Technologies are constantly being deployed and researched by the aviation industry to increase environmental performance
Traditionally, landing aircraft approach a runway by ‘stepping’ down from the cruising level to the ground (blue path). At each step, the pilots have to alter the thrust of the engines to level out the aircraft. New technology means that airlines can work with air traffic control and airports to create a much smoother descent to the runway, cutting out the stepping procedures and cutting fuel use and noise at the same time (green path). In fact, airlines estimate that each continuous descent approach can save 150kg of jet fuel (around 500kgs of CO2 ).
Winglets – the angled extension to the end of some aircraft wings – help with fuel efficiency by reducing the drag caused by airflow patterns over the wingtip. They have been used in a number of different designs, from the ‘wingtip fence’ to the ‘blended winglet’ that is being retro-fitted on some existing aircraft. A newer development in commercial aviation is the ‘raked’ wingtip which is a more subtle upward sweep of the wing, but produces a similar result as winglets.
A wingtip fence on an Airbus A319; a blended winglet on a Boeing 737 and the raked wingtip of a Boeing 777
Biofuels are derived from recently grown biological materials (as opposed to fossil fuels which come from biological material dead for millions of years). When being burnt, they emit only the amount of CO2 that they previously absorbed during growth. Biofuels can be made from a wide variety of plant material and in a number of countries they are commonly used to power road vehicles either as a blend with fossil fuels or as a stand-alone source of energy (e.g. in Brazil, where ethanol has achieved a 50% market share of the gasoline-powered fleet). Some of these so-called first-generation sources of fuel compete with food production, which is not an ideal situation.
Aviation can’t use many first-generation biofuels, due to the extreme operating conditions that aircraft fuels have to withstand, such as very high and very low temperatures. The most suitable fuels for aviation are the so-called "drop-in" fuels, which present similar properties as today's kerosene, can be mixed with it, and don't need modifications of aircraft engines or fuel infrastructure.
There is a lot of promise in research into second- and third-generation biofuels made from waste material like sawdust, harvest remnants and municipal waste, or from plants like jatropha (an oil-rich tropical plant growing on very dry and otherwise unusable land) or algae which don’t compete for land or the food supply. Research is progressing very rapidly in these areas, with test flights being undertaken by a number of airlines, alternative fuel manufacturers and the engine and plane makers. Algae oil is showing promise as either a fuel blend or a stand-alone fuel source, as it has similar energy properties as current jet fuel, is very fast growing and can be cultivated in otherwise inhospitable conditions.
The composite fuselage section of a Boeing 787 being constructed
Composites are made up of two or more different materials that are joined to create a new material. The aviation industry has been using carbon fibre composite materials for around 30 years to manufacture certain parts of an aircraft structure. The benefits of carbon fibre composite are that it is lighter and stronger than other materials. Now, aircraft makers are using composites to build entire sections of the main body of an aircraft. The Airbus A350 and the Boeing 787 will be substantially made from composite materials. These will provide many benefits for passenger comfort, but in environmental terms this means the aircraft can also be substantially lighter – meaning greatly reduced fuel consumption.
As with cars, trucks, trains and ships, the life of an aircraft will to come to an end at some point. Most aircraft are built to operate day-in, day-out for around 25 to 30 years. But what happens to an aircraft once it has finished its life? Instead of leaving aircraft to rust in a desert or at the side of a runway, manufacturers estimate that between 85% and 95% of an airframe is recyclable. Two major initiatives – PAMELA and the Aircraft Fleet Recycling Association – aim to make best use of the lifecycle of an aircraft and ensure that any waste left over is handled properly. The major manufacturers are also now designing new aircraft to ensure easy recycling at the end of their flying career. The videos below show how Airbus and Boeing approach the issue of recycling.
Find out how future generations of biofuels can and will be developed in a sustainable manner »