Did you ever get hungry in the middle of the night with no food in the sight? Thank God for all the instant food one can make. But wait, there’s no hot water. Well, good thing the stove is always on hand. Just open the regulator of the gas tank, turn the knob on the stove. Presto! You already have fire to boil the water. After a few minutes, food is there to be consumed. But wait, cooking your food was made possible by a process that actually took millions of years.
As early as 1860, LPG has been used in both homes and industry. But where did it come from? Actually, the propane used in LPG is a by-product of the processing of natural gas and the refining of crude oil. How is it done?
First let’s take a look at how the processing of natural gas gives rise to LPG. Natural gas, when it is drawn from the earth, is actually a mixture of several hydrocarbon gases with methane constituting about 90% of it. The remaining 10% is actually half propane and half a combination of other gases such as butane and ethane. The propane is removed by absorption. However, the process does not end there. Distillation and treatment of the “extracted” propane must still be done to remove the lighter fractions and to remove hydrogen sulfide, carbon dioxide, and water. Out of all the propane in use, 59% come from this process. The other 41% comes from crude oil refining. The crude oil drawn from an oil well has yet to be refined, and the refining process produces not only different petroleum products but also results in the derivation of propane. Whether derived from natural gas or crude oil, propane is transported either through pipes or shipped to different locations using different modes of transport.
But what exactly is propane, you may ask. Propane, C3 H8 or CH3-CH2-CH3, is a hydrocarbon. The production of hydrocarbons actually started millions of years ago with the death of marine life which were subsequently buried under sediments of oceans. These remnants of marine life were somehow changed into crude oil by pressure and heat. Another major source of hydrocarbons could be coal, which probably came from decayed vegetation covered by soil and rock. Pressure and heat could have also changed the dead matter into coal. As discussed, natural gas could also be a source of hydrocarbons.
Hydrocarbons are insoluble in water, are less dense than water and are highly combustible. To achieve the greatest amount of heat through combustion, oxygen is needed to completely oxidize the hydrocarbon into carbon dioxide. One can tell that a hydrocarbon is completely oxidized if the result is a blue flame. A yellow flame results from incomplete combustion.
Moreover, propane is a member of the family of hydrocarbons known as alkanes. Of all the hydrocarbons, only alkane are said to be saturated hydrocarbons. Some other members of the alkane family are methane, ethane, butane and isobutane. An alkane is a hydrocarbon with the general molecular formula of Cn H2n+2 is a hydrocarbon that can never have an odd number of hydrogen atoms!
What is so special about alkanes? For one, they are compounds of very low toxicity. Moreover, they are colorless and odorless. These properties make it difficult to detect gas leaks if alkanes are used pure. It is for this reason that the addition of an organic compound of sulfur called mercaptan is added to give a distinct odor to the gas.
Not all alkanes are gases under ordinary temperature and pressure. But propane is a gas. After propane is extracted from crude oil or natural gas, it is pressurized and transformed into a liquid, thus the name liquefied propane gas. Some alkanes naturally occur as liquids. Others occur as oily or greasy liquids or waxy solids under normal pressure and temperature.
But how do we get energy from the LPG tank we have at home? First of all, once the propane is released from its tank, by opening the regulator, it reverts back to its gaseous state. Like all hydrocarbons, the propane gas consumes oxygen as it burns. Carbon dioxide and water are then produced together with the liberation of heat, which is what we use for cooking. Amazing though it may seem, this is the same combustion reaction that happens in a car when it burns gasoline!
Even with the advent of electrical stoves, it has been found that LPG offers more efficiency, is more convenient and, more importantly, less harmful to the environment. This doesn’t mean, however, that LPG has no adverse effects on the environment. Like all hydrocarbons, it produces carbon dioxide when burned. This contributes to the greenhouse effect. It is therefore imperative to find an energy source that is both useful to man and also beneficial to the environment.
By Pedrito Zabat Jr.
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