NOVELTY - Making an activated carbon adsorbent having a predetermined pore size distribution and surface area, comprises (a) contacting (110) a char (C) with potassium hydroxide (KOH) at an activation temperature of 700-900 degrees C for 1 hour and a KOH:C ratio of 2-4.5, where the activated carbon adsorbent has a total pore volume of at least 1.0 cc/g and a Brunauer, Emmett and Teller (BET) surface area of at least 2000 m2/g if the KOH:C ratio is at least 3.    USE - The method is useful for making an activated carbon adsorbent having a predetermined pore size distribution and surface area, where the activated carbon adsorbent is useful for storing methane composition (all claimed), liquid cleanup, gas cleanup and other gas storage in fuel tanks of hydrogen-powered and natural-gas-powered vehicles, batteries, electrical capacitors, separation and purification devices, catalysts, molecular sieve devices, water treatment devices, catalyst supports, and ion exchange materials such as chromatography media, and as a gas adsorbent material, and the gas includes hydrogen and acetylene.    ADVANTAGE - The method is capable of making the briquetted form activated carbon adsorbent with predetermined pore size distribution, enhanced electrical conductivity and high surface area and adsorption properties.    DETAILED DESCRIPTION - Making an activated carbon adsorbent having a predetermined pore size distribution and surface area, comprises: either (a) contacting (110) a char (C) with potassium hydroxide (KOH) at an activation temperature of 700-900 degrees C for 1 hour and a KOH:C ratio of 2-4.5, where the activated carbon adsorbent has a total pore volume of at least 1.0 cc/g and a Brunauer, Emmett and Teller (BET) surface area of at least 2000 m2/g if the KOH:C ratio is at least 3; or providing (102) a char comprising an acid-activated, charred biomass feedstock, and the step (a) as above per se; or soaking (104) a biomass feedstock in phosphoric acid at 45 degrees C for 12 hours to form an acid-activated feedstock, washing (106) the acid-activated feedstock to adjust the pH of the acid-activated feedstock to 7, charring (108) the washed acid-activated feedstock at 480 degrees C under a nitrogen atmosphere to form a char, and the step (a) as above per se. INDEPENDENT CLAIMS are included for:    (1) a pre-mixed feedstock for producing the activated carbon adsorbent having a predetermined pore size distribution and surface area, comprising KOH flakes or solution and char at a KOH:C ratio of 2-4.5; and    (2) a stored methane composition comprising methane adsorbed to an activated methane adsorbent, where the methane is adsorbed at room temperature and a pressure of 35 bar, and the amount of methane adsorbed is 130 g or 200 g of methane for each kg of activated carbon adsorbent.    DESCRIPTION OF DRAWING(S) - The figure shows a flowchart of making an activated carbon adsorbent.    Providing a char comprising an acid-activated, charred biomass feedstock (102)    Soaking a biomass feedstock in phosphoric acid (104)    Washing the acid-activated feedstock to adjust the pH of the acid-activated feedstock (106)    Charring the washed acid-activated feedstock under a nitrogen atmosphere to form a char (108)    Contacting the char with potassium hydroxide. (110)