The oil reserves in the world may be limited, but they are not nearly as limited as corporations and governments want you to think.
Yes. That is the easy answer. But, try to find out just when we will run out, how much oil the major producers have in reality, what gas prices will look like as oil production begins the downhill slide, and what can possibly be done to ease the effects of potential crisis, and websites point you toward a whole bunch of theories with a minimum of pertinent information. The problem with answering an Armageddon-like question is that every person has a stake in oil, regardless of where they live. This means that every person is going to give an answer that they believe is in their best interest to give. But, the players with the biggest self-interest in promoting the stability of oil are threefold: oil companies (names like Exxon-Mobil net more profit than many other corporations in the world put together), oil producing countries, and oil consuming countries. While it is highly unlikely that a transition from oil will devolve the world back into an episode like the Mel Gibson Mad Max series, a change will happen. The peacefulness of that transition is up to the major players.
Why oil? Where did it come from, and why is it such a prevalent form of propulsion? Daniel Yergin's award-winning book, "The Prize," which was transcribed into a miniature television series, provides an extremely readable over-1,000 page analysis of the legacy. The short answer, which can be gleaned from the text, is that oil has an extremely high energy density. Compared to coal, oil has about one-third higher amount of energy released than coal (through the refining process, gasoline and diesel fuel gain some energy density). In addition, oil and gasoline exist in liquid form, which is much more conducive to combustion than chunks of coal. The reason for this increased energy density has to do with the origin of the materials. Coal came from plants, while oil came from animal matter. The types of animals that form oil are called diatoms, forminefera, and radiolaria. All of these are microscopic ocean life forms that break down over extremely long periods of time into crude oil. The end result is that the oil pools into underground formations, and exploring for oil is quite expensive (wildcatting or drilling exploration equipment comes at a premium for tough conditions like the North Sea). The end result is that oil can release more energy during combustion than coal, can be stored more easily, and can be removed from the ground much easier and more cheaply than coal. When faced with these same characteristics and choices, Winston Churchill made the decision to convert the entire British navy to oil, even though Britain had no oil and an abundance of coal! Essentially, the same advantages exist for using oil as the same base fuel for our automobiles.
So, oil is our fuel of choice. When will it run out? Oil predictions can easily fall into end of the world scenario categories, so it's important to sort through the rhetoric and mine out the nuggets of truth. If you don't sort through the garbage, then simple mathematics can lead you to some pretty disturbing conclusions. For example, the Energy Information Administration puts out proven oil reserve figures for the entire world from a variety of sources (available below, first link). These statistics indicate that the world's proven oil reserves are somewhere between 1.184 trillion and 1.342 trillion barrels of oil. The same website also cites the 2008 statistic of 85.4 million barrels as the world's daily usage of oil. Some simple division indicates that the proven oil reserves will last as many as 43 years or as few as 38 years, if and only if consumption remains at that constant, which will not happen. The entrance of Asia (particularly China and India) into the consumer market means that consumption will rise dramatically.
This type of speculation has led to a number of books and articles which proclaim that the sky is falling in one fashion or another. It isn't. It's important to realize that proven reserves are merely the statistics published by various governments for the sake of investor confidence and so forth. Remembering that each player has its own agenda, most governments are likely to short their proven reserves in an attempt to make other countries overproduce and run out first. The problem with listening to these projections is that oil equals geopolitical power in the global economy, which means that governments are playing a gigantic game of oily chess. Nobody can afford a checkmate, so nobody is going to publish an accurate presentation of the reserves that they know actually exist.
Yet, magnanimous breaths of fresh air do exist. I've been researching this topic for some years now, and the article in the final link below by Bill Kovarik is one of the first I have read that does some justice to balance the equation. Kovarik uses U.S. Geological Survey data to indicate that just about double of the proven reserves of the world is actually available and recoverable using current techniques. Geological organizations also indicate that there is perhaps almost the same amount of oil available as unconventional reserves, which includes tar sands and shale oil. Expanding calculations to include this new information means that we have perhaps 80-140 or more years of oil left.
Once again, however, some balance must be applied to this data. First, technologies will advance remarkably in the next 80-140 years, and the ability to locate and recover oil (as well as the rate at which we use it) will increase dramatically. This is something that even the USGS reports, which contain considerably less bias, cannot truly anticipate. Also important is that the more oil we drain, the more difficult it will be to utilize remaining reserves. Unconventional reserves do not have the same energy payoff as the currently utilized reserves. For example, shale oil must be crushed and heated out of the rock in order to retrieve it. This is an energy intensive process. What this means for consumers is that, as we are forced to harness more unconventional forms of oil, prices will rise above the curve of inflation.
Each generation tries to predict what the next will look like, but in truth, it's difficult to say just what life will be like in 100 years. Undoubtedly, there will still be some oil left, but the technologies currently being pursued (such as electric cars, solar, nuclear fusion, and various others) will lead to enough viable alternatives in order to eventually surpass the competitiveness of oil. Perhaps, consumer economics will dictate that as oil becomes rarer, the price of the product will simply lure consumers (and the industrial research their money funds) to other forms of propulsion.
Yergin, Daniel. The Prize: The Epic Quest for Oil, Money, and Power. New York: Simon & Schuster, 1991.