Natural Gas

Natural Gas Natural gas is a gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, propane, butane, and pentane—heavier hydrocarbons removed prior to use as a consumer fuel —as well as carbon dioxide, nitrogen, helium and hydrogen sulfide. Fossil natural gas is found in oil fields (associated) either dissolved or isolated in natural gas fields (non-associated), and in coal beds (as coalbed methane). When methane-rich gases are produced by the anaerobic decay of non-fossil organic material (biomass), these are referred to as biogas (or natural biogas). Sources of biogas include swamps, marshes, and landfills (see landfill gas), as well as sewage sludge and manure by way of anaerobic digesters, in addition to enteric fermentation particularly in cattle. Uses of Natural Gas

Power generation Natural gas is a major source of electricity generation through the use of gas turbines and steam turbines. Particularly high efficiencies can be achieved through combining gas turbines with a steam turbine in combined cycle mode. Natural gas burns cleaner than other fossil fuels, such as oil and coal, and produces less carbon dioxide per unit energy released.

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

Natural gas vehicles Compressed natural gas (methane) is a cleaner alternative to other automobile fuels such as gasoline (petrol) and diesel. As of 2005, the countries with the largest number of natural gas vehicles were Argentina, Brazil, Pakistan, Italy, Iran, and the USA. 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.

Residential domestic use Natural gas is one of the cheapest forms of energy available to the residential consumer. In fact, natural gas has historically been much cheaper than electricity as a source of energy. The Department of Energy (DOE) estimates that in 2002, natural gas is the lowest cost conventional energy source available for residential use. According to the DOE natural gas costs less than 30 percent of the cost of electricity. Not only is natural gas cheap for the residential consumer, it also has a number of varied uses. The best known uses for natural gas around the home are natural gas heating and cooking. Cooking with a natural gas range or oven can provide many benefits, including easy temperature control, self ignition and self cleaning, as well as being approximately one-half the cost of cooking with an electric range. Many of the top chefs prefer natural gas ranges for their quick heating ability and temperature control. Gone are the days of temperamental natural gas ranges, the newer generations of natural gas ranges allow for some of the most efficient, economical, and versatile cooking appliances ever. Although natural gas has many uses, and can supply energy to a vast number of residential appliances, there are some energy requirements around the house which cannot be satisfied by natural gas. A television, or blender, or microwave, for instance, will likely never be powered directly by natural gas, but will instead require electricity. However, natural gas can still provide energy for these appliances at the home, by what is known as 'distributed generation'.

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

Aviation Russian aircraft manufacturer Tupolev is currently running a development program to produce LNG- and hydrogen-powered aircraft. The program has been running since the mid-1970s, and seeks to develop LNG and hydrogen variants of the Tu-204 and Tu-334 passenger aircraft, and also the Tu-330 cargo aircraft. It claims that at current market prices, an LNG-powered aircraft would cost 5,000 roubles (~ $218/ £112) less to operate per ton, roughly equivalent to 60%, with considerable reductions to carbon monoxide, hydrocarbon and nitrogen oxide emissions. The advantages of liquid methane as a jet engine fuel are that it has more specific energy than the standard kerosene mixes 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.

Environmental effects

Global warming Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil However, in absolute terms it does contribute substantially to global emissions, and this contribution is projected to grow. According to the IPCC Fourth Assessment Report (Working Group III Report, Chapter 4), in 2004 natural gas produced about 5,300 Mt/yr of CO2 emissions, while coal and oil produced 10,600 and 10,200 respectively (Figure 4.4); but by 2030, according to an updated version of the SRES B2 emissions scenario, natural gas would be the source of 11,000 Mt/yr, with coal and oil now 8,400 and 17,200 respectively. (Total global emissions for 2004 were estimated at over 27,200 Mt.) When drilled in the US, the C02 pumped out with the natural gas is released directly into the atmosphere. This amount of C02 is not counted with the release of the C02 when natural gas is burned Sources Natural gas Natural gas is commercially produced from oil fields and natural gas fields. Gas produced from oil wells is called casinghead gas or associated gas. The natural gas industry is producing gas from increasingly more challenging resource types: sour gas, tight gas, shale gas and coalbed methane. Town gas Town gas is a mixture of methane and other gases, mainly the highly toxic carbon monoxide, that can be used in a similar way to natural gas and can be produced by treating coal chemically. This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices. However, depending upon infrastructure considerations, it remains a future possibility.

Biogas Methanogenic archaea are responsible for all biological sources of methane, some in symbiotic relationships with other life forms, including termites, ruminants, and cultivated crops. Methane released directly into the atmosphere would be considered a pollutant, however, methane in the atmosphere is oxidised, producing carbon dioxide and water. Methane in the atmosphere has a half life of seven years, meaning that every seven years, half of the methane present is converted to carbon dioxide and water.

NATURAL GAS

SUBMITTED BY: LADY ROXANNE M. SERRANO BSA 4A