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This work shows how knowledge of any biomass and choice of carbonisation process can offer a generalised route to predictability in the preparation of activated biocarbons. We demonstrate that based on O/C ratio of carbonaceous matter, it is possible to predictably generate biocarbons with suitable porosity, surface area density, volumetric surface area and packing density targeted towards record levels of CO2 and CH4 storage capacity. Highly porous carbons with controlled levels of microporosity of up to 97% of the surface area and 92% of the pore volume are generated. The level of synthetic control is such that it enables, on the one hand, exceptional CO2 storage at 25 °C and low pressure (1.5 and 5.4 mmol g−1 at 0.15 and 1 bar, respectively) or moderate pressure (23.7 mmol g−1 at 20 bar), indicating superior uptake under both post-combustion and pre-combustion CO2 capture conditions. The carbons may also be directed towards storing record levels of methane; at 25 °C and 100 bar, volumetric methane uptake of between 309 and 334 cm3 (STP) cm−3 was obtained, which values are considerably higher than all current benchmark materials and, moreover, surpass the United States Department of Energy (US DOE) target of 263 cm3 (STP) cm−3. Crucially, the carbons also have very attractive working capacity (deliverable methane for 100–5 bar) of 262 cm3 (STP) cm−3, 234 cm3 (STP) cm−3 (80–5 bar), and 210 cm3 (STP) cm−3 (65–5 bar).
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