How does hydrogen compare to gasoline?

Hydrogen is the simplest known element, but its energy content is the highest per unit of weight of any fuel (52,000 BTUs/pound). Hydrogen is less flammable than gasoline. Hydrogen disperses quickly. Being the lightest element (fifteen times lighter than air), hydrogen rises and spreads out quickly in the atmosphere. So when a leak occurs, the hydrogen gas quickly becomes so sparse that it is difficult to ignite.