Rolls-Royce is getting more committed to hydrogen

If one thing has become clear at last week’s Farnborough Airshow, it was that Rolls-Royce is getting ever-more committed to hydrogen. The engine maker announced a couple of technology developments related to hydrogen as well as hybrid-electric as well as a partnership with easyJet in its quest for more sustainable aviation. We discussed some in a bit more detail with Alan Newby, Director of Aerospace Technology and Future Programmes. Rolls-Royce is getting more committed to hydrogen. As reported earlier last week, Rolls-Royce announced a “leading-edge” hydrogen research program that includes ground tests later this year with an AE2100 turboprop engine, to be followed by tests on a Pearl 15 jet engine. This builds on its hydrogen research project with Loughborough University and German aerospace research center DLR. Directly related to this program is the partnership announced on the second day of the airshow with UK airline easyJet and called H2ZERO. The announcement was done by Rolls-Royce Chief Technology Officer, Grazia Vittadini, and easyJet CEO, Johan Lundgren. Actually, the initial partnership was announced back in December as a two-year collaboration on sustainability research. AirInsight discusses it in May with David Morgan, then the airline’s Director of Flight Operations and now Chief Operating Officer. “easyJet, as you know, are very keen proponents of hydrogen. They decided they want to work with us on the acceleration of those technologies”, says Alan Newby. “They are in the program to provide operational information. I can do lots of work proving that my engine will run, but how do I refuel it, what kind of mission ranges can I do, what does it mean for airport infrastructure? There is a whole load of stuff that frankly I don’t understand. And also, they bring a passion for hydrogen, they are very keen on hydrogen. They believe in hydrogen as a future and they also believe that their business model works well with today’s size of aircraft. They want to be seen to pull through the technologies, so that’s why they are keen to partner with us to accelerate the development of those technologies.” As Johan Lundgren said in an easyJet press statement: “The technology that emerges from this program has the potential to power easyJet-size aircraft, which is why we will also be making a multi-million-pound investment into this program. In order to achieve decarbonization at scale, progress in the development of zero-emission technology for narrowbody aircraft is crucial. Together with Rolls-Royce, we look forward to leading the industry to tackle this challenge head-on.” Three-pillar strategy Hydrogen is part of what Newby describes as a three pilar-technology roadmap toward sustainable aviation: gas turbine efficiencies, sustainable aviation fuels (SAF), and new technologies like electric/hybrid-electric and hydrogen. “Whatever we see for the medium and long-haul market, whether you are powering the engine on hydrogen or SAF, the optimum powerplant solution is a gas turbine”, explains Newby. “Because those fuels will be more expensive and scarce, the premium on efficiency increases effectively. It is in our interest and that of the industry to keep making more efficiencies. You see that with the Pearl on business jets and on UltraFan, which is just about ready to test.” The first UltraFan prototype engine is nearing final assembly and will start the first tests later this year. (Rolls-Royce) “SAF is the second pillar of our sustainability strategy. We will run UltraFan from day 1 on SAF. We have demonstrated our ability to do that by running almost all engines in the Trent family on SAF. We are also working with governments and the Jet Zero Council here in the UK, have an MoU with Shell, and are working with AirBP. I can get excited about hydrogen, but SAF I can drop in tomorrow. It’s not a technical problem, it is a supply problem.” Newby continues: “The third pillar is electrification and hydrogen. On electrification, we are working with Vertical Aerospace in the UK as a partner in working on their electrical system, we are working with Tecnam on a commuter aircraft, and we are working with Embraer as well. Yes, that will bring a relatively small contribution to decarbonization, but it does allow us to develop new mobility systems. We have the knowledge on working on rail systems and microgrid systems, but applying it to aerospace is new.” Rolls-Royce is providing the electric motors for the Vertical Aerospace VX4 eVTOL vehicle. (Richard Schuurman) “The world is now quite clear that battery-electric has really good promise for short-haul range aircraft, but if you want to go along the distance, then you can either do a hybrid-electric solution or fuel cells. With our electrical capability, it makes sense to have a fuel cell that generates electricity. That’s why we formed a partnership with Hyundai (on all-electric propulsion and hydrogen – RS) to explore that. In principle, you can have the same electrical system if I trade my batteries for fuel cells. It can be applied to Advanced Air Mobility vehicles, but the jury is out on how far you can go with fuel cells. Some people go to the top end of the regional market, others to short-range.” Challenges with fuel cells Alan Newby explains that developing fuel cell technology isn’t straightforward. “The challenge with fuel cells is that their power density in kilowatts per kilograms becomes a challenge as they get bigger. But also heat management as well: they run at very low temperatures, they produce low-grade heat, so heat management is a massive problem for those. I think fuel cells will be limited to the regional sector. It may go further with technology.” Rolls-Royce believes that direct injection of cryogenic hydrogen into a gas turbine is “the only realistic solution”, says Newby. “We have spent a lot of time doing the fundamental analyses, not just technical but also economic and environmental implications and sustainability. We have now decided it is time to go public with what we are doing.” “We have been working on the fundamentals of hydrogen for some time, on our own and through partnerships like the UK's FlyZero initiative. So we have been making sure that we understand the fundamentals and we have been doing some early-stage research on the combustion and fuel systems. We have got to a stage now where we are confident enough in the promise of hydrogen as a future fuel. We have got to go to the next stage in terms of verification. So we have announced the ground test program, fundamentally just to understand the principles of combustion of hydrogen. And then later, we will convert a Pearl engine to hydrogen and a full cryogenic system. That will give us then full-system level understanding of running a gas turbine on cryogenic hydrogen.” Add to that the knowledge that easyJet is offering, and the full picture of the pros and cons of using super-cold hydrogen will become clearer in the next couple of years.

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