Adsorbent pellets coated with an outer nano-porous layer can be loaded with gas at loading pressures of 250 bar or greater, enabling a much higher loading than can be achieved at low pressures. The nano-porous layer provides nano-valves which can be sealed with an adsorbate such as ethanol or a hydrocarbon to close the nano-valves. The closed nano-valves maintain the high loading pressure inside the adsorbent pellets, and thus maintain the gas loading, during storage of the loaded nano-valved adsorbent pellets at much lower pressure. To release the gas, the nano-porous layer can be heated to a temperature sufficient to vaporize the adsorbate and open the nano-valves.