The aviation industry has “come a long way in a short time” in considering alternative fuels but greenhouse gas emissions continue to grow, making prioritisation of action essential.
That is according to Mark Westwood, head of the Cranfield Centre of Aeronautics, who told a Westminster Energy, Environment & Policy Conference on ‘Next steps for aviation decarbonisation in the UK’: “Pre-Covid, the aerospace industry didn’t talk much about alternative fuels.”
However, Westwood said: “The story the atmosphere tells us is that the concentration of greenhouse gases continues to go up. It increased again in the last 12 months.”
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He argued: “That is why the number-one priority is around operational efficiencies – the things we can do today with the technology we have now, like air traffic management improvements, zero-emission ground vehicles and minimising the time aircraft have auxiliary power units running – remembering that every tonne of CO2 we save today is CO2 that won’t sit in the atmosphere for 100 years.”
Westwood identified sustainable aviation fuel (SAF) as “the second priority”, noting: “It’s a drop-in solution and, from a technology perspective, the challenges are relatively small.”
Rather than the technology, the challenges are around “the scalability of supply, the economics of the supply chain, land use and the effects on other users of using some feedstocks”.
Synthetically produced liquid hydrocarbons, or ‘power-to-liquid’ fuels, appear potentially the most promising form of SAF, but Westwood warned of the need for “lots of renewable energy to support power to liquid”.
He told the conference: “Priority number three is hydrogen – the most feasible alternative to natural or synthetic hydrocarbons.”
But he noted there are “lots of issues to be addressed with hydrogen production, storage and transport and the largescale supply of renewable energy” required to produce ‘green hydrogen’.
Westwood said: “There are also lots of challenges around aircraft design, propulsion, integration, safety regulation and the processes involved with handling liquid hydrogen at scale.”
Yet he insisted: “It’s a big opportunity for the UK to take a leading role.”
Cranfield was recently awarded a £69 million research and development for a programme on hydrogen handling, hydrogen combustion and investment in hydrogen infrastructure at airports.
Global demand to grow
The continuing growth of air travel means there has been “little or no progress” in reducing the industry’s overall emissions, the Westminster conference on aviation decarbonisation was told.
Andrew Chadwick, ecosystem director for air mobility and airports at transport innovation accelerator Connected Places Catapult, said: “Global demand will grow in the coming decades and our emissions will continue to grow unless we accelerate improvements in energy efficiency and switch to low carbon fuels.”
He argued: “So far, the sector has made little or no progress on this.”
Chadwick added: “Non-CO2 effects, on top of carbon emissions, account for between half and two thirds of [the total] warming effect, which means commercial aviation accounts for about 5% [of global warming].”
At the same time, he noted: “Only 1% of the world’s population accounts for 50% of aviation emissions.”
He told the conference: “If aviation were a country, it would be the sixth highest polluter in the world.”
However, Neil Cloughley, chief executive of Faradair Aerospace, said: “It’s unfair to say the industry hasn’t done anything to reduce emissions. We have much cleaner engines [today].”