[wutwutwutwut]

From the article:

> Sustainable aviation fuel can be made from any of 60 different feedstocks — among them plant oils, algae, greases, fats, waste streams, alcohols, sugars, captured CO2 and other alternative feedstock sources and processes. The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year.

[ya_throw]

By "article", you mean "marketing blub from someone trying to sell you something".

Ultimately, all of those "sustainable" feedstocks will have to be grown. As my quick maths points out, the size of the field we're going to need is just staggering.

>The Department of Energy estimates that the United States alone has the resources to produce 50–60 billion gallons of SAF per year.

I'd like to know where from. Actually, I looked it up. It's the "Billion Tonne Plan". It involves "thinning" all US forests, and planting practically every available acre with crops for biofuel. Basically, dedicating all of the available plant matter grown in the US to burning for transportation.

[wutwutwutwut]

First you claimed it was bogus and now you say the area needed is staggering. I wonder what's comes next.

[ya_throw]

It's bogus that jet fuel can be renewable, at least in anywhere near the quantity we currently use. Mainly because the amount of arable land needed is staggering, and we already are destroying virgin rainforest just to feed the world.

[pfdietz]

I mean sure, you can reach that conclusion if your number is off by a factor of 30.

The amount of carbon in paper, cardboard, and food in existing municipal solid waste streams in the US would be nearly enough to make the current US jet fuel demand. It's not like replacing all liquid fuel use -- jet fuel is about 6% of US liquid fuel demand.

[ya_throw]

Do you have a source for that?

Assuming we use the hydrogen conversion process you mentioned, and have fitted the 1000's of square miles of solar panels it would need - I find it hard to believe that the US throws away 90 billion kg of carbon-rich domestic waste every year (apparently, the US gets through about 15 billion gallons of jet fuel per year).

Obviously, even if this is true, we then need to address the other 94% of liquid fossil fuel use.

[pfdietz]

Fuel use: https://www.eia.gov/energyexplained/oil-and-petroleum-produc...

Materials landfilled in MSW:

https://www.epa.gov/facts-and-figures-about-materials-waste-... https://www.statista.com/statistics/1231960/municipal-solid-...

The point is not necessarily to suggest that landfilled material be what is used to make jet fuel, but to point out the volumes are not enormous compared to what's already flowing through the economy. The US produces even more agricultural waste -- over 200 million tonnes of corn stover each year, for example.

The other fuel uses may in many cases be replaced by non-fuels, for example by electrification. Aviation is a special case where the high energy density of chemical fuels, and particularly hydrocarbons, will often be unavoidably attractive.