[kevinmershon]

> This is a similar reaction to photosynthesis in plants, which produces glucose instead of rocket fuel.

This is silly, but also begs the sillier question why we aren't bioengineering plants to produce rocket fuel

[JumpCrisscross]

> why we aren't bioengineering plants to produce rocket fuel

Plants are self-assembling albeit inefficient photosynthesises.

On earth, where they can harvest their carbon in situ, that inefficiency outweighed by us not having to make them. Their main components by wet and dry mass, carbon and oxygen, are dissolved in atmosphere. In space, on the other hand, the major cost is lifting. (Even earth, farming quickly becomes uneconomical when just water costs balloon.)

In space you’re moving all the mass the plant is built out of at exorbitant cost. At that point, you might as well just assemble the machinery on the ground and get the efficiency boost.

I can only see an exception arising if lifting costs start scaling with volume more than mass, i.e. post chemical rocketry, at which point sending up compacted carbon and water and letting plants assemble themselves in space makes more sense than sending up panels and tiny labs. (That or you’re going somewhere with accessible carbon and/or oxygen.)

[mapt]

By far the most credible case for asteroid mining is water & carbon compounds. A little H, O, and C, and you have conventional hydrocarbon propellant + LOX.

I don't know what the actual claim that is being made here is; This seems to redirect ultimately to a lay press release from a state space agency rather than to a scientific paper. There do seem to be a number of competing articles on electrochemical synthesis of ethylene from CO2.

https://www.carboncapturejournal.com/news/artificial-photsyn...

https://www.nature.com/articles/s41467-024-50522-7

https://lanzatech.com/lanzatech-produces-ethylene-from-co2-c...

https://techport.nasa.gov/projects/93860

https://news.umich.edu/in-step-toward-solar-fuels-durable-ar...

https://www.eurekalert.org/news-releases/717409

[mattashii]

Glucose can be used as a component in solid fuels, you just need to find an oxidizer to mix in.

Alternatively, you can break it down into ethanol, which has been used as liquid rocket fuel since at least the first half of the '40s.

[PaulHoule]

See https://en.wikipedia.org/wiki/Qassam_rocket

This classic book tells the story of liquid rocket fuel development

https://library.sciencemadness.org/library/books/ignition.pd...

You'd think that you could mix any of a wide range of fuels with a wide range of oxidizers and get a good rocket fuel but it does not really work that way, most combinations are pretty awful, including the ethanol + O2 used in the V2. There was a time when there was interest in "storable" liquid propellants but once solid propellants reached this level of maturity

https://en.wikipedia.org/wiki/LGM-30_Minuteman

those were obsolete.

It is hard to beat H2+oxygen or hydrocarbons+oxygen if you pick the right hydrocarbons (rocket kerosene isn't quite the kerosene you use in a lamp)

I'm not sure if ethylene is really that good of a rocket fuel. In the context of a space economy I see it as a "reactive carbon" substance which is easy to make other things out of, say,

https://en.wikipedia.org/wiki/Polyethylene

in the sense that glucose is reactive carbon you can build structural carbohydrates and all sorts of biological molecules out of. There is talk about SpaceX establishing a methane economy on Mars, methane is definitely an easy to synthesize rocket fuel but it not very reactive and not on the path to making other things you might want.

[LargoLasskhyfv]

Reminds me of "UnkrautEx und Puderzucker".

Sort of early 'RoundUp' with high contents of Sodium chlorate combined with powdered sugar. Very dangerous! But fun :-)

Even more fun, but potentially fatal very fast would be Potassium chlorate.

But I've been cautious, and limited myself to selfmade blackpowder mostly, during the times one 'did that' as young boys with toys.

Still have all my fingers, no burn scars, full eyesight & hearing, though. Phew! :-)

[adrian_b]

The difficult part done by plants is synthesizing complex organic molecules that can be used as food.

For now and the near future there are no ways of doing that part otherwise than by using living plants or fungi, possibly with genome modifications.

The part with capturing solar light and splitting water and reducing carbon dioxide to a very simple carbon compound can be done with artificial means much more efficiently than in plants, so there is little doubt that this will become commonly used in the near future.

Ethylene or methane are good for fuel or for making plastic, but when a slightly more complex organic substance were made, e.g. glycine or glycerol, that could be used to feed a culture of fungi, which could be used to make human food, especially if genetically-modified to make higher quality proteins.

[awesome_dude]

Lichens!

Cyanobacteria that can exist in the vacuum of space AND produce oxygen... just not fast enough to be useful, but one day, a big hairy space ship will rule the universe!

See: https://www.reddit.com/r/space/comments/1acqxml/lichen_survi...

[andrewflnr]

Why aren't we engineering plants to produce automotive fuel? We ought to at least be able to do diesel.

