> [2] http://www.helmeth.eu/images/joomlaplates/documents/Publisha...

I've been seen exactly this link thrown at me multiple times when discussing synthetic methane, yet it comes with a fatal flaw: It doesn't consider the process to get the CO2 in the first place.

If this is supposed to produce (close to) climate neutral methane it needs to include Direct Air Capture to gather the CO2. It also needs almost perfect avoidance of methane leaks.

Luckily none of that matters very much: Most people agree that synthetic methane isn't very useful to begin with. We can do storage and many industry applications (like steel) simply with hydrogen and avoid the whole CO2 handling and the methane handling, and the few applications that absolutely need methane can be done with biogas.