The trouble is that these hydrocarbon will just be burned like all others, causing GHG release.
If you want something actually green, try ammonia via electrochemical methods, from hydrogen.
This is also why these gas investments are a trap. We're already generally low on gas for winter and increasing the intake will not help, plus any operational emissions is too much and has to be optimized. 270 g CO2e is a plenty in a series of small deployments to ruin the targets.
If methane is manufactured from CO₂ and H₂O, there is no net GHG release, it's just storage, same as ammonia or pure hydrogen (though large methane leaks would be a problem).
IMO, methane is good, if we are actively transitioning to manufactured methane. It's a plug-in substitute with existing distribution networks, storage and consumers, easy and cheap to handle. Though efficiency is pretty bad, so it's mostly good as cheap bulk storage.
Methane is not manufactured from straight gases. Usually it is either mined or steam reformed from oil or coal. You can see the problem - mining with concomitant pollution and release of previously bound CO2 when it's burned.
Attempting to do pure electrochemical reforming is extremely energy intensive, and requires rare metal membranes. As well as a way to concentrate CO2 from atmosphere reliably. (The Sleipnir problem.)
I am well aware methane is not currently generated from CO₂, as we are still using fossil fuels, not generating enough surplus energy to make the reverse process economical.
Do you have any numbers on synthesis energy efficiency? It is inherently energy intensive, as it is storing energy. Rare metal membranes may be current state of the art, but Nickel catalysts seem a popular alternative.
If you want something actually green, try ammonia via electrochemical methods, from hydrogen.
This is also why these gas investments are a trap. We're already generally low on gas for winter and increasing the intake will not help, plus any operational emissions is too much and has to be optimized. 270 g CO2e is a plenty in a series of small deployments to ruin the targets.