Carbohydrates have oxygen, hydrogen and carbon in their molecular structure. Carbohydrates are what we eat. Readily decomposed, won’t keep all that long. Dr. Atkins doesn’t like carbohydrates, but I do. Carbohydrates can be modified into liquid fuel, same process as making booze. In fact, ethanol is what gives booze its kick (and you a possibly serious hangover). Some nations don’t like what happens to their economy when they have import petroleum; they are rushing into ethanol production to get away from petroleum. That is creating a great deal of pressure on supplies of sugar and grain. Price of Pepsi may be going up a couple bucks a gallon, too. Hate to think what its gonna cost for dinner rolls..
Hydrocarbons have only hydrogen and carbon. Natural gas, petroleum and coal are hydrocarbons. We don’t eat that stuff. Very, very old stuff.

Petroleum, in Latin, means “rock oil”. Petroleum is a fossil fuel – it takes a very, very long time for petroleum to form.

It is possible to find internet sources who will assure you that my last statement is not true, that petroleum is not of organic origin. These will be perhaps the same people who will assure you that global warming is not occurring and that cigarettes are good for you. You are free to believe what you may. I state, in agreement with petroleum geologists, that petroleum is organic and is a fossil fuel.

Tar sands (renamed oil sands nowadays) and oil shale do not contain petroleum. They contain a substance called kerogen.

Petroleum and kerogen are not single substances but blends of substances. The various substances have common characteristics. They are hydrocarbons. The mix in kerogen is significantly different.

Petroleum and kerogen begin their cycle of existence in a shallow body of water with oxygen depleted depths. Organic material (plankton has been mentioned as a heavy contributor to the mix) dies and settle to the bottom where the lack of oxygen prevents final decomposition. It is ultimately swept into deeper waters, covered with sediments, and begins its slow transformation.

To become petroleum, it must be buried to a depth of at least 7,500 feet, but not more than 15,000 feet (approximately – there are different temperature gradients around the world). Under the increased temperatures encountered at those depths, and given a sufficient period of time – a very long time by human standards – the material becomes petroleum. Depths less than 7500 feet will result in kerogen. Depths greater than 15,000 feet will transform the material into natural gas.

Petroleum is fluid. It will migrate. It is lighter than rock. It will migrate upward to the surface given a chance, and be lost to us. To become an ‘oil field’ it must encounter a dome shaped layer of impervious rock, rather like an inverted saucer, to entrap it. That’s what petroleum geologists look for.

Natural gas: The most prevalent form is methane, the simplest hydrocarbon molecule. Four atoms of hydrogen are attached to one atom of carbon. Carbon has unique characteristics. One carbon atom can hook up to other carbon atoms in different configurations. Propane is three atoms of carbon hooked up to eight atoms of hydrogen. Butane is C4H10. A splendid visualization of these molecular structures can be found at www.lloydminsterheavyoil.com. You want a more complete education in organic chemistry, type ‘hydrocarbon’ in google and stand by.

In brief, hydrocarbon molecules containing one to four atoms of carbon are gaseous, from 5 to 15 will be in liquid form, fifteen atoms of carbon and above will be in solid form (asphalt and stuff like that). Hydrocarbons can be remarkably complex, with surprising numbers of atoms linked within the molecules. But more than 15 atoms of carbon indicates a solid.

When petroleum is brought to the surface, some of the molecules have low carbon counts – less than five – and those molecules separate out. That quantity of natural gas is commonly flared – burned — to dispose of it. There is usually not enough to warrant a gas pipeline to markets. Similarly, at plants where natural gas is prepared for marketing, liquids will settle out. These are termed ‘condensates’ and are part of the oil supply.

Crude oil is transmitted to a refinery, which will separate the composite into component parts – gasoline, jet fuel, asphalt, and so on. Gasoline itself if a compound substance – one component is called ‘octane’ which has a molecule containing eight carbon atoms . The amount of octane in gasoline is a measure of volatility. Some engines require a higher octane count.

Kerogen lacks the lighter molecules. You’ll find precious little octane in Kerogen. It is also a solid at ambient temperatures – the original term ‘tar sands’ was closer to the mark than ‘oil sands’. Kerogen won’t motivate your motor vehicle. To process kerogen into something resembling petroleum, a ton (give or take) of host material must be heated (oil shale must also be crushed beforehand) to render the kerogen into a state more like a fluid. Then the kerogen must be further processed to induce the chemical changes necessary to resemble petroleum. A whole great big bunch of natural gas is used in each of these processes, plus the diesel fuel necessary to dig the stuff up, transport it to the processing plant, and convert it into something more useful. If you subtract the energy required for production from the energy derived from the end product, you will have profited little. That’s why the darn stuff is so expensive.

Notice to anyone who feels he can come up with an answer to the difficulties – there’s a five billion dollar plant in southwestern Colorado constructed to process oil shale. It is vacant. It has been deserted by its owners. I betcha you could get it cheap. They couldn’t make it work. Have a go at if you feel confident.

What is often omitted from calculations – since so much energy is used, as the price of energy rises so does the cost of production and therefore the end price, in roughly the same proportion. Calculations that look at selling at tomorrow’s price but produced at today’s cost may look attractive (I see that form of calculation a lot) but can’t be expected to work. If you’re buying in you might want to check on that. Could be a gotcha.

Impurities occur in crude oil, and can be a considerable problem. You don’t want to be pushing sulphur through your engine. When crude is referred to as ‘sweet’ it refers to a low sulphur content. ‘Light’ refers to a mix that favors molecules containing lower amounts of carbon.

This has been a very brief glance at petroleum chemistry. I warmly recommend a visit to the www.lloydminsterheavyoil.com site for anyone even vaguely interested. They do a much better job of explanation than I. Keep reading, pal, and perhaps you can become chief chemist at a refinery

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