A storage tank for pressurized gas includes a liner defining an interior cavity for storing the pressurized gas. The storage tank further includes a nanoporous carbon shell formed from at least one pyrolyzed polymer. The liner is disposed at an inner side of the nanoporous carbon shell. The storage tank further includes a carbon fiber reinforced polymer layer disposed on an outer side of the nanoporous carbon shell opposite from the liner. The nanoporous carbon shell has an exposed surface at an exterior of the storage tank and is configured to permit gas permeated through the liner from the interior cavity to diffuse through the nanoporous carbon shell to the exposed surface.