The Airbus A320neo promises 20% fuel savings per seat
Fri 18 Sep 2015 – Despite progress in aircraft fuel efficiency performance, airframe and engine manufacturers are currently lagging behind goals established at ICAO for medium and long term technology advances in fuel burn reduction, according to analysis by the International Council on Clean Transportation (ICCT). The environmental research NGO has undertaken a study into the fuel efficiency improvement of commercial jet aircraft from 1960 to 2014 and has found the rate of improvement to vary greatly over the period. The biggest gains were made during the 1980s, when average annual fuel efficiency improved by 2.6%, whereas little or no improvement was seen during the 1970s and in the period from 1995 to 2005. Overall, the average fuel burn of new aircraft between 1968 and 2014 reduced by a compound annual reduction rate of 1.3% and with new aircraft types coming to market, the short term trend is a return to the historical average, predicts ICCT.
The ICCT report updates a 2009 study covering the period from 1960 to 2008, in which it not only covers new aircraft types and data since then but also uses refined metrics for measurement, including the efficiency metric value (MV) developed by ICAO CAEP for its aircraft CO2 standard that is due to be completed early next year. The metric used for the earlier study was based on fuel burned per passenger-km flown, as measured from the departure gate to the arrival gate, so including all fuel consumed for taxi, take-off, cruise, approach and landing. The most prominent difference between this metric and the ICAO MV is the latter takes into account only the cruise performance.
According to ICCT’s findings, the data suggests that over the long term, efficiency improvements measured under the MV largely track those under the fuel/passenger-km metric, although they diverge during certain periods. The most likely driver of this relates to the ICAO aim of making the MV ‘transport capability neutral’, meaning that differences in fuel efficiency associated with aircraft capabilities – such as range, payload and speed – should not be reflected in the metric.
The average fuel burn of new aircraft fell by about 45% from 1968 to 2014. The sharp reduction observed in the early 1970s (see Figure 1 below) can be explained by the entry into service of the first modern twin-aisle aircraft, the Boeing 747. Combined with its size and the use of the first high bypass turbofan engines, the early models of the aircraft contributed to a large increase in fuel efficiency. Deliveries of the aircraft, which made up to 39% of the total market in 1970, started to drop and smaller and less fuel efficient aircraft, such as regional jets, began to take over the market. The fuel efficiency of later years became more stable owing to a large number of commercial models and relatively consistent delivery patterns.
After remaining flat for a decade after 1995, average fuel burn of new aircraft began to fall again in 2005. By 2010, the average fuel burn of new aircraft fell by 1.1% per year on a fuel/passenger-km metric and a somewhat smaller amount of 0.7% on the ICAO MV. In total, the average fuel burn of new aircraft dropped by around 10% from 2000 to 2014 when measured on the fuel/passenger-km basis, corresponding to a 11% increase in fuel efficiency.
One driver in efficiency trends is jet fuel prices. The sharp increase starting in 2003 correlates well with the end of a period of flat efficiency for new aircraft in 2004, notes the report. However, it adds, improvements since 2005 remain relatively modest compared to those seen in the 1980s when the aviation sector faced a fuel price spike linked to the ‘Oil Shock’ of 1979 and US airline deregulation.
“While additional fuel efficiency improvements are expected over the short term as aircraft like the A320neo and 777X enter into service, fuel prices alone may not provide a consistent, long-term motivation for fuel efficiency improvements in the aviation sector,” says the report.
Despite progress, ICCT believes manufacturers are about 12 years behind 2020 and 2030 fuel burn reduction goals for new aircraft that were set by an ICAO CAEP panel of Independent Experts in 2010 (see Figure 2 below). The panel conducted a study, based on single-aisle and small twin-aisle aircraft, into potential future technologies, in order to determine medium and long term goals as part of a basket of measures to achieve ICAO’s collective global aspirational goal of improving annual fuel efficiency by 2%. The study estimated the fuel efficiency of new aircraft could be improved by up to 40% in 2020 and as much as 90% in 2030 compared to a 2000 technology baseline.
The authors of the ICCT report, Anastasia Kharina and Dan Rutherford, conclude there is therefore a strong need for a meaningful ICAO CO2 standard to provide extra incentive for new technology development and deployment and to help industry meet its environmental goals. They say a future update of their report would be necessary to reflect changes linked to aircraft such as the A320neo, 737 MAX, 777X and CSeries that are due to enter into service between 2016 and 2020 – before the earliest application date of the CO2 standard – and would be useful in reassessing industry’s progress towards the fuel burn technology goals.
ICCT report – Fuel efficiency trends for new commercial jet aircraft: 1960 to 2014
Figure 1. Average fuel burn for new commercial jet aircraft 1960 to 2014 (1968=100) (source: ICCT)
Figure 2. New single-aisle and small twin-aisle jet aircraft metric value vs. ICAO fuel burn technology goals (source: ICCT)
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