The schedule of conditions of the portable systems of energy production becomes increasingly constraining. Indeed, the new sources of energy must face an increase in the electric consumption of these devices and satisfy the tendency of miniaturization of the systems. In this context, the fuel cell represents a serious alternative to the batteries whose performances (150 to 200 Wh/kg) do not seem to be able to follow the evolution of this energy demand. 
Figure 1a: nano-powder of So porous hydrogenated 1b:morphology of powder on nanoscale
The fuel cell with hydrogen associated with a hydrogen tank offers on its side of the mass and voluminal performances very interesting making it possible right now to consider its integration in portable electrical appliance. Systems containing metal hydrides coupled to a planar portable fuel cell standard PaxiTech make it possible right now to reach energy densities similar to those of the best batteries (160 to 180 Wh/kg).
The only barrier to their marketing resides in the distribution and the storage of hydrogen. Today, the possible solutions for the fuel supply on a large scale are compressed hydrogen tanks with high pressure rather intended for the applications of strong powers, or having to store much energy, tanks of metal hydrides presenting of good voluminal performances, or a system containing chemical hydrides whose potential in term of energy is most promising.
Researchers of Institute of the Nanotechnologies of Lyon (INL, CNRS-ST2I, UMR-5270, site INSA) work out a new ecological source of hydrogen containing nanostructures of So porous (in a state of powder - to see Figure 1-a) strongly hydrogenated (SiHX, with x→2). These nanostructures can be obtained during chemical or electrochemical dissolution crystalline silicon. The morphology of this material on a nanoscopic scale is presented on the Figure 1-b. One can notice the many nanocrystals one inter-connected (of size 1-3 Nm) which constitutes the powder. In these nanocrystal,, all atoms of If are chemically dependent with at least a hydrogen atom.
Hydrogen can be produced, either by heating of the nano-powder, or by its simple treatment with an aqueous solution at ambient temperature and the atmospheric pressure.
The INL in collaboration with the company PaxiTech carried out a demonstration of the operation of a fuel cell intended to feed from the portable devices by using an experimental cartridge containing the hydrogenated nano-powder of If (Figure 2)
Figure-2 : 1.Produced Hydrogen 2. supplies a fuel cell of PaxiTech 3. crushes it itself supplies a head light portable .
This first experimentation showed that energy densities of about 500 to 600 Wh/kg could be reached by such systems based on this hydrogenated porous silicon nano-powder.
Collaboration between the INL and PaxiTech should make it possible in the next years to reach energy densities even higher.
