1) Impractical to transport -. Natural gas pipelines are economical, but are impractical across oceans. Many existing pipelines in North America are close to reaching their capacity prompting some politicians in colder climates to speak publicly of potential shortages.
2) Supply shortages/price increases -. Indigenous supply has not truly fallen -- but it has leveled off. Demand has risen, and there has also been a temporary decreases in production in the aftermath of Hurricanes Katrina and Rita. The worl’s supply is estimated to run out in 2085
3) Environmentally Harmful during extraction - Extraction of natural gas (or oil) leads to decrease in pressure in the reservoir. This in turn may lead to subsidence at ground level. Subsidence may affect ecosystems, waterways, sewer and water supply systems, foundations, etc.
4) Natural gas is explosive – Natural gas is lighter than air, and so tends to dissipate. But when natural gas is contained, such as within a house or in a tent, perhaps put over a house for fumigation, gas concentrations can reach explosive proportions and trigger very powerful blasts that can level houses, and even neighborhoods.
5) Harmful to air quality - dramatic worsening of indoor air quality due to sensitizing properties and other polluting effects of natural gas used for heating, cooking and operating appliances and equipment
6) High health risks to humans - The effects of the transmission and use of piped natural gas upon persons with environmentally induced illness/chemical sensitivity (2), asthma or allergies can be significant and extremely harmful. Similarly important is the potential impact in the development of new cases of illness and sensitivity, of asthma and other respiratory health problems and of all general illness involving compromised immune systems.

Natural gas is a gaseous fossil fuel consisting primarily of methane. It is found in oil fields and natural gas fields, as well as—in smaller quantities—in coal beds. When methane-rich gases are produced by the anaerobic decay of non-fossil organic material, these are referred to as biogas. Sources of biogas include swamps (swamp gas), marshes (marsh gas), landfills (landfill gas), Methane is a greenhouse gas which contributes to enhanced global warming when free in the atmosphere. However, methane in the atmosphere is oxidized, producing carbon dioxide and water, so that the greenhouse effect of released methane is relatively short-lived. Natural gas, when burned, produces much less carbon dioxide than more carboniferous fuel sources, such as coal.
Chemical composition
?methane (CH4 It may also contain heavier hydrocarbons such as ethane (C2H6), propane (C3H8) and butane (C4H10), as well as other sulfur containing gases.
Natural gas is tasteless and odorless. Before gas is distributed to end-users, it is odorized by adding thiols, to assist in leak detection. Natural gas is, in itself, harmless to the human body. Natural gas can kill, however if it is present in large concentrations -- and thus reduces the amount of oxygen available in the air, such that the amount of oxygen remaining is insufficient to sustain life.
Natural gas can also kill through an explosion. Natural gas is lighter than air, and so tends to dissipate. But when natural gas is contained, such as within a house or in a tent, perhaps put over a house for fumigation, gas concentrations can reach explosive proportions and trigger very powerful blasts that can level houses, and even neighborhoods.
Storage and transport
The major difficulty in the use of natural gas is transportation and storage. Natural gas pipelines are economical, but are impractical across oceans. Many existing pipelines in North America are close to reaching their capacity prompting some politicians in colder climates to speak publicly of potential shortages.
LNG carriers can be used to transport liquefied natural gas (LNG) across oceans, while tank trucks can carry liquefied or compressed natural gas (CNG) over shorter distances. They may transport natural gas directly to end-users or to distribution points, such as pipelines for further transport. These may have a higher cost requiring additional facilities for liquefaction or compression at the production point, and then gasification or decompression at end-use facitilies or into a pipeline.
In the past, the natural gas which was recovered in the course of recovering petroleum could not be profitably sold, and was simply burned at the oil field (known as flaring). This wasteful practice is now illegal in many countries, especially since it adds greenhouse gas pollution to the earth's atmosphere. Additionally, companies now recognize that value for the gas may be achieved with LNG, CNG, or other transportation methods to end-users in the future. The gas is now re-injected back into the formation for later recovery. This also assists oil pumping by keeping underground pressures higher.
Natural gas crisis