Carbon efficiency varies tenfold across industry, finds Brighter Planet green airline ranking report

Carbon efficiency varies tenfold across industry, finds Brighter Planet green airline ranking report | Brighter Planet,Atmosfair,Greenhorizon,Ryanair

Ryanair – the greenest airline of them all? (photo: Boeing)

Wed 6 July 2011 – A report just published by US-based Brighter Planet has found that airline carbon efficiency per passenger mile varies dramatically across the US and international sectors, and corporations and travellers looking to reduce their carbon footprint should focus on the efficiency factor when making flight decisions. Five key drivers account for the disparity and are critical for flight carbon measurement and management, says the report – aircraft fuel economy, passenger load factor, seat density, freight share and distance. However, it estimates air travel efficiency overall has improved by 20 per cent since 2000, saving the US airline industry alone $33 billion in fuel and prevented the release of 670 billion pounds (304 million tonnes) of CO2e.


Using an advanced flight carbon and energy model, Brighter Planet analysed data from the US Bureau of Transportation Statistics and ICAO covering US domestic flights since 2000 and international flights worldwide from 2007 to 2009, the latest years for which complete data is available. The combined database covered 4.5 million nonstop routes, 9 billion passenger departures and 12 trillion passenger-miles flown.


Brighter Planet uses carbon and calculation tools to advise companies on how to operate more efficiently to reduce their footprints and environmental impact. It claims to have helped clients avert hundreds of millions of pounds of CO2 emissions. Corporate travel sustainability management is taking off, it says, with nearly four in ten Global 500 companies publicly reporting carbon emissions from employee travel last year. However, oversimpliflying flight carbon analysis can introduce major inaccuracies and prevents considerable sustainability gains because of incorrect decisions that imply the only way to cut carbon is to reduce air travel.


The authors of the study accept it is not the first to rank airlines on sustainability but few, it maintains, have accounted for passenger volumes and all five efficiency drivers to provide as accurate a rating on real-world emissions per passenger per mile.


In ranking the 20 largest airlines in the US market, the report finds Continental earned the highest efficiency rating, with last-place American Eagle emitting more than twice as much carbon per passenger mile. Internationally, Ryanair was found to be the most efficient among the top 20 largest airlines, with SAS rated the worst.


Analysing the five drivers in turn, based on their fleet makeup, airlines vary dramatically in their average aircraft fuel economy. Among the 20 largest airlines, Cathay Pacific and United transport their average passenger on the most efficient planes, while American Eagle and ExpressJet operate the least efficient fleets.


As one would expect, when it comes to measuring seating density efficiency, European low-cost carriers easyJet and Ryanair top the rankings, although Cathay Pacific and KLM follow in third and fourth place respectively. Global carriers such as United, Air France, Lufthansa and British Airways unsurprisingly prop up the bottom of the rankings.


On load factors, Ryanair and easyJet again top the rankings, followed by Continental and the other major US carriers. Cathay Pacific and Southwest are found to have the lowest load factors and highest number of empty seats.


As 78% of commercial passenger flights also carry extra cargo beyond passengers and their baggage, and so reducing the share of emissions for which passengers are responsible, Brighter Planet has identified freight share as a key driver. Cathay Pacific and British Airways fill the top two rankings, followed by KLM, Air France and Lufthansa.


It almost goes without saying, says the report, that distance travelled is the single most important determinant of a passenger’s total flight footprint, and nearly every flight carbon calculator takes it into account. “But what’s less intuitive, and less often accounted for, is that distance also affects efficiency – fuel used per mile,” say the authors. “Takeoff and ascent guzzle far more fuel than cruising at altitude, making short flights more fuel intensive than all but the longest intercontinental flights, where fuel weight reduces efficiency.”


Major transcontinental carriers Cathay Pacific, Air France and British Airways make up the top three rankings in this fifth category, with US low-cost airlines propping up the bottom.


Although each of the five factors can have a large effect on efficiency, the impact is not uniform. The data compiled by Brighter Planet show some factors are much bigger drivers of efficiency variation than others. Aircraft fuel economy shows the strongest correlation with emissions per passenger mile, while seat density is the weakest predictor of a flight’s overall efficiency.


Selecting flights with high load factors and efficient aircraft models is therefore a better strategy for minimising emissions than choosing itineraries based on seating density and freight share, although the report advises corporate travel departments that accounting for all factors is the only way to ensure robust reporting and management.


Among the 20 largest airlines by passenger volume, Ryanair uses barely more than a third the fuel to transport its average passenger one mile compared to the least efficient, American Eagle.


Ryanair is ranked first or second for efficiency in load factor and seating density, while runner-up in the overall industry ranking, Cathay Pacific, ranks first on aircraft fuel economy, distance and freight share. European low-cost carrier easyJet is ranked third, followed by Continental, United, JetBlue, KLM, American, Delta and Alaska in the overall top ten.


In the US domestic market, Continental, JetBlue and Frontier take the top three slots. The report finds that passenger travel in the global international market is, on average, more efficient than the US domestic airline industry, a discrepancy it suggests is due in part to flight distance and size. Ryanair, Singapore Airlines and Delta take the top spots in this sector, while SAS, Lufthansa and SWISS bring up the rear as the least efficient of the 20 largest airlines.


Ryanair’s overall top ‘green’ ranking is somewhat ironic given that its CEO, Michael O’Leary, has gone on record as a ‘climate denier’, claiming that global climate change is a natural phenomenon and not caused by mankind. In an interview last year with The Independent newspaper, he described global warming as an invention by scientists in their quest for research money and there was no link with CO2 emissions such as from his aircraft. Corporate travellers are also likely to avoid using an airline like Ryanair that flies to airports often based many miles from city centres.


The Brighter Planet report says global air travel efficiency has increased markedly over the last decade, citing that in 2010 it took 20% less fuel to transport the average passenger one mile than in 2000. There has also been a narrowing of the efficiency variation across the market. While the efficiency spread remains very large, efficiency has improved more rapidly among the dirtiest flights than the cleanest ones, although that is to be expected.


The report concludes that the inexorable rise in oil prices, the increased efficiency emphasis by aircraft manufacturers, the novel routing and air traffic control technologies currently under development, and the prospect of airline carbon regulation in Europe mean potential is strong for sustained or even accelerated efficiency gains over the coming decade.


Similar attempts to measure the ‘greenness’ of airlines have been made in recent reports published by German carbon offset company Atmosfair and Canadian consultancy Greenhorizon (see article). The common thread is that all have three come up with different airline rankings due to differing methodologies applied.




Brighter Planet

Brighter Planet report – ‘Air Travel Carbon and Energy Efficiency’ (2.5mb PDF)



Update 7 July 2011:


A discussion on the issue of green airline rankings has opened up on the Green Aviation International group on LinkedIn



   Print Friendly and PDF

Copyright © 2007-2021 Greenair Communications

Related GreenAir Online articles: