What is Natural Gas?

Essential Energy

  • Natural gas is a colourless, odourless mixture of gases made up mostly of methane (CH4). Other gases that can form part of natural gas include small amounts of ethane (C2H6), propane (C3H8) and butane (C4H10).
  • Methane burns relatively cleanly to produce heat energy and the by-products of water and carbon dioxide. Inefficiencies in burning can produce small amounts of pollutants such as nitrogen oxides.
  • Natural gas is lighter than air. So if it leaks from a pipe or appliance, it won't sink and form dangerous pools of explosive gas but will disperse in the air.
  • In certain concentrations, natural gas can be explosive, so it should always be treated with care.
  • For safety reasons, an odour is added to the gas so that a person with a normal sense of smell can easily detect leakages.

A brief history of natural gas

  • As early as 2000 years ago, the Chinese piped natural gas into their homes through bamboo pipes for lighting purposes.
  • Prior to 1970, most of the gas used for cooking in Australian homes and by industry was produced from coal and oil at gasworks located nearby.
  • During the 1970s many gasworks closed down as natural gas was piped from gas fields, such as those in Bass Strait, to where it was needed.
  • As oil prices climbed and natural gas prices remained relatively stable, the use of gas in industry and homes accelerated. In the decade following the introduction of natural gas in Victoria (1970) gas sales increased ten-fold.
  • At the end of the 20th century, world reserves of natural gas were estimated at 113 trillion cubic metres (a trillion is a million million). This represented a 35 per cent increase from the 1979 estimate – mostly attributed to discoveries in (formerly) Soviet territories and the Middle East.
  • Today, natural gas is one of the world's most important fuel sources; in fact over 20 per cent of our energy usage is fueled by natural gas. Large amounts can be stored and safely transported over long distances in pipes, or as liquid in road tankers or large ships.

What is LPG?
LPG is Liquified Petroleum Gas and has these characteristics:

  • A non-toxic, non-corrosive, heavier-than-air hydrocarbon fuel containing one or more of the gases propane, butane and propylene.
  • Can be stored as a compact liquid under moderate pressure and burned as a dry gaseous vapour. (It expands to approximately 270 times its liquid volume when reverting to vapour).
  • Does not contain lead.
  • Is produced in refineries from oil using a process called fractionation.
  • Can be stripped from natural gas.

Where is gas found in Australia?

  • Australia is a relatively gas-rich country. Large gas-bearing basins have been identified throughout Australia with the largest reserves of gas in the Gippsland Basin in Victoria, the CooperBasin in central Australia, the Northwest Shelf region of Western Australia.
  • Current known and probable reserves are expected to supply Australia with gas until about 2050. Because gas exploration is a fairly recent event, itis expected that further exploration in the basins will lead to the discovery of much more natural gas. If new reserves are not discovered, we will need to take even greater measures to conserve our dwindling supplies and to use alternative forms of energy.

Natural gas and the environment

  • Natural gas is a non-renewable fuel source that took millions of years to produce in the earth's crust.
  • To make better use of the finite supply, we will need to develop more efficient household appliances and industrial processes.
  • Increased efficiency of natural gas use will reduce energy costs and reap benefits for the environment.
  • Natural gas is relatively clean burning and emits little sulphur and nitrogen oxide pollution into the atmosphere.
  • Natural gas itself can contribute to global warming if it leaks directly into the atmosphere. In fact, molecule-for-molecule, methane (the main component of natural gas) is several times more effective in trapping heat than CO2.

How we use natural gas

  • In our homes, over 60 per cent of gas is used for space heating, over 30 per cent for water heating and less than 10 per cent for cooking.
  • In the business sector, 90 per cent of gas is used forspace heating and 10 per cent for water heating. Almost all sectors of industry use gas, including the chemical, rubber, paper, metal, milk, plastics and vehicle industries.

New uses for natural gas
In the future, natural gas will have broader uses, including:

  • Air conditioning. Like the gas-powered refrigerators that are used in caravans, in the future, the air conditioning of buildings is possible using natural gas. This development means that buildings can use natural gas for heating in winter and cooling in summer.
  • Chemical feedstock. As petroleum becomes more expensive, natural gas will be used increasingly as a chemical feedstock to produce such things as plastics, medicines, paints and pesticides.
  • Cogeneration. Cogeneration is the combined production of heat energy and electricity from the same fuel source. Food processing, cleaning, washing and oil refining are examples of heat energy being used in commerce and industry. Instead of being wasted, this heat energy is put to use to drive a turbine used to produce electricity. Cogeneration is estimatedto save between 10 and 30 per cent of the fuel which would be required to produce the same amount of electricity and heat energy separately. A similar reduction in the production of carbon dioxide (CO2), a major greenhouse gas, can also be achieved.

Future sources of gas

  • Coal gasification. Research is improving the efficiency and reducing the costs of producing a substitute natural gas from coal. The economic viability of this process will depend on further reductions in production costs, which are currently higher than those of producing conventional natural gas.
  • Biogas. Biogas is produced when animal waste or other organic material decomposes in the absence of oxygen. This gas is usually made up of about 65 per cent methane - the main gas found in natural gas.
  • Hydrogen gas. Hydrogen is produced by splitting water (H2O) molecules by a process known as electrolysis which releases oxygen and hydrogen. When hydrogen is used as a fuel, the only by-products are water vapour and trace amounts of nitrogen oxides. Using hydrogen as a fuel in cars is an excellent way toreduce the 25,000 million tonnes of exhaust released into the atmosphere every year by petrol-burning cars. Advances in technology have made the production and use of hydrogen a real alternative to fossil fuels.

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