Here is a brief summary of what is going on with SAF:

https://techxplore.com/news/2024-04-airline-industry-biggest-climate-lack.html

' "We need to scale-up by 1,000-fold," says Hemant Mistry, director of net zero transition for the International Air Transport Association, which has pledged that the aviation industry will erase its carbon emissions by 2050, mostly by using huge quantities of cleaner jet fuel.

At its new facility dubbed Freedom Pines Fuels, LanzaJet plans to produce 9 million gallons of sustainable aviation fuel (SAF) per year. In one sense, that's just a tiny step forward: It would take 100 of these plants to fulfill just 1% of the ravenous appetite of the world's commercial air carriers, which consumed 90 billion gallons of jet fuel last year.

But it provides a glimpse of one direction the clean fuel industry wants to go. Most SAF today is derived from animal fats and waste oils, which are relatively scarce. Used cooking oil is already widely collected for road transportation with only modest room for growth, while a robust market has long converted animal fats into ingredients for pet food and detergents. Strong demand from aviation could push these other industries to switch to climate-harming ingredients, like palm oil, warn environmental groups.'

And:

' "This industry needs an absolutely huge amount of fuel," says Alethea Warrington, a senior campaigner at Possible, a UK-based climate charity that is skeptical of SAF and encourages less air travel. "Wherever you try to get this from, it throws up huge systemic problems."

And:

' SAF requirements in the US have gained little traction amid forceful opposition from the airlines. Instead, the Inflation Reduction Act created an incentive for SAF worth up to $1.75 per gallon. That expires in 2027, though, well before most proposed plants will be operating.

"That's not long enough to get projects built and constructed," says LanzaJet's Samartzis.'

To be clear, I have absolutely nothing against SAF, and using crop residue it may eventually perhaps be possible to produce it without disastrous impacts on food production, water use and so on, or soil health and the use of the same crop residue to sequester carbon.

As far as I can see, the notion that international flight should be massively expanded in the meanwhile relies on no costed, practical available alternatives to cope with it though, including the utterly ludicrous and vastly expensive DAC.

This is in my view not a plan, as the steps are not shown, costed, or demonstrated, but plunging on recklessly with the pious hope that ' something will turn up' to save us from our folly.

The current technically proven answer to aircraft GHG emissions is to not fly so much, certainly long range, or at least not expand international flights.

But not to worry, Boeing is on the case.

Road rail and ships can use electric, aviation is different.
If you wanna go fast we need new ideas