system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why aren't we making plant based fuel from eucalyptus trees instead of Fossil fuels?
gpt
There are only so many eucalyptus trees that are the right types to produce biofuel and it takes a ton of work to transport them and then convert them into usable fuel (and only certain kinds of fuel at that). They can't grow back quickly as well, so once you cut down an area you have to replant it and then wait years for it to regrow. So the cost is going to be very high, even if it's better for the environment.

Fossil fuels are a lot more convenient. It takes a lot of money to set up an oil well, sure, but then you're going to get tons and tons and tons of oil out of it with very little work, and that oil can be processed into many different fuels using refineries that we already have built and invested in. And oil companies aren't going to replace all that without a really really strong business reason.

Fossil fuels are going to run out at some point, but for now they're still cheaper and more flexible than most biofuels.