LNG and Beyond: Exploring Sustainable Fuels in the Marine Industry

With global climate deadlines looming and the marine industry aiming for net zero by 2050, shipping companies urgently need to consider lower-emission fuels to decarbonise. “We are at the start of a long voyage to decarbonise shipping,” says Camille Bourgeon, technical officer and air pollution specialist for the International Maritime Organisation (IMO). If no action is taken to embrace more sustainable technologies today, ship owners could be locked into using carbon-intensive fuels for up to three decades — the typical lifespan of a ship's engine.

Liquefied natural gas (LNG) is a significant bridge fuel in the marine fuel transition, offering reductions in greenhouse gas (GHG) emissions compared to traditional heavy fuel oil (HFO) predominantly used in marine transport. This review looks at the role of LNG and its implications for future sustainability and explores low-carbon marine fuel alternatives, such as methanol, that are currently being developed.

The Predominance of HFO in Shipping

HFO, or bunker fuel, is a residual product — the leftovers from crude oil refining processes. It is typically used with large shipping engines due to its low cost and high energy density. Most of the fuel used in the marine shipping industry is HFO, with the remaining share taken up by distillates like marine diesel oil and marine gas oil.

The industry's reliance on HFO is problematic, mainly because combusting HFO is highly polluting. In 2022, international marine shipping accounted for 2% of global energy-related CO₂ emissions. According to the International Energy Agency (IEA), a 15% reduction in these emissions by 2030 is necessary to stay on track with net zero.

As part of the IMO's plan to meet decarbonisation goals and reduce environmental impact, using LNG will aid the transition to sustainable fuels, like methanol and ammonia. While the path to net zero is not straightforward, the consequences of continuing to use traditional engine fuels are considerable for both the industry and the planet.

Preparing for the Energy Transition with LNG

The global energy transition focuses on reducing carbon emissions while ensuring energy security. In this context, LNG is gaining attention as a short-term solution because it produces fewer emissions when burned compared to coal or oil. LNG could serve as a lever for decarbonisation as renewable fuels are developed.

Beyond LNG's energy density and ease of transport, the marine industry has several other compelling reasons to switch to LNG.

Low Carbon Intensity

Relative to fossil fuels such as coal (for inland use) and HFO (for marine use), LNG combustion emits 50% less CO₂ and does not generate particulates like soot, dust or fumes. Factors contributing to carbon intensity include shipping distances, the use of renewable power and emissions control. Carbon intensity also varies by region due to differences in production practices and regulatory environments.

Seaborne transportation between producers and consumers is an important link in the LNG value chain. John Crane supports the marine transportation industry with market-ready technologies, including filtration solutions for boil off gas management (BOG) and power transmission couplings, designed for LNG applications.

Ample Supply

A sharp increase in the demand for LNG is inevitable as global industries adopt it as a bridge fuel. Shell expects a 50% rise in global demand by 2040, a prediction echoed by Keisuke Sadamori, Director of Energy Markets for the IEA, who emphasises the need for swift capacity expansion to meet future needs.

Fortunately, LNG has suitable infrastructure and supply for the current market, and promising new offshore solutions are emerging, such as floating LNG (FLNG) facilities. FLNG plants offer mobile extraction and processing by tapping into offshore LNG reservoirs. While the rugged technology powering FLNG is costly, it also provides economic advantages. For example, it doesn't require operators to build and maintain expensive onshore pipeline infrastructure.

The rise of FLNG facilities could catalyse the shift toward LNG-powered marine engines, driving economic and environmental benefits. With natural gas processed offshore, export ships can access the supply directly and carry it to bunkering ports worldwide. The concept of FLNG is well-suited to John Crane's history of innovation and the legacy of LNG leadership.

Established Global Supply Chain

There is an opportunity for marine transport to take advantage of LNG's well-developed supply chain, including liquefaction plants, shipping vessels and regasification terminals. Maersk recently announced dual-fuel vessels capable of using LNG or methanol, signalling a shift towards flexible fuel solutions.

To strengthen the industry's evolving infrastructure, John Crane offers a range of couplings designed to transmit power efficiently while accommodating the unique challenges of fuels like LNG, hydrogen and ammonia. Our ancillary equipment supports new energy in the marine market with products that include electrical generators, fire water pumps and water cannon pumps for security.

