[philipkglass]

That presentation leans heavily on biofuels/biomass as precursors to liquid fuels. In fact it doesn't mention any non-bio alternatives. That's not surprising given its age. Less than a decade ago biofuel looked cheaper than fully synthetic liquid electrofuels, considering the much higher cost of solar power back then.

I think that "power to liquids" is a much more likely path for large scale replacement of aviation fuel.

See for example "Power-to-Liquids as Renewable Fuel Option for Aviation: A Review"

https://onlinelibrary.wiley.com/doi/pdf/10.1002/cite.2017001...

The main problem with biomass is land requirements. You can get a little biomass "for free" just by using scrap from existing industries, but it rapidly runs into problems of land availability if you want to make enough carbon-neutral fuel for the world's commercial airlines. There's more than an order-of-magnitude improvement in usable power density if you replace biofuel plantations with an equal area of solar farms for making electrolytic hydrogen from water, plus a synthesis/refiner complex for hydrogenating CO2 and building up liquid hydrocarbons from the resulting methanol. It's also a lot less water-intensive and doesn't require any fertilizer.