Advancements in Marine Fuel Technology: Implementation of Liquefied Natural Gas (LNG) in Sustainable Shipping

Introduction:

The maritime fuel industry, a cornerstone of global trade, faces mounting pressure to adopt sustainable fuel solutions amid stricter environmental regulations and climate change concerns. Liquefied Natural Gas (LNG) has emerged as a promising alternative to conventional marine fuels, offering significant reductions in carbon dioxide (CO2), sulfur oxides (SOx), nitrogen oxides (NOx), and particulate emissions. Ongoing technological advancements have expanded the benefits of adopting LNG as a marine fuel, encompassing improvements in environmental and operational efficiencies. The rise of LNG has led to key advancements in LNG technology, including carbon capture and storage (CCS), innovative dual engine vehicles, and improved LNG bunkering, all enhancing efficiency, sustainability, and market competitiveness of LNG as a marine fuel.

Emissions:

In recent years, the demand for renewable and eco-friendly energy sources in the maritime industry has been on the rise. Today, the maritime sector mostly relies on bunker fuels, which is a fossil fuel that emits the heaviest and most polluting pollutants. These fuels emit particulate matter, SOx, NOx, ozone-depleting substances (ODS), and volatile organic compounds (VOCs), all devastating for the environment [1]. In search of an alternative, LNG has emerged as a more environmentally friendly substitute to fossil fuels.
While LNG is a cleaner fossil fuel, it still emits harmful pollutants. Figure 1 demonstrates that LNG produces 40% less CO2 than coal and 30% less than oil, which makes it the cleanest of the fossil fuels. Moreover, LNG produces 20% of the total NOx produced by both oil and coal. LNG also emits significantly less soot, dust and particulates compared to coal and oil and produces insignificant amounts of sulfur dioxide, mercury and other compounds considered harmful to the earth’s atmosphere [25]. Nonetheless, these harmful emissions are a concern for those trying to consider LNG as a long term solution to the global warming crisis.

Carbon Capture and Storage (CCS):

New technologies have been developed in carbon capture and storage (CCS) to mitigate the CO2  emitted by LNG production and combustion [21]. LNG companies are increasingly investing in CCS to limit their emissions and promote their climate credentials [22]. CCS works by capturing CO2 directly from the gases released during LNG production or usage. The CO2 is then compressed in order to be transported. Finally, the CO2 is injected into rock formations deep underground for permanent storage, typically saline aquifers or depleted oil
and gas reservoirs, effectively removing it from the atmosphere [21].
A leading force in the innovation of CCS technology is the International Maritime Organization (IMO)’s decarbonization movement. The IMO seeks to incorporate CCS on all LNG fueled vessels with the hopes of achieving zero carbon by 2050. To minimize interference with other shipboard systems, the IMO’s guidelines suggest that the CCS process be located on the deck of LNG vessels [50]. The CO2 capture and liquefaction units include key components such as the CO2 absorber, CO2 stripper, solvent tank, and various heat exchangers and compressors. These components are strategically arranged on the vessel to work in tandem with the LNG tanks, ensuring efficient integration with existing systems while maintaining safety and operational effectiveness [37]. By incorporating CCS into the LNG fueling process, the maritime industry can take a significant step toward achieving zero-carbon shipping by 2050, ensuring that LNG continues to play a crucial role in the transition to a more sustainable and low-emission global shipping industry.

Dual-Fuel LNG Vessels:

Speaking of the IMO, in 2020, the IMO 2020 was passed, which changed regulations and reduced the limits on sulfur content of all ships’ fuel from 3.5% to 0.5% by mass [42]. The new limit means a 77% drop in overall SOx emissions from ships, equivalent to an annual reduction of approximately 8.5 million metric tonnes of SOx [41].
This change has driven a sharp increase in the adoption of LNG-fueled vessels. Newer carriers are adopting dual fuel propulsion systems, allowing them to run on both LNG and conventional marine fuel. The combustion process in dual fuel ship engines is a sophisticated mechanism designed to effectively utilize both liquid and gaseous fuels. Typically, this process unfolds through two primary modes: diesel mode and gas mode. In diesel mode, liquid fuel, such as marine diesel oil (MDO) or heavy fuel oil (HFO), is injected into the combustion chamber, where it mixes with compressed air. The ensuing high pressure and temperature within the chamber ignite the fuel, initiating combustion to generate high-pressured gas. In gas mode, commonly LNG is blended with air and mixed into the combustion chamber. Dual fuel ship engines boast the capability of operating in a combined mode, wherein both liquid and gaseous fuels are utilized simultaneously. These dual fuel carriers reduce fuel consumption, emissions, and overall operational costs, contributing to a more sustainable shipping process [51].
These advancements have also been implemented on former models such as the Moss-type vessels (Type B LNG tanks). Generally, known as the most recognizable type of LNG carrier, Moss-type vessels feature spherical domes on the main deck [15]. These round tanks are made of materials such as aluminum or nickel steel, which are resistant to extreme cold caused by LNG  (shown in Figure 2). Due to the spherical shape, stress is equally distributed and the resistance to external forces is very high [16]. Therefore, Moss-type carriers have a great reputation for their safety and reliability as these tanks can regulate the pressure and temperature very well. Hence, they are preferable for long-distance transportation of LNG. These vessels are reaching new heights since as of October 2024, China has deployed the world’s largest Type B LNG fuel tank container ship. The vessel “Maria Cristina” has a capacity of 16,000 TEUs and is equipped with a 13,000-cubic-meter Type B LNG fuel tank. It is the first time China has independently developed the entire process of building a Type B LNG dual fuel tank. This has resulted in China becoming the largest importer of LNGs and second-largest re-exporter of LNGs [43].

