Hydrogen fuel energy: the future of maritime transport

Hydrogen (H) is the simplest and lightest of the elements. At standard conditions, it is an odourless gas with the formula H2. Although hydrogen is colourless, its nomenclature is derived from the many shades of the rainbow. Each colour represents the method used to produce it, resulting in different carbon intensity levels. Here are the three main types:

Green hydrogen is made through a process of electrolysis powered by renewable energy such as hydropower, wind and solar. Electrolysis involves using an electrical current to split water into hydrogen and oxygen. The process is simple and emits zero CO₂, making this the most desirable type of hydrogen. However, it remains expensive. The hope is that the cost of green hydrogen will decrease as production scales up.

Blue hydrogen is produced mainly from natural gas, using a process called steam reforming. During this process, natural gas is split into hydrogen and CO₂, but the carbon dioxide is processed industrially or stored using carbon capture and storage (CCS) technology. This means that blue hydrogen does not release CO₂ into the atmosphere. However, the long-term impacts of storage are unclear.

Grey hydrogen is the most common type. It is essentially the same as blue hydrogen, but does not include CCS, meaning that CO₂ is emitted directly into the atmosphere. As 10 metric tons of CO₂ are produced for each metric ton of hydrogen extracted, the process is harmful to the environment. Nearly all hydrogen consumed today is grey hydrogen. However, demand is projected to decline as the cost of cleaner hydrogen becomes more competitive.

Hydrogen fuel offers several benefits. First and foremost, it is abundant and can be produced from renewable sources, meaning that it does not have the supply limitations of fossil fuels. It is also extremely versatile and can be used in fuel cells or combustion engines and for a range of applications, including in the automotive, aerospace and maritime industries.

Hydrogen can also play a key role in the transition to clean energy. When produced using renewable sources, it can significantly reduce the carbon footprint of industries. In the maritime sector, hydrogen fuel technology is beginning to replace heavy fuel oils that emit high levels of CO₂, helping the industry to meet the International Maritime Organization’s targets for decarbonisation.

Hydrogen fuel is not without its challenges. One of the primary disadvantages is the energy-intensive production process. Storage and transportation are also difficult due to hydrogen’s low energy density by volume, which requires extensive infrastructure such as high-pressure tanks or cryogenic systems. Moreover, the initial cost of transitioning to hydrogen-powered systems is high, although this may decrease as technology matures and adoption becomes more widespread.

A hydrogen fuel engine operates similarly to a conventional internal combustion engine but uses hydrogen instead of petrol or diesel. Hydrogen is combusted with oxygen in a controlled manner to produce energy, emitting only water as a by-product. Despite significant performance benefits, these engines are not as efficient as fuel cells and may still emit nitrogen oxides (NOₓ), albeit at much lower levels than fossil fuels.

Unlike engines that burn fuel, fuel cells undergo an electrochemical reaction. A hydrogen fuel cell generates electricity by converting chemical energy from hydrogen and oxygen into electrical energy. Water and heat are the only by-products. The high efficiency and zero-emission nature of fuel cells makes them particularly attractive.

Several hydrogen ships are currently in operation or under development. One groundbreaking example is MF Hydra, the world’s first liquid hydrogen-powered ferry, which is equipped with hydrogen fuel cell technology.

Other examples include FPS Waal and Zulu06, which are retrofitted cargo vessels that operate on hydrogen fuel cells along European rivers. These ships demonstrate the potential of hydrogen in transport and are laying a foundation for broader adoption.

Hydrogen is increasingly being adopted for long-range maritime transport. The adaptability of hydrogen fuel technology allows vessels to sail longer distances than battery-powered ships while maintaining zero emissions. While initial costs remain high, the long-term benefits of using hydrogen are expected to make it a competitive alternative to traditional marine fuels. As these developments continue, hydrogen will play a vital role in helping to meet stringent decarbonisation targets.