[philipkglass]

Plants have very low sunlight conversion efficiency compared to solar farms. If you need chemical fuel instead of electricity, it would still be more efficient to use solar electricity to turn carbon dioxide and water into simple liquid fuels like methanol (usable in spark ignition engines) or dimethyl ether (usable in diesel engines).

[staplung]

Biodiesal is already a thing. Also, we (the US) already blend a portion (about 10%) of corn-derived ethanol to our gasoline. There are problems with it though, one of which is that overall, it probably has a higher carbon footprint (fertilizer, harvesting, processing, etc.) than just not using it.

[DanielHB]

We literally make ethanol from corn and sugar cane. And biodielse from soy.

It doesn't make economic and enviromental sense in most parts of the world (especially corn). In some places they are net-positive on carbon emissions compared to oil-derived gasoline. Tilling the fields, growing, harvesting, processing and transporting often emits more CO2 than the equivalent gasoline produced. Especially the initial tilling of the land to convert it to farmland releases A LOT of CO2 into the atmosphere (this is a one-time thing though).

In the US all (ground vehicle) gasoline sold needs to have 10% ethanol (corn-based), in Brazil it is 20% (sugar cane based). In Brazil almost all cars support 100% ethanol fuel and it is quite common to fuel with ethanol only.

https://en.wikipedia.org/wiki/Ethanol_fuel_in_Brazil

The whole bio-fuel industry is a very complex mix of economics (often requires subsidies to make sense), geopolitical (less imported oil), environmental concerns (mass scale farming soil degradation and CO2 emissions derived from it) and logistical (completely different transportation and refining process).

Fun fact ethanol freezes at a fairly high temperature and mixes with water which makes it not ideal for cold climates and boats. It is quite common for unaware boat owners to f-up their engines by buying car-grade fuel-station gasoline in Brazil.

[PaulHoule]

See https://www.aircela.com/ and many other e-fuel startups, that one makes a very pretty image of a "personal fuel synthesizer" which makes about a gallon of gas a day which is about what my wife and I use.

[asdff]

We do this for some plants. Hybrid palms are used for palm oil production due to the favorable yields and properties compared to parental species. One might ask why there are no cars powered off palm oil seeing as we can readily grow it across the world?

[dr_dshiv]

Over 1% of US land is devoted to biofuels. If we replaced those corn fields with solar, it would produce 4x the electricity currently consumed in the US.

[conradev]

Something like 40% of the corn grown in the US is turned into biofuel:

https://www.ers.usda.gov/publications/pub-details?pubid=1057...

[8bitsrule]

My guess: (in the US, at least) brains focussed on profits have taken less delight in exploration/invention. (Somewhat similar to what's been happening in science.)

[xandrius]

We kind of are but we are also in the process of stopping burning stuff to create energy for ourselves, as usually burning creates CO2.

[wombatpm]

Do you want plants you grind up into fuel or are you thinking Niven style Booster Trees?

[bparsons]

We do. It is called biodiesel. You can make it from any organic matter.

[astrocat]

we already do have plants that produce (sort of) high-energy-density liquids for us. So if you want gas to be as expensive as maple syrup then... sure. :)

[QuadmasterXLII]

We do and call it canola oil - which should give you an idea of whether eating canola oil is a good idea

[14]

Because we are too busy making ethanol to add to gasoline so that motorcycle mechanics and small engine mechanics are guaranteed to have unlimited work every spring.

In a more serious response almost all questions like yours can boil down to economics. You can be certain if there is a way make something at a profit someone will jump in and make it happen. If there is no money in it you can expect that even if it is more environmentally friendly it may be part of research but not going to be implemented unless it becomes profitable.

[sharpshadow]

In my opinion there is still a lot to discover around the manipulation of the environment of plants. Generally speaking its the milieu which has the primary effect on life. Genetic manipulation and environment settings should be applied together to find very specific appliances.

Very intriguing is the Primeval Code[0] in which plants and other life exposed to electrostatic fields changed significantly down to the genome.

Would be very interesting which other artificial settings and compositions affect life in which ways.

0. https://rexresearch.com/ebner2/BurginDerUrzeitCode.pdf

[Cthulhu_]

To be a pedantic armchair non-expert internet commenter, let plants rot and they produce methane which can in my head be used as rocket fuel. Also corn and other plants to ethanol.

[Ekaros]

Depending on system rocket fuel is not that choosy. Oxidiser is harder part, otherwise depending type of engine pretty much anything goes. Ofc, some do have better mass ratios, but in space that is less of concern.

[sneak]

FYI “begs the question” does not mean “raises the question”.

[elefanten]

Classically it doesn't, but colloquially it does. The dreaded "language changes and evolves" defense that frustrates pedants everywhere.

(I say this in the friendly spirit of a long-defeated fellow pedant who has hit people with your exact comment for decades)

[iancmceachern]

We are, there has been lots of work on algae biofuels, etc

[fiftyacorn]

Sounds like Day of the Triffids