Natural gas
Natural gas, also known as methane, is found in coal seams, shales and various types of rocks, including sandstone. It is a reliable clean burning fuel.
Natural gas is a fossil fuel that has been derived from layers of buried animals and plants that have been trapped underground and exposed to very high temperatures and pressure for many thousands of years.
As the plants and animals originally obtained their energy from the sun, this energy remains trapped in the form of carbon in the natural gas. Natural gas is therefore a hydrocarbon gaseous mixture with the prominent gas being methane. Other gas in the mixture includes traces of hydrogen sulphide, nitrogen and carbon dioxide.
Natural gas formed in this way has many uses, some of these being:
- Clean electricity generation
- Cooking and heating Engine fuel
- Fertiliser manufacturing
- Glass making
- Steel mills
- Plastics
- Paint Fabrics
Natural gas can be found in underground rock formations or in conjunction with various hydrocarbon reservoirs such as methane clathrates, where it has become trapped within frozen water, when it can also be referred to as methane hydrate, or in coal seams, where it is known as coal seam gas, or CSG. Natural gas is also found in close association with crude oil reservoirs. Natural gas can therefore be created by two mechanisims, over long periods of time. One being thermogenic and the other biogenic:
Thermogenic gas
is found deep in the earth where buried organic material has been exposed to extremely high pressure and temperatures.
Biogenic gas
is created by what are known as methanogenic organisims in landfills, bogs, marshes and shallow sediments.
Before natural gas can become commercially useful, it must have various impurities, including water, removed so it can meet the specifications laid down for marketable natural gas. This means it has to be dehydrated and its by-products of pentrane, butane, propane and ethane separated as well as the higher molecule weight hydrocarbons such as hydrogen sulphide that often finishes up being pure sulpher. Other by-products can be carbon dioxide, water vapour, nitrogen and helium.
Liquified Natural Gas (LNG) is natural methane gas that has been chilled to a temperature of minus 161 degrees Celsius. At this temperature the gas becomes a liquid which means it takes up less space for transportation and storage. LNG takes up one six-hundredth of the space that it occupies as methane in its gaseous form.
At the present time there are three projects producing LNG in Australia, with another seven being developed. The fields currently producing LNG are:
Pluto
Pluto is in Western Australia and started production in April 2012
Darwin
The Northern Territory gas field that commenced production in 2006
The North West Shelf Venture
in Western Australia, that began production in 1989
The seven LNG schemes being developed include the following:
- Ichthys (WA)
- Wheatstone (WA)
- Prelude (WA)
- Gorgon (WA)
- Curtis LNG (QLD)
- Gladstone LNG (QLD)
- Australia Pacific LNG (QLD)
It has been estimated that there are more than 800 trillion cubic feet of gas resources in Australia. This amount of gas would be sufficient to power a city containing one million people for at least 16,000 years. Geologists remain confident that these currently known resources will be added to in the future.
The Basics and Fundamentals of LNG
