> 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.)
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.
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
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,
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.
The early internet had some wild recipes online, almost unimaginable today. A bit curious how long I would have to dig to find those things, if at all, but really don’t feel to leave that trail.
Btw, when I did this the internet didn't exist, 1977 to 1980, I think. It was in schoolbooks for chemistry, not chlorate stuff, but blackpowder at least. I also went into university libraries for more advanced stuff, after understanding teachers gave hints, and warnings, about not doing anything which one doesn't really understand. Not limited to explosives. Toxicity, fumes, pH, and so on.
We've been really dumbed down. No more interesting experimental kits ( https://en.wikipedia.org/wiki/Chemistry_set ) . No more availability of the ingredients. I could walk into a drug store and get that stuff for chump change, there. Not needing to produce finest charcoal myself. Or sulfur. Potassium nitrate. Flashbulbs and a 9V-block and some wires for electrical ignition!1!!
Bang! Whee!
edit: Thinking about it I can't shake the feeling that it did not make us safer. Though that may depend on the country.
Anyway, one does hear and read about much more loud booms caused by reckless use of smuggled illegal fireworks year round. Be it just for fun, ripping up trashcans, recycling containers, shopping windows, ATMs...
Or the really 'good stuff' (military) smuggled in from afar.
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.
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!
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).
Solar panels have a manufacturing cost, though, while you could imagine a renewable plantation of diesel trees that needs no raw ingredients other than a handful of seeds. It could even be self-seeding, though there are some good reasons we don't usually produce GE crops with viable seeds.
I'm sure the economics don't work out for it: solar panels are already cheap, the land could grow other crops, etc. But photosynthesis being lower-yield than photovoltaic generation isn't enough to rule it out. Perhaps as science fiction, on a future mission to an Earthlike planet that doesn't have the right resources to produce semiconductors at scale.
Biodiesel is an oil plus an alcohol (usually 80% vegetable oil + 20% methanol) reacted using an alkaline catalyst like lye.
Methanol is also known as "wood alcohol", and can be made at ~40% yield by cooking down wood ("destructive distillation") in a specific fashion, or made from too-cheap-to-meter natural gas if you've got it. Anything you can do with natural gas can also be done with anaerobically fermented methane. You can also use ethanol (fermented from any carbohydrate crops) instead of methanol, creating a biodiesel with slightly different but still usable properties.
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Sunflower, rapeseed, and soybean oil have very well-established agricultural workflows which require very little labor input.
Palm oil is substantially higher yield, but more labor intensive and is associated with tropical rainforest destruction.
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You don't necessarily even need to react your vegetable oil. The original Diesel Cycle demonstration engines ran on straight peanut oil, and there are some truck engines out there (like the 12 valve Cummins) that will happily run on filtered waste fryer oil all day long. It's just a matter of tuning, viscosity, compression ratios, seal materials, and the like, being slightly different from petrochemical diesel fuel. Reacting vegetable oils into fatty acid esters ("biodiesel") does attain some modest engine benefits, but mostly it's to match compatibility with petrochemical diesel grades so that you don't, eg, need to replace your fuel lines & pumps with different diameter fuel lines & pumps.
Depends on the context? Could be used in facitilies to produce biochar for production of terra preta/black earth/chernozem which counts as carbon-sink and is very productive soil. Doubly dual-use, so to speak. On-demand. Either biochar, or wood gas. Maybe even both.
You wrote it like „diesel trees” would be working in a way where you simply chop it down and put it in your gas tank.
Making and then using „diesel trees” would definitely require special equipment and manufacturing pipelines that might be the same cost or more than those for solar panels.
It's my science fiction story, so I'm going to say the tree we engineered for this was the sugar maple: you can put a tap in it and collect highly pure diesel fuel with a pre-Columbian level of technology.
> Plants have very low sunlight conversion efficiency compared to solar farms.
Measured how? If nothing else, they seem to be good at carbon capture. And I don't see how you it could account for engineered for plants engineered to store more of their energy as oil.
Measured by the fraction of incident sunlight that gets transformed to usable energy. Solar farms generate about 30 times as much power per hectare as corn farms, assuming that you can use electricity directly:
"Ecologically informed solar enables a sustainable energy transition in US croplands"
As a rough estimate, you'd lose 2/3 of that energy if the electricity had to be turned into liquid fuels. That would still mean 10 times greater usable energy produced per acre.
Plants genetically engineered for fuel production might be somewhat more efficient in the future, but future solar farms are also probably going to be more efficient.
For anyone wanting to learn more - the holy grail of Ag engineering would be to increase the efficiency of rubisco, which is the rate-limiting enzyme in photosynthesis - so understandably there’s a ton of research at doing just that.
