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Comment by photochemsyn | Hacker News Reader

It looks like a modified Fischer-Tropsch, so they're likely concentrating CO2, blowing off one O to make pure carbon monoxide, and then adding hydrogen gas (from water) under pressure over a catalyst to generate long-chain hydrocarbons.

Now, what would be nice to see as a proof-of-concept is an entire oil tanker's worth of jet fuel made by this process. How far off is that?

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The Germans used this process during WW2 to cover a part of their fuel needs. That is enough of a "proof of concept".

So there is no doubt that it works. It was abandoned after the war only because it was more expensive than extracted petroleum.

Almost a century later after its invention, it should be possible to have better efficiencies than in the past.

Sasol of South Africa has made liquid fuels via the Fischer-Tropsch process for decades. The synthesis gas comes from coal or natural gas. Clean synthesis gas from water, CO2, and clean electricity should be a drop-in replacement for fossil derived syngas. But it's relatively expensive to make liquid fuels this way even when starting with cheap coal. I only expect synfuels to be used for performance critical applications and niches like keeping collectible classic cars running.

Yup.

For the Air Force, their particular need is to avoid billions of dollars in contractor expense for reliably supplying fuel to remote bases in hostile territory.

I read elsewhere on hacker news that the us military runs through 20 million barrels of fuel per day . I can imagine there is a great desire to be less dependent on suppliers both in terms of quantity and logistics. Imagine a nuclear powered aircraft carrier being able to generate fuel for its planes and support ships.

Since world production of oil is currently about 75 millions of barrels per day (mbpd)[1], this 20 mbpd figure is certainly wrong. Probably someone wanted to make the figure seem higher than it was and used gallons instead of the standard barrels unit. Even then, 1/2 million barrels of fuel per day would seem high to me when the US is not in an active shooting war.

20 million barrels of oil would be worth about $1.6 billion dollars. So the military would be spending about $580 billion a year on fuel. Or 3/4th its budget.

[1] https://ycharts.com/indicator/world_crude_oil_production

https://en.m.wikipedia.org/wiki/Energy_usage_of_the_United_S...

12M gallons a day, which is approx 285,000 barrels a day. Far below the 20 million barrels figure.

You’re missing the point. The really large number feels right.

Yes the US Navy has been researching synthesizing aviation fuel onboard nuclear powered carriers since at least 2013. The goal is to reduce fleet dependence on vulnerable tankers.

https://www.autoevolution.com/news/us-navy-aircraft-carriers... https://www.autoevolution.com/news/us-navy-aircraft-carriers...

Amazing. At what point do these carriers become totally self sufficient.

When they can make food from waste.

- water filtration/desalination

- Maybe in the future they could use fusion reactors for power, synthesizing Deuterium and/or Tritium to enhance their endurance (maybe indefinitely?)

- make the carrier (with minimal crew) and the planes into drones (AFAIK already in research/testing) since even if the material could be at sea forever the people could not endure and also many probably wouldn't sign up for such a job

> - water filtration/desalination

My understanding is the submarines have been doing that for a very, very long time. No challenge there.

Here's a random article from 2008 saying "decades": https://www.eastvalleytribune.com/opinion/nuclear-desalinati...

All subs and surface ships, literally since the very first nuclear powered vessel. Because all they did was switch to a different heat source for the desalination that ships had been doing for decades before that.

shouldnt itself manage fuel logistic or it is contracted away?

regardless of who is doing the logistics it's expensive.

synthesizing fuel also means nuclear powered aircraft carriers would be vastly more self sufficient

Since the 1950s.

https://www.sasol.com/media-centre/media-releases/sasol-prod...

The problem isn’t the proof of concept, it’s reducing the energy penalty. It takes a lot of energy to reverse combustion.

Instead of shipping hydrocarbon fuel, they will have to ship solar/wind/geothermal power plants, or some other dense source of energy such as nuclear reactors.

Is what the AF attempting much different from plans to make methane on Mars?

https://www.space.com/future-astronauts-methane-rocket-fuel-...

The Mars process is the Sabatier process, rather than Fischer-Tropsh, and reuslts in methane (and water) rather than heavier alkanes (petroleum-analogue hydrocarbons).

(Corrected from earlier misstatement of methanol production, thanks to philipkglass.)

The Sabatier process yields methane, the lightest member of the alkane series. Methane also has the best gravimetric energy density of the alkanes. But for ease of handling, heavier alkanes that liquefy at above-cryogenic temperatures are better.

Thanks, corrected.

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