Decarbonisation of Maritime Transport: Hydrogen and Methanol as Alternative Fuels

The transport industry is responsible for about 15 % of total greenhouse gas emissions. Heavy transport and maritime transport in particular account for 10 % of global carbon emissions. With a growing awareness of climate change and sustainability, decarbonising these sectors has become a priority. However, the electrification of these transport vehicles faces major challenges due to the long distances they have to travel and the heavy loads they carry.  Here, renewable hydrogen emerges as a promising alternative due to its high energy density compared to batteries.

Hydrogen in the Maritime Sector

Maritime transport plays a vital role globally today. Since 80% of goods are moved by sea, world trade and economies are directly dependent on this sector. Therefore, it needs to be protected and even incentivised, but this requires progress towards decarbonisation, since transport currently accounts for a quarter of the EU’s total greenhouse gas emissions.

Nowadays, greenhouse gas emissions from maritime transport are growing steadily. They are projected to be 130% higher than in 2008 by 2050 if no measures are taken, which clashes with decarbonisation targets. The European Union, for example, needs to reduce transport emissions by 90 %, including all forms of transport, to fulfil its climate neutrality targets.

Maritime transport faces its own decarbonisation challenges, due to the harsh conditions in which it must operate and the long distances to be covered with no frequent refuelling. Switching to pure electric solutions within this sector implies deploying large batteries, which results in weight, space and efficiency constraints.

This is where hydrogen stands out as an alternative that can overcome these obstacles. Its high energy density means that, compared to electric batteries, hydrogen can provide greater range without sacrificing charging capacity. However, as an emerging technology, it is still an expensive system compared to the petroleum derivatives that 96% of merchant ships use. Therefore, substantial investments in infrastructure (both ships and port facilities) are required to change the oil-centred scenario, but it is considered to be one of the main hopes for the full decarbonisation of the sector.

Advantages of Renewable Hydrogen in Maritime Transport

Renewable hydrogen offers several advantages over alternative energy solutions, such as battery electrification, mainly in maritime transport:

• • It offers a valuable solution for high-energy operations (high tonnage and/or long range), where batteries cannot reach.

• • Sustainability and Emission Reduction. As a carbon-free energy source, renewable hydrogen contributes directly to the reduction of greenhouse gas emissions linked to these transport vehicles.

• • It is a tested technology. Developing an efficient logistics chain to facilitate high volumes of production will ensure its competitiveness as a fuel.

Use of Methanol in the decarbonisation of Maritime Transport

Focused on methanol as a marine fuel, it has gained significant support within the shipping industry, which is currently in the quest for environmentally friendly options. The new IMO (International Maritime Organisation) environmental standards and energy transition require reducing the carbon intensity of international shipping by at least 40 % by 2030 compared to 2008 levels and by at least 70 % by 2050.

Methanol is a chemical with strong energy transmission properties. The global methanol market forecast to grow from $28.74 billion to $39.18 billion.

The Danish company Maersk recently announced the building of eight large ships powered by biofuel methanol. Renewable methanol is defined as methanol produced in a renewable and emission-free way, including one variant generated from renewable hydrogen. Methanol or methyl alcohol (CH₃OH) is a chemical compound highly demanded for its multiple applications: as a solvent, in construction materials and for the production of synthetic fuels.

Methanol and hydrogen fuel cells: As a cleaner alternative to fossil fuels, renewable methanol provides important benefits due to its ease of storage and transport, thus becoming a convenient choice for a wide range of energy systems. Technological developments, such as reforming and PEM fuel cells, maximise methanol’s efficiency and energy production, smoothing the path to a low-carbon future. With worldwide production forecast to increase dramatically, the transition to renewable sources of methanol will further enhance its environmental benefits.

Renewable methanol, which uses only renewable energy sources in the process, can be classified as follows:

• • Biomethanol: it is produced from the gasification of sustainable biomass sources such as livestock, agricultural and forestry residues and municipal waste.

• • E-methanol: it is produced from hydrogen generated from renewable electricity and carbon dioxide.

Advantages of using methanol:

• • Avoiding carbon taxes: diesel taxes can range from $250 to $450 per tonne of CO₂.

• • Sustainability: incorporating methanol ships will generate annual CO₂ emission savings of around 1 million tonnes.

• • Methanol is biodegradable and soluble in water.

• • Availability: Methanol is one of the most widely used chemicals in the world and it is available for bunkering in 88 of the world’s top 100 ports.

Methanol-fuelled combustion engines

MAN 6L21/31DF-M Engine

Man Energy Solutions has launched dual-fuel-methanol engines (MAN 6L21/31DF-M). These systems will be embedded in a diesel-electric propulsion system on board of the ship, driven by two fixed pitch propellers through gearboxes. The engines will be built by CMP, an engine manufacturing division of the China State Shipbuilding Corporation (CSSC).

A.P. Moller – Maersk will retrofit an existing ship to a dual-fuel engine vessel that can be powered by methanol and therefore run on green methanol, the first in the shipping industry to perform this conversion. The first engine retrofit of this type within the industry is scheduled to take place in mid-2024 and is intended to be replicated on sibling vessels when their scheduled inspection is completed in 2027.

