As should, by now, be apparent from all of our posts, the conversion of both Coal and Carbon Dioxide into hydrocarbons, into substances which can serve as Synthetic Petroleum and Substitute Natural Gas, as the products of such conversions are frequently labeled, requires that Hydrogen be somehow added to and combined with the Carbon that Coal and CO2 bring to the party.
That can in some cases be accomplished indirectly, as when Steam, H2O, is utilized in the gasification of Coal, as, for just one example, rather plainly stated in:
Texaco 1950 Coal + Steam = Hydrocarbon Syngas | Research & Development; which concerns: "United States Patent 2,516,974 - Gasifying Carbonaceous Material; 1950; Assignee: Texaco Development Corporation; The present invention relates to gasification of solid fuels and is more particularly concerned with the conversion of carbonaceous materials into a gaseous product ... composed primarily of carbon monoxide and hydrogen ... (which are) ... produced by the reaction of water vapor with carbon".