I always have the same question:
Where does the hydrogen come from?
I know the answer...just like to remind everyone that you don’t just pump hydrogen out of the ground.
Unicorns fart pure hydrogen ...
From the hydrogen tree, silly.
It grows on trees, crazy fast...
I have a fuel-cell powered toy car, bought it at a huge discount (about $12 instead of $150). It uses a catalyst to convert hydrogen and oxygen into electricity to power an electric motor to propel the car, and creates water as a by-product. A solar panel will generate the electricity necessary to convert the water into hydrogen and oxygen and stores it ready for the car to use again. Alternatively, a battery will provide the electricity to "create" the hydrogen. An external electricity source can also be used.
The toy car is just that, a toy that demonstrates fuel-cells. However, I found the process very wasteful. Much power was wasted creating a small amount of hydrogen. The electricity used to create the hydrogen, would have been better used to directly power the electric motor instead of being wasted creating the hydrogen.
Obviously, with this toy car the hydrogen is not being burned in a combustion process as with a normal car. Just wanted to point out that hydrogen can be split from water via electricity and a catalyst.