David Muckle, hydrogen systems business unit leader at Haskel, discusses why the aviation sector’s transition away from fossil fuels is not just necessary but possible with the right combination of technology, policy, and infrastructure development.

The emissions challenge facing the aviation sector is well-understood, and so are the solutions – hydrogen, Sustainable Aviation Fuels (SAFs), and carbon offsets, all have a role to play in reaching “Jet Zero”.

Hydrogen, in particular, has been gathering momentum as a low-carbon solution, with exciting UK-based companies such as Rolls Royce, Airbus and ZeroAvia all committing to significant R&D in the space. The Aerospace Technology Institute’s FlyZero study has determined that green liquid hydrogen, a byproduct of the electrolysis process that splits water into hydrogen and oxygen, is the most viable zero-carbon fuel for aviation with the potential to scale to larger aircraft.

The use of green hydrogen opens the possibility for large aircraft to utilise fuel cell, gas turbine, and hybrid systems for power. In fact, it is projected that green liquid hydrogen will become a cheaper and more eco-friendly alternative to Sustainable Aviation Fuels (SAFs) due to carbon pricing and the production inefficiencies associated with SAFs.

The UK Government’s Jet Zero Strategy has recognised the potential of hydrogen in revolutionising the aviation industry, placing it at the heart of its sustainable aviation roadmap. With its Jet Zero Strategy, the UK Government is demonstrating a strong commitment to accelerating the pace of hydrogen aviation.

However, hydrogen aviation is not without its challenges.

While hydrogen boasts a higher energy density than aviation fuel by mass, it is less dense by volume, thus presenting a challenge in terms of onboard fuel storage. The refuelling of aircraft also brings new challenges, as hydrogen has many properties which differ from traditional jet fuels. To be used as liquid hydrogen, it must be cooled to -253 degrees Celsius, which entails complex handling and compression procedures.

On the fuel side, the production of low-carbon hydrogen needs to scale up and reduce costs quite significantly.

The UK Government, recognising this challenge, has pledged support through several initiatives and revenue support schemes. These initiatives aim to drive cost reductions and create the necessary momentum for the scaling up of low-carbon hydrogen production.

However, there is one further challenge that is flying under-the-radar.

One of the most significant challenges in the path of hydrogen aviation is the substantial investment required for ground infrastructure. This includes developing new procedures and infrastructure for storage, processing, management, and aircraft refuelling. It is estimated that the investment needed in infrastructure to enable the use of hydrogen aviation at one airport is of a similar magnitude to the investment needed for a new terminal.

As we look towards the second half of the decade, when the first zero-carbon flights using low-carbon hydrogen are expected to occur, the task of developing the infrastructure necessary to support this transition looks to be a major challenge.

In anticipation of this, Haskel, a global leader in hydrogen compression and refuelling, is supporting Project HEART, which is a multiple-partner initiative focused on developing a holistic operational, infrastructure and technology model that is commercially viable, subsidy-free, and sustainable.

Project HEART will see Protium, the green hydrogen developer, overseeing the hydrogen infrastructure at a South Wales site called Pioneer 2 with an electrolyser provided by Norway’s Nel Hydrogen. According to Nel, it will be the company’s largest electrolyser deployment in the UK to date. From Pioneer 2, hydrogen will be compressed with the use of Haskel’s GENO compression system, with a small amount of storage on site.  The end-to-end hydrogen solution will encompass off-site green hydrogen production, its transfer to site, and the refuelling of fuel cell-electric propulsion aircraft via a mobile refueller.

Hosting the hydrogen production off-site offers several advantages compared to on-site or co-located hydrogen production which requires strict regulations and local planning rules, making it more difficult for a project developer.

A key benefit of off-site hydrogen production, as shown at Pioneer 2, is that it is highly scalable. Containerised electrolyser systems are modular in design, and this is what allows them to scale up. Furthermore, off-site production negates concerns about the complexity involved in assembly of hydrogen infrastructure at airport sites.

The initial focus for Project HEART will be regional airports, targeting aircraft with a capacity of 9-19 passengers and a range of around 500 miles.

This production, storage and distribution system will be tested operationally in the second half of 2024 at Kemble Airport, in Gloucestershire, where hydrogen-aviation startup ZeroAvia is developing the world’s leading hydrogen-electric propulsion system for its airplanes.

The aviation sector’s transition away from fossil fuels is not just necessary but possible with the right combination of technology, policy, and infrastructure development. While challenges remain, initiatives like Project HEART are creating a foundation for a sustainable aviation industry.Subscribe to the FINN weekly newsletter