NOVELTY - Treating a coal formation in situ comprises providing heat from at least one heat source to at least one portion of the formation. Heat is allowed to transfer from the source(s) to a selected section of the formation. The heat from the heat source(s) is controlled so that the average temperature within the majority of the selected section of the formation is less than about 375degreesC.    USE - Used for treating a coal formation in situ to produce hydrocarbons, hydrogen, formation fluids and/or novel product streams.    ADVANTAGE - The temperature and pressure in at least a portion of the formation is controlled during pyrolysis to yield improved products from the formation. The steam produced is removed from the formation and is utilized for various purposes, such as heating another portion of the formation, generating synthesis gas in an adjacent portion of the formation, generating electricity and/or as a steam flood in an oil reservoir. The energy input cost is reduced by heating a portion of coal formation by oxidation in combination with heating the portion of the formation by an electric heater, so that a more economical process is provided for heating a coal formation. The oxidation reaction is propagated slowly through a greater portion of the formation such that fewer heat sources are required to heat a great portion of the coal formation. By maintaining a portion of the formation in an unheated condition, structural strength is provided to the formation.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) treating a layer of coal formation in situ;    (2) an in situ process for heating a coal formation;    (3) an in situ process for producing hydrogen from a coal formation;    (4) installing a heater well into a coal formation;    (5) a system configured to heat a coal formation;    (6) a mixture produced from a portion of a coal formation;    (7) a condensable mixture produced from a portion of a coal formation;    (8) the in situ production of synthesis gas from a coal formation;    (9) forming a spent portion or formation within a coal formation;    (10) sequestering carbon dioxide within a coal formation;    (11) the in situ production of energy from a coal formation;    (12) producing ammonia using a coal formation, and    (13) treating hydrocarbons in at least a portion of a coal formation.