Description and History
No fossil fuel commands more headlines than oil, petroleum. Petroleum is a fossil fuel consisting of a mixture of carbon compounds (hydrocarbons). Components vary by location and range from very lightweight (including natural gas) to heavy (such as tar).
Petroleum seeps up from the ground in places. These natural oil wells were used in ancient times as fuel sources and otherwise. For example, tar is useful for coating wood and rope. Medieval distillation in the early days of chemistry produced kerosene, a favorite lamp fuel for centuries thereafter.
Petroleum reserves are distributed very unevenly, which has resulted in great wealth flowing to just a few countries, Saudi Arabia in particular. As these reserves are consumed, wealth will shift again. Petroleum will continue to command political attention and headlines.
Mining and Production
Petroleum is a liquid usually found by geological investigation to occur in pockets within layers of rock. Petroleum is typically under pressure; drilling a vertical hole for a pipe causes the petroleum to emerge naturally. Pumping and water injection are required for further extraction as the pressure eases.
Crude petroleum is sent by pipeline or tanker to a refinery, where it is separated by distillation into its various hydrocarbon components. Petroleum from each oil field has a different composition, which may include linear hydrocarbons, aromatics, and more complex molecules containing nitrogen, sulfur, and almost anything else.
This petroleum content is a great deal more varied than what is commercially interesting. Thus, refineries do some significant organic chemistry to process various distillation fractions into octane gasoline, jet fuel, and other interesting final products.
Properties and Uses
Since petroleum is a mixture of substances, it has a mixture of uses. The largest category of resulting product is the fuels that power vehicles and furnaces. Other organics from petroleum are the inputs for industries that produce solvents, synthetic fabrics, plastics, lubricants, and many, if not most, modern organic products.
Some of these products can also be produced from another input such as coal, but petroleum is generally the cheapest abundant source.