LNG Bunkering:

In recent years, LNG bunkering has undergone significant advancements, enhancing the efficiency, safety, and environmental performance of LNG as a marine fuel. As the maritime industry accelerates its transition to LNG to meet stricter emissions regulations and reduce its carbon footprint, the infrastructure for LNG bunkering has evolved rapidly.
Over the years, several new LNG bunkering terminals, both offshore and onshore, have been established globally. These facilities are designed to facilitate the safe and efficient transfer of LNG to vessels, supporting the increasing adoption of LNG as a marine fuel. Offshore LNG bunkering has emerged as a critical solution for enabling fuel supply to ships operating in remote regions or areas lacking sufficient onshore infrastructure. The development of Floating Storage Regasification Units (FSRUs) has been particularly notable. These mobile platforms allow for the storage, regasification, and bunkering of LNG directly to ships at sea [46]. For instance, the first LNG bunkering vessel operating in the Baltic Sea, Coralius, which can hold up to 6,000 m3 of LNG, has significantly boosted LNG availability for vessels in the region [51]. On top of that, major global ports have invested heavily in expanding LNG bunkering capacity. New LNG bunkering facilities have opened in key maritime hubs, including Rotterdam, Singapore, France, and the U.S. Gulf Coast [47]. The port of Rotterdam is Europe’s largest LNG bunkering port, as well as one of the top three bunkering ports worldwide [48]. Most recently, although the U.S. LNG exports have skyrocketed over the years as demonstrated in Figure 3, the U.S. still doesn’t have a LNG bunker terminal. The United States Army Corps of Engineers (USACE) sought authorization to site, construct, and operate the proposed GLBP small-scale natural gas liquefaction facility on Shoal Point, part of the Galveston Bay/Greater Houston port complex. The Galveston LNG terminal will comprise two natural gas liquefaction trains with a total expected capacity of around 600,000 gallons per day. With the permits requested, this project is estimated to be done by 2026 and will be the first dedicated LNG bunker terminal in the U.S [49].

Conclusion:

The maritime fuel industry is undergoing a transformative shift as the global demand for sustainable energy solutions intensifies in response to environmental concerns and stricter regulations. LNG has emerged as a key player in this transition, offering a cleaner alternative to conventional marine fuels by significantly reducing harmful emissions such as CO2, SOx, NOx, and particulates. The International Maritime Organization’s push for decarbonization, with targets such as zero carbon by 2050, further emphasizes the urgency for the industry to accelerate its adoption of cleaner energy. Moreover, technological advancements in LNG production, transportation, and bunkering, coupled with the integration of Carbon Capture and Storage (CCS) systems, are paving the way for a more sustainable maritime industry. Plus, the rise of dual-fuel LNG vessels and innovations in LNG bunkering infrastructure further enhances the efficiency of LNG. As the industry continues to evolve, the integration of LNG-powered vessels and supporting technologies will play a central role in shaping a greener, more sustainable future for maritime transport.

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About the Authors

Dr. Raj Shah is a Director at Koehler Instrument Company in New York, where he has worked for the last 25 plus years. He is an elected Fellow by his peers at IChemE, AOCS, CMI, STLE, AIC, NLGI, INSTMC, Institute of Physics, The Energy Institute and The Royal Society of Chemistry. An ASTM Eagle award recipient, Dr. Shah recently coedited the bestseller, “Fuels and Lubricants handbook”, details of which are available at ASTM’s LongAwaited Fuels and Lubricants Handbook 2nd Edition Now Available https://bit.ly/3u2e6GY.
He earned his doctorate in Chemical Engineering from The Pennsylvania State University and is a Fellow from The Chartered Management Institute, London. Dr. Shah is also a Chartered Scientist with the Science Council, a Chartered Petroleum Engineer with the Energy Institute and a Chartered Engineer with the Engineering council, UK. Dr. Shah was recently granted the honourific of “Eminent engineer” with Tau beta Pi, the largest engineering society in the USA. He is on the Advisory board of directors at Farmingdale university (Mechanical Technology), Auburn Univ (Tribology), SUNY, Farmingdale, (Engineering Management) and State university of NY, Stony Brook ( Chemical engineering/ Material Science and engineering). An Adjunct
Professor at the State University of New York, Stony Brook, in the Department of Material Science and Chemical engineering, Raj also has over 680 publications and has been active in the energy industry for over 3 decades. More information on Raj can be found at https://bit.ly/3QvfaLX
Contact: rshah@koehlerinstrument.com

Bishesh Shah is a freshman studying Chemical Engineering at Stony Brook University, set to graduate in May 2028. On campus, he is a freshman representative for his university’s Himalayan Student Association (HSA), a member of his university’s Bollywood dance team (SBU Junoon), a member of the American Institute of Chemical Engineers (AIChE) Chapter at Stony Brook University, and a member of the Stony Brook Environmental Club. He aspires to pursue a career in the energy and sustainability industries.

Udithi Kothapalli is a senior studying Chemical Engineering with a minor in Biomedical Engineering at Carnegie Mellon University, set to graduate in May 2025. She is also pursuing a minor in Biomedical Engineering. Udithi is actively involved in campus organizations, serving as the current president of the Indian Organization at her university. Additionally, she holds the position of industrial liaison for the American Institute of Chemical Engineers Chapter at Carnegie Mellon, demonstrating her commitment to both cultural and professional development within her field of study.