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.
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.
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.
> 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.
Either a perennial with oily fruit (someone mentioned palm oil down below), or something where you can relatively easily use the entire plant. The idea I keep coming back to is algae bred or engineered for oil content, but I'm not actually sure how feasible that is.
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.
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.
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.
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.
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.
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.
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!
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.
This won't enable perpetual space travel in case anyone thought so.
Rockets need to eject particles to generate force.
And to eject 1 kg of fuel, its photo synthesis system has to lose 1 km of mass in one way or another.
The solution is to find a way to generate thrust without rocket fuel ejection.
That's called a Bussard ramjet: collect hydrogen and fuse it for power to energise the collection mechanism and thrust to overcome the drag. I think the current consensus is that the interstellar medium round these parts is too thin to make it work in deep space.
Quite big tiny particles in this application: Xenon is a fairly hefty atomic number of 54 - exactly double iron.
And you need quite a bit of it: even fairly small spacecraft like probes can have nearly a tonne of the stuff. Which, considering there's only 30-40ish tonnes extracted per year at a cost of about 1.5ish dollars per gram is quite a bit!
Ions are small enough that you can bring enough for a whole trip pretty easily. Yes they're still consumable, but you need a tiny fraction of the reaction mass you need with a conventional rocket.
Maybe we could travel without bodies. Ala Lovecraftian astral travel or whatever. I mean you couldn't ship matter like that but for everything else it might work just fine.
Because English language news sources aren't particularly interested in developing the relationships necessary to report on Chinese scientific breakthroughs. It undermines the prevailing media narrative that China is behind and backwater.
Americans don't like the idea that maybe China is actually rocketing past them technologically and infrastructurally, so news doesn't really report on it much.
> It undermines the prevailing media narrative that China is behind and backwater.
The prevailing narrative, particularly around hacker news, is that China is a dangerous foe and it's technological progress is a sign that we need to give our own government more money and less oversight so that we don't lose our "technological advantage."
> Americans don't like the idea that maybe China is actually rocketing past them technologically and infrastructurally
I don't buy this explanation given it's value to American propagandists. American society is naturally competitive. There's only two likely reasons why it doesn't get reported.
It's either not as true as the Chinese would like you to believe or American industry is already profiting off of it.
Especially considering the ruling class does not like when people are reminded that China has its own space station and has never allowed a single non-Chinese person on it, while we failed in several ways over months to return the astronauts from the ISS, and President Trump just decreed that he’s going to give 600,000 (more?) Chinese students visas to study at American universities and invariably displacing their indigenous.
I personally have nothing against the Chinese and respect them being oddly far more interested in the wellbeing of their own people than remotely anything in any western country, but it sure is odd behavior by people who consider China a threat.
“China’s an enemy” … “let’s bring in 600,000 Chinese every single year to learn from us and take the knowledge back to China and the ones that remain will be embedded spies like the people of other foreign nations who have burrowed into America and its power structure”.
I'm not sure that a government that goes out of its way to try to silence political dissent and enforce social order through fear should be considered interested in the wellbeing of its people. [0][1][2]
Chinese scientific progress relatively rarely gets reported on because nearly all science reporting is a push-based system of institutions throwing press releases at publications. The publications don't have the chops to analyse or verify that information, or to go and find interesting research happening on their own, so they mostly stick with uncritically repackaging output from the places they trust.
Ah, all the great memories of making oxygen in the chem lab. Back when we used to rip the protons, neutrons, and electrons out of Flourine atoms and smash them into Nitrogen atoms until the N turned into O. Back when we made things the old-fashioned way.
> 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
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.
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.
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.
FYI “begs the question” does not mean “raises the question”.
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)
Why aren't we engineering plants to produce automotive fuel? We ought to at least be able to do diesel.
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.
what goes through my mind is the fact plants aren't low maintenance, the land has to be tended.
growing the fuel plant is probably easy.
How do you get it OUT of the plant?
Solar panels just sit there (they do need cleaning i admit) and produce electricity that we can manipulate very cheaply already.
What machine collects diesel from plants? Can you safely dispose of the plant matter?
I’d rather farm food where plants grow well and put up panels where they don’t..
> 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"
https://www.pnas.org/doi/full/10.1073/pnas.2501605122
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.
https://en.m.wikipedia.org/wiki/RuBisCO
Why do we need more efficient photosynthesis in plants? Is it for indoor cultivation?
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.
Ok, yeah, if your reference for biofuel is corn, where you can only use a tiny fraction of the plant, no kidding it'll look bad.
Which plant do you estimate is a much better pick?
Either a perennial with oily fruit (someone mentioned palm oil down below), or something where you can relatively easily use the entire plant. The idea I keep coming back to is algae bred or engineered for oil content, but I'm not actually sure how feasible that is.
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.
Corn ethanol is a farm subsidy. It gets greenwashed as something positive because plant=natural=good.
It’s not great for the environment, but it keeps a food surplus available in crisis instantly by just turning off the ethanol production facilities
True. But it might be cheaper to store the corn for a year and then dispose of it, replace it with fresh corn.
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.
Surely you can make cornstarch from it, and that problem only lasts a year.
>corn-derived ethanol to our gasoline
Stupidest possible thing to do with food. Especially since in some operations you put in more diesel than take ethanol out.
