Suppose the world originally had three trillion (3. x 10¹²) barrels of oil and its exploration began in 1850. Suppose 10.0% of the remaining undiscovered oil has been found in every quarter century since 1850. Call the discovered but not yet consumed oil, reserves. Suppose oil consumption was 1.0 x 10⁸ barrels in 1850, and further suppose oil consumption has grown by a factor of 5 in every quarter-century since 1850. When will the oil start to run out? (That is, when will the reserves become negative?) Give your answer to the nearest 25 years and provide a spreadsheet showing reserves and consumption as a factor.

This is a model of supply and demand for oil. It looks at the amount of available oil and its rate of consumption to draw conclusions about continuing the current course of our oil-based economy.