What You Need to Know
Natural Gas: A Cleaner Energy Source
Natural gas is a naturally-occurring mixture of methane and other hydrocarbon gases usually considered a fossil fuel. Up until recently, it was a relatively minor source of energy in the United States, but that has been changing. Recent efforts to promote natural gas as an energy source focus on its ability to burn cleanly. It emits less carbon dioxide and less nitrogen oxide than coal and oil, giving natural gas a smaller greenhouse gas footprint than those fuels. While it has long been recognized as a cleaner fuel than the more common fossil fuels of coal and oil, it has also been more difficult and more expensive to access. Unlike oil, it does not occur in large, still pools underground. Rather, the gas is trapped in numerous small pores in certain forms of rock.
Shale
These rocks are known as shale, a sedimentary rock formed under immense pressure late in the rock cycle. Shales of this sort underlie much of the United States. Most well-known, and prominently featured in debates about hydraulic fracturing, is the Marcellus Formation, an extremely thick shale layer which runs from New York as far south as Virginia and Kentucky. Because of this rock, natural gas is sometimes referred to as "shale gas".
For more information on shale:
For more information on shale:
Shale Formations
Natural gas companies are exploring possible drill sites at nearly every shale formation in the country. Natural gas exploration now comprises thousands of wells across the United States. Shale formations are extremely common, and any one of them are seen as a possible source of natural gas.
For more information on shale formations:
For more information on shale formations:
Hydraulic Fracturing
Because of the difficulty of extracting natural gas from these shale formations, normal drilling techniques designed for oil are not sufficient. Instead, a technique known as "hydraulic fracturing" has been developed by the energy industry as an efficient, cost-effective form of retrieving methane gas. Hydraulic fracturing involves drilling a well deep into the Earth and then drilling perpendicular to that well. Then, a potent mixture of chemicals and water are forced, under high pressure, into the well. This high-pressure mixture fractures the rock around the well, releasing the gas contained within which then escapes up to the surface to be captured and transported as fuel. A single well can be fracked up to 19 times before the end of its life. Wells typically produce their highest yield in the first year of life, though they can be exploited for up to forty years.
The chemicals used in the fracturing process are a mix of up to 750 different substances, many of which are known toxins, hazardous air pollutants, or carcinogens. The natural gas industry does not release the list of chemicals used in their activities, and many states provide legal protections for their secrecy.
For more information on hydraulic fracturing:
For more information on hydraulic fracturing:
Greenhouse Gases
The traditional fossil fuels of coal and oil emit large amounts of greenhouse gases, chiefly carbon dioxide and nitrogen oxide. These gases, when released into the atmosphere, trap heat and have a warming effect on the Earth. The large amounts of coal and oil burned in the United States on a daily basis contribute to this warming effect, making the possibility of a cleaner alternative fuel very appealing. In fact, a recent paper by the WorldWatch Institute cited EPA figures when it said, "the total GFGs emitted during the combustion of natural gas are 53.07 kg CO2e/MMBtu... and the total GHGs emitted during the combustion of coal are 95.13 kg CO2e/MMBtu." (link)
Uses of Natural Gas
Ride-On of Maryland's natural gas-fueled buses.
Natural gas is heavily promoted as a clean alternative fuel, and has been adopted by public transit systems in cities around the world. It is seen as a tool to decrease oil dependence, and is considered a "transition fuel" from oil to a cleaner future. Natural gas is commonly used for:
- vehicles
- small motors, such as lawn mowers
- heating and cooling systems
- electricity generation
- fertilizer production
- industrial manufacturing