A somewhat less (but still!) ambitious project is to retrofit C4 photosynthesis into rice. It's something like 50% more efficient, and has evolved independently dozens of times, so it's probably a lot more feasible.
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.
If you are disposing of the corn anyway, why not turn it into Ethanol and then burn it as car fuel?
The only real issue with Ethanol IMO is that corn Ethanol is preventing progress in advanced synthesis made out of, ex: switchgrass cellulose. There are better sources of ethanol if we invest into them.
They are used for all sorts of things we eat, corn nuts, hominy, grits, corn meal/flour and all the things those are used in. Personally, I find it far more palatable than sweet corn and it is far more useful/versitile/nutritious than sweet corn; it is a traditional cereal grain and can be used for all those things we use wheat and rye for.
There are many varietals of rice. Most do not grow in marsh land. Farmers often do flood the fields at the beginning of a rice growing season in order to drown out any competing plants. Flooding is not necessary though. Rice will grow with normal irrigation.
Yes. Rice tolerated flooding better than weeds so it is used as a cheap and easy weed control. Also some places grow fish alongside rice in the same land, getting some extra pest control and fertilizer for free.
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.
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.
> 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).
And the social implications of converting farmland from growing food to growing sugar cane/corn/soy. It is a VERY complex topic, but it seems overall it is a marginally positive thing for Brazil (even in emissions). While a very negative thing in the US because of all the subsidies required to make corn ethanol viable and overall negative emissions impact compared to oil gasoline.
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.
Cool! They have the numbers, too. Their system needs electricity for electrolysis, 75kWh per gallon of fuel. Compare to 0.24-0.87 kWh/mi for electric cars.
For a car that gets 30mpg that is 2.5 kWh/mi which is 3x worse than the the least efficient electric car, 10x worse than the best.
Still people will want to keep classic cars running in the future and there will be some market, enthusiasts will be willing to pay upwards of $8/gallon. Methanol-to-gasoline fuel is very high octane, around 96, which should keep old engines happy.
The most significant market, I think, for e-fuels are large vehicles such as construction trucks and farm tractors. California has absolutely terrible air quality not just in cities but in ag areas and it would be ideal to synthesize
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?
There are. Millions of them. Most any diesel can run just fine on veg oils, even used cooking oil. (Some very modern cars might need the electronic control systems tweaked.) There have been times/places where grocery stores put limits on oil once it became cheaper than diesel.
So now, on top of clearing forests and destroying ecosystems for farmland and infinite suburbia, we should clear even more forests to get fuel for cars, so we can drive them through the infinite suburbia.
The forests are cleared because they are allowed to be sold for clearance. Doesn't matter if its palm oil or for cows or sugarcane or ranch homes or solar panels or data centers. People tend to want a return on their investment in land vs spending serious capital to not do anything with a jungle. If you want to limit this you need to prevent land from being sold to entities that would like to profit from it. The specific thing being grown is basically irrelevant.
So many incorrect statements... you know the world is bigger than your (presumably US) backyard.
I suggest travelling around the world a bit and visiting ie Borneo how entire rainforest ecosystem is being reduced to nothing just due to palm oil plantations, mostly for biofuel and cheap&bad for health food additive.
Similar sight across many places out there. What you wrote ain't valid for a single one.
The issue is once again the forest is allowed to be sold. If you open up land for development, that is typically what tends to happen. People will seek out whatever use case makes sense with that land. No one wants to lord over a nature preserve. Everyone wants to make their buck into a buck fifty. Clearcutting of the rainforest in Borneo could be solved with a pen stroke by the government in charge but it seems they are more interested in supporting industrialization than preservation.
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.
No magic required: the tech for transporting electricity predates writing, and that by about six millenia; while reusable storage was only about 27 years after dynamo generators, 1859 vs. 1832.
Magically transporting and storing liquid fuels involves an unbelievably massive supply chain of trucks and refineries and storage tanks and gas stations.
If we need infrastructure to make use of energy we can ‘magic’ it up.
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.)
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. :)
Internal combustion engines and humans fundamentally use the same chemical process to generate energy. The fact that something can be used as automotive fuel alone says nothing about whether or not it is safe for human consumption.
Different process, same outcome: hydrocarbons are broken down and oxidized into CO2. We just do it with some enzymes in the Krebs cycle instead of doing a high temperature reaction.
Of glucose, not a hydrocarbon, but there are plenty of organisms that use hydrocarbons directly.
We don't because we use glucose as our easily transportable fuel, which we evolved because plants happened to produce glucose when we evolved. If there were plants producing some hydrocarbon in fruits we'd have evolved mitochondria to use that instead.
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.
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.
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.
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.
Yip, the reality is that words mean what people think they mean, and that changes over time. Don't think I'm yet ready to accept 'I could care less', but the colloquial meaning of begging the question is logical, reasonable, and is only objectionable on historical grounds.
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.)