What is Natural Gas? Natural Gas Properties
Natural gas is a colourless and odourless fossil fuel consisting mainly of methane CH4, which is the simplest hydrocarbon. It is formed by the decomposition of prehistoric vegetable and animal matter, and trapped in porous rock formations beneath the surface of the earth. Other compounds of natural gas include ethane, propane, and butane.
Natural gas is lighter than air, and this fact enhances its safety. Unlike other fuels such as diesel, petrol or LPG, which are heavier than air, should a natural gas leak occur, the gas will readily dissipate into the atmosphere. This eliminates the risk of the fuel accumulating or pooling at ground level and causing a greater risk or hazard.
Natural gas is colourless and odourless when it is extracted from the earth, and an odorant is added for safety, before it is piped to consumers, as a ready means of leak detection. An average person can easily detect the smell of gas at a concentration as low as 1% by volume in air. That concentration is about 5 times lower than the level that will support combustion.
Natural gas will not explode in the presence of a flame until it reaches a very specific concentration in the air - below a certain level it is deemed too lean to burn and above a certain level it may be too rich to burn. Within a flammable range, the gas will ignite and may cause an explosion.
The flammable range is expressed by Lower Explosive Limit ("LEL") and Upper Explosive Limit ("UEL"). The LEL is the concentration of natural gas in the air below which the propagation of a flame will not occur on contact with an ignition source. The natural gas LEL is 5%. This means that, in most cases, the smell of gas would be detected well before combustion conditions are met. The UEL is the concentration of natural gas in the air above which the propagation of a flame will not occur on contact with an ignition source. The natural gas UEL is 15%.
Natural gas has no known toxic or chronic physiological effects (that is, it is not poisonous). Exposure to a moderate concentration may result in a headache or similar symptoms due to oxygen deprivation but it is likely that the smell would be detected well in advance of concentrations being high enough for this to occur.
It is an ideal fuel for many applications:
- Residential - cooking, heating and hot water
- Commercial – cooking, heating, drying and hot water
- Industrial - processing and manufacturing
- Power generation – in power station turbines and cogeneration plants
- Transport – as a fuel for vehicles such as trucks and buses