TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Apparatus: One or more of the heat sources comprise at least two heat sources, where heat is superposed to pyrolyze some coal in the formation. The heat sources comprise electrical heaters, surface burners, flameless distributed combustors or natural distributed combustors. Pressure and temperature within the formation are controlled as a function of either properties. A valve is coupled to the heat sources or to the production well, to control the pressure. Heat is controlled at an average rate of less than 1degreesC/day during pyrolysis.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: A selected volume (V) of the coal formation is heated by the heat sources, where the formation has an average heat capacity (Cv). The heating energy/day provided to the volume is upto Pwr which is given as: Pwr = hasteriskVasteriskCvasteriskrhoB, where Pwr is heating energy/day, h is average heating rate of formation and rhoB is formation bulk density. Heating rate is less than 10degreesC/day.Heat transfer is performed by conduction and thermal conductivity of the selective portion is greater than 0.5 W/(mdegreesC). The controlled pressure is at least 2 bar absolute. The pressure within the formation is altered to inhibit production of hydrocarbons with carbon number greater than 25. Pyrolysis temperature is 27degreesC. Heat transfer involves increasing the permeability of a majority of selected portion to greater than 100 millidarcy.Preferred Composition: The produced mixture comprises condensable hydrocarbons (CHC) or non-condensable hydrocarbons (Non-CHC) with molar ratio of ethene to ethane of 0.001-0.15. The hydrocarbons comprise 0.1-15 wt.% olefins. CHC is nitrogen, oxygen, oxygen containing compounds optionally with phenols, sulfur, aromatic compound, multi-ring aromatics with more than two rings, asphaltenes or cycloalkanes. Non-CHC is hydrogen. The mixture also comprises more than 0.05 wt.% ammonia. At least a portion of the hydrogen contained in the mixture is recirculated into the formation. Heat is controlled to yield greater than 60 wt.% of CHC, measured by Fischer Assay. The produced mixture is separated into a gas stream and a liquid stream. Hydrogen sulfide and carbon dioxide produced from the mixture are separated.