenhouse gas emissions from the maritime industry.

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Ships generate approximately 5-10% of all Sulphur Dioxide anthropogenic emissions at a global level.

Challenges and solutions

There are several technologies aimed at reducing emissions from the shipping industry.

Technology	Opportunities	Challenges
LNG	LNG is a cleaner-burning fossil fuel compared to traditional marine fuels, resulting in lower emissions of SOx and PM. It also produces fewer NOx and CO₂ emissions.	Most LNG is fossil natural gas Complexity and cost Limited bunkering and port infrastructure
Biofuels	Biofuels derived from renewable sources like vegetable oils and waste products can be used as an alternative to conventional fuels, reducing carbon emissions.	Availability because of demand from road transport and aviation Limited production capacity Cost
Hydrogen	Hydrogen can be used as a fuel source for ships when produced through renewable methods, emitting only water vapour as a byproduct.	Non-mature technology Low energy density Infrastructure and storage Limited supply and cost of green hydrogen
Ammonia	Ammonia is another potential carbon-free fuel option for ships when produced using green hydrogen. It emits only nitrogen and water when burned.	Limited supply and cost of green ammonia Low energy density compared to bunker oil Safety and toxicity needs to be addressed
Wind-assisted propulsion	Installing sails or other wind-assist technologies can harness wind power to supplement engine propulsion.	Can only support other propulsion technologies
Liquid Gas	Using liquid fuels, such as LPG, produces fewer harmful emissions compared to traditional fossil fuels like diesel or heavy fuel oil. It emits lower levels of sulphur dioxide (SO2), PM and NOx.	Most liquid fuels are still made from fossil sources Cost of retrofit
Electricity	Small engines can be electrified	Only suitable for small leisure craft

Zero-emissions technologies such as green hydrogen and green ammonia are still in the early stages of development and will require an exponential scale-up in production, substantial infrastructure as well as adoption by the global shipping industry.

The role of Liquid gas

With a well-developed infrastructure and proven technology, Liquid Gas provides a convenient solution to expedite the energy transition in the maritime industry. It presents a viable alternative energy source to traditional fuels such as heavy fuel oil, marine diesel fuel and marine gas oil.

Lower CO2 emissions

Reduced air pollutants

A step towards ammonia-powered ships

Compliance with regulations

Existing infrastructure

No risk of spillage

Lower CO₂ emissions

Compared to heavy fuel oil, Liquid Gas combustion emits fewer CO₂ emissions per unit of energy produced. Although not a zero-emission fuel, LPG has a lower carbon footprint, making it a transitional option towards more sustainable energy sources.

Reduced air pollutants

Liquid Gas produces significantly lower levels of SOx and NOx compared to conventional maritime fuels. This would lead to improvements in air quality and reduced acid rain formation.

A step towards ammonia-powered ships

LPG engines have the potential to be adapted to use green ammonia as a fuel or as a carbon-free combustion promoter, which would eliminate CO₂ emissions entirely and significantly reduce other emissions.

Compliance with regulations

As international regulations such as the International Maritime Organization’s (IMO) sulphur cap and stricter emissions standards come into play, Liquid Gas could provide a compliant alternative without the need for exhaust gas cleaning systems (“scrubbers”).

Existing infrastructure

With more than 1,000 existing storage facilities and terminals, LPG infrastructure is well-developed globally.

No risk of spillage

Liquid Gas is non-toxic.

Currently, LPG is already a preferred marine fuel solution for LPG carriers.

Liquid Gas and
the energy transition

Liquid Gas can play a key role in reducing emissions from global shipping

Compared to heavy fuel oils, LPG emits approximately 97% less SOx, 20% less NOx and 90% less PM while cutting carbon emissions by roughly 20%. Therefore, LPG is compliant with existing emission standards including the IMO’s sulphur cap of 0.5% and requirements regarding operating in emission control areas (ECA).
Liquid fuels also have economic advantages that allow for a cost-competitive transition to lower-carbon fuels. Studies based on data from over 70,000 ships in South Korea show that LPG in ships could reduce annual fuel costs by up to 25.9%.
LPG is also easier to handle than LNG, as cryogenic materials are not required for the fuel tanks. This also results in lower investment costs for such a system.

Liquid fuels are a viable alternative gaseous fuel for all sizes and types of boats and ships.
With more than 1,000 existing storage facilities and terminals, the LPG infrastructure is well-developed globally. This implies that LPG can be effectively supplied using existing facilities while new terminals can be built faster and at lower cost.
LPG-powered propulsion installations could be made ammonia-ready with a relatively small investment, making LPG vessels compatible with ammonia pathways. LPG can therefore act as a bridging energy until the ammonia technology is ready for commercialisation.