How net zero will change aviation – and the shape of aircraft

There’s more awareness than ever about the environmental impact of flying. Aviation accounts for just 2.5% of global carbon dioxide emissions, but demand is set to increase, driven by economic growth and population trends.

A recent IMechE green paper, Aero 2050: Flying More Sustainably, explores the routes towards decarbonisation and challenges on the way to net zero. It builds on a 2011 report, Aero 2075: Flying into a Bright Future?, and is intended as a living document, to be updated as technology and regulation develop. 

Greener alternatives 

The report predicts a future where aircraft are powered by a mix of fuels and propulsion systems, optimised for size, range and capacity. Urban air mobility vehicles are likely to be battery-electric, with hydrogen fuel cells providing alternatives. Small commuter aircraft carrying fewer than 19 passengers may combine battery-electric and hydrogen fuel cell systems. A switch to high-speed rail, encouraged by policymakers, would have minimal impact on overall emissions, accounting for less than 5% of aviation CO₂.

Regional aircraft, with 20 to 80 seats, are expected to operate on hydrogen or sustainable aviation fuel (SAF)-powered turboprops and turbofans, with a small subset using battery-electric systems. Short-range aircraft with 81 to 165 seats will be predominantly powered by advanced turbofans fuelled by high-blend ratio SAF or hydrogen. Medium-range aircraft, flying distances up to nearly 3,800 nautical miles, are a priority for emissions reduction, accounting for around 45% of aviation’s carbon footprint. Long-haul, high-capacity aircraft will predominantly use advanced turbofans running on SAF.

Each propulsion technology comes with challenges. Battery-electric aircraft need major energy density improvements, alongside sustainable sourcing of materials and responsible disposal. Hydrogen systems need careful tank design, high-performance fuel cells and reliable gas turbine operation. SAF must overcome technical limitations, while production must scale to meet demand, supported by sustainably generated electricity.

Industry adaptation

Certification and workforce development are equally crucial. New systems and fuels require intensive testing and certification programmes. Engineers will need updated academic and technical training for aircraft with different architectures and energy systems.

Aircraft design itself will undergo a transformation. Future airframes will be conceived around the fuel and propulsion system rather than simply accommodating kerosene in the wings. Hydrogen storage may be integrated within the fuselage or external pods, while distributed propulsion units, thinner high-aspect-ratio wings and smart electrical systems will manage power distribution for hybrid or fully electric flight. Maintenance processes will need to adapt to these new architectures, balancing safety, performance and operational cost.

Funding challenge

This will all require substantial investment. The complexity, long timescales and technological risks may limit private capital, making government support vital. The UK aerospace sector, with a turnover of £34bn in 2019, is a global leader. 

Recent government investments in green technologies, combined with development strategies, can help maintain the UK’s position at the forefront of sustainable aviation while signalling against climate change.

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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.