A global fleet of composite planes could reduce carbon emissions by up to 15%, according to new research by the University of Sheffield, University of Cambridge, and UCL (University College London).

Experts predict that global air traffic will increase four-fold between now and 2050. Changing to the lighter materials could avoid 500 million t of CO₂ emissions in 2050 alone, a value researchers say roughly corresponds to current emissions levels.

The study is said to be the first to carry out a comprehensive life cycle assessment (LCA) of a composite plane, such as the Boeing Dreamliner 787 or Airbus 350, and extrapolate the results to the global fleet.

The LCA covers manufacture, use, and disposal, using publicly available information on the 787 fuselage and from the supply chain—such as the energy usage of the robots that construct the planes. The study compares the results to the traditional—and heavier—aluminium planes.

Emissions during the manufacture of composite planes are over double those of aluminium planes. But because the lighter aircraft use significantly less fuel, these increased emissions are offset after just a few international flights. Over its lifetime, a composite plane creates up to 20% fewer CO₂ emissions than its aluminium equivalent.

“This study shows that the fuel consumption savings with composites far outweigh the increased environmental impact from their manufacture," said Alma Hodzic, Professor in Advanced Materials Technologies at the University of Sheffield. "Despite ongoing debates within the industry, the environmental and financial savings from composites mean that these materials offer a much better solution.”

The researchers fed the data from the LCA into a wider transport model to gauge the impact on CO₂ emissions as composite planes are introduced into the global fleet over the next 25 years, taking into account other factors including population, economic prosperity, oil prices, and speed of adoption of the new technology.

The study estimated that by 2050, composite planes could reduce emissions from the global fleet by 14-15% relative to a fleet that maintains its existing aluminium-based configuration.

“The overall emissions reduction for the global fleet is lower than the reduction for an individual plane, partly, because by 2050, not all the fleet will be of composite construction," said Andreas Schäfer, Professor in Energy and Transport at UCL. "New planes entering the fleet before 2020 could still be in use by 2050, but the faster the uptake of this technology, the greater the environmental benefits will be.”

According to Hodzic, “The industry target is to halve CO₂ emissions for all aircraft by 2020 and while composites will contribute to this, it cannot be achieved by the introduction of lighter composite planes alone. However, our findings show that composites—alongside other technology and efficiency measures—should be part of the picture.”