Design to Green: on the way to the Green Aircraft
“Reduce emissions” is the new dogma whatever the means of transport envisaged: car, boat, helicopter … Airplanes, of course, are no exception in the industrial challenge of the 21st century.
The complete lifecycle of the aircraft must be reviewed with an eco-responsible approach. The “ecologically sustainable” value becomes a major criterion in the choices of design, industrialization, manufacturing, and operations of the aircraft, just like traditional values such as performance or cost.
Let us briefly review some guidelines that could limit the environmental impact of an aircraft throughout its lifecycle.
The green Aircraft in the Design phase
The first axis concerns the optimization of the overall aircraft architecture, for example the fuselage shape, the engines location, the airfoils shape, or the choice of on-board systems that consume few energy.
Then, the recurring battle in aeronautics consists in reducing the weight of the aircraft through the choice of efficient materials such as new light metallic alloys or new innovative composites.
In addition, optimizing the aerodynamics of both fixed and moving airfoils, such as the wings and wing tips, will help to maximize laminar flow.
Last but not least, the greatest impact on the carbon footprint relies on the choice of the propulsion system. Several choices are considered:
- Continue the current trends already started around “open rotor” or engines with high dilution rates
- Find alternative fuels to fossil fuels
- In the short term (horizon 2028), engines could be powered with synthetic fuels or “green” biofuels (for example created from residues, used oils, wastes…). In addition, hybrid thermal-electric motors could emerge, waiting for lighter and more efficient batteries
- In the medium term (horizon 2035-2040), breakthrough technologies could be envisaged with traditional engines supplied with hydrogen, or electric hybrid engines or even 100% electric engines supplied with “green” hydrogen as the primary fuel source (i.e. H2 not produced from hydrocarbons)
In Production phase
The manufacturing of a green aircraft involves the development of a green industrial system, not only respectful of its consumptions and emissions in its choice of infrastructure and its facilities, but also by the choice of its supply chain: one could imagine the selection of suppliers based on “green” criteria, the limitation of flows across countries, local supply, etc.
In addition, we must maximize eco-production from recycled materials, not only for the primary structure of the aircraft (aerostructure) but also for cabin interiors, for instance by taking inspiration from the textile and furniture industries.
In Operations phase
Optimizing flight paths (control the routes, manage the airport approach, smooth the traffic, etc.), and maximizing ground movements on the tarmac (taxiing, waiting time before takeoff, parking phase, etc.) will directly reduce fuel consumption.
In addition, it will still be necessary to optimize the operations of the aircraft, which means performing more flights with the same number of aircrafts.
Finally, the development of the “smart maintenance“, which consists, for instance, in carrying out repair & overhaul activities at the right time and in the right place, will help to reduce the aircraft’s environmental footprint.
In Retirement phase
The control of dismantling and recycling activities, to give a second life to systems and structural elements, is a first area to be considered in order to recover wastes from the aircraft at the end of its life.
In addition to these lines of investigation specific to the aeronautics sector, other energy savings could be foreseen during the lifecycle of the green aircraft, for instance thanks to the digital revolution. It is shaking up the ways of designing, producing and even operating our means of transport. However, one must keep in mind that the ecological footprint of digital transformation is significant (e.g. data storage), and an effort shall be considered to control the environmental impact.
