That’s nonsensical, because you burn the methane and put the carbon right back into the atmosphere. It didn’t clean anything. It’s merely a carbon neutral form of chemical energy. H2, ammonia, methanol would be just as carbon neutral.
Well, it's there in the title of the article, so don't shoot me. If the premise of the article is bs, it doesn't make sense to discuss efficiency.
Is it nonsensical though? IDK, it seems somehow better than extracting the gas from the ground and adding it to the system. Also if there's another more complex chemical not for burning, that you can synthesize from the methane, it would be a net gain.