Fossil fuels.
Extraction of oil

Thermal Power Plant Cercs. Catalonia

Treatment of fossil fuels

Thermal energy and combustion.
Effects of thermodynamics

Gas Natural

Gas natural

Natural gas is a fossil fuel; a fossil energy source. It is a primary energy. This means that it can be obtained directly without transformation.

Other primary energy sources are:

  • Solar energy.
  • Charcoal.
  • Oil.

Natural gas began to be used from the 1960s as a preferred fuel. However, in some sectors, such as transport, oil continues to predominate.

It is also used as a raw material for many chemicals.

The construction of gas pipelines and the gas trade has led to major armed conflicts between different countries of the world in the 20th and 21st centuries.

Impact with the environment

It is the cleanest fossil energy in terms of waste and atmospheric emissions.

Direct effects

However, methane that is released into the atmosphere directly ( before it burns) is harmful to the environment. Since it can trap heat in the atmosphere, methane contributes to climate change. Methane is more effective at trapping heat than those other greenhouse gases.

Gas combustion also generates greenhouse gases such as nitrogen oxides or SO 2 sulfur dioxide . Therefore, it also contributes to global warming.

Acid rain

These gases in the atmosphere are also the cause of acid rain. Acid rain is the rain that forms when humidity in the air combines with nitrogen oxides, sulfur dioxide, or sulfur trioxide. In interaction with rainwater, these gases form nitric acid, sulfurous acid and sulfuric acid.

Eventually, these chemicals fall to the ground accompanying rainfall.

Indirect effects

The extraction and transportation of natural gas produces alterations or indirect damage to the environment. Some examples of these damages are:

  • Deforestation
  • Community displacement
  • Ecosystem destruction by the construction of gas pipelines to transport gas.

Gas exploration and extraction can be highly polluting and destructive, especially when reservoirs are at the bottom of the sea or in fragile environmental areas such as the Arctic, jungles or forests, among others.

Natural gas efficiency

In a thermal power plant, natural gas is the most efficient fuel. In the following table we show a comparison of values:

Generation of electricity in a thermal power plant
Gas natural50.7%

There is the possibility of using natural gas directly, without converting it into electricity. For example to obtain hot water. In this case, it has a much higher efficiency of 91.2%.

It is also cheaper and easier to store than coal and petroleum products.

Composition of natural gas

Natural gas is a lighter mixture of gases than water. It is not toxic. It is colorless. In principle it is odorless. It is made up of a mixture of hydrocarbons.

Its composition is as follows:

  • Methane (CH 4 ). Methane is a simple molecule made up of one carbon atom and four hydrogen atoms. The main component but also contains other light hydrocarbons in a much lower proportion.
  • Ethane (C 2 H 6 )
  • Propane (C 3 H 8 )
  • Butane (C 4 H 10 )
  • Pentane (C 5 H 12 ).

The chemical composition of natural gas varies significantly depending on its geographical and geological origin. The composition of this non-renewable energy source is usually associated with other molecules or elements such as carbon dioxide (CO 2 ), nitrogen (N 2 ) or rarely helium (He) that must be extracted when the gas is destined for uses. industrial and domestic.

In some deposits, for example that of Lacq (France), there may be traces of organic compounds of hydrogen sulfide (SH 2 ) and organic sulfur compounds (bitter finger gases).

What are hydrocarbons?

Hydrocarbons are molecules made of carbon and hydrogen atoms. Its calorific value varies greatly depending on its composition. The highest are between 8,500 and 10,200 kilocalories per cubic meter of gas.

How is natural gas produced?

Natural gas, like other fossil fuels, has been formed over millions of years by the anaerobic (oxygen-free) decomposition of large amounts of the remains of dead organisms deposited on what had then been the bottom of the sea or lake.

Over time, the organic matter mixed with mud was buried under heavy layers of sediment. The matter was subjected to high pressure and temperature, without air, for a long time. These conditions over time chemically altered it. Due to this decomposition, gases were evolved, especially natural gas.

How do you get energy from natural gas?

The internal energy of natural gas is contained in the carbon-hydrogen (CH) chemical bonds. This energy can be extracted by combustion.

Gas naturalCombustion is a thermodynamic reaction of exothermic oxidation. This reaction converts the chemical energy of the bonds into heat energy.

The combustion phenomenon generally generates a flame that generates light.

Where is it stored?

Natural gas is often found in underground bags. Near oil bags, which remains in a liquid state.

Both fossil fuels are found in rocks of sedimentary origin. Geological phenomena imprison them, giving rise to large underground pockets.

Natural gas can be presented in two ways:

  1. In dry form; totally gaseous.
  2. In wet form; mixed with longer hydrocarbons, which are easily separated as liquids by compression, cooling or absorption.

Dry natural gas is predominantly methane (60% -95%), but may contain appreciable amounts of ethane (5% -20%) depending on the region where it is found.

What is vehicular natural gas?

Vehicular natural gas is the gaseous by-product of oil that is used as fuel in millions of vehicles . It is an alternative to  gasoline or diesel.

Many times the term vehicular natural gas is used as a synonym for compressed natural gas, and in other cases the combination of vehicular compressed natural gas. However, this gas can also be liquefied natural gas, which is also used as vehicular fuel, although to a much lesser extent.

This type of gas is not the same gas for domestic use, since the gas for domestic use is a mixture of propane and butane. In this case, the vehicle is methane gas. The difference between the two is basically given by the humidity present in propane, and absent in methane.

Vehicular natural gas is generally compressed to 3,000 PSI. In this way a greater amount of volume can be stored in the cylinders. This means more autonomy to the vehicle.


Published: August 17, 2016
Last review: April 27, 2020