Boosting efficiency could slash aviation emissions, study says

The study, which analysed more than 27 million commercial flights across 26,000 city pairs in 2023, also found that airlines could shave 11 per cent off emissions immediately through more strategic use of their most efficient existing aircraft on current routes.

It comes as both Qantas Group and Virgin Australia look to increase their usage of more efficient aircraft such as the Airbus A320neo family, Boeing 737 MAX family, and Embraer E190-E2.

“Efficiency-based policies have a great potential to curb aviation emissions, and can be in airlines’ own economic interest,” said lead author Professor Stefan Gössling of Linnaeus University.

“But the reality is that many airlines continue to fly with old aircraft, low passenger occupancies, and growing proportions of premium-class seating.”

While average aviation emissions were 84.4 grams of CO₂ per kilometre per passenger in 2023, emissions varied from 60 to 360 grams per kilometre per passenger depending on the type of aircraft used.

“[Analysis] revealed enormous variability in emissions efficiency, with some routes producing nearly 900 grams of CO₂ per kilometre for each paying passenger – almost 30 times higher than the most efficient, at around 30 grams of CO₂ per kilometre,” researchers said.

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“Replacing all aircraft with the most efficient models – the Boeing 787-9 (long-haul) and the Airbus A321neo (short and medium-haul) – would result in fuel savings of 25 per cent to 28 per cent.”

Business and first-class seats are up to five times more carbon-intensive than economy seats, and increasing passenger numbers to the maximum configuration for these aircraft could slash emissions by 22 per cent, the researchers said.

Additionally, average load factors in 2023 were around 79 per cent, and if this were increased to 95 per cent, emissions could be further cut by 16 per cent.

According to co-author Dr Milan Klöwer (Department of Physics, University of Oxford), while it would require “systemic changes”, implementing all three recommendations could cut emissions by 50 to 75 per cent.

“Our results clearly show that efficiency-focused policy could swiftly reduce aviation emissions by more than half, without reducing flight numbers or waiting for future fuels. These are tools that we can use right now,” he said.

“While economically and practically unfeasible to replace all older aircraft short term, this analysis shows the potential more efficient aircraft have in comparison to other efficiency gains.

“Realistically, this would be a long-term transition – one that could be promoted by policies that reward efficiency, so that the most efficient aircraft are favoured whenever replacement decisions are made.”

Qantas has ordered 48 A321XLR aircraft to replace its older 737-800s, while Virgin Australia has a total order of 26 737 MAX 8s and a number of larger MAX 10s, as well as eight Embraer E190-E2s for regional WA operations.

Jetstar has been renewing its own fleet using A321neo and A320neo aircraft, and currently has 25 A321neos and five A321neos, with more expected to arrive over coming years.