Air France-KLM’s Dutch arm operated a passenger flight from Amsterdam to Madrid that the carrier says was the first in the world to use sustainably derived synthetic aviation fuel.The Boeing Co. 737-800 narrow-body plane carried 500 liters of the fuel produced by Royal Dutch Shell Plc, equating to more than 5% of the total requirement for the trip, KLM said in a statement Monday.

While flights partly powered by plant-derived biofuels have become commonplace as aviation seeks to reduce its reliance on fossil fuels, fully synthetic propellants have taken longer to develop. KLM said the Madrid flight, which took place on Jan. 22, was groundbreaking in combining carbon capture with solar and wind power to produce a fully sustainable kerosene substitute.

“The introduction of sustainable aviation fuel is very important to us,” KLM Chief Executive Officer Pieter Elbers said in a webinar on SAF, where news of the flight was disclosed. “The captain informed the passengers that this was a big step for the industry. They didn’t notice any difference.”

KLM also operated the first commercial service to use biofuel in 2011, powered by a 50:50 blend of kerosene and used cooking oil. Availability since then has “been really a challenge,” so that it currently meets less than 1% of the airline’s needs, Elbers said.

Synthetic jet fuel is derived from carbon dioxide and water and could help fill the gap, though the electrolysis used to secure hydrogen for the process eats up large amounts of power, making its industrialization a major challenge.

Fuel for the KLM flight was produced in a Shell lab using carbon dioxide captured from Europe’s biggest oil refinery in Pernis, near Rotterdam, and from a cattle farm in the northern Netherlands.

Marjan van Loon, Shell’s president for the Netherlands, said the aim now is to turn synthetic fuel from “something that is technically possible to something that is economically viable,” reducing costs and accelerating production.

Synthetics and biofuels are seen by airlines as vital to cutting emissions before hydrogen and electric power make flying truly carbon free, something that’s unlikely to be viable until well into next decade for even short-haul airliners.

©2021 Bloomberg L.P.