What I want to tell you about now is the start of something new. A start of sustainable aviation. Against the backdrop of a rapidly increasing global drive to combat climate change initiated by the Paris agreement in 2015, the goals and actions of this one sector remained veiled in obscurity. Flying was not mentioned in the agreement as there seemed at that point no way to achieve sustainable aviation. But by now, even aviation has caught up to the reality of 2021, in which becoming sustainable is inevitable for survival. In this feature, I want to take you along in the advent of sustainable aviation.
The Aviation Sector Needs A Push For Innovation
The story starts with the Wright brothers, who in 1903 developed the first flying machine which was heavier than air. In the following years, as world wars engulfed the world, the airplane developed rapidly, as a tool of war it was indispensable. Between the 1960s and 1980s, the current commercial airplane market developed, as Airbus, a European consortium and Boeing, the consolidation of American manufacturers, developed a duopoly1. Meaning that those two firms produced more than 90% of all aircraft. This was detrimental for innovation, and in the past 40 years, airplanes have barely changed.
Often, what is required to achieve sustainable innovation is not guided by large incumbents. Newspapers did not develop the internet; Shell did not make the first solar panel; Volkswagen did not produce the first mass produced electric car. Especially within aviation and the Boeing-Airbus duopoly, neither firm needed to make a move as long as the other did not either. And becoming a radical new player in the field of aviation is next to impossible when you look at the time needed for development (10-15 years) and capital costs (multiple billions) required to build a commercial aircraft2. In short this meant that no innovation and thus no change was forced.
But now, starting in 2020, finally we are seeing change. Research reports3,4 on the feasibility and technical opportunities are arising, showing that the development of radically new propulsion systems and aircraft designs will be required to achieve sustainable aviation. Policy reports (often lobbied for by the industry itself, showing the lack of attention aviation receives from lawmakers) on European5 and national6 levels describe pathways to achieve sustainable aviation and set clear goals for 2030 and 2050. And finally, within the industry both large airplane manufacturers such as Airbus7, as well as airports such as Royal Schiphol Group8 are showing that they want to achieve the goal of net zero carbon emissions from aviation by 2050.
The next step is how. How can planes that fly with millions of liters of kerosine each year become sustainable in 30 years? The answer is long and nuanced, although it is well described in the papers I reference. In short, there are 3 possibilities currently.
Potential Sustainable Solutions
The first is electric aviation. Though initially leading, the weight to energy ratio as well as the density to energy ratio of batteries is currently very low. This means that to fly a large aircraft, you would need to bring along many batteries, which would add to the weight, which would require more power and therefore more batteries. This means that in the foreseeable future electric aviation is not feasible on a large scale (Figure 1).
The second possible opportunity is SAFs9, which stands for sustainable aviation fuels. This can be anything from biofuels which are produced either from industry residuals or from crops, to synthetic fuels which are produced by combining captured carbon with green hydrogen10. However, these fuels cost enormous amounts of money to produce and are made with scarce resources such as captured carbon, hydrogen or industry residuals.
The final possible solution is building hydrogen powered aircraft. These come in two forms. Either the airplane engine burns the hydrogen in a modified turboprop engine (as has already been done by the United states military in 1956 as well as in the Russian Tupolev aircraft in 1989) or hydrogen can be used to produce electric energy in a fuel cell which in turn powers electric engines. If you want to read more about the science behind hydrogen powered aviation, check out Bjorn Fehrm’s blog. However, hydrogen is only feasible if we see radically new airplane designs and if the supply of green hydrogen increases.
Currently, the most feasible option is pursuing sustainable aviation fuels, as they are “drop-in” fuels that can be used within current aircraft. However, in the longer term to achieve cost efficient aviation that truly does not have a negative effect on the climate, hydrogen powered aircraft are vital (Figure 2). Finally, we must combine technologies, as the solution lies not in one quick fix, but in the combination of many.
To conclude, the era of sustainable aviation is starting now. Start-ups such as Zero-avia and SkyNRG and research initiatives as student team AeroDelft show to be important catalysts in the process, but more importantly it will depend on systematic changes on the way we force innovation within aviation. Even though progress was made in the last few decades, in the first 40 years of innovation, aviation went from a wooden structure with canvas wings that flew for 4 minutes (wright brothers), to giant aircraft that became the most important weapon during the Second World War. Now we must create a similar change in just 30 years, and it is starting now.
Disclaimer: These comments on sustainable aviation are of Vincent de Haes personally. These comments reflect his personal opinion and thus does not necessarily reflect his employers opinion on the topic.
- Olienyk, J., & Carbaugh, R. J. (2011). Boeing and Airbus: Duopoly in Jeopardy?. Global Economy Journal, 11(1), 1850222.
- Markish, J. (2002). Valuation techniques for commercial aircraft program design (Doctoral dissertation, Massachusetts Institute of Technology).
- Clean Sky 2 (2020) Hydrogen-powered aviation: A fact-based study of hydrogen technology, economics, and climate impact by 2050. https://www.cleansky.eu/sites/default/files/inline-files/20200507_Hydrogen-Powered-Aviation-report.pdf
- TU Delft and NLR (2021) TOWARDS A SUSTAINABLE AIR TRANSPORT SYSTEM [White paper] NLR. https://www.nlr.nl/wp-content/uploads/2021/02/Whitepaper_NLR_TUDelft.pdf
- NLR, SEO Amsterdam Economics. (2021). Destination 2050: A ROUTE TO NET ZERO EUROPEAN AVIATION (Rep.). NLR-CR-2020-510. doi: https://www.destination2050.eu/wp-content/uploads/2021/02/Destination2050_Report.pdf
- Ministerie I&W. (2020). Verantwoord vliegen naar 2050: Ontwerp-luchtvvaartnota 2020-2050 (Rep.). Ministerie van infrastructuur en waterstaat.
- Airbus (2020) Airbus reveals new zero-emission concept aircraft. Airbus Home > Media: https://www.airbus.com/newsroom/press-releases/en/2020/09/airbus-reveals-new-zeroemission-concept-aircraft.html
- Royal Schiphol Group (2020) Vision 2050 Storyline. Royal Schiphol group: https://www.schiphol.nl/en/schiphol-group/page/strategy/
- WEF (2020) Joint Policy Proposal to Accelerate the Deployment of Sustainable Aviation Fuels in Europe A Clean Skies for Tomorrow Publication [White Paper] World Economic Forum: https://www.weforum.org/reports/joint-policy-proposal-to-accelerate-the-deployment-of-sustainable-aviation-fuels-in-europe-a-clean-skies-for-tomorrow-publication
- E4Tech (2019). Study on the potential effectiveness of a renewable energy obligation for aviation in the Netherlands. Rijksoverheid: https://www.rijksoverheid.nl/documenten/rapporten/2020/03/03/bijlage-1-onderzoek-e4tech-sgu-obligation-for-aviation-in-the-netherlands-final-v3
- Ustolin, F., & Taccani, R. (2018). Fuel cells for airborne usage: Energy storage comparison. International Journal of Hydrogen Energy, 43(26), 11853-11861.