Overview

Natural gas is commonly used to heat homes and power electric generators. However, the gas itself remains a mystery. What makes it so efficient? How is it formed and produced? We will take a closer look at the fuel itself and unravel the mystery of the gas that burns blue.

Natural Gas

In its impure form natural gas is mostly methane, but other hydrocarbons do exist. These hydrocarbons include pentane, ethane, propane, and butane with the compliment of some other trace elements. The hydrocarbons are what give natural gas its high combustion property and methane the clean burning property. When natural gas is refined to a gaseous state, the hydrocarbons and impurities are removed and methane is essentially burned. However, when natural gas is used as a liquid to fuel engines, the hydrocarbons are needed for a good combustion to occur. Thus, natural gas has become an important fuel source when used both ways.

Natural gas is measured by its use and as a gas. The cubic foot is the standard unit for measuring the gas under normal temperature and pressure. It has become useful for production companies, but very inefficient as a unit for energy. Thus, the unit of energy is the British thermal unit or the BTU. However, when natural gas is delivered to a home, it is measured in therms, which is equivalent to 100,000 BTUs .

Production

Natural gas can be formed in three ways: thermogenically, biogenic, and abiogenic. Thermorganically is the most common and the most widely accepted way natural gas is made. By this theory, it is made the same way oil is made except that it is compressed closer to the ground; thus, requiring lower temperatures. This way of producing natural gas is not prehistoric; in fact, it continues today relatively close to an abiogenic reaction. An abiogenic reaction is when hydrogen and carbon molecules found in the earth rise near the surface of the earth. As they rise, they interact with other minerals in the ground and a reaction occurs. As their resultant compounds rise to the surface, which are atmospheric gases, they may leave methane deposits if under high pressure. The third and final theory is biogenic. Microorganisms called methanagens produce methane. These organisms break down organic matter and produce methane, but most of it is lost in the atmosphere. However, some methane does get trapped in the ground, and is recoverable for later use. Landfills are an example of this.

Although natural gas is abundant, it is not always easy to get to. Specifically, natural gas is not easy to get to when it forms 15,000 thousand feet under the ground. These areas may include shale deposits, colabed mines, and geopressuired zones. However, this limitation is only dependent on the technological advancements of the methods being used. Thus, if the technology improved, the natural gas obtained from these places cannot be considered unconventional.

Once natural gas has been found, test are run to determine the most efficient recovery rate. These test are run so producers can avoid harming the environment and the formation. If the formation where the gas is found cannot provide enough pressure on it own, then a pump or lifting system is used. Once a pump has been set into place, it's only allowed to run part of a time, rather then constantly. This is done so the gas can accumulate in the well.

Advantages

Natural gas' largest advantage is it chemical composition; it is basically methane (CH₄). Because methane only has one carbon in its composition, it produces very low carbon emissions. With the other hydrocarbons only have the number of carbon molecules ranging from 1-4, when they burn; the same holds true. In addition, the blue flame that results from burning the flame is from the molecules completing a perfect combustion, because of their chemical structure.

Natural gas' second largest advantage is conveniency. The gas is pumped directly into the consumer home with a network that is as efficient as delivering electricity. This network cannot be easily damaged by weather or conditions. Secondly, natural gas is in abundance in the US, thus the need to import from foreign countries is minimal. Because of this abundance, natural gas is cheaper than oil to burn.

Disadvantages

Because of its composition, natural gas is readily combustible and thus explosions are not unheard of . As a precaution a substance, like ethyl mercaptan, is added to the gas to give it an odor when it leaks. However, when gas leaks and does build up in buildings or other structures, the structure can suffer light to moderate damage if ignited. Natural gas can be toxic, if the fields in which it is extracted are not treated. Lastly, the extraction of the gas can be harmful to the environment, if subsidence is created when it is extracted.

Disclaimer: Both photos courtesy of NGSA