The Dream of Green Aviation

As more and more of us fly around the globe, aviation is taking an increasing toll on the environment. Is there a way to make our trips to far-away islands or family across the country more sustainable? In this feature series, my co-author Gerhard Richter and I went on a journey to Think-Tanks and innovation labs, to find out more. Here is an excerpt translated from German into English:

Sound bite Andreas Sizmann [Physicist at Bauhaus]

The technical trick is to concentrate sunlight and reverse the combustion process. That means we extract oxygen from water and CO2, and then get hydrogen and carbon monoxide. Applying the Fischer Tropsch process, the two gases can then react to fuel.

“Solar-Jet,” that’s what the researchers have named their new fuel. In the future, huge solar plants might be able to supply the aviation industry with this ecofriendly kerosene. It would be compatible with the same types of airplanes that exist today. The production could take place in the desert, would occupy less space than needed for biofuels, and thus save fertile land for food production. But the development is still in a very early stage: so far, only 50 milliliters of the solar fuel have been produced. The procedure to harvest carbon dioxide from the air still needs to be fully developed. For the moment, the carbon dioxide used for Solar-Jet is still extracted from regular sources [in the ground].

Sound bite Askin Isikveren

“Our mission statement or requirement, as we call it in engineering, is actually set by the European Commission. They produced a document in 2011 – it’s referred to as “Flight Path 2050” – and they have a whole host of things that they would like the aerospace, the aeronautical industry to fulfill by the year 2050.”

The Australian Askin Isikveren is head of the Department of Visionary Aircraft Concepts at Bauhaus Luftfahrt.

Sound bite Askin Isikveren

“The three main ones are actually focusing on the environment. The first one is 75 percent [fewer] carbon dioxide emissions. The second one [is] 90 percent [fewer] nitrous oxide emissions, and the third one [is a] 65 percent reduction in perceived noise, the external noise [that] the aircraft generates when you’re taking off, for example.”

The goal is to drastically reduce the ecological impact of each kilometer that a passenger travels, as compared to the emissions of an aircraft commissioned in the year 2000. At the same time, the sector is expected to grow by 3 to 5 percent each year. This vision for European aviation in the year 2050 was created by representatives of research institutions, the aviation industry, and the energy company Shell.

Sound bite Askin Isikveren

“Even [for] seasoned engineers, you know, experienced engineers, it sounds like a tough effort. However, we’ve done initial studies at Bauhaus, and we’ve up come up with various scenarios.… So, we find, as we draw towards 2035, fairly realistic ideas are there for us to bring together and realize a reduction of over 50 percent. As we go towards 2050, … this 75 percent reduction … becomes rather difficult. And a whole host of what we call disruptive technologies, technologies … we’re not that familiar with, we have to start considering those.”

Isikveren and his team at Bauhaus have thus started to develop concepts for completely new kinds of airplanes. At the moment, their flagship [design] is the Ce-Liner, a fully electric airplane for short and medium distances. It would cost billions to develop this new type of aircraft. And money is not the only obstacle for takeoff…. Batteries of 2,000 watt-hours per kilogram – which would be required – do not yet exist. It is highly uncertain whether they will be developed at all over the coming decades.

Fasten Seat Belt Sound

Pilot (fictional announcement)
Ladies and Gentlemen, a quick announcement: we will now cross a slightly critical stretch of turbulence. Please fasten your seat belts.

Fasten Seat Belt Sound

Sound bite Stefan Gössling [previously introduced: expert on aviation and climate change]

“Greenwashing means suggesting you can do more with technology than is really known … and choosing to focus the discussion on relative reductions. The real question is absolute development. Saving 2 or 3 percent in fuel per kilometer each year is not relevant if each of us flies 5 or 10 or 30 kilometers more each year.”

The attractive promises of the aviation industry do not convince Stefan Gössling. The European Commission’s publication “Flight Path 2050” is pure marketing to him.

Sound bite Stefan Gössling

“This report stands out mainly in two ways. The first, if I may say so a bit cynically: it contains a lot of nice pictures. And second, it wins over the reader through an absence of facts.”

The number of passengers is growing. Travel distances are getting longer and longer. As a result, the consumption of kerosene has skyrocketed. According to the UN’s International Civil Aviation Organization [ICAO], carbon dioxide emissions from the aviation industry will multiply many times over by 2050. Most of what new technologies can save will be consumed by the growth of the sector.

