For those that don't know natural gas is a think tank tested way to brand methane. Natural gas is methane. They are the same thing. When you hear natural gas think "methane" because that is what natural gas is. For some reason "natural" makes you think it's a perfectly fine and good thing, but that's just good ol' propaganda that you believed because you didn't know any better.
Petroleum is also "natural". It forms naturally, in nature, all by itself, and it combusts if you light it on fire. It's so natural we can't make it ourselves that's why we drill wells several miles down and then inject compressed fluids at insane pressure to fracture the rock formations that natural petroleum is trapped in.
The problem is that methane is significantly worse than CO2 as a greenhouse gas, and if you burn methane, it breaks down into CO2. So when you hear "Clean burning natural gas" you are being spoon fed bullshit. It's not clean burning, it's lighting methane on fire to produce the same greenhouse gas they want you to think they're cutting down on.