A new midsize aircraft concept unveiled on December 6th in the UK provides a tantalising insight into a future in which aircraft powered by liquid hydrogen could deliver the same performance and comfort as today’s widebody jetliners.
Unveiled as part of the FlyZero project, led by the UK’s Aerospace Technology Institute (ATI) and funded by the UK Government, the new midsize aircraft concept aims to catalyse research into future long-haul commercial jetliners with zero carbon emissions.
Chris Gear, Director, FlyZero Project, said, “At a time of global focus on tackling climate change, our midsize concept sets out a truly revolutionary vision for the future of global air travel keeping families, businesses and nations connected without the carbon footprint.”
The challenge to reduce carbon emissions is especially severe in the aviation sector due to the large power requirements required to transport hundreds of passengers over thousands of kilometres along with the standardisation, safe fuel handling requirements and already existing infrastructure at airports around the world.
Development of commercial jetliners and the aero engines which power them is also a time consuming and costly endeavour taking close to a decade with the aircraft and engines remaining in service for 30-40 years afterwards.
The development of hydrogen-powered zero-emission aircraft now has greater importance following the conclusion of the COP26 climate conference in Glasgow, which saw 24 countries, representing approximately half of global aviation emissions, agreeing to work together to achieve a new aviation decarbonisation goal.
Revolutionary Concept
The FlyZero research project aims to realise zero-carbon emission commercial aviation by the end of the decade. The detailed findings from the FlyZero project are slated for publication early next year and will include three final aircraft concepts (regional, narrowbody and midsize), technology roadmaps, market and economic reports and a sustainability assessment.
ATI FlyZero’s midsize aircraft concept demonstrates a zero-carbon emission aircraft with a 54-metre wingspan powered by two turbofan engines using hydrogen combustion. The aircraft will carry up to 279 passengers with a range of 5,250NM. It will be able to fly from London to destinations such as San Francisco (4,664NM), Delhi (3,642NM), Beijing (4,414NM), Vancouver (4,105NM), Mexico City (4,815NM) and Rio De Janeiro (4,983NM). Destinations farther away from London, such as Auckland (9911NM), Sydney (9188NM) and Honolulu (6289NM), will be attainable with a single fuel stop.
FlyZero has identified the various onboard technologies needed to develop the concept aircraft. These advanced technologies include wings without fuel tanks (dry wings), hydrogen tanks, cryogenic fuel systems, fuel cells and electrical power systems and hydrogen gas turbines. All these systems will need to be developed and proven for commercial use and the infrastructure and ground equipment needed for refuelling before zero-carbon emission flight becomes a reality.
FlyZero’s midsize aircraft concept has cryogenic fuel tanks in the aft fuselage and two smaller ‘cheek’ tanks along the forward fuselage, in which its liquid hydrogen fuel is stored at a temperature around minus 250 degrees Celsius. The cheek tanks play an essential role in maintaining the aircraft’s centre of gravity, as the fuel within them is burnt off.
Potential Energy
According to ATI’s report ‘Realising Zero-Carbon Emission Flight’ - primary energy source comparison and selection, “On average, approximately 20% of an aircraft’s take-off mass is fuel, leaving approximately 25% for payload (passengers) and approximately 55% for the aircraft ‘dry mass’ i.e., everything else (aircraft structure, propulsion system powerplant, auxiliary systems etc).” Compared to Kerosene, which is used in aircraft fuel, hydrogen has approximately three times the available energy content per kg. Compared to a battery, hydrogen has about sixty times the available energy content per kg.
Emma Gilthorpe, CEO, Jet Zero Council, said, “The Aerospace Technology Institute’s pioneering research highlights the potential for hydrogen in realising zero-carbon global connectivity. This ground-breaking green technology looks set to play a critical role in decarbonising flight and through the work of the Jet Zero Council, the UK aviation sector is exploring all avenues to ensure we protect the benefits of flying for future generations, while cutting the carbon cost.”
While there remain considerable technological challenges to realise green liquid hydrogen-powered flight, it is expected that by the mid-2030s, the technology will have progressed sufficiently to deliver a new generation of highly efficient hydrogen-powered aircraft with operating economics superior to conventional aircraft.