Getting energy from Hydrogen
There are two ways you can use hydrogen as a fuel- by burning it in an engine or by using it in a fuel cell...
Hydrogen and Oxygen give out energy when they react
1) Hydrogen and oxygen react to produce water- which isn't pollutant
2) The reaction between hydrogen and oxygen is exothermic- it releases energy
3) Put these two facts together and you get something useful: You get energy by reacting hydrogen and oxygen- either in a combustion engine or in a fuel cell.
Hydrogen gas can be burnt to power vehicles
1) Hydorgen gas can be burnt in oxygen as a fuel in the combustion engines of vehicles.
2) Pros: Hydrogen combines with Oxygen in the air to form just water- so it's very clean.
hydrogen + oxygen -> water
3) Cons: You need a special, expensive engine. Although hydrogen can be made from water, which there's plenty of, you still need to use energy from another source to make it. Also hydrogen's hard to store safely- it's very explosive.