[dmurray]

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.

[tekno45]

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?

[mapt]

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.

...

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.

...

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.

[tekno45]

Thanks! very interesting space that i barely understand lol. hope it didn't come off as know it all, just questions.

[aaronblohowiak]

I’d rather farm food where plants grow well and put up panels where they don’t..

[motorest]

> I'd rather farm food where plants grow well and put up panels where they don’t..

False dichotomy. There are places where food does not grow at all and can be used to grow fuel crops. Say, the ocean.

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

[Tade0]

No need for diesel trees when there's wood gas, which was successfully used to power vehicles:

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

It's wildly inefficient though and not worth the trouble compared to solar panels and batteries.

[LargoLasskhyfv]

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.

[ozim]

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.

[dmurray]

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.

[arghwhat]

No no, you integrate the pump directly into the tree. Skip the farms, just plant the trees at the station in place of the current pumps.

[anvandare]

Forest fires would definitely get a lot more exciting.

[ozim]

Maybe that's quite the reason why we didn't do it :)