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Oil is a liquid hydrocarbon, and a major source of energy as a vehicle fuel and in electricity production. It is also a raw ingredient in many other products, such as plastics, fertilisers, and consumer products, including pharmaceuticals and cosmetics.

The curse of oil
The curse of oil. Supplying the world's addiction to oil has destroyed much of Nigeria's natural habitat.

Oil, like methane and coal, is a fossil fuel, so-called because it consists of the remains of dead organisms, largely zooplankton and algae, which have been compressed and chemically changed by enormous pressures and temperatures for millions of years underground. All three fossil fuels are known to be major causes of global warming, since they introduce greenhouse gases, primarily CO2 and methane, into the atmosphere.

A major target, therefore, in combating climate change resulting from anthropogenic global warming is to reduce as much as possible the use of fossil fuels. Research and pilot projects have proven that this is possible, and can be even economically beneficial. For example, substituting renewable energy for fossil fuel sources will create far more employment. The only real hurdle to the transition to a cleaner economy are the vested interests of oil companies, and the intransigence of the political orders beholden to them. There are, however, signs that the pendulum is finally swinging towards concrete steps to wean the world off fossil fuels. The only question is will it be soon enough?

Chemical Structure of Oil


Petroleum [From Latin petra = rock; oleum = oil] refers to the black substance which is pumped from beneath the surface by drilling. In this 'crude' form, the oil is a mixture of hydrocarbons of various molecular weights.

Alkanes are non-cyclic chains with general formula $C_nH_{2n+2}$. For each carbon atom, there are four bonds: to the adjacent carbon atoms in the chain, and to two or three hydrogen atoms. Since the two end carbons have only one adjacent carbon, the end carbons are bonded to three hydrogens, otherwise the carbons within the chain have two carbon bonds and two hydrogen bonds. The number of hydrogens is therefore two times the carbon number plus two.

The number of carbons in the alkanes found in petroleum varies, but those which may be refined to petrol (gasoline) are 5 to 8 carbons: pentane ($C_5H_{12}$, hexane ($C_6H_{14}$, heptane ($C_7H_{16}$, and octane ($C_8H_{18}$. The heavier Alkanes (9 to 16 carbons) form heavier fuels (diesel, kerosen, jet fuel), and larger than 16 carbon molecules are refined to fuel oil and lubricating oil, and 25 or more carbons in a chain will form hydrocarbons used for paraffin wax, and 35 for asphalt.

Uses of Oil

Vehicle fuel (petrol, gasoline (Am.)), kerosene, asphalt, chemical reagents in the making of plastics and pharmaceuticals.

Oil Production

The easiest petroleum to extract comes up on its own, due to the pressure difference between its reservoir and the surface. A large percentage of available reserves of this type have already been depleted, so new fields require a system, such as hydraulic fracturing, to force the hydrocarbons out of rock strata, usually shale.

There has been a long debate about 'peak oil': a term referring to the moment in time when demand would permanently outstrip supply, because of dwindling reserves. Despite many false predictions, it has always been possible to find new reserves, or improved technologies have made inaccessible reserves viable, so that production can satisfy demand. The oil crises of the 1970s were the result of political upheavals, not shortage of viable oil fields. The spike in oil prices in 2004-6 was countered by new extraction techniques, primarily shale oil, and fracking for gas.

But, the combination of depletion of oil reserves, political chaos in the Middle East, and unprecedented political pressure to reduce CO2 emissions to avoid catastrophic climate change, the presumption of oil being the world's primary, cheapest energy source is being challenged.

Oil Economics

Traditionally, the unit for oil is the 'barrel'. This equates to 159 litres. In 2015, the world consumed 90 million barrels a day, an amount only slightly more than the 87 million barrels in 2000. The 30 billion barrels consumed each year prices the industry at around 2 trillion dollars (at $70 a barrel), making it the world's richest industry.

When the price of oil on the commodities markets varies, the profits of the oil companies vary directly. During the oil price boom in 2004-6, the price for a barrel of oil went as high as $150, doubling the profits of the oil companies. This had two effects, each working against the other: 1. the high profits meant reserves which had previously been economically unviable, because they were too expensive to extract, were now opened up. This led to oil exploration in remote areas like Alaska, and the environmentally destructive practice of fracking. 2. Industry and private use of oil fell because the price of oil made certain processes unviable, and people began to use alternatives, which previoulsy had been economically uncompetitive with oil.

Substitutes and Alternatives

Vehicle Fuel

Biofuels: Synthetic fuels have long been used for combustion engines. The USA has a corn grain biofuel programme in place, and Brazil has long used sugarcane as a vehicle fuel.

Hydrogen: although not a 'source' of energy, hydrogen produced by electrolysis, or chemically from alcohols, is a gas. However, it can be pressurised to a liquid, and used as a mobile fuel for vehicles. Hydrogen is probably too dangerous to use as a combustion fuel, but can be used in a chemical process in a fuel cell to generate electricity, to power an electric motor.

Research is underway into the feasibility of a 'hydrogen economy', to replace the current 'hydrocarbon economy'.

Electricity Production

Much has been made of the fact that natural gas (methane) is 'cleaner' than oil. 'Cleaner' is not 'clean', and gas is still a fossil fuel. In the intervening phase, till renewable energy can supply all the needs, it is proposed to use gas rather than oil, where possible, to reduce CO2 and other environmental problems, such as sulphur dioxide from sulphur impurities. However, gas supplies are not endless, and the supplying countries are politically not secure. Reliance on gas supplies, for example from Russia, is proving to be quite a liability for countries dependent on them, as it is quite a powerful political wildcard.

Coal is the other fossil alternative for electricity production. Coal generates 50% of the world's electricity. There are ways to make coal more efficient, such as combined cycle plants, and scrubbing the flue gases of pollutants, such as NOx and SOx. However, coal is still producing more CO2 per unit energy than the other fossil fuels. Little progress has been made towards CO2 capture and storage systems, mainly because the same vested interests lobbying for coal use do not want the economic costs involved.

The best possible replacement for oil in electricity production is not another fossil fuel but a renewable energy source. Hydropower has been used for over a century quite successfully, but is not without its own environmental issues. China plans to expand its hydropower capacity to meet its growing energy demands, but few other countries have much potential left to be tapped.

Another traditional energy source that could be done on a more industrial scale is biomass. This is a growing sector, and energy is reclaimed from agriculture, domestic refuse, including waste, and sustainable forestry.

Utilising the physical energy of wind, sun and water is the goal of much investment. These tend not to be suitable for large regional power plants, but can be quite effective on the small, privately operated level. Large-scale solar plants are being developed in places with high solar resources.

Content © Andrew Bone. All rights reserved. Created : December 3, 2015 Last updated :February 6, 2016

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