Sustainable aviation fuel reducing aircraft carbon emissions

With the recent COP26 climate change conference and the ongoing discourse around the Paris Agreement, global industries must find ways to reduce emissions to meet 2030 targets by 55% below gas emission levels greenhouse effect of 1990. The aviation industry is currently committed to reducing net CO emissions from aviation2 50% by 2050 compared to 2005 levels.

To study: Estimation of future CO reduction at fleet level2 Emissions from sustainable aviation fuel. Image Credit: Oleg V. Ivanov /

recently presented one of the first studies, published in the journal Frontiers of energy research, which studies the impact of operating commercial aircraft using sustainable aviation fuel (SAF). The study, published in Frontiers, models the behavior of a for-profit airline using the Fleet-Level Environmental Assessment Tool (FLEET) to perform its assessment.

Different cases of biofuel penetration levels considered in this study.

Different cases of biofuel penetration levels considered in this study. Image credit: Jain, Samarth et al., Frontiers in Energy Research

One of the factors that make it an attractive solution is the fact that it requires minimal modification to existing aircraft, making it the ‘fastest’ approach to reducing carbon emissions from aviation: “The actual impact will be determined by the degree of adoption and use of SAF by airlines, the impact of SAF on ticket prices and future growth in travel demand,” explains Samarth Jain, senior author and graduate research assistant at Purdue University.

FLEET modeling tool

In order to properly assess the environmental impact of SAF on commercial air travel, it is necessary to model airline operations, model and forecast future passenger demand, as well as model introduction and release. future use of various types of aircraft.

The Fleet Level Environmental Assessment Tool (FLEET) is a system dynamics-inspired simulation that combines all of these models into one tool. FLEET estimates future CO at fleet level2 emissions, demonstrates the possible upper and lower limits of future aviation emissions when introducing SAF for use in airline fleets.

The tool can reflect the performance of new technology aircraft which are expected to consume less fuel and generate less noise than current aircraft; with these aircraft models, FLEET simulates how an airline would use these new aircraft to meet passenger demand on a network of routes, “ Jain said.

Sustainable Aviation Fuel (SAF)

“? FAS can be made from renewable sources such as plants, cooking oil, municipal waste, including textiles and food waste, and woody biomass.

Today, HEFA is the only SAF used in aviation, HEFA refines vegetable oils, used oils or fats and converts them to SAF by hydrogenation. It is a safe and proven fuel, which can reduce life cycle emissions by up to 80%, compared to traditional aviation fuel.

Comparison of the price of conventional jet fuel (CJF) in FLEET with the price of “benchmark”, “constant” and “special” biofuel (in 2005 US dollars).

Comparison of the price of conventional jet fuel (CJF) in FLEET with the price of “benchmark”, “constant” and “special” biofuel (in 2005 US dollars). Image credit: Jain, Samarth et al., Frontiers in Energy Research

SAF is also an alternative fuel, which means it can be added to standard jet fuel at a ratio of up to 50% for use in airplanes in operation today. About 14 billion liters of SAF are subject to forward purchase contracts, as more than 45 airlines currently implement its use to meet aviation industry goals and long-term climate goals.

Future impact scenarios

The researchers ran five future SAF scenarios and two future passenger demand projections to assess future biofuel use impact scenarios that are fully detailed in the study. Overall, the results suggest that the introduction of SAF for use in airline fleets and the projected demand scenarios could have a significant impact on future aviation CO at the fleet level.2 emissions.

The researchers clearly state that the penetration levels of SAF should exceed 50% if used as an alternative fuel in order to have the best possible result, but in general, the use of SAF indicates that future emissions may decrease: With the current modeling, the introduction of SAF with Highpenetration levels could lead to the lowest possible emissions, serving as a the best case scenario for the future CO of aviation2 emissions, “ explains Jain.

Representation of FLEET inspired by system dynamics [adapted with permission from (Moolchandani et al., 2017)].

Representation of FLEET inspired by system dynamics. Image credit: Jain, Samarth et al., Frontiers in Energy Research

One of the striking features of the study is that it found that even if airlines meet higher passenger demand for certain future scenarios, carbon emissions could potentially be still lower than the current baseline scenario – use of conventional jet fuel.

Therefore, increasing the use and deployment of SAF for use in the commercial aviation industry could help put the industry as a whole on track to meet its 2050 commitments and achieve its four-pillar action plan: improving technology; more efficient operations; improvement of infrastructure; and a single global market-based measure, to close the remaining emissions gap.

References and further reading

Jain, Samarth et al. “Estimation of the future CO reduction at the fleet level2 Emissions from sustainable aviation fuel “. Frontiers of energy research, vol 1, 2021, DOI:

International Air Transport Association, “Sustainable Aviation Fuel”. [  accessed December 2021]

International Air Transport Association, ‘Working Towards Ambitious Targets’. [ accessed December 2021]

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