Why Hydrogen?

hydrogen infrastructure

Here we explain why for Project Fresson hydrogen fuel cells are considered an optimum solution for aviation, and how advances in technology mean that hydrogen is viable for this application. 

Hydrogen has been a known technology for some time, and is already being used in heavy duty commercial vehicles such as long-haul trucks and buses because for fleet operators it offers not only zero carbon emissions but also cost-effective solutions in terms of total cost of ownership.

Paul Hutton, Cranfield Aerospace: “We did look briefly at pure battery electric to see if that had any chance of delivering what we wanted, but even before the formal project started, we realised it would need to be something other than just a battery to get a useable range.”

“Having looked at the hybrid electric range extender option in some respects it looked quite promising, but when we started doing the project, doing the detailed analysis and understanding the weight implications whichever angle we took, we couldn’t get a solution which was greener, while still being safe and still providing a usable range.”

“We were looking at hydrogen in parallel with that. Hydrogen was coming up more and more including very credible storage solutions to get the weight down because the tanks required to carry gaseous hydrogen can be very heavy. So that was improving. The availability of fuel cells with the right level of output was improving, and the availability of hydrogen as a fuel, that whole infrastructure seemed to be accelerating at the same time.”

Dr Cedric Rouaud, Ricardo: “For Project Fresson, Ricardo is providing the fuel cell system including its controller, which is the primary source of electricity on the aircraft. The fuel cell system includes the fuel cell stack and the balance of plant. Fuel cell systems use hydrogen and oxygen from ambient air to generate electricity. The only by-product is water vapour, and hence a hydrogen fuel cell aircraft has zero carbon emissions.”

“Ricardo was chosen to be part of Project Fresson because of our industry-leading experience in systems engineering and model based development approaches, as well as our expertise in fuel cell and thermodynamic or thermal systems development. Leveraging that experience and expertise, one of the most crucial services that we are providing for the project is managing the balance of plant. The balance of plant includes all ancillaries which are used to provide the fuel cell stacks with the right amount – in terms of temperature, pressure, mass flowrates, relative humidity – of hydrogen and air and also coolant. The balance of plant has to work in all operating conditions from cold operations to high temperatures (on the ground) and at high altitudes, including low pressure and temperature.”

“All balance of plant ancillaries include: pumps, valves, injectors, compressors and heat exchangers. They could be heavy, bulky and expensive. Ricardo has developed a process to improve the balance of plant components for multiple stack layouts for aerospace but also large applications requiring multiple stacks such as commercial vehicles, rail and marine. Using the Ricardo hydrogen fuel cell system development approach with multiple stacks balance of plant leads to an efficiency improvement of 5-15% depending on duty cycle against the conventional approach of balance of plant and control development, so there are tangible performance benefits for customers.”

Stuart MacIntyre, Innovatus: “In terms of storage solutions for gaseous hydrogen for the hydrogen fuel cell propulsion systems, from a tank perspective, it is clear that hydrogen fuel cell propulsion is a very viable technology, for almost any transport related application. However, the tank in particular as this project is an example of is a key enabler in the whole process. So, traditional heavy weight hydrogen tanks are often hard to integrate into these types of applications.”

“The Innovatus Shyft tank technology resolves that challenge using very novel latest generation carbon composite manufacturing techniques to create multi-chamber hydrogen storage tanks which are super lightweight, very high pressure capable but most importantly, completely formable to the application required. So, in this case aerodynamics are key, weight is paramount and hydrogen storage volume is a principal descriptor of the range of the system. Innovatus brings this technology into the programme to carry enough hydrogen efficiently in the form factor to release the performance of the platform.

“Project Fresson represents a proof of concept of how hydrogen fuel cell technology could be integrated into any number of different transport sector applications and the tank is a key component to creating the performance envelope needed.”

Mark Kelk, Cranfield Aerospace: We are also working with governments around the globe on the installation of infrastructure trials so we can demonstrate to operators that this capability and can be put into an operational set up readily. Getting hydrogen from renewable sources through electrolysers is all part and parcel of the grand design.”

Lara Harrison, Britten-Norman: “It’s not just about the flight time. If we use batteries, we are not only getting less flight time and more weight compared with the hydrogen solution, but it’s also about how our customers operate, charging times and infrastructure. Current charging times in the automotive sector are still seen as a barrier to consumer adoption of electric vehicles, so when you put that in the context of the aviation sector, especially hops from island to island, the charging really becomes an issue. So, for us, the hydrogen solution is better suited for real world application.”


Cranfield Aerospace Solutions is leading the Project Fresson consortium project which is seeking to deliver the world’s first truly green passenger carrying airline services using hydrogen fuel cell technology. The project will develop a commercially viable, retrofit powertrain solution for a nine-passenger Britten-Norman Islander aircraft, and will accelerate the growth of the UK aerospace supply chain for new technologies critical to zero emissions aircraft.