Chinese astronauts make rocket fuel and oxygen in space

> 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

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.

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.