Reducing the weight and cost of hydrogen storage tanks remains one of the technological issues that engineers must overcome to make fuel cell vehicles more practical. Aside from the large metal cylinders currently used in most applications, one of the primary options has been various types of solid state storage that absorbs and then releases the hydrogen.
Source: Hydrogen storage breakthrough could come from Russian space program
A possible breakthrough may have emerged out of the Russian space program. Hydrogen and fuel cells have been used in the space program since the 1960s. This new approach, being adapted by Israeli researchers, uses tiny glass tubes to store the hydrogen. The tubes, known as capillaries, are bundled together in an array and reports say they are both strong and efficient.
Testing in Germany is claimed to have validated safety protocols, however, it remains to be seen if the capillary arrays can actually be produced cost effectively. No indication is given of the actual size of the tubes or storage density.
Swiss startup C.En is planning to license the technology to companies that will produce energy storage systems beginning in 2010. They claim the idea can be scaled from smaller consumer electronics-sized devices up to tanks that could be used in automobile.