Sound bite Stefan Gössling

“Unfortunately, it is not stated very clearly in the document that this is a huge conflict awaiting us. The solution is supposed to be technology that doesn’t exist yet, or the EU-ETS, an emission trading scheme for aviation.”

But for Stefan Gössling, the European Union emission trading scheme is no credible solution either. In the 1990s, the Kyoto Protocol established a framework for climate protection. But it contained no specific requirements for aviation and marine traffic. The solution was to be negotiated on an international level within the ICAO. But up to now, this hasn’t happened. Emission certificates are required only for flights within the European Union and a few other countries. However, the European Emission Trading Scheme, or ETS, does not quite work. Moreover, it is an open system, allowing air carriers to buy emission certificates from other countries.

Sound bite Stefan Gössling

“But India or China do not have national caps for their emissions and no national goals to lower them. In other words, we can buy emission reductions from projects all over the world until eternity, without this having any practical implications for air traffic.”


Sound bite Bertrand Piccard

“Philosophically speaking, aviation also has a role. It is to inspire people.”

[says] the son of a family of pioneers, Bertrand Piccard. His grandfather Auguste broke records as a balloonist, and his father Jacques reached unprecedented depths in the world’s oceans. The psychiatrist Bertrand Piccard and his copilot were the first to fly nonstop with a hot-air balloon around the earth.

Sound bite Bertrand Piccard

“Very often, the protection of the environment is boring and expensive, and it’s presented as a big problem that doesn’t motivate anybody. So we believe that we have to make the protection of the environment really exciting, spectacular! To show that it’s the new adventure of the twenty-first century. And Solar Impulse has this goal; Solar Impulse is a way to demonstrate how the new clean technologies can save energy, save the natural resources of our planet, and show that renewable energies can achieve absolutely incredible things. The pioneering spirit today is not to go back on the moon. It’s to make a better quality of life and to protect humankind.”

Piccard’s new baby is the “Solar Impulse.” For twelve years now, he has been working on the solar airplane with business partner André Borschberg. It is more than just an idea. After a number of successful flights, the two pilots plan to fly around the world in the spring of 2015 – up in the air for up to five days in a row and without using a single drop of fuel. Former Swiss Air Force pilot André Borschberg proudly describes the team’s accomplishment:

Sound bite André Borschberg

“So first of all we use the sun as a source of energy; so by having solar cells integrated in the airplane, we transform the sunrays into electricity. And this electricity is used to propel the airplane [by means of] electric motors. [It] is stored in two different ways – [in the] batteries, but also in altitude. Which means, during the day we climb to very high altitudes, and we use this altitude at the beginning of the night to slowly fly down, [to] sink at a very, very low speed for a few hours. And this saves time of the batteries.”

Would it be possible to apply a concept like this to larger passenger aircraft as well? When it comes to the future of aviation, Bertrand Piccard is modest in his expectations. At the moment, only one pilot fits into the Solar Impulse. Its wing-span is wider than that of a jumbo jet, but it can carry only the weight of a car. The aircraft is sensitive to turbulence and must be flown in good weather. Even with vastly improved solar cells, it would not be possible to lift a commercial airliner into the air, explains a video on the topic by Airbus – but solar power might one day supply the onboard electronics.

Bertrand Piccard and André Borschberg see their solar airplane as a statement: If green technologies can achieve so much in the air, it can definitely be done on the ground. But the pilots would not rule out the idea that one day solar technology might play a bigger role in the air.

Sound bite Bertrand Piccard

“Today we don’t have the technology to transport two hundred people in a solar airplane, but the Wright brothers also did not have the technology for that. And nevertheless, forty years after the Wright brothers, people were crossing the oceans with commercial airplanes.”

Fasten Seat belts Sound

— Except starts at 13:02, ends at 24:22 —


Radio feature broadcast January 8, 2015, by Deutschlandradio Kultur
Original Language: German
Length of excerpt: 11 minutes. Start at minute 13:02

Concept, interviews, and manuscript: Anja Krieger
Editor at Deutschlandradio: Jana Wuttke
Narration: Ilka Teichmüller
Voice-overs: Gilles Chevalier, Ulrich Lipka
Director: Moritz von Rappard
Total length: 28 minutes
Full MP3 (German)
Full text (German)

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