What is Natural Gas?

Natural gas, in itself, might be considered a very uninteresting gas – it is colorless, shapeless, and odorless in its pure form. Quite uninteresting – except that natural gas is combustible, and when burned it gives off a great deal of energy. Unlike other fossil fuels, however, natural gas is clean burning and emits lower levels of potentially harmful byproducts into the air. We require energy constantly, to heat our homes, cook our food, and generate our electricity. It is this need for energy that has elevated natural gas to such a level of importance in our society, and in our lives.

Natural gas is a combustible mixture of hydrocarbon gases. While natural gas is formed primarily of methane, it can also include ethane, propane, butane and pentane. The composition of natural gas can vary widely, but below is a chart outlining the typical makeup of natural gas before it is refined.

In its purest form, such as the natural gas that is delivered to your home, it is almost pure methane. Methane is a molecule made up of one carbon atom and four hydrogen atoms, and is referred to as CH₄.

Ethane, propane, and the other hydrocarbons commonly associated with natural gas have slightly different chemical formulas, which can be seen here.

Typical composition of natural gas:

Methane CH4 70-90%

Ethane C2H6 0-20%

Propane C3H8 0 – 5%

Butane C4H10 0 – 5%

Carbon Dioxide CO2 0-8%

Oxygen O2 0-0.2%

Nitrogen N2 0-5%

Hydrogen sulfide H2S 0-5%

Rare gases Ar, He, Ne, Xe trace

Natural gas is considered ‘dry’ when it is almost pure methane, having had most of the other commonly associated hydrocarbons removed. When other hydrocarbons are present, the natural gas is 'wet'.

Natural gas has many uses: it is used residentially, commercially, and industrially. Found in reservoirs underneath the earth, natural gas is commonly associated with oil deposits. Production companies search for evidence of these reservoirs by using sophisticated technology that helps to find the location of the natural gas, and drill wells in the earth where it is likely to be found. Once brought from underground, the natural gas is refined to remove impurities like water, other gases, sand, and other compounds. Some hydrocarbons are removed and sold separately, including propane and butane. Other impurities are also removed, like hydrogen sulfide (the refining of which can produce sulfur, which is then also sold separately). After refining, the clean natural gas is transmitted through a network of pipelines, thousands of miles of which exist in the United States alone. From these pipelines, natural gas is delivered to its point of use.

Natural gas can be measured in a number of different ways. As a gas, it can be measured by the volume it takes up at normal temperatures and pressures, commonly expressed in cubic feet. Production and distribution companies commonly measure natural gas in thousands of cubic feet (Mcf), millions of cubic feet (MMcf), or trillions of cubic feet (Tcf).

While measuring by volume is useful, natural gas can also be measured as a source of energy. Like other forms of energy, natural gas is commonly measured and expressed in British thermal units (Btu). One Btu is the amount of natural gas that will produce enough energy to heat one pound of water by one degree at normal pressure. To give an idea, one cubic foot of natural gas contains about 1,027 Btus. When natural gas is delivered to a residence, it is measured by the gas utility in 'therms' for billing purposes. A therm (a unit of heat equal to 1.055 056 × 108 joules) is equivalent to 100,000 Btu's, or just over 97 cubic feet, of natural gas.

8.4 Answer the questions on the text:

1) In what way is natural gas an uninteresting gas? How does natural gas differ from other fossil fuels? 2) What is natural gas? What is the composition of the typical natural gas? 3) What is the difference between the ‘dry’ and ‘wet’ natural gas? 4) Why is natural gas refined? 5) What happens to natural gas after refining? What happens to impurities like propane, butane and sulfur? 6) How do companies measure the volume of natural gas? 7) How is natural gas measured as a source of energy? 8) What is one Btu? 9) How does the gas utility measure natural gas? 10) Where do we use natural gas?

8.5 Give English equivalents to the following word-combinations from the text:

бесцветный, бесформенный и без запаха; в чистом виде, обычный состав (2), редкие газы, называться, считаться, почти чистый метан, признаки (наличия) коллектора, сложная технология, удалять примеси, отдельно, после очистки, перекачивать (транспортировать) по сети трубопроводов, доставлять до места использования; компании, занимающиеся добычей и распределением, источник энергии, нагретьодин фунт воды на один градус.

8.6 Match the words in list A with their equivalents in list B and translate them:

List A 1) combustible 2) to give off 3) makeup 4) commonly 5) to transmit

6) a great deal of 7) to elevate 8) to search for 9) to refine 10) odorless.

List B a) usually b) much/many c) to remove impurities d) inflammable e) to raise
f) without smell g) to emit h) to move i) composition j) to look for.

8.7 Choose the only correct variant to fill in the gaps:

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