Introduction to Natural Gas2

   Properties of Natural Gas:

    Natural gas is colorless, odorless, tasteless, shapeless and lighter than air with a specific gravity of about 0.6-0.8. It is gaseous at any temperature over -161º C. When it is at its natural state, it is not possible to see or smell natural gas. For safety reasons, a chemical odorant that smells a little like rotten eggs, Mercaptan, is added to natural gas so that it can be smelled if there is a gas leak.

     Methane is highly flammable, burns easily and almost completely, while it emits very little air pollution. Natural gas is neither corrosive nor toxic, its ignition temperature is high, and it has a narrow flammability range, making it an inherently safe fossil fuel compared to other fuel sources. It is inflamed during a range of 5-15% by volume of gas in air. The self-ignition Temperature of natural gas is 537-540 Celsius degrees. In addition, because of its specific gravity of 0.60, lower than that of air (1.00), natural gas rises if escaping, thus dissipating from the site of
any leak. Due to economic and ecological advantages that it presents as well as its safety qualities (e.g. reduced flammable range), natural gas is an increasingly attractive source of energy in many countries. At present, natural gas is the second energy source after oil. According to Energy Information Administration, natural gas accounted for 23% of world energy production in 1999. It has excellent perspectives for future demand. Natural gas is considered the fossil fuel of this century, as petroleum was last century and coal two centuries ago.   

  

Uses of Natural Gas:   

   For hundreds of years, natural gas has been known as a very useful substance. The Chinese discovered a very long time ago that the energy in natural gas could be harnessed, and used to heat water. In the early days of the natural gas industry, the gas was mainly used to light streetlamps, and the occasional house. However, with much improved     distribution channels and technological advancements, natural gas is being used in ways never thought possible.

      Natural gas is used extensively in residential, commercial and industrial applications:-

· Electric Power generation:

    Natural gas is a major source of electricity generation through the use of gas turbines and steam turbines. Most grid peaking power plants and some off-grid engine-generators use natural gas.

· Domestic use:

    Including Natural gas dispensed from a simple stovetop can generate heat in excess of 2000°F (1093°C) making it a powerful domestic cooking and heating fuel. In much of the developed world it is supplied to homes via pipes where it is used for many purposes natural gas-powered ranges and ovens, natural gas-heated clothes dryers, heating/cooling, and central heating. Home or other building heating may include boilers, furnaces, and water heaters. Compressed natural gas (CNG) is used in rural homes without connections to piped-in public utility services, or with portable grills. Natural gas is also supplied by independent natural gas suppliers through Natural Gas Choice programs throughout the United States. However, due to CNG being less economical than LPG, LPG (propane) is the dominant source of rural gas.

· Transportation:

    CNG is a cleaner alternative to other automobile fuels such as gasoline (petrol) and diesel. As of 2008 there were 9.6 million natural gas vehicles worldwide. The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines. Gasoline/petrol vehicles converted to run on natural gas suffer because of the low compression ratio of their engines, resulting in a cropping of delivered power while running on natural gas (10%–15%). CNG-specific engines, however, use a higher compression ratio due to this fuel's higher octane number of 120–130.

· Fertilizers:

     Natural gas is a major feedstock for the production of ammonia, via the Haber process, for use in fertilizer production.

· Aviation:

   The advantages of liquid methane as a jet engine fuel are that it has more specific energy than the standard kerosene mixes do and that its low temperature can help cool the air which the engine compresses for greater volumetric efficiency, in effect replacing an intercooler. Alternatively, it can be used to lower the temperature of the exhaust.

· Hydrogen

    Natural gas can be used to produce hydrogen, with one common method being the hydrogen reformer. Hydrogen has many applications: it is a primary feedstock for the chemical industry, a hydrogenating agent, an, and the fuel source in hydrogen vehicles.

     In petrochemical  ethylene, propylene, and  butylene         

        Environmental effects:

CO2 emissions:

   Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil and far fewer pollutants than other hydrocarbon fuels. In addition, natural gas itself is a greenhouse gas more potent than carbon dioxide. Although natural gas is released into the atmosphere in much smaller quantities, methane is oxidized in the atmosphere, and hence natural gas affects the atmosphere for approximately 12 years, compared to CO2, which is already oxidized, and has effect for 100 to 500 years.

Other pollutants:

Natural gas produces far lower amounts of sulfur dioxide and nitrous oxides than any other hydrocarbon fuel. Carbon dioxide produced is 117,000 ppm vs. 208,000 for burning coal. Carbon monoxide produced is 40 ppm vs. 208 for burning coal Nitrogen oxides produced is 92 ppm vs. 457 for burning coal. Sulfur dioxide is 1 ppm vs. 2,591 for burning coal. Mercury is 0 vs. .016 for burning coal. Particulates are also a major contribution to global warming. Natural gas has 7ppm vs. coal's 2,744ppm.

Pollutant

Pollutant	Natural Gas	Oil	Coal
Carbon Dioxide	117,000	164,000	208,000
Carbon Monoxide	40	33	208
Nitrogen Oxides	92	448	457
Sulfur Dioxide	1	1,122	2,591
Particulates	7	84	2,744
Mercury	0.000	0.007	208,000

 

Fossil Fuel Emission Levels-(Pounds per Billion Btu of Energy Input).