In 2015, 3.6 billion passengers were carried by the world’s airlines causing 781 million tons of CO2 emissions. The International Air Transport Authority (IATA) predicts global passenger demand to grow by 3.8% over the next 30 years which constitutes a 2.1x increase in passenger demand. While today, according to the Air Transport Action Group (ATAG), the aviation industry is only responsible for 2% of human caused carbon-dioxide emissions it is critical to contain emissions and find more environmentally friendly technologies as the industry grows. If no action is taken the aviation’s share of carbon emissions will not only grow in total but also as a percentage of total emissions. Emitted CO2 in an aircraft is directly related to burned fuel. Therefore, technologies to reduce fuel consumption per passenger mile are critical.
With a 45% market share in commercial aircraft sales globally in 2015, Airbus is the world’s largest aircraft manufacturer and is heavily invested in the design and manufacture of more fuel efficient aircraft.
Airbus investment in fuel efficiency can be broadly divided into three areas: The A350 program, the A320neo program and concept studies in innovative technologies of the future.
Firstly, with the A350XWB Airbus has heavily invested in innovative composite materials (53% of the airframe) in its latest long-range aircraft program allowing a significant weight reduction of the airframe, which directly results in lower fuel burn. With an order book of 860 aircraft and already 41 in operation this will truly make an impact on modern aviation as the A350 takes to the skies.
Secondly, after selling almost 8,000 aircraft of its A320 series Airbus has now developed the A320neo (neo = new engine option), a newer and more fuel efficient version. With a geared turbo-fan engine the aircraft saves 15% of fuel. Geared turbo-fan engines have only recently been developed and are based on the following principle: An engine generates thrust by accelerating a mass flow of air. It is much more efficient to accelerate a lot of air by a small amount vs. accelerating a little bit of air by a large amount (both resulting in the same thrust). A gearbox allows the outer fan to rotate at a slower speed than the turbine in the engine core. As a result, the fan can be much larger and accelerate a larger amount of air by less resulting in higher efficiency. With more than 4,800 orders for the A320neo Airbus is working hard to keep up deliveries.
In addition to above large scale aircraft programs, Airbus is also working on several green aviation concepts of the future. For example, the company is heavily investing into electric aircraft propulsion with its all-electric E-Fan demonstrator aircraft, a one-seater currently under development that successfully crossed the English Channel in 2015. By combining the E-Fan lithium ion batteries with a combustion engine, Airbus has developed a hybrid technology that allows a reduction of 75% of CO2 emissions by passenger mile.
Beyond the design and manufacture of aircraft, Airbus is also working on innovative air traffic control (ATC) concepts under the name “Smarter Skys”. For example, current descend patterns into airports are rather inefficient not allowing the aircraft to glide. Another example of ATC inefficiencies are holding patterns at congested airports. Avoiding these can yield vast fuel and emission savings.
Going forward, while on a good track Airbus should invest more heavily into biofuels. Electrically powered aircraft are only a feasible model for small aircraft over short distances. The scale and range of modern commercial aircraft require much larger amounts of energy that are only available in fossil fuels. Biofuels are similar to fossil fuels but are made from living things such as algae or wood. They can easily be blended with kerosene and current engines can be used with no need for changes in the aircraft’s propulsion system. According to ATAG an airplane’s carbon footprint could be reduced by 80% through use of biofuels. While biofuels still cause emissions the plants and algae used to create the biofuels remove the equal amount of emissions from the atmosphere and are thereby cause no net emissions. So far Airbus has partnered with a number of organizations such as China’s Tsinghua university or Sinopec to explore possible sources of biofuels but beyond a number of test flights no meaningful progress has been achieved. Given the great potential for biofuels to reduce emissions without having to make changes to the current engine technology is a huge advantage and should be much further pushed.
With global temperatures rising the time to act is now. Airbus is on the right track to reduce CO2 emissions but pushing heavier on biofuels would allow the industry to have a more immediate impact, avoiding lengthy product development cycles of newer engines or airframes.