“The aerospace industry is really going to be in the spotlight because the decarbonisation of land-based transport is going to happen fairly quickly,” predicts Stewart Dawson from the UK’s Advanced Manufacturing Research Centre (AMRC).
ADS, the trade body for UK aerospace manufacturers has projected that aerospace will be the most polluting transport sector by 2050, as air traffic grows and emissions from cars and trucks shrink dramatically.
When it comes to manufacturing aerostructural components, cutting lifecycle emissions is likely to force an end to milling components from solid blocks, and eventually mean a shift towards the so-called “circular factory”.
Aerospace manufacturers and their suppliers have historically sought to reduce emissions by focusing on the energy use within factories. But a detailed lifecycle analysis carried out by High Value Manufacturing Catapult last year found that that factories themselves make an almost insignificant contribution.
Drawing on data collected from several of the UK’s biggest aerospace manufacturers, the researchers discovered that more than 90 percent of the energy embodied in a finished plane is contained within the materials before they even reach the factory door.
“It’s been a massive blind spot for the industry,” argues Dawson, who is responsible for Future Propulsion and Sustainable Manufacturing, as well as hydrogen.
“Aerospace manufacturers are focused very much on energy efficiency within the factory. But the analysis shows that that’s not the place to focus your efforts.”
Titanium, aluminium, and carbon fibre, the chief materials used for most structural aerospace components are highly energy-intensive, especially titanium which is often produced in countries, such as Russia, Kazakhstan and China, where coal and gas are the dominant energy sources used in the material’s primary production.
As the jet fuel an aircraft burns over its life generates about 100 times more emissions than those generated during its manufacture, the materials’ low weight more than offsets the emissions released in making them.
But their production releases significant emissions nonetheless. To reduce them, Dawson believes manufacturers need to focus on improving the “buy-to-fly ratio”, the proportion of titanium, aluminium and carbon fibre purchased which ends up in finished planes.
Using current subtractive manufacturing techniques, as much as 90 percent of the aluminium and 75 percent of the titanium used to make a typical structural component is simply milled away.