By Bjorn Fehrm

December 7, 2022, © Leeham News was at Airbus Summit: Airbus briefed media and influences on its Sustainability progress during briefings in Toulouse and Munich last week. Here is an update on where Airbus is with its programs.

The overall impression is of tangible progress on techno brick research and development and echo systems programs like SAF production and hydrogen supply and ground infrastructure.

At the summit, key customers like Airlines, technology partners, and leasing companies were part of the panels, giving the customer perspective and the view of the passengers.

The presented areas

Status were given for the following areas;

• The status of SAF for the installed fleet and deliveries of regular turbofan jets.
• The status of technology development for the 2035 introduction of a hydrogen-fueled airliner.
• To what extent can hybrid be a part of Sustainable airliners, and how shall it be done?
• Can helicopters be more sustainable, and how?
• What part of air transport can UAM traffic systems do better?

SAF for yesterday’s and today’s turbofan airliners

Airbus had invited Neste, a pioneer in Sustainable Aircraft Fuel (SAF) to discuss the present status. Today most aircraft and engines can accept up to 50% mix of SAF/Jet-A1 blend. But we only have 0.1% SAF in production right now of the total usage of 350 million tonnes of jet fuel per year.

Neste will increase its production with new production plants from today’s 0.1 million tonnes to 2.2 million tonnes by 2026. Total production by 2026 will be around 5 million tonnes, a too-low figure.

To foster investment in SAF production capacity, we need a strong demand signal. Airbus and several airlines have set a goal of a 10% SAF mix by 2030 by it, creating a demand signal to the SAF producers.

It’s important to understand that a 10% mix for all 25,000 airliners flying each day is far more important than that one or two types can be delivered capable of flying a 100% mix by 2030. With a 100 or 200-per-year production rate, a 100% mix for an aircraft type will do nothing to reach carbon neutrality by 2050. A blend of 10% SAF by 2030 and 50% by 2040 will.

Airliners need changes in fuel systems and engines to go beyond 50%. It can only be achieved with newly produced aircraft. What shall we then do with the other 24,000 flying each day?

The development of a ZEROe airliner

Airbus has committed to introducing a hydrogen-fueled airliner by 2035. Several activities must be completed for such an introduction to be successful:

• An airplane must be developed, certified, and produced.
• An ecosystem with green hydrogen production and distribution must be set up.
• Governments, Regulators, and Airlines must be brought onto the project so commercial traffic can be operated on commercially acceptable terms.

Hydrogen airliner development

Airbus is working on all the technobricks (Airbus speak for all the parts/system that are needed) that need to be explored and matured so a configuration decision can be made in 2027 after flight trials of a hydrogen Turbofan and a Fuel Cell turboprop has been done 2026 on a test A380 (Figure 1).

The tricky bits are the hydrogen fuel tank with piping/filling system and the fuel cell-based turboprop system. The hydrogen-burning turbofan is relatively straightforward; GE/CFM, Pratt & Whitney, and Rolls-Royce all have hydrogen-burning gas turbine knowledge and can offer an engine for 2035.

The tricky side of H2-burning engines is the emissions. CO2 emissions are zero, but the engine emits NOx and water vapor. The NOx emissions are reduced to around 20%, so it’s a five times improvement over today’s engine, and steam injection in the combustor, like for the SWITCH engine, could reduce this further.

The water vapor forming condensation trails is a problem that needs more research. It’s an altitude problem. There will be no condensation trails below and above a certain altitude. How tricky it will be to avoid the condensation altitudes is not fully understood. Therefore, Airbus is flying a glider with an H2 engine this winter; to learn more about this phenomenon.

The 2026 A380 flights with an H2 converted GE Passport engine will also investigate the contrail problem with a sniffer aircraft flying behind the A380 to sample the exhaust from the engine.

The fuel cell turboprop units will benefit from bench tests in Airbus’ ZEROe system test house in Ottobrun Munich. Systems are run with complete hydrogen-fueled fuel cell systems that power electric MegaWatt motors, running in normal conduction form and superconduction setups (Figures 2 and 3).

The results from these and OEM tests with burning H2 engines go into trade studies around different ZEROe airliners. These studies have already settled the H2 tank placement behind the rear pressure bulkhead of the fuselage.

