Methane comparison to CO2 and Coal

If you comparing making electricity from "clean burning" NG vs from coal,
it turns out that Methane (NG) is AT LEAST 1.2x (20%) worse than coal
and may be up to 2x (100%) worse at the 20 year time horizon. (Howarth),

This is because NG production and transmission is a notoriously leaky process.
Not all methane is burned.  Lots is lost due to various
vectors for fugitive emissions (venting though faults,  well casing failures,
pipeline leaks, blowdowns, etc.).

Methane, a potent greenhouse gas, is > 20 times more powerful than
carbon dioxide at trapping heat. (Steingraber)

Considering all factors,  raw methane when leaked into the atmosphere
is 105 times greater impacts of that of CO2.