A process for producing a high-carbon biogenic reagent, said process comprising: (a) providing a carbon-containing feedstock comprising plant or plant-derived biomass; (b) drying said feedstock to remove at least a portion of moisture contained within said feedstock; (c) deaerating said feedstock to remove at least a portion of interstitial oxygen, if any, contained within said feedstock or said dried feedstock; (d) preheating said dried feedstock in a preheating zone in the presence of a substantially inert gas for from at least 5 minutes to at most 60 minutes and with a preheating temperature selected from at least 80°C to at most 500°C; (e) in a pyrolysis zone, pyrolyzing said feedstock in the presence of a substantially inert gas for from at least 10 minutes to at most 120 minutes and with a pyrolysis temperature selected from at least 250°C to at most 700°C, to generate hot pyrolyzed solids, condensable vapors, and non-condensable gases, wherein conditions for the step of pyrolyzing are selected to maintain the structural integrity or mechanical strength of said high-carbon biogenic reagent relative to said feedstock; (f) separating at least a portion of said condensable vapors and at least a portion of said non-condensable gases from said hot pyrolyzed solids; (g) in a cooling zone, cooling said hot pyrolyzed solids, in the presence of said substantially inert gas, for at least 5 minutes and with a cooling-zone temperature less than said pyrolysis temperature, to generate warm pyrolyzed solids; (h) in a cooler that is separate from said cooling zone, cooling said warm pyrolyzed solids to generate cool pyrolyzed solids; and (i) recovering a high-carbon biogenic reagent comprising at least a portion of said cool pyrolyzed solids, wherein said high-carbon biogenic reagent has an energy content of at least 25,586 kJ/kg [11,000 Btu/lb], at least 27,912 kJ/kg [12,000 Btu/lb], at least 30,238 kJ/kg [13,000 Btu/lb], at least 32,564 kJ/kg [14,000 Btu/lb], at least 33,727 kJ/kg [14,500 Btu/lb], or at least 34,192 kJ/kg [14,700 Btu/lb] on a dry basis. (a) providing a carbon-containing feedstock comprising plant or plant-derived biomass; (b) drying said feedstock to remove at least a portion of moisture contained within said feedstock; (c) deaerating said feedstock to remove at least a portion of interstitial oxygen, if any, contained within said feedstock or said dried feedstock; (d) preheating said dried feedstock in a preheating zone in the presence of a substantially inert gas for from at least 5 minutes to at most 60 minutes and with a preheating temperature selected from at least 80°C to at most 500°C; (e) in a pyrolysis zone, pyrolyzing said feedstock in the presence of a substantially inert gas for from at least 10 minutes to at most 120 minutes and with a pyrolysis temperature selected from at least 250°C to at most 700°C, to generate hot pyrolyzed solids, condensable vapors, and non-condensable gases, wherein conditions for the step of pyrolyzing are selected to maintain the structural integrity or mechanical strength of said high-carbon biogenic reagent relative to said feedstock; (f) separating at least a portion of said condensable vapors and at least a portion of said non-condensable gases from said hot pyrolyzed solids; (g) in a cooling zone, cooling said hot pyrolyzed solids, in the presence of said substantially inert gas, for at least 5 minutes and with a cooling-zone temperature less than said pyrolysis temperature, to generate warm pyrolyzed solids; (h) in a cooler that is separate from said cooling zone, cooling said warm pyrolyzed solids to generate cool pyrolyzed solids; and (i) recovering a high-carbon biogenic reagent comprising at least a portion of said cool pyrolyzed solids, wherein said high-carbon biogenic reagent has an energy content of at least 25,586 kJ/kg [11,000 Btu/lb], at least 27,912 kJ/kg [12,000 Btu/lb], at least 30,238 kJ/kg [13,000 Btu/lb], at least 32,564 kJ/kg [14,000 Btu/lb], at least 33,727 kJ/kg [14,500 Btu/lb], or at least 34,192 kJ/kg [14,700 Btu/lb] on a dry basis.