The static Center of Gravity (CG) influence of duel tanks there (dual for redundancy) is compensated by moving the wing backward. As H2 is lighter than jet fuel for the same energy content, the variation in the center of gravity with different H2 levels during the mission is acceptable with such a tank placement.

The trade studies around the different propulsion alternatives are made with different size regional to single-aisle aircraft sizes. A typical size aircraft would be 100 seats with a 1,000nm range. It would be the practical limit for a fuel cell alternative, whereas an H2-burning alternative can be larger.

The hydrogen supply ecosystem

A major part of a feasible hydrogen airliner by 2035 is producing and distributing the necessary hydrogen to the aircraft. Airbus has a dedicated team that works with the hydrogen industry’s stakeholders to enable such an ecosystem, Figure 4.

It can use the space industry, which has used hydrogen as one of its primary fuels for 70 years, but also the road truck industry. Several truck manufacturers base their future long-haul trucks on hydrogen (due to energy density and refueling times), while their distribution trucks use batteries.

The world’s largest truck company, Daimler, with its Mercedes trucks, has decided on liquid hydrogen, LH2. It’s developing production and filling stations for the LH2 and will set this up in the thousands.

These will give Airbus and the H2 industry valuable insights, as it needs to equip perhaps 20 to 50 airports with this capacity to form a viable ecosystem. The pilot airport, Lyon, is already preparing to run its ground equipment vehicles on hydrogen from a pilot H2 storage and distribution system at the airport. Air Liquid will assist in setting this up based on its space launcher H2 knowledge.

Airbus showed examples of the hydrogen infrastructure that airports like Lyon will install, Figure 5.

How to use hybrid technology for airliners

The hybrid technology part of the Airbus Summit was refreshing. Airbus has realized that using hybrid technology to propel airliners doesn’t make sense. The energy source available, batteries, are just too inefficient. This is valid today but also tomorrow.

It doesn’t mean hybrid technology is dead in an airliner; it just has to be used cleverly. Forget about using it to propel the aircraft. A plane the size of an A320 uses 18 to 22 MegaWatt (MW) power to the fan during takeoff and 5 to 7 MW during cruise. There is NO way batteries can supply useful energy for such power needs (a battery system weighs about 5 tonnes for 1 MWh of energy).

Instead, use the electric technology in an expanded “more electric airplane” scheme. Place the auxiliary gearbox generators on the spools as starter motor generators and use these to assist the engines with their tricky power changes. Also, put electric motors on the main wheels and taxi on electric power. Convert a number of bleed or hydraulic power functions to electric.

We used to call this “the more electric aircraft.” The Airbus hybrid is an extension of this theme, rather than the classic hybrid interpretation, where electric energy is involved in the aircraft’s propulsion. It uses the advantages of electric functions and avoids the downside, the heavy and expensive batteries.

Can helicopters be more sustainable, and how

Helicopters are incredibly flexible as they can take off and land almost everywhere. But they are also noisy, vibrate a lot, and consume a lot of energy per passenger kilometer.

Airbus is the world’s largest helicopter manufacturer and is hard at work to address the above drawbacks and make the helicopter more environmentally friendly and sustainable.

It works on electrifying several of today’s mechanical functions to replace these with intelligently controlled electrical functions. For this purpose, it uses technology demonstrators, Figure 6.

What part of air transport can UAM traffic systems do better?

As described in my Friday Corner, Airbus is one of the few eVTOL developers that need not pitch to investors. Its strategy for the CityAirbus NG is long-term, and Airbus is very cognisant of public perception of eVTOLs flying above people’s heads to transport executives to and from an airport.

It has, therefore, identified the EMS (Emergency Medical Services) as its first use case. It has engaged with Europe’s most digitally aware country, Estonia, to create an end-to-end optimized emergency service called LifeSaver.

Airbus is one of the few OEMs that is perfectly honest with its eVTOL performance, speed of 65kts, and range of 43nm, a fraction of other OEMs’ claims.

The CitryAirbus NG is, therefore, the close-range component of this system, which has unique features by being quiet and environmentally friendly (no gas turbine exhaust and noise like from a helicopter). Its drawback is load capability (no stretchers) and range. So the eVTOL is a complement to a helicopter fleet.

The approach shows how the eVTOL forms part of something larger, important, and end-to-end optimized; the saving of people’s lives where the first hour makes all the difference in survivability.

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