British boffins say aircraft could fly on trash, cutting pollution debt by 80%

Sustainable aviation fuels (SAFs) made from sources other than fossil fuels have the potential to reduce emissions by up to 80 percent, UK researchers have found.

Boffins from the National Centre for Atmospheric Science (NCAS) and the University of Manchester testing various blends of traditional jet fuel and SAF said preliminary data shows that airline travel might not such a guilty trip over pollution due to more efficient engine controls.

According to their research, emissions of ultrafine black carbon at low thrust were 45 percent less in number and 80 percent less in mass for every kilogram of blended SAF. It gets better at higher-altitude flight, said Dr Paul Williams, an NCAS researcher based at the University of Manchester.

"While an aircraft is cruising there would be less non-volatile particulate matter produced, which in turn impacts contrail formation," Williams said. "This could have the potential to reduce the climate warming effects of aviation globally."

SAFs are primarily made from corn and other crops, but waste resources have also been converted into synthetic jet fuel. The US Department of Energy (DoE) lists wood mill waste, agricultural residues, fats and greases, municipal solid waste, and other less-than-appealing sources as possible base materials for SAF.

Crucially, SAFs can replace traditional jet fuel, meaning existing aircraft can use it without the need to rework their existing hardware.

Williams said the findings also point to improved air quality near airports, where much of the ultrafine black carbon from commercial jets settles as they idle at low thrust before takeoff. Williams told The Register that SAF/petroleum blends with lower aromatic content produce less soot, and those with lower sulfur content produce less volatile particles, which he said is consistent with other research into SAFs.

Is a sustainable aviation future possible?

Aviation regulators in the US have committed to building a net-zero aviation system by 2050, which the US said will require a sharp uptick in SAF production. According to the DoE, while the US has enough resources to meet its goal of phasing out fossil fuels from the aviation industry by 2050, the UK might not have the same advantage.

A report from the Royal Society released earlier this year concluded that the UK would need to devote half of its existing farmland to SAF production, or more than double its renewable electricity supply, to meet net zero aviation goals.

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"Producing enough SAF will be a challenge," Williams told us. He noted that there are several technologies in the pipeline that could help the aviation industry become sustainable, like hydrogen-fueled and electric aircraft, but those technologies are still in their early days of development.

"There are a lot of hurdles here, not just with generation and supply but the associated infrastructure," Williams said in an email. "I don't think there is the data yet to say whether aviation is on track or not."

Rolls-Royce and Easyjet tested the world's first hydrogen aviation engine late last year, but the test was stationary and no timetable for getting the engine flying has been established. Airbus has since joined the project, with plans to get a hydrogen-powered jet in service by 2035 it's hoped.

As for hybrid and electric aircraft, those are being developed as well, but delays abound, among them concerns that battery technology simply isn't efficient enough to make the weight trade-off worth it. Batteries are just too heavy to give electric airplanes enough range at the moment and can be a serious fire risk if not properly managed, as Boeing found out when its entire fleet of 787 aircraft was briefly grounded after two aircraft had the worst kind of smoking on board. ®