The Availability of Fusion Power

Now that we know that fusion is a relatively powerful energy source, the next question naturally is "Are there enough resources for mankind's use? Or, like coal and natural gas, will supplies of tritium and deuterium eventually be depleted?"

Fortunately for the future of fusion power, tritium and deuterium are virtually inexhaustible resources. There is 1 deuterium atom in every 6500 hydrogen atoms in ordinary seawater. Tritium, the other reactant, can be bred from lithium, an element common in the earth's crust.

Thus, theoretically, humans can continue to utilize fusion power indefinitely. After all, the amount of seawater on earth is practically unlimited.