By Jeremy Williams

Today Virgin Atlantic flew one of their planes from London to New York on 100% sustainable aviation fuel, or SAF. It’s a world first – so far SAF has only been used as a percentage in a fuel mix. This will be the first time that a commercial airliner has taken on nothing but biofuels, and it aims to prove that this is a viable and realistic step towards low carbon flight.

Despite the world first, there’s a sense of deja vu about Virgin Atlantic’s press release. I distinctly remember Richard Branson posing next to a jet powered by (5%) coconut biofuels and declaring “a biofuel breakthrough for the whole airline industry.” That was in 2008.

Then there was an almost identical press showcase ten years later when a Virgin plane flew from Orlando to London on (5%) waste-derived ethanol. That was declared to be a milestone as well, one that would unlock investment in the mass production of SAF.

If you squint really hard, you can see the global trend that was unleashed by this historic occasion. In 2019 less than 0.01% of global aviation fuel was SAF, according to IATA. By 2020 that had risen to 0.03%, then 0.04%, and last year we had reached the dizzy heights of 0.1%.

Step back and consider the implications here. Virgin Atlantic proved in 2008 that you could fly an airliner on 5% SAF. Fifteen years later the industry was using 0.1% in its fuel mix. Kudos to Branson and Virgin for plugging away at this, but aviation fuel is too cheap and this is not an industry that seems serious about sustainability.

Is that going to change though? Is today’s breakthrough the real one? Maybe. SAF production is ramping up. From that 0.1% last year, SAF use is expected to double to 0.2% this year, and we should remember the power of exponential growth.

Yesterday I wrote about hydrogen, and how we need to answer three questions about it: does it work? Is it affordable? And is it actually green? SAF faces exactly the same questions. Yes, it works and today’s flight proves that again. It may be affordable shortly, given the investment money finally pouring into the sector.

Is it really green? That’s the more slippery one. Today’s flight was powered with SAF made from used cooking oil. That’s not exactly something that will scale well. We eat a lot of chips in Britain, but not so many chips that you can decarbonise whole fleets of airliners with our used oil. SAF can also be made from household waste, which is more involved but perhaps more promising.

You can also make it from sugar, vegetable oil, agricultural residues – all sorts of things. There are 42 recognised feedstocks for making SAF so far – which of these are actually green? Which of them compete with food production? Which of then compete with other uses within a circular economy? Those are complex questions.

Aviation isn’t going anywhere. Unless you are particularly radical, there’s a role for flying in almost every vision of a low carbon future, even if it is at considerably lower rates. That means a role for SAF in some capacity, and so we need experiments like Virgin’s. It’s a necessary step towards sustainable flight, but we’d be kidding ourselves if we thought the problem of aviation’s emissions have been solved.

First published in The Earthbound Report.