[csl]

The BFR runs on a mix of liquid oxygen and methane, according to Wikipedia.

Ignoring obvious scalability problems, wouldn’t it be possible to manufacture that with a pretty decent environmental footprint from various carbon neutral bio sources?

[wcoenen]

SpaceX plans to refuel the BFR on Mars with methane and oxygen produced via the Sabatier process and electrolysis [1]. They might do the same thing on Earth, even if only for the bragging rights of being carbon neutral.

[1] https://en.wikipedia.org/wiki/Sabatier_reaction#Manufacturin...