In our reports yesterday, concerning "US Patent 4,011,153 - Liquefaction and Desulfurization of Coal using Synthesis Gas" and "United States Patent 4.040,976 - Process of Treating Carbonaceous Material with Carbon Dioxide", we documented that, in various Coal conversion and liquefaction processes, valuable Methane gas is, or can be, generated as a by-product.
Should you refer to those reports, you will see statements such as "off-gas could be ... utilized for methane production" and "reactor effluent (can be made) to react further ... to form ... methane".
Aside from the fact that Methane can be utilized to react with recovered and reclaimed Carbon Dioxide, in various "reforming" reactions, such as described best and most lately by Penn State University scientists Craig Grimes and Chunsan Song; and, by former West Virginia University graduate student Mahesh Iyer; and, made thereby to synthesize a variety of valuable liquid hydrocarbons, all as we have documented for you, Methane can, as well, again as we've documented, be utilized to great benefit in some processes of Coal conversion.