Similar to coal, crude oil, or petroleum, is formed from former living organisms that did not undergo biodegradation as a result of a lack of oxygen. Here large quantities of aquatic organisms accumulated and were buried at the bottom of lakes and oceans resulting in carbon rich rocks which are gradually exposed to increased heat and pressure causing the carbon deposits to decompose (Organic geochemistry – A retrospective of its first 70 years, Kvenvolden, Keith A. (2006)). The oil, once formed, can then migrate necessitating it become trapped in a porous rock that is sealed from above by an impermeable layer forming what is known as an oil reserve. Several unconventional sources of oil, such as the Canadian tar sands, use carbon sources that have not finished forming into oil.
Prior to the 1850’s oil was less widely used than coal however bamboo drilled wells in China are recorded in 347 AD and Babylonian records indicate it being used for lighting as much as 4000 years ago. However widespread use of petroleum was not adopted until it was learned how to refine kerosene from it in 1849 which resulted in a rapid expansion in the exploitation of the resource over the following decades as it was cheaper, easier and more reliable to produce than whale oil. Within 30 years, Nicholaus Otto had invented the first internal combustion engine. Nowadays refined petroleum has a vast array of uses with 97 million barrels being produced per day in late 2015 to meet demand. Its primary use is in transportation (63.7% in 2012), from cars to planes to moving the oil through pipelines. It is also a major source of power such as diesel generators (8.5%) as well as an important material in industrial production both as an aid to processing, e.g. a lubricant and solvent, and the raw material being converted, e.g. manufacture of plastic goods.
In New Zealand oil is currently central to the economy with 152 thousand barrels being consumed daily in 2013 with it being vital to transportation and producing 31% of our domestic electricity needs. Domestic production is not used for fuel production due to a lack of ability to refine it, with only 2% being processed at the Marsden Point refinery with most fuel for domestic use is imported. Historically leaded fuel was also a problem as the lead emissions caused neurological issues, however regulations introduced in 1996 in New Zealand banned leaded fuel.
Oil spills are one of the most visible form of oil pollution (air pollution being largely invisible). The spill itself is highly toxic with most organisms dying if exposed and soaking into the soil meaning toxins can remain for years if not thoroughly cleaned up. Being lighter than water, oil spills on water will spread out in a thin layer covering large areas. The use of dispersing agents on these spills makes them appear to clear up, however studies show this massively increases the toxicity as it makes them more readily absorbed and harder to see. New Zealand has experienced several such spills in its waters, such as the Rena in 2011 and the Don Wong in 1998 causing widespread contamination, and though these were cleaned up they caused significant damage in the meantime and highlighted the difficulty New Zealand would face in the event of a major spill.
Despite these pollution concerns oil looks set to remain a vital resource for years to come. Alternatives exist in many areas but are underdeveloped and cannot meet demand. Increased efficiency in its use, such as recycling plastics and driving less or in more fuel efficient vehicles, are more practical measures for reducing the use of oil in the short term.