NOVELTY - Composition comprises a processed biogas composition that is renewable and comprises a gaseous carbon fuel made from biomass and with characteristics that include an energy density of at least 700 British thermal unit (BTU)/cubic ft (26 MJ/cubic meter), a carbon monoxide concentration of less than 20 vol.%, and a carbon dioxide concentration of less than 15 vol.%.    USE - The composition is useful for preparing organic-carbon-containing feedstock as biogas, i.e. gaseous renewable fuel or natural gas substitute.    ADVANTAGE - The processed biogas is a suitable renewable natural gas substitute for devices that use natural gas as a feedstock to generate heat or electricity such as, for example, furnaces and natural gas fired household devices. The low salt content of the processed organic-carbon-containing feedstock into the oxygen-deficient thermal sub-system substantially reduces adverse side reactions that may produce higher carbon monoxide and carbon dioxide concentrations in the resulting processed biogas. This makes the biogas from renewable feedstock a suitable substitute for natural gas, a material that is getting more expensive to acquire in both monetary and environmental cost. During the beneficiation section of the process, the substantial reduction of water-soluble salts reduces the adverse results that occur with the subsequent use of the processed organic-carbon-containing feedstock. In addition, energy needed to remove water from unprocessed organic-carbon-containing feedstock to a content of below 20 wt.% and a substantial amount of the water-soluble salt is significantly less than for conventional processes. The total cost per weight of the beneficiated feedstock is reduced by at least 60% of the cost to perform a similar task with known mechanical, physiochemical, or thermal processes to prepare renewable organic-carbon-containing feedstock for use in subsequent fuel making operations such as an oxygen-deficient thermal sub-system. The processed biogas has the advantages of coming from a renewable source, i.e., agricultural and plant materials, without the burdens of current biomass processes that are inefficient and result in gases having an unsatisfactorily low energy density and high concentration of carbon monoxide and carbon dioxide.    DETAILED DESCRIPTION - Composition comprises a processed biogas composition that is renewable and comprises a gaseous carbon fuel made from biomass and with characteristics that include an energy density of at least 700 British thermal unit (BTU)/cubic ft. (26 megajoules (MJ)/cubic meter), a carbon monoxide concentration of less than 20 vol.%, and a carbon dioxide concentration of less than 15 vol.%. The processed biogas is made from unprocessed organic-carbon-containing feedstock that is converted into the processed organic-carbon-containing feedstock with a beneficiation sub-system, and to the processed biogas with an oxygen-deficient thermal sub-system. An INDEPENDENT CLAIM is included for a process of making processed biogas, a gaseous fuel, composition, which involves: (a) inputting into a system comprising a first and a second subsystem an unprocessed organic-carbon-containing feedstock that is renewable and includes free water, intercellular water, intracellular water, intracellular water-soluble salts, and at least some plant cells comprising cell walls that include lignin, hemicellulose, and microfibrils within fibrils; (b) passing unprocessed organic-carbon-containing feedstock through the first sub-system, a beneficiation sub-system process, to result in processed organic-carbon-containing feedstock having a water content of less than 20 wt.% and a salt content that is reduced by at least 60 wt.% on a dry basis from that of the unprocessed organic-carbon-containing feedstock; and (c) passing the processed organic-carbon-containing feedstock through the second sub-system, an oxygen-deprived thermal sub-system process, to result in processed biogas, a gaseous fuel composition having an energy density of at least 700 BTU/cubic ft (26 MJ/cubic meter), a carbon monoxide concentration of less than 20 vol.%, and a carbon dioxide concentration of less than 15 vol.%.