Natural+Gas

Natural gas is a fossil fuel and is classified as a naturally occurring hydrocarbon gas mixture. "Raw" natural gas contains ethane, methane, small hydrocarbons, and a varying amount of water vapor, carbon dioxide, hydrogen sulfide, and helium. The natural gas that enters your home is basically pure methane after the "raw" gas is processed. This refining also eliminates essentially all of the sulfur-containing compounds; making natural gas release practically no sulfur dioxide. This makes it a clean burning fuel source.

__Formation__ Natural gas is composed from the remains of plants and animals. As they decomposed, because they were exposed to intense heat and pressure, some of these remains were turned into gases.This is very similar to the process by which oil is created. The amounts of heat and pressure that the remains were exposed to determined if they would turn into oil or gas. As a result of this process, natural gas is buried deep inside the Earth.

__Extraction:__ In order to be able to use natural gas, we first must extract it. Once geologists locate a potential deposit of natural gas, a well is drilled. The natural gas is then pumped out and transported to be processed. Another method that is more controversial is called hydraulic fracturing (or "fracking").

__Processing and storage:__ Once the gas has been extracted, it is transported to a processing plant. This is usually done with an extensive pipeline system. Once the gas reaches the refinery, it is treated so that any by- products are removed. A chemical called mercaptan (or something similar) is added. This chemical is what gives natural its "rotten egg" smell. Pure natural gas is actually odorless, but the chemicals are added so that you can detect leaks.

After the gas is completely processed, it doesn't always go directly to the people who will use it. Demand for natural gas is much higher in the winter because many people use it to heat their homes. As a result, natural gas is often stored on underground reservoirs. These can include things like old coal or salt mines. When there is a demand for natural gas, it is released from underground and goes where it is needed.

__ Natural gas is used for... __ -heating homes -generating electricity -power vehicles

Additional links (very helpful when creating this page) [|The US Energy Information Agency's page on natural gas] [|The EIA's kids' page on natural gas] [|The American Petroleum Institute's page on natural gas] [|Pacific Gas and Electric's website]

CO2 emissions
Natural gas is often described as the cleanest fossil [|fuel], producing less carbon dioxide per [|joule] delivered than either coal or oil [|[22]] and far fewer pollutants than other hydrocarbon fuels[// [|citation needed] //]. However, in absolute terms, it does contribute substantially to global [|carbon 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 5.3 billion tons a year of CO2 emissions, while coal and oil produced 10.6 and 10.2 billion tons respectively (figure 4.4). According to an updated version of the [|SRES B2] [|emissions scenario], however, by the year 2030, natural gas would be the source of 11 billion tons a year, with coal and oil now 8.4 and 17.2 billion respectively because demand is increasing 1.9% a year. [|[38]] ( [|Total global emissions] for 2004 were estimated at over 27,200 million tons.) 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. Natural gas is composed mainly of methane, which has a [|radiative forcing] twenty times greater than carbon dioxide. Based on such composition, a ton of methane in the atmosphere traps as much radiation as 20 tons of carbon dioxide; however, it remains in the atmosphere for 8–40 times less time. Carbon dioxide still receives the lion's share of attention concerning greenhouse gases because it is released in much larger amounts. Still, it is inevitable when natural gas is used on a large scale that some of it will leak into the atmosphere. (Coal methane not captured by [|coal bed methane extraction] techniques is simply lost into the atmosphere. Current estimates by the EPA place global emissions of methane at 3 trillion cubic feet (85 km3) annually, [|[39]] or 3.2% of global production. [|[40]] Direct emissions of methane represented 14.3% of all global anthropogenic greenhouse gas emissions in 2004. [|[41]]

Use
In order to assist in detecting [|leaks], a minute amount of [|odorant] is added to the otherwise colorless and almost odorless gas used by consumers. The odor has been compared to the smell of rotten eggs, due to the added [|butyl mercaptan]. Sometimes a related compound, [|thiophane] may be used in the mixture. Situations in which an odorant that is added to natural gas can be detected by analytical instrumentation, but cannot be properly detected by an observer with a normal sense of smell, have occurred in the natural gas industry. This is caused by odor masking, when one odorant overpowers the sensation of another. As of 2011, the industry is conducting research on the causes of odor masking. [|[47]]

Explosions caused by natural [|gas leaks] occur a few times each year. Individual homes, small businesses and other structures are most frequently affected when an internal leak builds up gas inside the structure. Frequently, the blast will be enough to significantly damage a building but leave it standing. In these cases, the people inside tend to have minor to moderate injuries. Occasionally, the gas can collect in high enough quantities to cause a deadly explosion, disintegrating one or more buildings in the process. The gas usually dissipates readily outdoors, but can sometimes collect in dangerous quantities if flow rates are high enough. However, considering the tens of millions of structures that use the fuel, the individual risk of using natural gas is very low. Natural gas heating systems are a minor source of [|carbon monoxide] deaths in the United States. According to the US Consumer Product Safety Commission (2008), 56% of unintentional deaths from non-fire CO poisoning were associated with engine-driven tools like gas-powered generators and lawn mowers. Natural gas heating systems accounted for 4% of these deaths. Improvements in natural gas furnace designs have greatly reduced CO poisoning concerns. [|Detectors] are also available that warn of carbon monoxide and/or explosive gas (methane, propane, etc.).