Musk has stated it's SpaceX intention to create methane from the CO2 in the air, powered by solar panels. (Basically the same technology they want to use on Mar

Musk has stated it's SpaceX intention to create methane from the CO2 in the air, powered by solar panels. (Basically the same technology they want to use on Mars to produce the return trip propellant) Burning the methane will of course release CO2 back into the atmosphere, but if they indeed make the methane by pulling CO2 from the air, it would effectively make Starship (the fuel anyway) carbon neutral. (I guess actually it's a bit carbon negative because some of the engine burn will happen in space).