Alternative Marine Fuel Options

Several alternative marine fuels have the potential to meet operational needs in the push for sustainable shipping. Key factors for evaluating alternative fuels include energy density, sustainability, safety and compatibility with current infrastructure.

Bio and Synthetic LNG

Bio-LNG (liquefied biomethane) has a lower carbon footprint than traditional natural gas, as it is derived from feedstocks such as agricultural manure and waste. It combines well with conventional LNG; when blended at a 20% ratio, bio-LNG could cover 16% of the total energy demand for shipping fuels by 2030 and up to 63% by 2050, according to a study by SEA-LNG.

Synthetic LNG is a manufactured product identical to conventional LNG but carbon neutral. The first step is to produce zero-carbon hydrogen (H₂) using electrolysis. The next step is to chemically combine the H₂ with captured CO₂ to produce methane (CH₄), which is then liquified; all the power sources must be renewable to ensure carbon neutrality. Bio and synthetic LNG use the same infrastructure and equipment as traditional LNG, such as storage tanks, bunkering and ships.

Methanol

Methanol represents a compelling alternative to HFO for marine engines, particularly in the context of environmental sustainability. Methanol is a clean-burning fuel that emits no sulphur oxides, minimal nitrogen oxides and little particulate matter. Typically derived from natural gas, carbon-neutral methanol can be produced from renewables such as zero-carbon hydrogen or biomass.

From a practical perspective, methanol is liquid at ambient temperature, meaning transport ships do not require cryogenic or high-pressure containment systems to use it as fuel. Methanol is an internationally traded commodity with a network of existing ports and infrastructure, and methanol ship-engine technology is relatively mature.

Methanol's potential as a low-carbon marine fuel is not just theoretical. In February 2023, the vessel Cajun Sun completed the first-ever net zero voyage powered by bio-methanol. This long-haul trip from the U.S. to Belgium demonstrated the feasibility and environmental benefits of using an alternative marine fuel.

Even though methanol holds great potential, it also presents challenges, such as the risk of fuel contamination that can harm engines and other components. Filtration solutions adhering to the highest quality standards are essential for addressing this issue and supporting the transition to sustainable fuels, such as methanol as a marine fuel. Read our case study Proven Filtration Solutions Help 'World's First Green Container Ship' Increase Reliability and IMO 2050 Progress to learn more.

Hydrogen and Ammonia

Hydrogen from renewable power is possibly the gold standard for clean combustion, as it is truly a zero-emissions fuel. However, hydrogen's large-volume storage needs pose a challenge for long-haul shipping. Compressing and cryogenically cooling H₂ to a liquid could solve this issue. A more likely avenue is using ammonia as an energy carrier for hydrogen.

Ammonia (NH₃), a compound of nitrogen and hydrogen, can be combusted in engines without emitting CO₂. In ambient conditions, storing and transporting ammonia is easier than gaseous or liquid hydrogen because ammonia is energy-dense, allowing more fuel to be stored in a smaller space. Additionally, ammonia remains liquid in ambient temperatures under moderate pressure, whereas hydrogen requires cryogenic temperatures or high-pressure containment to stay in liquid form.

When produced using renewable energy, ammonia is carbon-free. However, its high toxicity demands stringent safety controls to contain the hazards posed by leaks. The development of ammonia engines for marine shipping is currently ongoing.

Supporting Marine Decarbonisation with Market-Ready Technologies

Sustainable, often low-carbon fuels are gaining ground in multiple industries, including marine. Dual-fuel marine vessels and low-carbon fuel production, such as methanol, are advancing, and John Crane supports this transition with certified filtration solutions that efficiently manage contamination and contain harmful fuels in the marine sector.

With a portfolio that also includes an extensive range of power transmission couplings and ancillary equipment, such as electrical generators, fire water pumps and water cannon pumps for security, John Crane is prepared to support the evolving needs of the marine transportation industry. Our longstanding experience in fuel gas filtration and LNG and alternative fuel applications positions us as a reliable partner for powering the industry's path to net-zero emissions.

Learn more about John Crane's solutions for sustainable fuels and new energy.