Under normal circumstances, Europe’s skies would be packed right now with aircraft jetting people from the drizzly north of the bloc to the beaches of the south, with an attendant, hefty carbon footprint.
If hydrogen could be used to fuel air transport, a study by the European Union has found, the climate effects of aviation could be reduced by 75-90%.
The European Commission, EU research program Horizon 2020 and trade body Hydrogen Europe commissioned management consultants McKinsey & Company to produce the Hydrogen-powered aviation: Preparing for take-off study.
Short-haul flights with low passenger numbers could be the first to become hydrogen-fueled, wrote the authors of the report, with such a move adding only around 10%, or $5-10, to passenger costs. Hydrogen use in that aviation segment could occur within eight to 15 years, the study stated, pending technological breakthroughs, certification and standards, and new infrastructure.
Ticket prices would rise around 30-40% for medium range flights, according to the study, as the larger fuselages required to store liquid hydrogen would lead to 25% more in-flight energy consumption.
With long-haul hydrogen flights costing passengers 40-50% more per ticket – due to more onerous design demands – the use of synthetic fuel, or synfuel, may be a more practical route to decarbonizing such journeys for now, the report found. Design innovations such as stealth-bomber style ‘blended wings’ could bring down hydrogen-related flight costs but will require at least another 20 years of development, according to the EU report.
The authors of the study said the hydrogen costs per abated ton of CO2 equivalent would be less than $60 for regional and commuter flights and $70-220 for short and medium-range journeys. “This compares favorably to $210-230 per ton CO2 equivalent for synfuel-form direct air capture for short to long-range aircraft,” stated the report.
Bart Biebuyck, executive director of the Fuel Cells & Hydrogen 2 Joint Undertaking formed by the European Commission, Horizon 2020 and Hydrogen Europe, said: “The cost of producing clean hydrogen came down in recent years thanks to cheaper renewable electricity and bigger and cheaper production technology. At the same time, fuel cell performance in terms of durability, capacity and cost has made big steps forward. This combination has now made it possible to look to such solutions for decarbonization of the aviation industry and the results of the study are clear on the huge potential of hydrogen in aviation. The hydrogen and fuel cell sector is ready to work hand in hand with the aviation industry to design, test and produce the required components and make zero-emission aviation an everyday reality.”
The report also explored the use of hydrogen as a combustible liquid in revamped jet engines, using it in fuel cells for electricity production and recombining it to synthetic fuels. The study found using hydrogen as a combustion liquid would lead to a climate impact reduction of 50-75% as non-CO2 emissions such as NOx and water vapor would continue to contribute to global warming. Fuel cell-based power would prompt climate impact reductions of 75-90%, and synthetic fuels 30-60%. The study claimed fuel cell propulsion offered the best economics, except on long-haul flights.
Aviation produces 900 million tons of carbon dioxide per year. With an industry growth rate of 3-4% per year before the onset of Covid-19 and efficiency improvements playing catch-up at just 2% per year, the sector’s CO2 emissions were set to double by 2050. Incrementally deploying hydrogen aircraft in the segments where they are the most cost-efficient means of decarbonization would see 40% of all aircraft hydrogen-powered by mid century, with the balance synfuel/biofuel-powered, to prevent the emission of 2.7 gigatons of CO2.
The report’s authors recommended a target of making all short-range flights hydrogen fuel based by 2035 and called for research into liquid hydrogen fuel and propulsion components, aircraft systems, infrastructure and regulatory requirements, to achieve that goal.
Work to do
“Research and innovation is vital to realize the full potential of hydrogen technologies for [the] decarbonization of aviation,” said Patrick Child, European Commission deputy director-general for research and innovation. “The EU’s future Horizon Europe research and innovation framework program is a fantastic opportunity to advance this agenda, working in partnership with industry and the research community. The excellent co-operation between the existing joint undertakings dedicated to hydrogen fuel cells and clean aviation illustrates the need for close synergies between the two sectors as we work together on the ambitious objectives of the post-Covid recovery and the European Green Deal.”
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The innovations required to make hydrogen flight a reality include a need for lighter, more efficient fuel tanks, with a target of 12 kWh/kg and a gravimetric index of 35%, and fuel cell systems targeting 2 kWh/kg. Jet engines capable of burning hydrogen with low NOx emission are also needed as well as systems for safely handling liquid nitrogen. Industry insiders speculate such advances could be achieved within 5-10 years, according to the EU study.
The question also remains as to where the hydrogen necessary would come from. With Europe currently generating just under 10 million tons per year of the global 78 million, transforming just short-haul flights to the new fuel would drive an estimated 40 million-ton hydrogen market by 2050.