Increasing emissions regulations as well as advances in technology and standards around the use of LNG have created opportunities for it to be used as a bunkering fuel, which can offer substantial environmental benefits compared to traditional heavy marine fuel.
This includes the elimination of particulate matter in the exhaust as well as a reduction in nitrogen oxide and sulphur oxide emissions by 85 and 95 per cent, respectively.
Demand projections for LNG bunkering show substantial increases in the coming years, with Shell estimating demand for LNG as a marine fuel would grow from 2.3 million tonnes a year in 2021 to 35 million tonnes a year in 2035.
New carbon intensity measures for ships, developed under the International Maritime Organisation’s (IMO) greenhouse gas reduction strategy, came into effect last November and requires ships to improve their efficiency in the short term to reduce emissions.
Moreover, it became mandatory at the start of 2023 for all ships to calculate their attained Energy Efficiency Existing Ship Index to measure their energy efficiency and to initiate the collection of data for the reporting of their annual carbon intensity indicator and its rating.
Ships running on low-carbon fuels will receive higher ratings than ships running on fossil fuels, but there are many improvements that can be implemented to raise a rating.
These include hull cleaning to reduce drag, speed and routing optimisation, installation of low-energy light bulbs, and installation of solar/wind auxiliary power for accommodation services.
The IMO will also be introducing stricter limits on maritime emissions throughout the Mediterranean Sea, which is a region well placed to boost the use of LNG with 16 LNG bunkering locations and several major hubs such as the ports of Barcelona, Algeciras and Gibraltar.
In 2021, LNG bunkering operations at the Port of Barcelona accounted for nearly 11 per cent of total bunkering operations, according to the port.
The new IMO rules will see the Mediterranean become an emission control area (ECA) on 1 May 2025, rendering very low sulphur fuel non-compliant as a shipping fuel.
Jason Stefanatos, Global Decarbonisation Director at maritime advisory firm DNV, said the Mediterranean becoming an ECA would increase interest in LNG.
He added: “We expect that many business cases [for the use of LNG as a marine fuel] would change for these vessels compared to the past.”
DNV has reported that LNG-fuelled ships account for the largest share of the alternative-fuelled ship orderbook, with about 440 LNG ships in operation and 97 on order, but it expects there will be about 425 LNG-fuelled ships on order by 2025 and 505 vessels by 2026.
The firm has also tripled its forecast demand for LNG to more than 3.5 million tonnes by 2024, which will see LNG bunkering newbuilds and infrastructure continue to advance in support of this demand.
The Port of Singapore hosts the world’s largest ship bunkering hub, and saw 50,000 metric tonnes of LNG bunker sales from March 2021 until the end of that year.
Singapore’s port and maritime authority have signalled they plan to diversify fuel offerings in line with their push for maritime decarbonisation.
Conducting safe ship-to-ship LNG bunkering operations in Singapore is important for the continued growth of LNG as a fuel in shipping, according to Shell Global Downstream LNG General Manager Tahir Faruqui.
He said: “Shell believes LNG is the first step to decarbonise the shipping sector, as it offers immediate emissions reductions.
“LNG is a fuel in transition as it has the potential to get to net zero emissions through bio-LNG and synthetic LNG (from green hydrogen).”
The majority of Europe’s major ports offer LNG bunkering, including those in the Netherlands, Germany, and Norway, as well as ports in Asia and the Americas.
There are also more than 50 LNG bunkering facilities currently under consideration, with a vast majority of these planned in Europe.
More recent projects include the Suez Canal as part of Egypt’s development towards becoming an LNG bunkering hub by 2025, similar to Singapore.
Other Middle Eastern countries such as the United Arab Emirates, Oman, and Qatar also have LNG bunkering hubs under construction, spurred by a series of technological advances and new standards, such as the 2019 ISO standard for LNG quick connect and disconnect couplings.
Developing best practice around LNG fuel
Being in the early stages of market adoption, LNG as a marine fuel needs improved standards around hose assemblies and couplings to enable safer and more efficient loading and refuelling.
This is even more pressing considering the special challenges associated with handling LNG safely, the most significant being the extremely low temperatures and high volatility of LNG.
It is crucial for any pressurised liquid system involving LNG to ensure the product is transferred without incurring damage to the piping and potentially causing a leak.
The main differences between loading LNG into fuel tanks and loading heavy fuel oil is that LNG is carried as a boiling, cryogenic liquid, which means temperature and pressure influence its behaviour.
The liquid is at its boiling point of about negative 162 degrees Celsius, and so exposure can be hazardous to both personnel and any conventional steel structures or piping.
A third difference is that vapour from LNG bunkering can form explosive clouds in confined spaces and requires special handling of the vapour when bunkering.
However, bunkering methods have been developed where no vapour is emitted from the tanks, or it is returned to the bunkering vessel or terminal.
The Society for Gas as a Marine Fuel (SGMF) last year released technical guidance on how to apply and interpret some of the statutory requirements for the filling and loading limits of LNG fuel tanks.
Its release was prompted by several recent reports of issues and LNG leakages related to the connection and connectors used between hose bunker systems and the gas-fuelled vessel manifolds.
The SGMF identified the main issue as being differential movement and applied forces between supply and receiving bunkering equipment, which were causing leakages where dry/connect couplings were used.
There are statutory safety limits on filling and loading LNG fuel tanks, most notably the International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels.
However, the methods by which the filling and loading limits should be calculated for LNG fuel tanks have been interpreted differently by some vessels in operation and under construction, depending on the tank type, shipyard, or classification society.
Differing interpretations have resulted in lower loading limits being applied by some vessels, reducing the amount of LNG in tanks.