Source of this statistic about aircraft carbon emissions ?

August 30, 2022 2:37 PM

I was told recently of a statistic which suggested that carbon emissions by passenger aircraft (grams per passenger/km) will fall by 2% every year for the next decade due to advances in technology. This seemed unlikely to me and I'm interested to know where this statistic might have come from.

It's a difficult area to Google so I'm hoping someone here with domain knowledge might be able to advise me.

The implicit context of the quote was emissions with respect to long distance jet aircraft but I do wonder if actual statistic is related to all aircraft.

posted by southof40 to Technology (4 answers total)

This seems reasonable to me. Aircraft are becoming more fuel efficient and as older aircraft are retired and replaced with newer, emissions per passenger-km will decrease over time. For example, the 787 and A350 are significantly more efficient per passenger-km than planes they are replacing. Unfortunately, of course, these increases in efficiency are completely wiped out by more people flying more often and further. Passenger-kms are increasing much faster than efficiency, so the net effect is rapidly increasing aviation emissions.

Here's a statement similar to what you're talking about:

"On average, passenger aviation emitted 90 grams of CO2 per passenger-kilometer in 2019, a decrease of 2% from 2018 and of 12% from 2013. Thus, airlines remain on track to meet their goal to improve fuel efficiency by 2% per year for international flights."
posted by ssg at 2:54 PM on August 30, 2022

I don't know about the accuracy of the 2% reduction rate, but there are three different things at play with aircraft emissions that will lead to improved efficiency:

1. Older aircraft get retired every year either due to wear or operating economics, and the latest models in service have higher efficiency.
2. ICAO has standards which are forcing new designs and new production aircraft to be more efficient. In a few cases this also leads to older models being phased out.
3. Airspace modernization like FAA NextGen or Eurocontrol's SES is being implemented and will allow aircraft to take more direct routes between points, significantly reducing the amount of fuel burned. The default system has aircraft fly between a number of fixed, ground-based waypoints.

posted by cardboard at 2:57 PM on August 30, 2022

All of the above - Plus, every time they reduce leg room that's a decrease in emissions per passenger!
posted by Lady Li at 6:03 PM on August 30, 2022

The original passenger jet engines were designed without really taking fuel economy into account. They were the Concorde of their day, very expensive to operate, but it didn't matter because the passengers were willing to pay. Since the 1978 deregulation of airfares, we have transitioned to planes being the "rocket bus to Galveston", to quote Patton Oswalt. Thus efficiency has become important, since fares are basically flat in nominal (unadjusted) dollars since then. Part of the reason why the 737 Max 8 crashed was the quest for efficiency, since the engine openings keep getting larger while the body of the plane stays the same. This permits more and less turbulent airflow through the engines, saving fuel. Simulation has gotten a lot better so you can design everything from the flow over the body of the aircraft to the flow within the engines. The body of the airplane is also, lighter, carbon fiber was for race cars and yachts 20 years ago and now is a standard material. The seat cushions are lighter. It's astonishing how much more efficient airplanes are.
posted by wnissen at 9:57 AM on August 31, 2022