LIQUEFIED natural gas, or LNG, is natural gas that has been liquefied by reducing its temperature to about minus 160ºC.
LIQUEFIED natural gas, or LNG, is natural gas that has been liquefied by reducing its temperature to about minus 160ºC.
The liquefaction process increases the fuel density by a ratio of 600:1. In other words, LNG takes up 1/600th the volume of natural gas, making it feasible to transport over long distances without using pipelines.
Liquefaction also removes undesirable elements such as water, nitrogen and, critically, carbon dioxide, leaving a product that is nearly pure methane.
Gas fields with high CO2 content require special measures to deal with this by-product. The Gorgon project, for instance, plans to geosequester the CO2. About 4 million tonnes a year of CO2 will be pumped into a saline aquifer below Barrow Island.
In Western Australia, the natural gas is normally located in large reservoirs located under the seabed. The gas is extracted via large offshore platforms, like North Rankin, and transported to the liquefaction plant by pipeline.
In Queensland, the industry is seeking to exploit coal seam gas. This presents technical challenges that have not been addressed on a large scale.
For instance, an offshore project like Pluto requires the drilling of seven wells, whereas a CSG project will need about 1,500 wells.
In PNG, the gas is located in the highlands. Irrespective of the source, the liquefaction process is essentially the same.
The gas is transported to export markets in large refrigerated sea tankers, which deliver the LNG to regasification facilities. LNG is converted back into gas by a simple vaporisation process.
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