The 12-month study UK study into zero-carbon emission commercial air travel has considered the feasibility of zero-carbon emission aircraft. The FlyZero project’s report “Our Vision for Zero-Carbon Emission Air Travel” concluded that aviation can achieve net-zero 2050 through the development of both Sustainable Aviation Fuel (SAF) and green liquid hydrogen technologies.
Funded by the UK Government, the UK’s Aerospace Technology Institute (ATI) is leading the FlyZero project, and last December, it unveiled a new liquid hydrogen-powered midsize aircraft concept to catalyse research into the future long-haul commercial jetliners with zero carbon emissions.
ATI said that green liquid hydrogen is the optimum fuel for zero-carbon emission flights and could power a midsize aircraft with 280 passengers from London to San Francisco directly or from London to Auckland with just one stop. To achieve this goal and secure market share on new hydrogen-powered aircraft, UK companies must be ready to demonstrate technologies by 2025.
This timescale was vital for new zero-carbon emission aircraft to enter service by 2035 and achieve the industry’s net-zero 2050 target.
“Zero-carbon emission flight can be a reality. Tackling the challenge of our generation requires accelerated technology development and urgent investment in green energy together with regulatory and infrastructure changes,” said Chris Gear, Project Director – FlyZero. The next three years are crucial if the UK develops the technologies, builds liquid hydrogen skills, and demonstrates the capability to enable its aerospace sector and supply chain to secure its role in a new era for aviation.
The report also calls for work to be done in parallel to advance SAF technologies, as both SAF and liquid hydrogen are required to achieve the net-zero 2050 target. The ATI report states that liquid hydrogen is forecast to become cheaper and greener from the mid-2030s than ‘Power to Liquid’ (PtL) SAF (expected to be the primary SAF as demand increases). Compared to liquid hydrogen, more electrical energy is required to produce PtL SAF, and the availability of raw materials limits the scalability of other SAFs.
Hydrogen Future
ATI’s project report states that the greatest opportunity for reducing carbon emissions would be achieved by introducing a midsize hydrogen-powered aircraft by 2035 and a narrowbody aircraft by 2037. The entry into service of such aircraft would reduce the aviation industry’s carbon emissions by 2050 by up to four Gt (gigatons) if half the global commercial fleet were to be hydrogen-powered by then. This reduction would be equivalent to four years of total global aviation carbon emissions. While a gas turbine engine burning hydrogen emits no CO2 or Sox, it will generate water emissions over 2.5 times higher than fossil-fuel-powered engines. However, harmful NOx emissions will be reduced by 50% to 70%, and particulate matter will largely be eliminated.
The UK’s efforts to place its industry on the cutting-edge of hydrogen propulsion technology could be replicated by India as it needs to rapidly create the talent pipeline for such technologies. Government support is already driving greater innovation in India’s aerospace, defence, and electric mobility sectors, and this approach needs to be extended towards hydrogen propulsion. India can build on decades of expertise in aerospace innovation and growing proximity with global OEMs who have engineering centres in India. The FlyZero report calls for a hydrogen research and development facility to be created in the UK, with open access for academia and a range of industries, including aerospace, automotive, marine, space and energy. India can also consider a similar approach.
The ATI report stresses that it is important that the UK government and Hydrogen UK work on the recommendation to ensure aviation is recognised as an essential use case for H2 in future energy strategies. It also asks that academic research into the climate impacts of hydrogen-powered aircraft be prioritised. This research should focus on predicting and modelling the effects of water vapour and contrails for different atmospheric conditions and assessing the impact of different fuels and propulsion systems on emissions and contrails through laboratory tests and airborne research.
As per the ATI report, the UK could grow its market share in civil aerospace with targeted investment in technology to 19% by 2050 (up from 12% today). This would increase the sector’s gross value added to the economy from £11bn to £36bn and the number of aerospace jobs from 116,000 to 154,000.
“Realising zero-carbon flight is one of the most ambitious challenges we can contemplate,” said UK Industry Minister Lee Rowley, adding that it could also be one of the biggest economic opportunities for the UK’s world-leading aerospace sector. The UK was the first major economy to legislate to bring overall greenhouse gas emissions to net-zero by 2050.
Range Of Possibilities
For liquid hydrogen propulsion to be viable to achieve zero-carbon emission flight, revolutionary technology breakthroughs will be required in six areas: hydrogen fuel systems and tanks, hydrogen gas turbines, hydrogen fuel cells, electrical propulsion systems, aerodynamic structures and thermal management. The UK has little expertise and capability in liquid hydrogen fuels and will need to build these skills in short order. There is also the potential for a greater thrust towards integrating sustainability into design and manufacture and further improving the reuse of hydrogen-powered aircraft materials.
FlyZero has developed three concept aircraft to address the regional, narrowbody and midsize market segments and forecasts that hydrogen-powered aircraft will have superior operating economics over their kerosene or SAF-powered rivals from around 2035. This is due to the carbon pricing and production inefficiencies relating to SAF. The current focus on blending SAF with kerosene enables existing aircraft to remain in service with minimal re-certification but delivers only incremental improvements in aerospace decarbonisation. Thus, while introducing SAF is an important part of the solution, meeting the net-zero 2050 target will require significant developments in capacity for chemical processing and direct air capture. A midsize commercial aircraft powered by liquid hydrogen offers a greater opportunity to reduce carbon emissions. FlyZero’s regional concept uses a liquid hydrogen-powered fuel cell with electric motors, while the narrowbody and midsize concepts both utilise hydrogen-powered gas turbines. These concept aircraft have design ranges between 1,482 km and 10,649 km and will be able to carry between 75 and 280 passengers.
The accelerated introduction into the service of a large commercial aircraft similar to FlyZero’s midsize concept is touted as the optimum route to decarbonising aviation. A midsize first approach would also allow infrastructure development to be focused on fewer but larger international hub airports. A large liquid hydrogen-powered commercial aircraft would be capable of reaching anywhere in the world with just one stop. Such an aircraft would also be less commercially risky than developing a narrowbody first.
According to ATI, an unprecedented amount of renewable energy capacity will be required to deliver the quantity of hydrogen needed for aviation. Transporting hydrogen to airports will also require gaseous pipelines or liquid hydrogen tanker deliveries. Amongst the other recommendations of the report is the call to explore using aviation tax or levy receipts to support the development of a zero-carbon emission aircraft. It further asks for consideration to use incentives, pricing and taxation to influence passenger behaviour and shift demand towards sustainable forms of aviation.
NB: FlyZero contributing companies: Airbus, Belcan, Capgemini, easyJet, Eaton, GE Aviation, GKN Aerospace, High Value Manufacturing Catapult (MTC), Mott MacDonald, NATS, Reaction Engines, Rolls-Royce and Spirit AeroSystems.