Assessing aviation’s climate impact with an open-access application

CAST for Climate and Aviation – Sustainable Trajectories, , is a tool for simulating and assessing climate trajectories for aviation. The objective is to evaluate various development scenarios for aviation and to assess their compatibility with the goals laid down in the 2015 Paris Climate Agreement, i.e. limiting global warming to well under +2°C. It can also be used to increase user awareness of aviation’s different climate impacts such as CO2 emissions or contrails.

An educational application

Interactive and educational, CAST is available for use in manual mode for the general public in order to increase user awareness of the environmental challenges facing aviation by highlighting the quantified impact of the different parameters that we can influence. In addition, the expert mode can be used to measure trends and to gain a finer assessment of the effectiveness of the impact reduction strategies in relation to international commitments in the fight against global warming.

CAST lets users simulate their own carbon trajectories for aviation by working with several levels of action using cursors. These levers of action include reducing aircraft energy consumption, the use of new fuels such as biofuels or hydrogen, and the growth in air traffic.

“CAST takes an engineering approach that is scientific and rich in objective models for aircraft systems, providing a better understanding of the challenges facing aviation,” Thomas said.

Thomas Planès is a post-graduate at ISAE-SUPAERO who has been working for over a year with the CEDAR (*) research chair in eco-design. His thesis, titled “Assessment of the environmental impact of aircraft architectures in the preliminary design phase”, seeks to integrate environmental issues starting in the initial aircraft design phases.

• His first line of research involves modelling the energy performances of the main subsystems found in the latest aircraft architectures in order to optimize their dimensioning and their integration.
• The second concerns the development of a life cycle analysis methodology adapted to preliminary aircraft designs. Life cycle analysis can notably be used to estimate the CO2 emissions released by an airplane from its construction through to the end of its life.
• The last line of research concerns expanding aviation as a whole to face climate challenges, notably using CAST.

Interview with Thomas Planès

What were your motivations for developing this tool?

I first started to take an interest in environmental issues when I was studying at the Centrale Nantes engineering school. Little by little, I began to realize the scope of the challenges facing us, such as the biodiversity crisis, resource depletion and global warming. This motivated me to work on these issues. My interest for the aviation field therefore oriented my professional project toward the environmental and climate challenges facing aviation. I then had the opportunity to prepare my thesis on these topics at ISAE-SUPAERO.

During my first year, I realized that it was hard to find references for the analysis of aviation transition scenarios and I suggested creating a special tool, CAST. My thesis supervisors, Valérie Pommier-Budinger, Scott Delbecq and Emmanuel Bénard, gave me their support in developing the methodology. Scott also helped me in developing CAST as a scientific web app.

CAST was designed to increase awareness of aviation’s climate transition for a wide-range of audiences – students, citizens interested in the ecological transition and aeronautics specialists. One of its purposes is to provide an interactive educational tool that is accessible on line.

What are the tool’s advantages and uses?

CAST helps to streamline and contribute to the debate between those who are for continuing the growth in air traffic and those calling for a drastic reduction. It gives an objective analysis that is transparent, concrete and cross-cutting, helping to assess sustainable trajectories for aviation.

Furthermore, it is important to adopt reasoning that covers the entire aircraft fleet for these issues. If you fly 4 times as many airplanes that consume half as much jet fuel, you will still emit twice as much CO2!

There are many possible uses. The analyses are notably based on the notion of carbon budget, in other words the maximum amount of CO2 that we can still emit while limiting global warming to 2°C, for example. I can give you an example to illustrate what I mean.

The commitments made players in the aviation field such as ATAG (Air Transport Action Group) can be modelled using CAST. For example, an analysis of ATAG’s commitments in 2009 shows that aviation would consume 3.5% of the entire world carbon budget for 2°C until 2050 and 8.1% of it for 1.5°C. But aviation today accounts for just 2.6% of worldwide CO2 emissions.

Do you foresee any additional developments?

We plan to update CAST regularly, integrating new features. In the coming decades, alternatives to jet fuel will be available in limited quantities, so we want to integrate models to determine the availability of energy resources for aviation.

*CEDAR chair developed in partnership with Airbus

Thomas’ conference during the 2020 Open Day