ICCT report on commercial aircraft fuel burn trends argues for a more stringent ICAO CO2 standard
Thu 17 Sept 2020 – After stagnating from around 1990 to 2005, the average fuel burn of new jet aircraft decreased at a faster pace from the late 2000s and continued during the last decade, finds a new study by the International Council on Clean Transportation (ICCT). This is attributed to the introduction of new, more fuel-efficient narrowbody and widebody aircraft such as Boeing’s 787 and 737 MAX and Airbus’s A350 and A320neo. Depending on the metric used, the average fuel burn reduction was 1.0 to 1.5 per cent per year since 2010. As the only known new aircraft model on the horizon is Boeing’s 777X, the reduction may slow down in the upcoming decade, forecasts the study, but if cost-effective technologies were adopted by the manufacturers, the improvement could be accelerated by up to 2.2% annually through to 2034. ICCT recommends the current ICAO CO2 emissions standard be tightened in order to provide such incentives.
The ICCT study updates a previous analysis published in 2015 covering the fuel burn of new commercial jet aircraft from 1960 to 2014 by taking into account new aircraft types and deliveries from 2015 to 2019, as well as to include dedicated freighters delivered from 1960 to 2019 in order to offer a fuller picture of the commercial jet aircraft market. Fuel burn has been assessed using two indicators: block fuel intensity in grams of fuel per tonne-kilometre and the CO2 metric value (MV) developed by ICAO. The latter, say the study’s authors, Sola Zheng and Dr Dan Rutherford, aims to provide a ‘transport capability neutral’ means of regulating aircraft fuel burn. Over the long run, ICCT’s analysis shows the two indicators are well correlated.
The average block fuel intensity of new aircraft decreased 41% from 1970 to 2019, a compound annual reduction rate of 1.0%. When including the prior decade, during which widebody aircraft like the Boeing 747 family joined the fleet, the rate increases to 1.3%. Some time periods saw more drastic reductions in fuel burn than others, notably in the 1980s when block fuel intensity dropped an average 2.8% each year (see graph below). That was followed by two decades of more modest improvements at an average rate of less than 1% per year.
The reductions in fuel burn were also compared in the study with ICAO’s aircraft CO2 emissions standard, under which all new aircraft will need to meet fuel burn targets for their specific sizes in order to be sold globally starting in 2028. ICCT’s analysis shows that the average new aircraft delivered in 2016, the year the standard was finalised, already complied with the 2028 requirements. In 2019, the average new aircraft delivered passed the standard by 6%, it says.
“As this research shows, ICAO’s CO2 standard lags the existing efforts of manufacturers by more than 10 years,” say the authors. “This suggests ICAO should review and tighten its CO2 standard as quickly as possible.”
They also recommend individual governments, such as the United States, which is currently undergoing a consultation period on adopting legislation that will follow the standard (see article), should consider implementing a more stringent domestic standard, such as applying it to in-service, rather than just new, aircraft. Countries such as Canada and regions such the European Union have already adopted the ICAO standard but there are precedents, such as on aircraft noise and safety, for States to adopt more stringent requirements.
“Future standards for new aircraft will also be needed,” they add. “Introducing flexibility mechanisms like averaging and banking would allow for more ambitious, cost-effective standards.
“A meaningful CO2 standard could urge the industry to focus available resources on producing and deploying newer, more fuel-efficient aircraft.”
Besides tightening the standard, additional measures could be considered, they recommend, to promote structural efficiency – which they say is not rewarded under the MV metric – in particular with regard to promoting the use of lightweight materials and efficient aircraft design. Differentiated landing fees based on the fuel burn of in-service aircraft are another potential incentive. Regional jets are slightly favoured by the ICAO MV metric, masking their higher fuel burn compared to larger jet aircraft and the authors suggest the requirements could be strengthened in the next round of standard setting.
The authors hope to expand their analysis in future updates to include general aviation aircraft, notably turboprops and business jets, and a reassessment of industry’s progress towards ICAO’s fuel burn technology goals would also be informative, they say.
Average fuel burn of new commercial jet aircraft, 1960 to 2019 (1970=100) (source: ICCT) :