At present there are two leading prospects for ‘alternative’ vehicle fuels to replace oil-based fuels: hydrogen and electrical batteries. The attractions of hydrogen as a fuel are several-fold.

• It is super-abundant, present in the air and an element in numerous other materials, notably water
• It reacts exothermically without the presence of oxygen
• It can be stored fairly easily for long periods of time
• It has a very high weight-to-energy ratio
• Although ‘flammable’ in the presence of oxygen or air, its low density at ambient temperatures means that it is less hazardous than gasoline
• It is not a carbon-based fuel.

Some of the problems:

• Although it is abundant, it is hard to isolate. Doing so requires energy
• At ambient temperatures it is a low-density gas. Compressing it requires energy
• It reacts with a number of other materials, which complicates handling.

When considering hydrogen as a fuel for vehicles, these strengths and weaknesses shape the attractiveness of hydrogen as a viable option.