Hydrogen Fuel Cells in the Aviation Industry

Aviation 8 minute read

Hydrogen fuel cell technology has the potential to change aviation as we know it. The technology is already airborne and expected to play an important role in the decarbonization of the aviation industry.

 

However, in order to make it a reality there are still challenges that need to be solved. What are the next steps to make hydrogen fuel cells a viable option for commercial aircraft?

Liquid hydrogen storage and weight optimization in aircraft

There is a lot of development going on as to where liquid hydrogen can best be stored in an aircraft: the fuselage, the wings, or in external tanks. Preferably as much hydrogen as possible, as we should expect a hydrogen-powered aircraft to use up all its fuel during a single flight. Even so, pressurized tanks make it easier to store liquid hydrogen on smaller aircraft as well. Such tanks are available on the market, and relatively easy to integrate, but are not weight-optimized; a crucial factor to consider.

There are two different techniques for using hydrogen in an aircraft. One is through a hydrogen fuel cell, where the hydrogen is converted to electricity in order to power an electric propeller (e-fan or e-prop). The other is to combust the hydrogen in an aircraft turbine, less efficient but more power dense. The hydrogen fuel cell solution works better on small- to midsize aircraft, and the turbine variant would be preferable for larger, long-haul aircraft.

Scaling up hydrogen fuel cell capacity to meet aviation requirements

Another technical challenge is to scale up hydrogen fuel cells and their balance of plant. In order to adapt in the automotive and marine industries, component and fuel cell weight optimization is not nearly as important as it is in aviation applications. Here, weight becomes a critical issue, especially since the fuel cell must also provide a very high power output. A lot of effort is put in scaling up hydrogen fuel cells and their balance of plant, in order to adapt them for the needs in aircraft. The balance of plant refers to the supporting components and auxiliary systems, such as compressors, cooling systems, pressure regulators, etcetera.

Most fuel cell systems today are made for vehicles, marine or stationary applications. However, these systems do not have nearly the power density as an aircraft requires. In this kind of application, the hydrogen fuel cell needs to have a much greater power output and be as light as possible. Moreover, the fuel cell must be able to provide the maximum power output even at high altitudes, where the power output typically drops along with the air pressure.

More time and resources will be needed to achieve solutions that meet both the propulsion power requirements and weight demands of aircraft. The fuel cell and aviation industries are well on their way in this direction. But as we scale up hydrogen fuel cell capacity, we also need to look beyond our own experience and expertise: to consider how other industries have worked with similar solutions and learn from their development processes.

Aviation hydrogen storage through industrial synergies and collaboration

A key part of solving the issue of hydrogen storage in aircraft is to look at how other industries have handled it. In the case of aviation, space programs are especially useful for comparison, as all spacecraft use liquid hydrogen as one of their fuels.

The technical solutions for the aviation industry would have to be cheaper, and commercial aircraft certainly carry a lot more passengers than space shuttles do. Still, there are industrial synergies that the aviation industry can learn from. The work in the vehicle and marine industries provide similar insights. The marine industry is particularly good at implementing new technology and developing regulations in parallel. Achieving large-scale hydrogen production and liquefaction, for example, will benefit both industries.

While a lot more research and development will be needed, the technology and knowledge is largely already here. As we test, evaluate, and adapt our solutions, we get closer to realizing the potential that hydrogen fuel cells have for the aviation industry.

PowerCell Group is involved in projects within the Clean Aviation Joint Undertaking, the European Union’s leading research and innovation programme for, among other topics, reducing the aviation industry’s CO2 emissions. The project has several focus areas, hydrogen storage in aircraft being one of them. Engineering companies, airports, certification authorities, consultants, aircraft manufacturers, and industry suppliers in the aircraft industry all work together to solve the issues at hand. We believe that this international, multidisciplinary collaboration is essential to accelerating the transition toward new technologies and the decarbonization of the aviation industry.

Meeting airports infrastructure demands

The most important non-technical challenge related to hydrogen fuel cells concerns infrastructure. Airports need to provide systems for fast and secure refuelling on-site, complete with properly trained staff. Permits, procedures and safety regulations that have to be in place, along with large quantities of liquified hydrogen.

The best way to prepare for the change to come – and get the ball rolling – is to fund early demonstrations and early implementation; plant a supply-demand seed. The authorities and the market have a joint responsibility in developing this infrastructure to meet the market demands and environmental standards. Similarly, both big enterprises and startups have their roles to play. Startups in particular need to push innovative technology and challenge established perceptions and solutions. Here too, the synergies between the different parties will be important in and of themselves, as they will help the entire industry progress faster.

Next generation hydrogen fuel cell solutions for aviation

Other industries may have come further in their adoption of fuel cell technology, but that also allows the aviation industry to learn from their experiences. Industrial synergies help all the actors involved, especially when it comes to the major issues that tend not to be industry-specific, such as storage solutions or refuelling infrastructure.

While PowerCell Group is only one piece of this larger industry puzzle, we are already working with mature hydrogen fuel cell technology and solutions that are in operation today, including in the aviation industry. The knowledge we acquire from different applications helps us create better solutions for different industries. Moreover, it makes it easier for us to help other stakeholders as well: OEMs (Original Equipment Manufacturer) with their product development, agencies and authorities in their certification work, for example.

So yes, we have only just begun to tap into the potential that hydrogen fuel cell technology holds for the aviation industry. But the technology itself is in place, giving us new, concrete insights on how best to develop it for the future. The next generation of hydrogen fuel cells is one of these areas. For the aviation industry, they represent a major step toward finding fuel cell solutions that can be adapted for larger hydrogen-powered aircraft than those used today.

Andreas Bodén

CTO, PowerCell Group