A method of making a fuel, the method comprising: shearing a fiber source to provide a first fibrous material; passing the first fibrous material through a first screen having an average opening size of about 1.59 mm or less (1/16 inch, 0.0625 inch) to provide a second fibrous material; wherein the method comprises shearing the second fibrous material, and passing the resulting fibrous material through the first screen or through a second screen having an average opening size less than the first screen; and combining the resulting fibrous material with a bacterium and/or enzyme, the bacterium and/or enzyme utilizing the resulting fibrous material to produce a fuel comprising hydrogen, an alcohol, an organic acid and/or a hydrocarbon, preferably wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, 1,4-butane diol, glycerin, and mixtures thereof, or wherein the organic acid is selected from the group consisting of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, palmitic acid, stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, oleic acid, linoleic acid, glycolic acid, lactic acid, γ-hydroxybutyric acid and mixtures thereof, or wherein the hydrocarbon is selected from the group consisting of methane, ethane, propane, isobutene, pentane, n-hexane, and mixtures thereof, or wherein the second fibrous material has a BET surface area of greater than about 0.25 m 2 /g, or wherein the second fibrous material has a BET surface area of greater than about 1.25 m 2 /g, or wherein the second fibrous material has a porosity of greater than about 85 percent. shearing a fiber source to provide a first fibrous material; passing the first fibrous material through a first screen having an average opening size of about 1.59 mm or less (1/16 inch, 0.0625 inch) to provide a second fibrous material; wherein the method comprises shearing the second fibrous material, and passing the resulting fibrous material through the first screen or through a second screen having an average opening size less than the first screen; and combining the resulting fibrous material with a bacterium and/or enzyme, the bacterium and/or enzyme utilizing the resulting fibrous material to produce a fuel comprising hydrogen, an alcohol, an organic acid and/or a hydrocarbon, preferably wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, 1,4-butane diol, glycerin, and mixtures thereof, or wherein the organic acid is selected from the group consisting of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, palmitic acid, stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, oleic acid, linoleic acid, glycolic acid, lactic acid, γ-hydroxybutyric acid and mixtures thereof, or wherein the hydrocarbon is selected from the group consisting of methane, ethane, propane, isobutene, pentane, n-hexane, and mixtures thereof, or wherein the second fibrous material has a BET surface area of greater than about 0.25 m 2 /g, or wherein the second fibrous material has a BET surface area of greater than about 1.25 m 2 /g, or wherein the second fibrous material has a porosity of greater than about 85 percent.