Oil supplies
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Crude oil is a finite resource. It is estimated that there is a total of 2,390 billion barrels (380 km³) of crude oil on Earth. Estimates of undiscovered reserves range widely from 275 to 1,469 billion barrels (44 to 234 km³).
Between 1859 and 1968, 200 billion barrels (31 km³) of oil were used, and since then oil production has stabilized at 22 billion barrels (3.5 km³) per year. In 2004, as prices reach record highs, world consumption is on track to 30 billion barrels per year.
It is believed that about 77% of crude oil has already been discovered, and 30% of it has been used so far. Current estimates are that oil reserves will become scarce by the 2050s, although this date has been pushed forward many times as new oil wells are discovered.
However, the above numbers must be treated carefully as they include only reserves that are economically recoverable at present. They do not include tar sands and bitumen, nor do they take into account possible coal derived production. Old car tires, junkyard plastics, and crumbling asphalt roads can be melted down and oil recycled. Although these processes are not currently economical, they could be used to produce significant quantities of hydrocarbons in the future, and they may become important as crude oil production dwindles, or if new technology makes them easier to exploit.
Most known reserves are concentrated in the Near East — around 41%. North America, Russia, and Antarctica are also rich in crude oil.
As all the oil on earth is used up, a vast number of oil-derived products will have to find alternative methods of production, including gasoline, lubricating oils, plastics, tires, roads, synthetic fabrics, etc. Science has already found many alternatives to all these products, but in most cases the oil-derived method is still cheaper.
Saudi national oil company, Saudi Aramco, controls the largest amount of proven oil reserves in the world.