It's my understanding that corn produces the most (edible) calories per square metre of any of our farmed plants
edit: Looked it up - Rice has the highest number of calories per square metre of farmland, just that it requires marshy/swamp land to grow.
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.
Something like 40% of the corn grown in the US is turned into biofuel:
https://www.ers.usda.gov/publications/pub-details?pubid=1057...
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.
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.
Mythbusters: https://youtu.be/QEX1YFXYTdI
TopGear: https://youtu.be/GOFbsaNeZps
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.
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.
Or if we just put those panels on any other land. Land isn't the constraint here.
Sure if we could magically transport and store it. Like we can for liquid fuels.
Do you want plants you grind up into fuel or are you thinking Niven style Booster Trees?
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. :)
We do and call it canola oil - which should give you an idea of whether eating canola oil is a good idea
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.
> same chemical process
Our digestive systems heat and oxidize hydrocarbons to generate kinetic energy? You sure about that?
We do use oxidation to generate energy.
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.
We do. It is called biodiesel. You can make it from any organic matter.
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...
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.
This won't enable perpetual space travel in case anyone thought so.
Rockets need to eject particles to generate force. And to eject 1 kg of fuel, its photo synthesis system has to lose 1 km of mass in one way or another.
The solution is to find a way to generate thrust without rocket fuel ejection.
Can we "swim" through space? Collect particles from space, add energy, expell them backwards to generate a net thrust.
That's called a Bussard ramjet: collect hydrogen and fuse it for power to energise the collection mechanism and thrust to overcome the drag. I think the current consensus is that the interstellar medium round these parts is too thin to make it work in deep space.
There's a huge density difference if you aren't close to a planet or star.
Solar sails are probably more practical.
Yep: https://en.wikipedia.org/wiki/Bussard_ramjet
Gather interstellar hydrogen, use it to run a fusion engine for propulsion and power. :)
Also: https://memory-alpha.fandom.com/wiki/Bussard_collector
Star Trek assumed that all warp class vehicles would require them for operation and in-situ fuel replenishment.
no particles needed, we already have ion drive, just need electricity
Just out of curiosity, what do you think an ion is?
Ions are atoms ..... tiny particles
Quite big tiny particles in this application: Xenon is a fairly hefty atomic number of 54 - exactly double iron.
And you need quite a bit of it: even fairly small spacecraft like probes can have nearly a tonne of the stuff. Which, considering there's only 30-40ish tonnes extracted per year at a cost of about 1.5ish dollars per gram is quite a bit!
Ions are small enough that you can bring enough for a whole trip pretty easily. Yes they're still consumable, but you need a tiny fraction of the reaction mass you need with a conventional rocket.
Maybe we could travel without bodies. Ala Lovecraftian astral travel or whatever. I mean you couldn't ship matter like that but for everything else it might work just fine.
This is from January, have there been any updates in the past 7 months?
There is exceptionally little material info in this article and so very much speculation
Apparently it has been in production since 2015. Why is this the first we are hearing about it?
Because English language news sources aren't particularly interested in developing the relationships necessary to report on Chinese scientific breakthroughs. It undermines the prevailing media narrative that China is behind and backwater.
Americans don't like the idea that maybe China is actually rocketing past them technologically and infrastructurally, so news doesn't really report on it much.
> It undermines the prevailing media narrative that China is behind and backwater.
The prevailing narrative, particularly around hacker news, is that China is a dangerous foe and it's technological progress is a sign that we need to give our own government more money and less oversight so that we don't lose our "technological advantage."
> Americans don't like the idea that maybe China is actually rocketing past them technologically and infrastructurally
I don't buy this explanation given it's value to American propagandists. American society is naturally competitive. There's only two likely reasons why it doesn't get reported.
It's either not as true as the Chinese would like you to believe or American industry is already profiting off of it.
The Chinese also aren't the most transparent when it comes to their own technological advances. Certainly much less transparent than NASA.
Especially considering the ruling class does not like when people are reminded that China has its own space station and has never allowed a single non-Chinese person on it, while we failed in several ways over months to return the astronauts from the ISS, and President Trump just decreed that he’s going to give 600,000 (more?) Chinese students visas to study at American universities and invariably displacing their indigenous.
I personally have nothing against the Chinese and respect them being oddly far more interested in the wellbeing of their own people than remotely anything in any western country, but it sure is odd behavior by people who consider China a threat.
“China’s an enemy” … “let’s bring in 600,000 Chinese every single year to learn from us and take the knowledge back to China and the ones that remain will be embedded spies like the people of other foreign nations who have burrowed into America and its power structure”.
I'm not sure that a government that goes out of its way to try to silence political dissent and enforce social order through fear should be considered interested in the wellbeing of its people. [0][1][2]
[0]: https://www.icij.org/investigations/china-targets/china-tran...
[1]: https://www.airuniversity.af.edu/JIPA/Display/Article/358765...
[2]: https://www.cfr.org/in-brief/peng-shuai-china-disappeared-ho...
Chinese scientific progress relatively rarely gets reported on because nearly all science reporting is a push-based system of institutions throwing press releases at publications. The publications don't have the chops to analyse or verify that information, or to go and find interesting research happening on their own, so they mostly stick with uncritically repackaging output from the places they trust.
Ah, all the great memories of making oxygen in the chem lab. Back when we used to rip the protons, neutrons, and electrons out of Flourine atoms and smash them into Nitrogen atoms until the N turned into O. Back when we made things the old-fashioned way.