Towards climate-neutral air transport

Emis­sion-free flight

Electric flight – emission-free, with a new look and quieter
Elec­tric flight – emis­sion-free, with a new look and qui­eter
Image 1/6, Credit: DLR (CC-BY 3.0)

Electric flight – emission-free, with a new look and quieter

Elec­tric flight com­bines sev­er­al ad­van­tages; it is lo­cal­ly emis­sion-free, qui­eter, and makes com­plete­ly new mo­bil­i­ty op­tions pos­si­ble.
First flight of four-passenger fuel cell aircraft
First flight of four-pas­sen­ger fu­el cell air­craft
Image 2/6, Credit: DLR (CC-BY 3.0)

First flight of four-passenger fuel cell aircraft

In Septem­ber 2016, Hy4, the first four-seater pas­sen­ger air­craft pow­ered sole­ly by a fu­el cell sys­tem, em­barked on its first flight from Stuttgart air­port.
The road to climate-neutral aircraft
The road to cli­mate-neu­tral air­craft
Image 3/6, Credit: © DLR. All rights reserved

The road to climate-neutral aircraft

DLR is con­duct­ing a con­cep­tu­al study to bring an eco­log­i­cal­ly ef­fi­cient medi­um-haul air­craft in­to com­mer­cial flight by 2040.
Electric drive enables innovative aircraft concepts
Elec­tric drive en­ables in­no­va­tive air­craft con­cepts
Image 4/6, Credit: DLR (CC BY-NC-ND 3.0)

Electric drive enables innovative aircraft concepts

Short and medi­um-haul air­craft con­cept with a hy­brid elec­tric drive.
 Artist's im­pres­sion of the Electric Flight Demonstrator
Artist's im­pres­sion of the Elec­tric Flight Demon­stra­tor
Image 5/6, Credit: DLR/Hendrik Weber,

Artist's im­pres­sion of the Electric Flight Demonstrator

While so far on­ly bat­tery-pow­ered small air­craft are in op­er­a­tion and hy­brid-elec­tric small air­craft are cur­rent­ly un­der­go­ing flight tests, DLR, to­geth­er with Siemens, MTU Aero En­gines and RU­AG Avi­a­tion, has con­duct­ed a fea­si­bil­i­ty study for a 19-seat test air­craft based on a Dornier Do-228. The study shows promis­ing chances of suc­cess for the con­ver­sion and test­ing of a na­tion­al Elec­tric Flight Demon­stra­tor, which has a com­plete elec­tric propul­sion sys­tem in the 500-kilo­watt pow­er class in the ex­pan­sion stages of bat­tery elec­tric op­er­a­tion and hy­brid elec­tric op­er­a­tion with an ad­di­tion­al gas tur­bine gen­er­a­tor.
Exhaust gas measurements during formation flight
Ex­haust gas mea­sure­ments dur­ing for­ma­tion flight
Image 6/6, Credit: NASA

Exhaust gas measurements during formation flight

Be­hind the DC-8, which is us­ing bio­fu­el, sci­en­tists on board the DLR Fal­con mea­sure the ex­haust gas com­po­si­tion.

The objective has now been set in Germany and Europe, with the aim of achieving climate neutrality in the economy and society. This is how it is worded in the EU's 'Green Deal'. The consequences of climate change also compel us to strive towards climate-neutral air transport, as this sector is responsible for 3.5 percent of global warming. New technologies are needed to ensure global mobility in the future. With 25 institutes and facilities active in aeronautics research, DLR is driving this change forward with sustainable technologies for environmentally compatible air transport. Expertise from DLR's space, energy and transport research programmes is also playing an important role in this.

DLR's ultimate vision is zero-emission air transport. Achieving the climate targets that have been established will require a disruptive approach. Aircraft and air transport must be considered as a complete system. DLR is one of the few research institutions in the world with the capability to simultaneously equip aircraft with new propulsion systems, record their emissions and model the resulting climate impacts within the context of the global air transport system. This systems expertise places DLR in the role of architect. From fundamental research through to applications, DLR works in close coordination and collaboration with the aircraft industry and the air transport sector.

Efficient aircraft configurations with an optimised mix of propulsion technologies

In concrete terms, the energy requirement of new aircraft must be reduced by at least half by 2050. In order to meet this target, these will have to become significantly lighter and more aerodynamically efficient, in combination with the introduction of innovative flight control and sensor systems. Efficient aircraft configurations will require an intelligent mix of alternative propulsion system concepts. In future, small and regional aircraft will be able to take off using battery or hybrid-electric systems, while medium-haul aircraft will be capable of flying using direct hydrogen combustion or fuel cells. On long-haul routes, aircraft will use Sustainable Aviation Fuel (SAF) in combination with highly efficient turbines.

Climate-optimised flight routes offer important possibilities for savings, and these can be harnessed quickly and for all aircraft. This is especially important given that two-thirds of the climate impacts of air transport are due to non-carbon-dioxide effects. Contrails play a significant role in this. They occur in specific places and are thus a key area of focus for routing.

The digitalisation of air transport is an essential tool in this comprehensive transformation. Optimised flight routes rely on complex computer simulations. New aeronautics technologies will make their initial flights as digital twins on a computer before being tested in the real world. Many of them have to be researched from the fundamentals, tested in practice and finally certified. DLR is in prime position to do this, with its research aircraft, wind tunnels, propulsion demonstrators and supercomputers.

In 2020, DLR published the white paper 'Zero Emission Aviation' with the German Aerospace Industries Association. DLR is currently working on a Zero Emissions strategy for aeronautics research.

21 articles
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  • Dr.-Ing. Markus Fischer
    Ger­man Aerospace Cen­ter (DLR)

    Deputy Board Mem­ber Aero­nau­tics
    Telephone: +49 2203 601-3698
    Fax: +49 2203 601-2767
    Linder Höhe
    51147 Cologne

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