Abstract:
The choices that airlines make about the aircraft they fly, the number of seats they
have on each aircraft, the routes they fly and the passenger segments they focus on
have significant impacts on their environmental performance (which can be assessed
in terms of an airline’s CO2 emissions per passenger kilometre, fuel burn or other
suitable metric). Each of the main airline business models (network, charter, low
cost carrier (LCC), regional) involves practices that may improve or degrade
environmental performance. This project analyses the factors that affect each
business model’s environmental performance and considers the potential for
changes to business models to improve the environmental sustainability of the
aviation sector.
The evolution of aircraft fuel consumption, average sector length and CO2 emission
levels (per passenger kilometre) were investigated. From 1986 to 2004 total fuel
consumed by European airlines1 increased by 220%, while the amount of fuel
consumed per passenger km has decreased by 27% (or 2% per year). Average
distance flown has increased by 21% and the average number of passengers carried
per flight by 5%.
The CO2 emissions of intra-EU air services from the UK generated by each business
model (network, LCC, charter, regional) was established for the years 1997, 2000
and 2006. Emissions were estimated by route, stage length, aircraft type used,
number of seats supplied on each aircraft and the distance flown, following the IPCC
recommended approach to carbon dioxide calculation. The LCCs share of total
emissions has risen to 46% of all intra-EU routes originating in the UK in 2006 from
12% in 1997. At 112g/pkm this group’s CO2 emissions are lower than either
network carriers or regional airlines (at 144g/pkms and 216g/pkms respectively) in
the EU market. However the lowest emissions level is achieved by charter airlines at
106g/pkm.
Some activities airlines have undertaken to reduce on-board weight were also
considered. These include reducing water carriage, lowering tankered fuel levels
and re-designing the duty free sales process. A calculator that estimates the carbon
dioxide emissions that can be prevented by removing weight from a number of
aircraft types was developed. It estimates that 456.2 tonnes of CO2 emissions can be
prevented if an airline operating a daily North Atlantic service with a Boeing 747-400
could reduce 1 tonne (metric) from its takeoff weight.
One of the main policy instruments that can internalise the environmental costs of
aviation is the European Emissions Trading Scheme. Prior to its introduction the UK
government has increased its Air Passenger Duty as a quasi-environmental taxation
measure. The success of such fiscal measures in dampening the demand for air transport will largely depend on the price elasticity of demand and indicative ranges
for long and short haul leisure and business passengers are given.
A model of air transport CO2 emissions, which was developed to test various
scenarios, suggests that should current growth rates continue, emissions for the
global aviation market may grow by over 50% between 2009 and 2020. With high
growth rates, the share of emissions for low cost carriers would also grow
significantly, however, it is also clear that network carrier’s growth of long haul flying
also means that the absolute emissions levels of this group is also likely to rise. The
output of the model is used to test the sensitivity of changes to business model,
such as increasing load factors, increasing the number of seats on board an aircraft,
and differing growth rates for each business model.
A stakeholder workshop and seminar for this project and a sister Omega project
“Passenger Expectations” was held in December 2008. Key outcomes of the seminar
was that passengers seem to have little appetite for changes in behaviour (such as
willingness to take fewer longer overseas holidays or to holiday within the UK) that
might reduce the demand for air services and that further passenger education
regarding the relative impact of flying compared to other GHG generating activities is
required. Further research is required to assess passenger willingness to forego
service levels, timetable frequency, flight times to maximise load factors, minimise
aircraft weight and therefore fuel consumption.
Future studies may extend this work in two ways: assessing the feasibility of fully
adopting the various weight reduction strategies suggested for airlines; and by
investigating network carriers’ freight operations as a source of carbon dioxide
emissions.
Keith Mason and Chikage Miyoshi
Cranfield University
March 2009