So far, air traffic has been responsible for around three percent of global greenhouse gas emissions. A team of researchers has now investigated whether and how this could be changed with alternative fuels and what that would cost. According to this, passenger aviation could become largely CO2-neutral by 2050, but only with significantly increasing CO2 pricing, fixed feed-in quotas for the fuels produced using solar energy and enormous investments in the construction of solar systems.
Air travel is a growing problem for the climate. With 680 percent growth from 1960 to 2018, it is now responsible for three percent of global carbon dioxide emissions. The climate effect is additionally intensified by the contrails, in which ice crystals form around the exhaust gases emitted by the aircraft and keep them in the air for hours. Even if the corona pandemic almost brought global air traffic to a standstill at times, experts expect aviation to recover relatively quickly. Then the worldwide annual carbon dioxide emissions of the passenger aircraft currently operated with conventional fuels could rise again to around 1.8 billion tons by 2050 – two and a half times as much as in 2018.
Renewable energy fuels and CO2 pricing
Researchers working with Stefan Gössling from Linnaeus University in Sweden have now investigated how this could be prevented. To do this, they used computer models to test a scenario according to which passenger air traffic could become CO2-neutral by the year 2050 – through the use of synthetic fuels that are not generated from fossil fuels but from precursor substances such as CO2 using electricity from renewable energies . These technologies already exist, including in the form of so-called power-to-liquid, but are still significantly more expensive than conventional aircraft fuels. In order to enforce them, one would therefore need a compulsory share of these alternative fuels – with correspondingly higher costs.
The scientists have now calculated what that would cost and how much it would bring for the climate. “In our scenario, the drive is switched to non-biogenic, electricity-based fuels,” explains Felix Creutzig from the Mercator Research Institute on Global Commons and Climate Change. Specifically, the researchers calculated a scenario in which a ten percent increase in the price of flights would lead to a ten percent decrease in passenger demand. With regard to the share of alternative fuels, they assumed that the statutory feed-in quota would increase linearly to 100 percent. With CO2 pricing from a gradual increase from 100 euros in 2022 to 800 euros per ton of CO2 in 2050.
Saving of 27 gigatons of CO2 possible – but with space problems
The result: “With around 150 percent higher fuel costs and almost 40 percent higher overall costs, significantly more would still be flown in 2050 than in 2018,” reports Creutzig. Global aviation would then have around 16 trillion passenger kilometers in 2050 – that would be about half as much as in the business-as-usal scenario, but twice as much as in 2018. The atmosphere would then remain in the period from 2022 to 2050 as a whole Emissions of around 27 gigatons of CO2 are saved. The savings effect would be less if politicians only rely on the feed-in quota and not additionally on CO2 pricing. It would be bigger if the Corona dent were not overcome until later than 2022.
However, in order to enable the feed-in quota for synthetic fuels, which has increased to 100 percent, sufficient space is required for the new energy sources. Around 320 million tons of synthetic fuels would be required for the around 16 trillion passenger kilometers in the variant assumed by the study. As the researchers explain, the most cost-effective and space-saving option currently available to produce the electricity required for this CO2-free would be solar power plants. However, around 140,000 square kilometers of space would be required for these – which corresponds to around 40 percent of the area of Germany or roughly all of Nepal.
According to the scientists, the locations for such a large number of solar cells and thus for the production of future aircraft fuel could most likely be in desert regions. “That naturally raises questions about safe transport, and generally about the social and political consequences of such large investments,” emphasizes Gössling. “But for CO2-free air traffic in 2050 you have to start now with the production of synthetic fuels on a large scale and gradually ramp it up. That is why the corona crisis is a time window to change course – towards a more moderate but reasonably sustainable growth path, ”summarizes the researcher.
Source: Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH, Article: Environmental Research Letters, doi: 10.1088 / 1748-9326 / abe90b