Hydrogen storage[edit]
SWNT's capillary effects can be used to condense gases to high density. This allows for gases, most notably hydrogen (H
2), to be stored at high densities without condensation into liquid form. Potentially, this method could support a hydrogen-powered car. Current storage methods involve liquifying the gas, which costs 25–45% of the potential energy. SWNT storage yields a volume to energy ratio slightly smaller than that of gasoline, allowing comparable range.[42]
An area of controversy and frequent experimentation regarding the storage of hydrogen by adsorption in carbon nanotubes is the efficiency by which this process occurs. The effectiveness of hydrogen storage is integral to its use as a primary fuel source since hydrogen only contains about one fourth the energy per unit volume as gasoline.