M2Power 250 PowerCell Group Engine

The innovative M2Power propulsion system combines methanol propulsion with fuel cell technology, simplifying decarbonisation by generating clean hydrogen for a seamless integration of the system into the ship. It is a system developed by the Swedish company, in partnership with RIX Industries, that provides 250 kW of efficient, reliable and environmentally friendly electricity for marine applications. It is designed to replace traditional marine diesel gensets and offers a fully integrated experience for a smooth transition to zero emissions.

The M2Power is a revolutionary solution for power generation in the marine environment, offering unparalleled efficiency and ease of integration. Focused on safety, performance and sustainability, the generator sets a new standard for marine electrification, smoothing the route to a greener future. The fuel feedstock comprises a mixture of 2.5 % methanol, 37.5 % deionised water by weight (+/-0.5 %) and is distinguished by its high energy efficiency. The M2Power 250 efficiently converts methanol into clean energy, outperforming conventional internal combustion engines. It converts 40-45 % of the methanol energy into electricity. Efficiency is even higher if the waste heat from cooling the fuel cells is used in the ship’s thermal management system.

The M2Power 250 has received DNV GL’s Approval in Principle (AiP), confirming its compliance with industry standards and environmental regulations, thereby offering a reliable and innovative solution for sustainable offshore power generation.

Main characteristics of methanol-fuelled ships

The main features to highlight of this technology are:

• • A methanol-fuelled ship can operate for more than 60,000 hours on methanol fuel alone.

• • It is an evolving technology. Technological advances in piping systems, or injection valves are helping to generate more efficient solutions.

• • Enable compliance with the IMO 2020 standard. Developed by the International Maritime Organization (IMO) to try to reduce the sulphur content in marine fuels by 0.50%. The methanol bar system allows compliance with IMO 2020 Tier III without requiring post-treatment exhaust gas application.

• • Versatile engines. Current solutions involve two-stroke engines, which run on both methanol and conventional ship fuels.

Application cases and projects under development

The potential of renewable hydrogen in maritime transport is reflected in many pilot projects and case studies around the world. Here we highlight some of the most innovative projects that are setting the foundations for future mass adoption of hydrogen within this sector:

MF Hydra

It is the world’s first liquid hydrogen-powered ferry operated by the Norwegian company Norled (Norway). It became operational on 31 March 2023, a historic milestone for both Norled and Norway as a leading shipping nation. MF Hydra covers the triangular maritime route between Hjelmeland-Skipavik-Nesvik.

The German company Linde Engineering supplied the on-board hydrogen storage systems. Ballard has developed the fuel cells that produce electricity from hydrogen. Westcon in Ølensvåg was responsible for equipping and completing the ship alongside system integrator SEAM in Karmøy. Seam also supplied the automation scope for the hydrogen propulsion system. Corvus Energy has supplied the batteries for the MF Hydra and the ship has been approved by Det Norske Veritas (DNV).

The MF Hydra is 82.4 metres in length with a load of up to 300 passengers and 80 cars. It will be able to reach a speed of 9 knots with 2×200 kW fuel cells and generators and 2×440 kW powering the Shottel propellers.

The ferry is fitted with an 80 cubic metre tank to store hydrogen and is expected to reduce its annual carbon emissions by up to 95%.

Maersk Line

Danish shipping company Maersk launched the world’s first green methanol-powered cargo ship in September 2023 in the port of Copenhagen. The new container ship, commissioned in 2021, has two engines: one powered by traditional fuels and the other running on green methanol, an alternative component which uses biomass or carbon and hydrogen captured from renewable energy. The new ship emits 100 tonnes of carbon dioxide less per day effectively compared to diesel-powered ships.

At the same time as the launch of this ship, Maersk, jointly with its founding family, has established a new company called C2X which aims to produce green methanol. The new company is exploring green methanol projects near the Suez Canal in Egypt, the port of Huelva, the USA, India and Australia. C2X, 80% owned by the family investment company and 20% owned by Maersk’s public company, plans to produce three million tonnes of green methanol per year by 2030.

As mentioned above, the Danish company Maersk has announced the building of eight large ships powered by biofuel methanol.

Future Perspectives and Conclusion

Renewable hydrogen has the potential to transform the maritime transport sector in the next few years. As renewable hydrogen production costs decrease and refuelling infrastructure grows, renewable hydrogen is expected to compete more effectively against fossil fuels and other energy solutions.

The interest in green methanol production opens up a new growth opportunity for the green hydrogen sector to produce e-methanol. Therefore, large multinationals such as the Danish shipping company Maersk are signing commitments to produce green hydrogen to generate e-methanol and thus decarbonise their maritime goods transport fleet.

To sum up, renewable hydrogen and e-methanol represent a feasible and sustainable solution towards the challenges of decarbonisation in maritime transport. It will require a balance of technological innovation, government support and shipping industry commitment to achieve such goals.