He projected that world oil production would peak at about 12.5 billion barrels per year , sometime around the year 2000 .
In 1956 , Hubbert calculated that the world held an ultimate cumulative of 1.25 trillion barrels , of which 124 billion had already been produced .
Hubbert projected that world oil production would peak at about 12.5 billion barrels per year , sometime around the year 2000 .
In 1956 , Hubbert calculated that the world held an ultimate cumulative of 1.25 trillion barrels , of which 124 billion had already been produced .