there are several types of fuel cells.
the most mature one is proton exchange membrane fuel cell (PEM)
the difficulties right now are at several parts:
1. hydrogen storage
2. membrane design
3. catalyst
How to reduce the price of fuel cell is most concern.
1. The most advance materials for hydrogen storage materials.
metal hydride nanoparticle: 5% mass amount
carbon nanotubes: (suspected) 8%
high pressure tank with polymer inside wall above 200 bar.
target is 6.5%
another proposal
